This work was supported by the Lehigh University Start-up Package. We thank Dr. Walter Fast for providing the GST-PAD4 plasmid for protein expression.

1. PAD4 Transformação, expressão e purificação <ol><li> Para PAD4 Transformação, transformar o plasmídeo pGEX contendo PAD4 GST fusão em E. quimicamente competente Coli (células BL21 (DE3)), as células para a expressão de proteínas utilizando o seguinte procedimento. Prepare (cloreto de cálcio) quimicamente competentes E. Coli (células BL21 (DE3)), as células de acordo com protocolos padrão. <ol><li> Descongelar 50 ul de previamente preparada quimicamente competentes BL21 (DE3) células em gelo e misturar com 1 ul do plasmídeo pGEX contendo o gene PAD4 num tubo de cultura de 5 mL. Incubar a mistura em gelo durante 10 minutos, enquanto agitando a cada 2 min. </li><li> Calor chocar as células colocando a mistura em um banho de água a 42 C ° durante 40 seg. Colocar imediatamente a mistura de células-plasmídeo para trás em gelo durante 2 min para permitir que as células para recuperar. Adicionar 1 ml de caldo LB estéril à mistura e colocar em gelo durante 1 min. </li><li> Incubar o calor células chocados a 37 ° C, agitação a 250 rpm durante 1hr. Pipetar 75 ul das células transformadas numa placa de ágar resistente à ampicilina e incubar a 37 ° C durante 15 h. Placa armazenar a 4 ° C. </li></ol></li><li> PAD4 Expressão. <ol><li> Picareta 1 colónia de células BL21 (DE3) a partir da placa de ágar e ampicilina-se em 5 ml de LB contendo ampicilina 1x. Colocar na incubadora e agite O / N a 37 ° C. </li><li> Transferir os 5 ml de LB (kits) em 1 L de LB estéril contendo 1x tri-hidrato de ampicilina (PM 403,45 g / mol). Ponto de crescimento num incubador com agitação a 37 ° C. Monitorar a OD 600 do crescimento. Quando o crescimento atinge uma DO600 de 0,3, mova o crescimento em 16 ° C agitando incubadora. </li><li> Ao atingir uma DO600 de 0,6, induzir as células com 0,3 mM isopropylthiagalactoside (IPTG, MW 238,30 g / mol). Permitir que as células agitar por 15 horas a 16 ° C. </li><li> Células colheita por centrifugação a 4000 xg durante 20 min a 0 ° C. Decantar o sobrenadante e pellet loja a -80 ° C. </li></ol></li><li> PAD4 Purificação <ol><li> Re-suspender o sedimento contendo o PAD4 expressa em BL21 (DE3) células num tampão de NaCl 50 mM (PM 58,44 g / mol), 300 mM de NaH 2 PO 4 (PM 119,98 g / mol), 10 mM de imidazole (MW 68,077 g / mol), 0,1 mM de fluoreto de fenilmetilsulfonilo (PMSF, MW 174,94 g / mol) e 1 mM de ditiotreitol (DTT, 154,25 g / mol), pH = 8,0. </li><li> Lisar as células por sonicação durante 15 min a 4 ° C. Após sonicação, centrifugar o lisado celular a 20000 xg durante 20 min a 0 ° C. Deitar fora e salvar sobrenadante. Lote do sobrenadante com glutationa (GSH) esferas de agarose durante 30 minutos à TA. </li><li> Drenar o sobrenadante das esferas de GST / coluna por acção da gravidade. Lavar as pérolas com 4 x 25 ml de 1x PBS (solução salina tamponada com fosfato, pH = 8,0) à temperatura ambiente. </li><li> Eluir PAD4 com 2 x 10 ml de tampão de eluição, 50 mM de tris (hidroximetil) aminometano (Tris Base, MW 121,14 g / mol), 10 mM de glutationa (GSH, MW 307,32 g / mol), pH = 8,0. </li><li> Concentre PAD4 usando 100k MW corte-off tubos de centrífuga e centrifugar a 4000 xg durante 20 min a 4 ° C. Aliquota de proteína em 200 ul volumes de 1,0 ml em tubos de microcentrífuga e armazenar a -80 ° C. </li></ol></li></ol> 2. Preparar soluções estoque para amortecedores <ol><li> Pesam-se cloreto de sódio (NaCl, PM 58,44 g / mol) e preparar uma solução 2 M. Misturar a solução até que clara. </li><li> Pesar Tris (hidroximetil) aminometano (Tris Base, MW 121,14 g / mol) e preparar uma solução 2 M, pH = 8,0. Misturar a solução até que clara. </li><li> Pesam-se di-hidrato de cloreto de cálcio (CaCl 2 2H 2 O, MW 147,01 g / mol) e preparar uma solução 500 mM. Misturar a solução até que clara. </li><li> Pesar de Tris (2-carboxietil) fosfina (TCEP, MW 250,19 g / mol) e preparar uma solução 200 mM. Misturar a solução até clara e armazenar a -20 ° C. </li><li> Pesar ditiotreitol (DTT, MW 154,25 g / mol) e preparar uma solução 1 M. Misturar a solução até clara e armazenar a -20 ° C. </li><li> Prepararuma solução de 0,5% de Triton X-100. </li><li> Pesar o ácido etilenodiaminotetracético (EDTA, MW 292,24 g / mol) e preparar uma solução 100 mM. Misturar a solução até que clara. </li><li> Pesar Z- Arg-Arg-7- amido- metilcumarina cloridrato de 4- (ZRcoum, MW 621,69 g / mol) e preparar uma solução a 10 mM em sulfóxido de dimetilo (DMSO). </li></ol> 3. PAD4 Ensaio a 37 ° C <ol><li> De 10 ações ZRcoum mM, preparar uma solução de 125 mM de ZRcoum na água. Esta solução 125 uM ZRcoum será Solução A. </li><li> Preparar um tampão de NaCl a 62,5 mM, Tris 62,5 mM, 12,5 mM de CaCl2, 6,25 mM de DTT, e PAD4 5 uM (pH = 8,0). Este será Solução B. </li><li> Preparar um tampão de NaCl a 62,5 mM, Tris 62,5 mM, 12,5 mM de CaCl2, e 6,25 mM de DTT (pH = 8,0). Este será Solução C. </li><li> Pesar tripsina, cristalino (a partir de pâncreas bovino) e preparar um 10 mg / ml em 100 mM de EDTA. Misturar a solução até clara e armazenar a -20° C. Este será Solução D. </li><li> Obter uma placa de 96 poços e designar um número de poços para controlos (sem PAD4) e os poços de ensaio (+ PAD4). </li><li> Pipeta 160 mL de solução B para poços de teste e pipeta de 160 mL de solução de C em poços de controlo. Incubar durante 15 min a 37 ° C. </li><li> Pipetar 40 ul de solução A em todos os poços e incubar a 37 ° C durante 45 min. </li><li> Pipetar 10 ul de dH2O a metade dos poços de controlo e metade dos poços de teste. Para a outra metade dos poços de controlo e controlos de ensaio e pipetas 10 mL de solução de D. Incubar durante 10 min a 37 ° C. </li><li> Obter uma leitura de fluorescência em um leitor multimodal com um comprimento de onda de excitação de 345 nm e um