Name: purification of the membrane compartment for endoplasmic reticulum-associated degradation of exogenous antigens in cross-presentation
Uploaded: 2017-08-21T14:00:00.000+00:00
Duration: 12 min 48 s
Description: Watch this Scientific Journal Video about Purification of the Membrane Compartment for Endoplasmic Reticulum-associated Degradation of Exogenous Antigens in Cross-presentation at JoVE.com

Bu eser Takasaki Üniversitesi Sağlık ve refah tarafından desteklenir.

1. büyüyen hücreler ve ayrıca eksojen antijenleri bir biotin proteinli etiketleme kullanarak <ol><li>hazırla bOVA kit üretici takip &#39; s protokolü. 
	Not: Normalde, ortalama 1 M OVA başına 2 M biotin bOVA içerir.</li>
	<li>RPMI-1640 2 mM L-glutamin, 1 mM sodyum pyruvate, 0,1 mM gerekli olmayan amino asitler, 100 U/mL penisilin-streptomisin, 55 mM 2-mercaptoethanol, 10 mM HEPES (pH 7.5) ve 5'te 37 ° C'de % 10 fetal buzağı serum (bundan sonra RPMI) ile takıma hücrelerde DC2.4 büyümek % CO 2 oksijen kuluçka (bundan sonra söz, hücreleri bu durum inkübe). DMEM % 10 fetal buzağı serum, 3.7 g/L NaHCO 3 (bundan sonra DMEM) yerine RPMI ile takıma kullanmak mümkündür.</li>
	<li