comprimento de onda de emissão de 465 nm. </li></ol> 4. Ensaio PAD4 à TA <ol><li> De 10 ações ZRcoum mM, preparar uma solução de 50 mM de ZRcoum na água. Esta solução ZRcoum 50 uM será Solução A. </li><li> Preparar um tampão de Na 100 mMCl, 100 mM Tris, 20 mM de CaCl2, 2 mM de TCEP, 0,02% de Triton X-100, e 8 PAD4 uM (pH = 8,0). Este será Solução B. </li><li> Preparar um tampão de 100 mM de NaCl, 100 mM Tris, 20 mM de CaCl2, 2 mM de TCEP, 0,02% e Triton X-100 (pH = 8,0). Este será Solução C. </li><li> Pesar tripsina, cristalino (a partir de pâncreas bovino) e preparar um 10 mg / ml em 100 mM de EDTA. Misturar a solução até clara e armazenar a -20 ° C. Este será Solução D. </li><li> Obter uma placa de 384 poços e poços para designar controles (sem PAD4) e poços de teste (+ PAD4). </li><li> Pipetar 25 mL de solução B para poços de teste e pipeta de 25 mL de solução de C em poços de controlo. Permitir tampão com / sem PAD4 a incubar nos poços durante 20 min à TA. </li><li> Pipetar 25 ul de solução C em todas as cavidades e incubar durante 45 min à temperatura ambiente. </li><li> Pipetar 10 ul de dH2O a metade dos poços de controlo e metade dos poços de teste. Para a outra metade dos poços de controlo e controlos de ensaio, pipetae 10 ul de solução de D. Incubar à temperatura ambiente durante 10 min. </li><li> Obter uma leitura de fluorescência em um leitor multimodal com um comprimento de onda de excitação de 345 nm e um comprimento de onda de emissão de 465 nm. </li></ol> 5. PAD4 tempo do curso ensaios a 37 ° C e RT <ol><li> De 10 ações ZRcoum mM, preparar uma solução de 125 mM de ZRcoum na água. Esta solução 125 uM ZRcoum será Solução A. </li><li> Preparar um tampão de NaCl a 62,5 mM, Tris 62,5 mM, 12,5 mM de CaCl2, 6,25 mM de DTT, e PAD4 5 uM (pH = 8,0). Este será Solução B. </li><li> Pesar tripsina, cristalino (a partir de pâncreas bovino) e preparar um 10 mg / ml em 100 mM de EDTA. Misturar a solução até clara e armazenar a -20 ° C. Este será Solução C. </li><li> Obter duas placas de 96 poços e pipeta de 160 mL de solução B em # quantidade de poços (número de poços vai depender de quantos pontos de tempo). </li><li> Incubar uma placa de 96 poços, a 37 ° C. Incubar a outra placa de 96 cavidades, à TA. </li><li> Pipette 40 ul de solução A em todos os poços em ambas as placas de 96 poços e imediatamente pipeta 10 ul de solução C em t = 0 o mínimo de poços. Continue a adição de 10 ul de solução C em pontos de tempo específicos até que todos os poços foram temperada. </li><li> Obter uma leitura de fluorescência em um leitor multimodal com um comprimento de onda de excitação de 345 nm e um comprimento de onda de emissão de 465 nm. </li></ol> 6. Ensaio de Inibição PAD4 à TA <ol><li> De 10 ações ZRcoum mM, preparar uma solução 83 mM de ZRcoum na água. Esta solução ZRcoum 83 uM será Solução A. </li><li> Pesar Cl-amidina (MW 424,8 g / mol) e preparar uma solução stock de 100 uM. Este será Solução B. </li><li> Preparar um tampão de 100 mM de NaCl, 100 mM Tris, 20 mM de CaCl2, 2 mM de TCEP, 0,02% de Triton X-100, e 8 uM PAD4 (pH = 8,0). Este será Solução C. </li><li> Preparar um tampão de 100 mM de NaCl, 100 mM Tris, 20 mM de CaCl2, 2 mM de TCEP, 0,02% e Triton X-100 (pH = 8,0). Thé será Solution D. </li><li> Pesar tripsina, cristalino (a partir de pâncreas bovino) e preparar um 10 mg / ml em 100 mM de EDTA. Misturar a solução até clara e armazenar a -20 ° C. Este será Solução E. </li><li> Obter uma placa de 384 poços e poços para designar controles (sem PAD4), poços de teste (+ PAD4) e poços de inibição (PAD4 + Cl-amidina). </li><li> Pipetar 25 mL de solução C em poços de teste e pipeta de 25 mL de solução de D em poços de controlo. Permitir tampão com / sem PAD4 a incubar nos poços durante 20 min à TA. </li><li> Pipetar 10 ul de solução B em poços de inibição e incubar durante 20 min a RTe. </li><li> Pipetar 15 ul de solução A em todos os poços e incubar durante 45 min à temperatura ambiente. </li><li> Pipetar 10 mL de solução E para todos os poços. Incubar à temperatura ambiente durante 10 min. </li><li> Obter uma leitura de fluorescência em um leitor multimodal com um comprimento de onda de excitação de 345 nm e um comprimento de onda de emissão de 465 nm. </li></ol> 7. Ensaio Lisado celular brutoà TA <ol><li> Após a colheita de células PAD4 crescimento de 1 L, ressuspender as células em 10 ml de 50 mM Tris, 50 mM de NaCl, 0,1 mM de fluoreto de fenilmetilsulfonilo (PMSF, MW 174,94 g / mol) e 1 mM de ditiotreitol (DTT, 154,25 g / mol), pH = 8,0. </li><li> Lisar as células por sonicação durante 15 min a 4 ° C. Centrifuga-se o lisado celular a 20000 xg durante 20 min a 0 ° C. Concentra-se o sobrenadante claro até metade do volume por centrifugação a 4.000 rpm a 4 ° C utilizando 100k MW tubos de centrífuga de corte. </li><li> De 10 ações ZRcoum mM, preparar uma solução de 250 mM de ZRcoum na água. Esta solução 250 uM ZRcoum será Solução A. </li><li> Preparar um tampão de 100 mM de NaCl, 100 mM Tris, 20 mM de CaCl2, e TCEP 2 mM (pH = 8,0). Este será Solução B. </li><li> Pesar tripsina, cristalino (a partir de pâncreas bovino) e preparar um 10 mg / ml em 100 mM de EDTA. Misturar a solução até clara e armazenar a -20 ° C. Este será Solução C. </li><li> Obter um preto placa de 384 poços e designcomeu poços para controles (não lisado celular) e poços de teste (+ lisado celular). </li><li> Pipetar 100 mL de solução B para todos os poços e pipeta 60 mL de lisado de células nos poços de teste. Incubar durante 20 min à TA. </li><li> Pipetar 40 ul de solução A em todos os poços e incubar durante 45 min à temperatura ambiente. </li><li> Pipetar 10 ul de solução C a todos os poços. Incubar à temperatura ambiente durante 10 min. </li><li> Obter uma fluorescência leitura em leitor multimodal com um comprimento de onda de excitação de 345 nm e um comprimento de onda de emissão de 465 nm. </li></ol>

<ol><li>Jensen, O. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Interpreting+the+protein+language+using+proteomics%5BTitle%5D)+AND+%22Nat.+Rev.+Mol.+Cell+Biol%22%5BJournal%5D)">Interpreting the protein language using proteomics.</a> Nat. Rev. Mol. Cell Biol. 7, 391-403 (2006).</li>
<li>Sims, R. J. 3rd, Reinberg, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Is+there+a+code+embedded+in+proteins+that+is+based+on+post-translational+modifications%5BTitle%5D)+AND+%22Nat.+Rev.+Mol.+Cell+Biol%22%5BJournal%5D)">Is there a code embedded in proteins that is based on post-translational modifications.</a> Nat. Rev. Mol. Cell Biol. 9, 815-820 (2008).</li>
<li>Pandey, A., Mann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Proteomics+to+study+genes+and+genomes%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Proteomics to study genes and genomes.</a> Nature. 405, 837-846 (2000).</li>
<li>Berger, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+complex+language+of+chromatin+regulation+during+transcription%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">The complex language of chromatin regulation during transcription.</a> Nature. 447, 407-412 (2007).</li>
<li>Fischle, W., Wang, Y., Allis, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Binary+switches+and+modification+cassettes+in+histone+biology+and+beyond%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Binary switches and modification cassettes in histone biology and beyond.</a> Nature. 425, 475-479 (2003).</li>
<li>Taverna, S. D., Li, H., Ruthenburg, A. J., Allis, C. D., Patel, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((How+chromatin-binding+modules+interpret+histone+modifications%3A+lessons+from+professional+pocket+pickers%5BTitle%5D)+AND+%22Nat.+Struct.+Mol.+Biol%22%5BJournal%5D)">How chromatin-binding modules interpret histone modifications: lessons from professional pocket pickers.</a> Nat. Struct. Mol. Biol. 14, 1025-1040 (2007).</li>
<li>Seet, B. T., Dikic, I., Zhou, M. M., Pawson, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Reading+protein+modifications+with+interaction+domains%5BTitle%5D)+AND+%22Nat.+Rev.+Mol.+Cell+Biol%22%5BJournal%5D)">Reading protein modifications with interaction domains.</a> Nat. Rev. Mol. Cell Biol. 7, 473-483 (2006).</li>
<li>Strahl, B. D., Allis, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+language+of+covalent+histone+modifications%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">The language of covalent histone modifications.</a> Nature. 403, 41-45 (2000).</li>
<li>Vossenaar, E. R., Zendman, A. J., van Venrooij, W. J., Pruijn, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((PAD%2C+a+growing+family+of+citrullinating+enzymes%3A+genes%2C+features+and+involvement+in+disease%5BTitle%5D)+AND+%22Bioessays%22%5BJournal%5D)">PAD, a growing family of citrullinating enzymes: genes, features and involvement in disease.</a> Bioessays. 25, 1106-1118 (2003).</li>
<li>Gyorgy, B., Toth, E., Tarcsa, E., Falus, A., Buzas, E. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Citrullination%3A+a+posttranslational+modification+in+health+and+disease%5BTitle%5D)+AND+%22Int.+J.+Biochem.+Cell+Biol%22%5BJournal%5D)">Citrullination: a posttranslational modification in health and disease.</a> Int. J. Biochem. Cell Biol. 38, 1662-1677 (2006).</li>
<li>Nakashima, K., Hagiwara, T., Yamada, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Nuclear+localization+of+peptidylarginine+deiminase+V+and+histone+deimination+in+granulocytes%5BTitle%5D)+AND+%22J.+Biol.+Chem%22%5BJournal%5D)">Nuclear localization of peptidylarginine deiminase V and histone deimination in granulocytes.</a> J. Biol. Chem. 277, 49562-49568 (2002).</li>
<li>Hagiwara, T., Hidaka, Y., Yamada, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Deimination+of+histone+H2A+and+H4+at+arginine+3+in+HL-60+granulocytes%5BTitle%5D)+AND+%22Biochemistry%22%5BJournal%5D)">Deimination of histone H2A and H4 at arginine 3 in HL-60 granulocytes.</a> Biochemistry. 44, 5827-5834 (2005).</li>
<li>Kearney, P. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Kinetic+characterization+of+protein+arginine+deiminase+4%3A+a+transcriptional+corepressor+implicated+in+the+onset+and+progression+of+rheumatoid+arthritis%5BTitle%5D)+AND+%22Biochemistry%22%5BJournal%5D)">Kinetic characterization of protein arginine deiminase 4: a transcriptional corepressor implicated in the onset and progression of rheumatoid arthritis.</a> Biochemistry. 44, 10570-10582 (2005).</li>
<li>Christophorou, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Citrullination+regulates+pluripotency+and+histone+H1+binding+to+chromatin%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Citrullination regulates pluripotency and histone H1 binding to chromatin.</a> Nature. 507 (7490), 104-108 (2014).</li>
<li>Brinkmann, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Neutrophil+extracellular+traps+kill+bacteria%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Neutrophil extracellular traps kill bacteria.</a> Science. 303, 1532-1535 (2004).</li>
<li>Li, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((PAD4+is+essential+for+antibacterial+innate+immunity+mediated+by+neutrophil+extracellular+traps%5BTitle%5D)+AND+%22J.+Exp.+Med%22%5BJournal%5D)">PAD4 is essential for antibacterial innate immunity mediated by neutrophil extracellular traps.</a> J. Exp. Med. 207, 1853-1862 (2010).</li>
<li>Wang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Histone+hypercitrullination+mediates+chromatin+decondensation+and+neutrophil+extracellular+trap+formation%5BTitle%5D)+AND+%22J.+Cell.+Biol%22%5BJournal%5D)">Histone hypercitrullination mediates chromatin decondensation and neutrophil extracellular trap formation.</a> J. Cell. Biol. 184, 205-213 (2009).</li>
<li>Wang, S., Wang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Peptidylarginine+deiminases+in+citrullination%2C+gene+regulation%2C+health+and+pathogenesis%5BTitle%5D)+AND+%22Biochim.+Biophys.+Acta%22%5BJournal%5D)">Peptidylarginine deiminases in citrullination, gene regulation, health and pathogenesis.</a> Biochim. Biophys. Acta. 1829, 1126-1135 (2013).</li>
<li>Trouw, L. A., Mahler, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Closing+the+serological+gap%3A+promising+novel+biomarkers+for+the+early+diagnosis+of+rheumatoid+arthritis%5BTitle%5D)+AND+%22Autoimmun.+Rev%22%5BJournal%5D)">Closing the serological gap: promising novel biomarkers for the early diagnosis of rheumatoid arthritis.</a> Autoimmun. Rev. 12, 318-322 (2012).</li>
<li>Chang, X., Fang, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((PADI4+and+tumourigenesis%5BTitle%5D)+AND+%22Cancer+Cell+Int%22%5BJournal%5D)">PADI4 and tumourigenesis.</a> Cancer Cell Int. 10, 7(2010).</li>
<li>Wang, L., Chang, X., Yuan, G., Zhao, Y., Wang, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Expression+of+peptidylarginine+deiminase+type+4+in+ovarian+tumors%5BTitle%5D)+AND+%22Int.+J.+Biol.+Sci%22%5BJournal%5D)">Expression of peptidylarginine deiminase type 4 in ovarian tumors.</a> Int. J. Biol. Sci. 6, 454-464 (2010).</li>
<li>Chang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Investigating+the+pathogenic+role+of+PADI4+in+oesophageal+cancer%5BTitle%5D)+AND+%22Int.+J.+Biol.+Sci%22%5BJournal%5D)">Investigating the pathogenic role of PADI4 in oesophageal cancer.</a> Int. J. Biol. Sci. 7, 769-781 (2011).</li>
<li>Zhang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Genome-wide+analysis+reveals+PADI4+cooperates+with+Elk-1+to+activate+c-Fos+expression+in+breast+cancer+cells%5BTitle%5D)+AND+%22PLoS+Genet%22%5BJournal%5D)">Genome-wide analysis reveals PADI4 cooperates with Elk-1 to activate c-Fos expression in breast cancer cells.</a> PLoS Genet. 7, (2011).</li>
<li>Tanikawa, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Regulation+of+histone+modification+and+chromatin+structure+by+the+p53-PADI4+pathway%5BTitle%5D)+AND+%22Nat.+Commun%22%5BJournal%5D)">Regulation of histone modification and chromatin structure by the p53-PADI4 pathway.</a> Nat. Commun. 3, 676(2012).</li>
<li>Cui, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+induction+of+microRNA-16+in+colon+cancer+cells+by+protein+arginine+deiminase+inhibition+causes+a+p53-dependent+cell+cycle+arrest%5BTitle%5D)+AND+%22PLos+One%22%5BJournal%5D)">The induction of microRNA-16 in colon cancer cells by protein arginine deiminase inhibition causes a p53-dependent cell cycle arrest.</a> PLos One. 8, (2013).</li>
<li>Jones, J. E., Causey, C. P., Knuckley, B., Slack-Noyes, J. L., Thompson, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Protein+arginine+deiminase+4+%28PAD4%29%3A+Current+understanding+and+future+therapeutic+potential%5BTitle%5D)+AND+%22Curr.+Opin.+Drug+Discov.+Devel%22%5BJournal%5D)">Protein arginine deiminase 4 (PAD4): Current understanding and future therapeutic potential.</a> Curr. Opin. Drug Discov. Devel. 12, 616-627 (2009).</li>
<li>Li, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Regulation+of+p53+target+gene+expression+by+peptidylarginine+deiminase+4%5BTitle%5D)+AND+%22Mol.+Cell+Biol%22%5BJournal%5D)">Regulation of p53 target gene expression by peptidylarginine deiminase 4.</a> Mol. Cell Biol. 28, 4745-4758 (2008).</li>
<li>Wang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Anticancer+peptidylarginine+deiminase+%28PAD%29+inhibitors+regulate+the+autophagy+flux+and+the+mammalian+target+of+rapamycin+complex+1+activity%5BTitle%5D)+AND+%22J.+Biol.+Chem%22%5BJournal%5D)">Anticancer peptidylarginine deiminase (PAD) inhibitors regulate the autophagy flux and the mammalian target of rapamycin complex 1 activity.</a> J. Biol. Chem. 287, 25941-25953 (2012).</li>
<li>Slack, J. L., Causey, C. P., Thompson, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Protein+arginine+deiminase+4%3A+a+target+for+an+epigenetic+cancer+therapy%5BTitle%5D)+AND+%22Cell.+Mol.+Life+Sci%22%5BJournal%5D)">Protein arginine deiminase 4: a target for an epigenetic cancer therapy.</a> Cell. Mol. Life Sci. 68, 709-720 (2011).</li>
<li>Luo, Y., Knuckley, B., Lee, Y. H., Stallcup, M. R., Thompson, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+fluoroacetamidine-based+inactivator+of+protein+arginine+deiminase+4%3A+design%2C+synthesis%2C+and+in+vitro+and+in+vivo+evaluation%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">A fluoroacetamidine-based inactivator of protein arginine deiminase 4: design, synthesis, and in vitro and in vivo evaluation.</a> J. Am. Chem. Soc. 128, 1092-1093 (2006).</li>
<li>Knuckley, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Substrate+specificity+and+kinetic+studies+of+PADs%5BTitle%5D)+AND+%22Biochemistry%22%5BJournal%5D)">Substrate specificity and kinetic studies of PADs.</a> Biochemistry. 1, 4852-4863 (2010).</li>
<li>Knipp, M., Vasak, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+colorimetric+96-well+microtiter+plate+assay+for+the+determination+of+enzymatically+formed+citrulline%5BTitle%5D)+AND+%22Anal.+Biochem%22%5BJournal%5D)">A colorimetric 96-well microtiter plate assay for the determination of enzymatically formed citrulline.</a> Anal. Biochem. 286, 257-264 (2000).</li>
<li>Knuckley, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+fluopol-ABPP+HTS+assay+to+identify+PAD+inhibitors%5BTitle%5D)+AND+%22Chem.+Commun%22%5BJournal%5D)">A fluopol-ABPP HTS assay to identify PAD inhibitors.</a> Chem. Commun. 46, 7175-7177 (2010).</li>
<li>Bicker, K. L., Subramanian, V., Chumanevich, A. A., Hofseth, L. J., Thompson, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Seeing+citrulline%3A+development+of+a+phenylglyoxal-based+probe+to+visualize+protein+citrullination%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Seeing citrulline: development of a phenylglyoxal-based probe to visualize protein citrullination.</a> J. Am. Chem. Soc. 134, 17015-17018 (2012).</li>
<li>Wang, Q., Priestman, M. A., Lawrence, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Monitoring+of+protein+arginine+deiminase+activity+by+using+fluorescence+quenching%3A+multicolor+visualization+of+citrullination%5BTitle%5D)+AND+%22Angew.+Chem.+Int.+Ed.+Engl%22%5BJournal%5D)">Monitoring of protein arginine deiminase activity by using fluorescence quenching: multicolor visualization of citrullination.</a> Angew. Chem. Int. Ed. Engl. 52, 2323-2325 (2013).</li>
<li>Jones, J. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Synthesis+and+screening+of+a+haloacetamidine+containing+library+to+identify+PAD4+selective+inhibitors%5BTitle%5D)+AND+%22ACS+Chem.+Biol%22%5BJournal%5D)">Synthesis and screening of a haloacetamidine containing library to identify PAD4 selective inhibitors.</a> ACS Chem. Biol. 7, 160-165 (2012).</li>
<li>Dreyton, C. J., et al. Optimization and characterization of a pan protein arginine deiminase (PAD) inhibitor. , (2010).</li>
<li>Shimoyama, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Deimination+stabilizes+histone+H2A%2FH2B+dimers+as+revealed+by+electrospray+ionization+mass+spectrometry%5BTitle%5D)+AND+%22J.+Mass+Spectrom%22%5BJournal%5D)">Deimination stabilizes histone H2A/H2B dimers as revealed by electrospray ionization mass spectrometry.</a> J. Mass Spectrom. 45, 900-908 (2010).</li>
<li>Luo, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Inhibitors+and+inactivators+of+protein+arginine+deiminase+4%3A+functional+and+structural+characterization%5BTitle%5D)+AND+%22Biochemistry%22%5BJournal%5D)">Inhibitors and inactivators of protein arginine deiminase 4: functional and structural characterization.</a> Biochemistry. 45, 11727-11736 (2006).</li>
</ol>

The authors have nothing to disclose.

Herein, a fluorescence based assay was successfully developed that monitors the activity of PAD4. The assay has proven to be incredibly robust in a number of high-throughput conditions and is also compatible with whole cell lysates37.
The affinity between the histone proteins and the DNA strands surrounding it loosens due the neutralization of the positive charge on the arginine side chain upon citrullination. It was envisioned that the neutralization of the arginine side-chain coul...

Um grande número de proteínas de mamífero são fortemente modificado pela acção de enzimas após a biossíntese de proteínas pelo ribossoma. Estas modificações pós-translacionais (PTMs) pode aumentar significativamente a diversidade funcional do proteoma mudando o tamanho, carga, estrutura, e estado de oligomerização (entre outras características) de proteínas 1-3. Como resultado, a variação na estrutura da proteína podem conduzir a consequências fisiológicas, tais como a degradação das proteínas, a diferenciação celular, a sinalização, a modulação da expressão do gene, e interacções proteína-proteína. Enquanto essas modificações são predominantes em uma grande porcentagem de todas as proteínas humanas, o terminal termina em proteínas histonas passam por um número anormalmente elevado de modificações covalentes 4. Proteínas histona são uma família de proteínas estruturais que facilitam a condensação de ADN genómico. Modificações covalentes das caudas das histonas não estruturados são realizadas e regulado por uma series de enzimas que podem catalisar a modificação covalente de resíduos (escritores), inverter as mesmas modificações (borrachas), e distinguem entre as mudanças que estão sendo impressas para as caudas das histonas (leitores) 5-7. Na verdade, a maioria dos PTMs conhecidos pode ser observado dentro deste segmento curto da histona, incluindo a metilação, fosforilação, acetilação, sumoilação, ubiquitinação, e citrulinação 8. Citrulinação envolve a conversão de peptidil-arginina para o t ARN não codificado peptidil-citrulina (Figura 1A). As proteínas, responsáveis ​​por esta cadeia lateral de neutralização, são membros da DAP (p eptide um eiminase rginine d) a família de proteínas, todas as quais são enzimas dependentes de cálcio 9,10.. Até à data, cinco membros da família PAD foram descritos (PAD1, PAD2, PAD3, PAD4, e PAD6). Cada membro desta família parece alvejar proteínas celulares distintas e também exibe uniperfis de distribuição de tecido Que. PAD4 é o único membro desta família de proteínas conhecida por estar localizada dentro do núcleo através de uma sequência de localização nuclear 11. Deste modo, tem sido demonstrado que deiminate um número de alvos nucleares, incluindo cadeias laterais de arginina sobre as caudas N-terminais das histonas H2A arginina resíduo 3 (H2R3), H3 (H3R2, H3R17, e H3R26) e H4 (H4R3) 12, 13. Enquanto cada uma das isozimas PAD têm funções fisiológicas específicas e críticos, PAD4 tem recebido bastante mais atenção devido ao seu papel numa série de processos humanos em ambas as células doentes e saudáveis. Recentemente, PAD4 mostrou ser um membro da rede transcricional pluripotência 14. Ambos os níveis de expressão PAD4 e atividade mostraram-se elevados durante a reprogramação e estatais chão estados pluripotentes em camundongos. Ao controlar a regulação de genes de células-tronco, PAD4 pode reter um papel crucial na eficiência de reprogramação celular. PAD4 também tem sido implicado naformação de armadilhas extracelulares de neutrófilos, o qual após a ligação de agentes patogénicos possibilitar a sua recarga do sistema. O hypercitrullination de proteínas histona por PAD4 induz descondensação da cromatina, o que serve como o material de base para o encapsulamento de bactérias patogénicas por a armadilha extracelular, assim, afastar infecções bacterianas 15,16. Além disso, foi encontrado PAD4 a desempenhar um papel activo num número de doenças humanas. Foi previamente mostrado que a expressão aberrante de PAD4 está associada com o aparecimento e gravidade da artrite reumatóide, a doença de Alzheimer, doença de Parkinson, e esclerose múltipla 17. Na verdade, a presença de anticorpos anti-citrulinados proteína é um dos biomarcadores de diagnóstico e de prognóstico mais fiáveis ​​e definitivas 18 de artrite reumatóide. Do mesmo modo, a actividade desregulada PAD4 foi recentemente observado num número de cancros humanos incluindo ovário, mama, pulmão, umad cânceres de esôfago 19-22. A ligação entre PAD4 e cancro tem sido mostrado para ser mediada através do oncogene ELK1 ou através da proteína supressora de tumor p53 22,23 e trabalho anterior sugeriu que PAD4 poderia ser um alvo terapêutico anti-cancro da novela 17,24,25. Como prova do princípio do estudo, a depleção de PAD4 através shRNA na linha celular de cancro colo-rectal HCT116 foi revelado para ser suficiente para induzir a apoptose e paragem do ciclo celular 26. Um inibidor irreversível PAD4 recentemente desenvolvido conduziu a uma redução de setenta por cento da massa do tumor em ratos 27. Muito notavelmente, a inibição PAD4 apareceu para actuar como uma terapia-alvo que resultou na morte selectiva de células cancerígenas, enquanto poupando células não transformadas. O uso de pequenas moléculas para desligar a função de PAD4 pode vir a ser uma nova e poderosa estratégia para atingir as células cancerosas ou para aumentar quimioterápicos de câncer existentes 28. Infelizmente, a potenda inibidor reversível PAD4 tem ainda a ser descoberto. Uma série de inibidores covalentes foram desenvolvidos usando o / alça imidine flúor cloro que imita o substrato arginina 27,29,30 e provaram ser ferramentas práticas para a compreensão do papel da PAD4 em ambas as células estaduais saudáveis ​​e doentes. No entanto, estas moléculas inibem a todos os PADs activos com potência similar. Portanto, a necessidade de um ensaio fácil, que relata sobre a actividade de PAD4 é crucial. Até à data, PAD4 ensaios foram descritos que vincular a liberação de amônia a partir da reação de uma leitura colorimétrica 31, utilizar um análogo do substrato chloroamidine fluorescente etiquetado para teste de polarização fluorescente de 32, contam com a reação assistida por ácido entre glioxal e citrulina 33, e par a actividade PAD4 a um passo de fluorescência dequenching 34. Destes, apenas a estratégia haloacetamidine modificador covalente tem provado ser compatíveis com scre de alto rendimentoplataformas ening 32,35,36. Nós descrevemos um ensaio baseado fluorescência fácil, que mede de forma confiável a atividade de PAD4. O ensaio, que exibe uma forte relação de sinal-para-ruído, a velocidade de análise, e robustez de medição, tem o potencial para descobrir um verdadeiramente potente e selectivo inibidor PAD4.

<table><tbody><tr><td>LB Broth, Miller (LURIA-BERTANI)</td><td>Amresco</td><td>J106-2KG</td><td>&lt;a href=&quot;http://www.amresco-inc.com/&quot;&gt;http://www.amresco-inc.com&lt;/a&gt;</td></tr><tr><td>Ampicillin Trihydrate (Off-white Powder), Fisher BioReagents</td><td>Fisher Scientific</td><td>BP902-25&amp;nbsp;</td><td>&lt;a href=&quot;http://www.fishersci.com/&quot;&gt;http://www.fishersci.com&lt;/a&gt;</td></tr><tr><td>Isopropylthiagalactonse (IPTG)</td><td>Life Technogolies</td><td>15529-019</td><td>&lt;a href=&quot;http://www.lifetechnologies.com/&quot;&gt;http://www.lifetechnologies.com&lt;/a&gt;</td></tr><tr><td>All Buffer Salts&amp;nbsp;</td><td>Fisher Scientific</td><td></td><td>Can purchase from Fisher Scieintifc; VWR; Acros; Sigma-Aldrich; etc.</td></tr><tr><td>Protino Glutathione (GSH) agarose&amp;nbsp;</td><td>Machery-Nagel</td><td>745500.10</td><td>Store at 4 &amp;deg;C; http://www.mn-net.com/</td></tr><tr><td>Chloroamidine&amp;nbsp;</td><td>Cayman Chemical&amp;nbsp;</td><td>10599</td><td>Store at -20 &amp;deg;C; https://www.caymanchem.com/app/template/Home.vm</td></tr><tr><td>Triton X-100</td><td>Sigma Aldrich</td><td>X100-100ML</td><td>&lt;a href=&quot;http://www.sigmaaldrich.com/&quot;&gt;www.sigmaaldrich.com&lt;/a&gt;</td></tr><tr><td>Corning/Nunclon MicroWell plates (96 and 384)</td><td></td><td></td><td>Purchase from Corning; Sigma-Aldrich</td></tr><tr><td>Tecan Infinite 200 / Tecan i-control microplate reader software</td><td></td><td></td><td>&lt;a href=&quot;http://www.tecan.com/&quot;&gt;www.tecan.com&lt;/a&gt;</td></tr><tr><td>Europium Ex. 340/40 Em. 475/15 filter</td><td></td><td></td><td>&lt;a href=&quot;http://www.perkinelmer.com/&quot;&gt;http://www.perkinelmer.com&lt;/a&gt;</td></tr></tbody></table>

fluorescence-based monitoring of pad4 activity via a pro-fluorescence substrate analog

Post-translational modifications may lead to altered protein functional states by increasing the covalent variations on the side chains of many protein substrates. The histone tails represent one of the most heavily modified stretches within all human proteins. Peptidyl-arginine deiminase 4 (PAD4) has been shown to convert arginine residues into the non-genetically encoded citrulline residue. Few assays described to date have been operationally facile with satisfactory sensitivity. Thus, the lack of adequate assays has likely contributed to the absence of potent non-covalent PAD4 inhibitors. Herein a novel fluorescence-based assay that allows for the monitoring of PAD4 activity is described. A pro-fluorescent substrate analog was designed to link PAD4 enzymatic activity to fluorescence liberation upon the addition of the protease trypsin. It was shown that the assay is compatible with high-throughput screening conditions and has a strong signal-to-noise ratio. Furthermore, the assay can also be performed with crude cell lysates containing over-expressed PAD4.

Inicialmente, foi demonstrado que ZRcoum pode informar sobre a actividade de PAD4 num formato de placa de 96 poços. Os poços foram incubados com o substrato ZRcoum e na presença / ausência de PAD4. Após um período de incubação de 45 min a 37 ° C, a fluorescência foi medida com um 340/40 - 475/15 nm filtro (Figura 2A). Como esperado, os níveis permaneceram baixos de fluorescência como o fluoróforo dentro ZRcoum (ou a citrulina ZRcoum...

Watch this Scientific Journal Video about Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog at JoVE.com

Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog

PAD4 is an enzyme responsible for the conversion of peptidyl-arginine to peptidyl-citrulline. Dysregulation of PAD4 has been implicated in a number of human diseases. A facile and high-throughput compatible fluorescence based PAD4 assay is described.

Monitoramento baseado em fluorescência de PAD4 Atividade através de um substrato Analog Pro-fluorescência

Post-translational modifications may lead to altered protein functional states by increasing the covalent variations on the side chains of many protein ...

fluorescence-based-monitoring-pad4-activity-via-pro-fluorescence

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

9.9K visualizações.  Lehigh University. PAD4 is an enzyme responsible for the conversion of peptidyl-arginine to peptidyl-citrulline. Dysregulation of PAD4 has been implicated in a number of human diseases. A facile and high-throughput compatible fluorescence based PAD4 assay is described.

Vídeo: Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog

Fluorescence detection methods for microfluidic droplet platforms

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that accompany system miniaturisation. Advantages include the ability to efficiently process nano- to femoto- liter volumes of sample, facile integration of functional components, an intrinsic predisposition towards large-scale multiplexing, enhanced analytical throughput, improved control and reduced instrumental footprints.1
In recent years much interest has focussed on the development of droplet-based (or segmented flow) microfluidic systems and their potential as platforms in high-throughput experimentation.2-4 Here water-in-oil emulsions are made to spontaneously form in microfluidic channels as a result of capillary instabilities between the two immiscible phases. Importantly, microdroplets of precisely defined volumes and compositions can be generated at frequencies of several kHz. Furthermore, by encapsulating reagents of interest within isolated compartments separated by a continuous immiscible phase, both sample cross-talk and dispersion (diffusion- and Taylor-based) can be eliminated, which leads to minimal cross-contamination and the ability to time analytical processes with great accuracy. Additionally, since there is no contact between the contents of the droplets and the channel walls (which are wetted by the continuous phase) absorption and loss of reagents on the channel walls is prevented.
Once droplets of this kind have been generated and processed, it is necessary to extract the required analytical information. In this respect the detection method of choice should be rapid, provide high-sensitivity and low limits of detection, be applicable to a range of molecular species, be non-destructive and be able to be integrated with microfluidic devices in a facile manner. To address this need we have developed a suite of experimental tools and protocols that enable the extraction of large amounts of photophysical information from small-volume environments, and are applicable to the analysis of a wide range of physical, chemical and biological parameters. Herein two examples of these methods are presented and applied to the detection of single cells and the mapping of mixing processes inside picoliter-volume droplets. We report the entire experimental process including microfluidic chip fabrication, the optical setup and the process of droplet generation and detection.

Droplet-based microfluidic platforms are promising candidates for high throughput experimentation since they are able to generate picoliter, self-compartmentalized vessels inexpensively at kHz rates. Through integration with fast, sensitive and high resolution fluorescence spectroscopic methods, the large amounts of information generated within these systems can be efficiently extracted, harnessed and utilized.

Métodos de detecção de fluorescência para as plataformas de gotículas microfluídicos

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that ...

Bioengenharia

An Optimized Single-Molecule Pull-Down Assay for Quantification of Protein Phosphorylation

Phosphorylation is a necessary posttranslational modification that regulates protein function and directs cell signaling outcomes. Current methods to measure protein phosphorylation cannot preserve the heterogeneity in phosphorylation across individual proteins. The single-molecule pull-down (SiMPull) assay was developed to investigate the composition of macromolecular complexes via immunoprecipitation of proteins on a glass coverslip followed by single-molecule imaging. The current technique is an adaptation of SiMPull that provides robust quantification of the phosphorylation state of full-length membrane receptors at the single-molecule level. Imaging thousands of individual receptors in this way allows for quantifying protein phosphorylation patterns. The present protocol details the optimized SiMPull procedure, from sample preparation to imaging. Optimization of glass preparation and antibody fixation protocols further enhances data quality. The current protocol provides code for the single-molecule data analysis that calculates the fraction of receptors phosphorylated within a sample. While this work focuses on phosphorylation of the epidermal growth factor receptor (EGFR), the protocol can be generalized to other membrane receptors and cytosolic signaling molecules.

The present protocol describes sample preparation and data analysis to quantify protein phosphorylation using an improved single-molecule pull-down (SiMPull) assay.

Um ensaio de recuo de molécula única otimizado para quantificação da fosforilação de proteínas

Phosphorylation is a necessary posttranslational modification that regulates protein function and directs cell signaling outcomes. Current methods to ...

Bioquímica

Análise de cAMP com cADDis: Triagem de célula única a alta taxa de transferência

Real-Time cAMP Dynamics in Live Cells Using the Fluorescent cAMP Difference Detector In Situ

cAMP Difference Detector In Situ (cADDis) is a novel biosensor that allows for the continuous measurement of cAMP levels in living cells. The biosensor is created from a circularly permuted fluorescent protein linked to the hinge region of Epac2. This creates a single fluorophore biosensor that displays either increased or decreased fluorescence upon binding of cAMP. The biosensor exists in red and green upward versions, as well as green downward versions, and several red and green versions targeted to subcellular locations. To illustrate the effectiveness of the biosensor, the green downward version, which decreases in fluorescence upon cAMP binding, was used. Two protocols using this sensor are demonstrated: one utilizing a 96-well plate reading spectrophotometer&#160;compatible with high-throughput screening and another utilizing single-cell imaging on a fluorescent microscope. On the plate reader, HEK-293 cells cultured in 96-well plates were stimulated with 10 &#181;M forskolin or 10 nM isoproterenol, which induced rapid and large decreases in fluorescence in the green downward version. The biosensor was used to measure cAMP levels in individual human airway smooth muscle (HASM) cells monitored under a fluorescent microscope. The green downward biosensor displayed similar responses to populations of cells when stimulated with forskolin or isoproterenol. This single-cell assay allows visualization of the biosensor location at 20x and 40x magnification. Thus, this cAMP biosensor is sensitive and flexible, allowing real-time measurement of cAMP in both immortalized and primary cells, and with single cells or populations of cells. These attributes make cADDis a valuable tool for studying cAMP signaling dynamics in living cells.

Autor em destaque: Avançando na detecção de cAMP em tempo real em células usando o biossensor cADDis

The protocol presented in this study illustrates the effectiveness of the cAMP Difference Detector In Situ in measuring cAMP through two methods. One method utilizes a 96-well plate reading spectrophotometer with HEK-293 cells. The other method demonstrates individual HASM cells under a fluorescent microscope.

Dinâmica de cAMP em tempo real em células vivas usando o detector de diferença de cAMP fluorescente in situ

cAMP Difference Detector In Situ (cADDis) is a novel biosensor that allows for the continuous measurement of cAMP levels in living cells. The biosensor is ...

Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling

Two electrode voltage clamp electrophysiology (TEVC) is a powerful tool to investigate the mechanism of ion transport1 for a wide variety of membrane proteins including ion channels2, ion pumps3, and transporters4. Recent developments have combined site-specific fluorophore labeling alongside TEVC to 
concurrently examine the conformational dynamics at specific residues and function of these proteins on the surface of single cells.
We will describe a method to study the conformational dynamics of membrane proteins by simultaneously monitoring fluorescence and current changes using voltage-clamp fluorometry. This approach can be used to examine the molecular motion of membrane proteins site-specifically following cysteine replacement and site-directed fluorophore labeling5,6. Furthermore, this method provides an approach to determine distance constraints between specific residues7,8. 
This is achieved by selectively attaching donor and acceptor fluorophores to two mutated cysteine residues of interest.
In brief, these experiments are performed following functional expression of the desired protein on the surface of Xenopus leavis oocytes. The large surface area of these oocytes enables facile functional measurements and a robust fluorescence signal5. It is also possible to readily change the extracellular conditions such as pH, ligand or cations/anions, which can provide further information on the mechanism of membrane proteins4. Finally, recent developments 
have also enabled the manipulation of select internal ions following co-expression with a second protein9.
Our protocol is described in multiple parts. First, cysteine scanning mutagenesis proceeded by fluorophore labeling is completed at residues located at the interface of the transmembrane and extracellular domains. Subsequent experiments are designed to identify residues which demonstrate large changes in fluorescence intensity (&lt;5%)3 upon a conformational change of the protein. Second, these changes in fluorescence intensity are compared to the kinetic parameters of 
the membrane protein in order to correlate the conformational dynamics to the function of the protein10. This enables a rigorous biophysical analysis of the molecular motion of the target protein. Lastly, two residues of the holoenzyme can be labeled with a donor and acceptor fluorophore in order to determine distance constraints using donor photodestruction methods. It is also possible to monitor the relative movement of protein subunits following labeling with a donor and acceptor fluorophore.

Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling

We will describe a method which measures the kinetics of ion transport of membrane proteins alongside site-specific analysis of conformational changes using fluorescence on single cells. This technique is adaptable to ion channels, transporters and ion pumps and can be utilized to determine distance constraints between protein subunits.

Examinando o Dynamics Conformacional de Proteínas de Membrana In situ Com Labeling-Site dirigido Fluorescência

Two electrode voltage clamp electrophysiology (TEVC) is a powerful tool to investigate the mechanism of ion transport1 for a wide variety of membrane ...

Biologia

Monitoring Kinase and Phosphatase Activities Through the Cell Cycle by Ratiometric FRET

F&ouml;rster resonance energy transfer (FRET)-based reporters1 allow the assessment of endogenous kinase and phosphatase activities in living cells. Such probes typically consist of variants of CFP and YFP, intervened by a phosphorylatable sequence and a phospho-binding domain. Upon phosphorylation, the probe changes conformation, which results in a change of the distance or orientation between CFP and YFP, leading to a change in FRET efficiency (Fig 1). Several probes have been published during the last decade, monitoring the activity balance of multiple kinases and phosphatases, including reporters of PKA2, PKB3, PKC4, PKD5, ERK6, JNK7, Cdk18, Aurora B9 and Plk19. Given the modular design, additional probes are likely to emerge in the near future10. 
Progression through the cell cycle is affected by stress signaling pathways 11. Notably, the cell cycle is regulated differently during unperturbed growth compared to when cells are recovering from stress12.Time-lapse imaging of cells through the cell cycle therefore requires particular caution. This becomes a problem particularly when employing ratiometric imaging, since two images with a high signal to noise ratio are required to correctly interpret the results. Ratiometric FRET imaging of cell cycle dependent changes in kinase and phosphatase activities has predominately been restricted to sub-sections of the cell cycle8,9,13,14.
Here, we discuss a method to monitor FRET-based probes using ratiometric imaging throughout the human cell cycle. The method relies on equipment that is available to many researchers in life sciences and does not require expert knowledge of microscopy or image processing.

FRET-based reporters are increasingly used to monitor kinase and phosphatase activities in live cells. Here we describe a method on how to use FRET-based reporters to assess cell cycle-dependent changes in target phosphorylation.

Atividades de monitoramento quinases e fosfatases através do ciclo celular por raciométrica FRET

F&ouml;rster resonance energy transfer (FRET)-based reporters1 allow the assessment of endogenous kinase and phosphatase activities in living cells. Such ...

FRET Microscopy for Real-time Monitoring of Signaling Events in Live Cells Using Unimolecular Biosensors

F&ouml;rster resonance energy transfer (FRET) microscopy continues to gain increasing interest as a technique for real-time monitoring of biochemical and signaling events in live cells and tissues. Compared to classical biochemical methods, this novel technology is characterized by high temporal and spatial resolution. FRET experiments use various genetically-encoded biosensors which can be expressed and imaged over time in situ or in vivo1-2. Typical biosensors can either report protein-protein interactions by measuring FRET between a fluorophore-tagged pair of proteins or conformational changes in a single protein which harbors donor and acceptor fluorophores interconnected with a binding moiety for a molecule of interest3-4. Bimolecular biosensors for protein-protein interactions include, for example, constructs designed to monitor G-protein activation in cells5, while the unimolecular sensors measuring conformational changes are widely used to image second messengers such as calcium6, cAMP7-8, inositol phosphates9 and cGMP10-11. Here we describe how to build a customized epifluorescence FRET imaging system from single commercially available components and how to control the whole setup using the Micro-Manager freeware. This simple but powerful instrument is designed for routine or more sophisticated FRET measurements in live cells. Acquired images are processed using self-written plug-ins to visualize changes in FRET ratio in real-time during any experiments before being stored in a graphics format compatible with the build-in ImageJ freeware used for subsequent data analysis. This low-cost system is characterized by high flexibility and can be successfully used to monitor various biochemical events and signaling molecules by a plethora of available FRET biosensors in live cells and tissues. As an example, we demonstrate how to use this imaging system to perform real-time monitoring of cAMP in live 293A cells upon stimulation with a &beta;-adrenergic receptor agonist and blocker.

F&#246;rster resonance energy transfer (FRET) microscopy is a powerful technique for real-time monitoring of signaling events in live cells using various biosensors as reporters. Here we describe how to build a customized epifluorescence FRET imaging system from commercially available components and how to use it for FRET experiments.

FRET Microscopia para Monitoramento em Tempo Real de eventos de sinalização em células vivas utilizando biossensores unimolecular

F&ouml;rster resonance energy transfer (FRET) microscopy  continues to gain increasing interest as a technique for real-time monitoring  of biochemical ...

Simultaneous Multicolor Imaging of Biological Structures with Fluorescence Photoactivation Localization Microscopy

Localization-based super resolution microscopy can be applied to obtain a spatial map (image) of the distribution of individual fluorescently labeled single molecules within a sample with a spatial resolution of tens of nanometers. Using either photoactivatable (PAFP) or&#160;photoswitchable (PSFP) fluorescent proteins fused to proteins of interest, or organic dyes conjugated to antibodies or other molecules of interest, fluorescence photoactivation localization microscopy (FPALM) can simultaneously image multiple species of molecules within single cells. By using the following approach, populations of large numbers (thousands to hundreds of thousands) of individual molecules are imaged in single cells and localized with a precision of ~10-30 nm. Data obtained can be applied to understanding the nanoscale spatial distributions of multiple protein types within a cell. One primary advantage of this technique is the dramatic increase in spatial resolution: while diffraction limits resolution to ~200-250 nm in conventional light microscopy, FPALM can image length scales more than an order of magnitude smaller. As many biological hypotheses concern the spatial relationships among different biomolecules, the improved resolution of FPALM can provide insight into questions of cellular organization which have previously been inaccessible to conventional fluorescence microscopy. In addition to detailing the methods for sample preparation and data acquisition, we here describe the optical setup for FPALM. One additional consideration for researchers wishing to do super-resolution microscopy is cost: in-house setups are significantly cheaper than most commercially available imaging machines. Limitations of this technique include the need for optimizing the labeling of molecules of interest within cell samples, and the need for post-processing software to visualize results. We here describe the use of PAFP and PSFP expression to image two protein species in fixed cells. Extension of the technique to living cells is also described.

We demonstrate the use of fluorescence photo activation localization microscopy (FPALM) to simultaneously image multiple types of fluorescently labeled molecules&#160;within cells. The techniques described yield the localization of thousands to hundreds of thousands of individual fluorescent labeled proteins, with a precision of tens of nanometers&#160;within single cells.

Simultânea Multicolor Imagem de Estruturas Biológicas com fluorescência Fotoativação Localização Microscopia

Localization-based super resolution microscopy can be applied to obtain a spatial map (image) of the distribution of individual fluorescently labeled ...

Utilizing pHluorin-tagged Receptors to Monitor Subcellular Localization and Trafficking

Understanding membrane protein trafficking, assembly, and expression requires an approach that differentiates between those residing in intracellular organelles and those localized on the plasma membrane. Traditional fluorescence-based measurements lack the capability to distinguish membrane proteins residing in different organelles. Cutting edge methodologies transcend traditional methods by coupling pH-sensitive fluorophores with total internal reflection fluorescence microscopy (TIRFM). TIRF illumination excites the sample up to approximately 150 nm from the glass-sample interface, thus decreasing background, increasing the signal to noise ratio, and enhancing resolution. The excitation volume in TIRFM encompasses the plasma membrane and nearby organelles such as the peripheral ER. Superecliptic pHluorin (SEP) is a pH sensitive version of GFP. Genetically encoding SEP into the extracellular domain of a membrane protein of interest positions the fluorophore on the luminal side of the ER and in the extracellular region of the cell. SEP is fluorescent when the pH is greater than 6, but remains in an off state at lower pH values. Therefore, receptors tagged with SEP fluoresce when residing in the endoplasmic reticulum (ER) or upon insertion in the plasma membrane (PM) but not when confined to a trafficking vesicle or other organelles such as the Golgi. The extracellular pH can be adjusted to dictate the fluorescence of receptors on the plasma membrane. The difference in fluorescence between TIRF images at neutral and acidic extracellular pH for the same cell corresponds to a relative number of receptors on the plasma membrane. This allows a simultaneous measurement of intracellular and plasma membrane resident receptors. Single vesicle insertion events can also be measured when the extracellular pH is neutral, corresponding to a low pH trafficking vesicle fusing with the plasma membrane and transitioning into a fluorescent state. This versatile technique can be exploited to study localization, expression, and trafficking of membrane proteins.

Labeling the extracellular domain of a membrane protein with a pH sensitive fluorophore, superecliptic pHluorin (SEP), allows subcellular localization, expression, and trafficking to be determined. Imaging SEP-labeled proteins with total internal reflection fluorescence microscopy (TIRFM) enables the quantification of protein levels in the peripheral ER and plasma membrane.

Utilizando Receptores pHluorin-tag para monitorar subcelular Localização e Tráfico

Understanding membrane protein trafficking, assembly, and expression requires an approach that differentiates between those residing in intracellular ...

Monitoramento baseado em fluorescência de PAD4 Atividade através de um substrato Analog Pro-fluorescência

Resumo

Explore mais vídeos

Métodos de detecção de fluorescência para as plataformas de gotículas microfluídicos

Um ensaio de recuo de molécula única otimizado para quantificação da fosforilação de proteínas

Dinâmica de cAMP em tempo real em células vivas usando o detector de diferença de cAMP fluorescente in situ

Dinâmica de cAMP em tempo real em células vivas usando o detector de diferença de cAMP fluorescente in situ

Dinâmica de cAMP em tempo real em células vivas usando o detector de diferença de cAMP fluorescente in situ

Examinando o Dynamics Conformacional de Proteínas de Membrana In situ Com Labeling-Site dirigido Fluorescência

Atividades de monitoramento quinases e fosfatases através do ciclo celular por raciométrica FRET

FRET Microscopia para Monitoramento em Tempo Real de eventos de sinalização em células vivas utilizando biossensores unimolecular

Simultânea Multicolor Imagem de Estruturas Biológicas com fluorescência Fotoativação Localização Microscopia

Utilizando Receptores pHluorin-tag para monitorar subcelular Localização e Tráfico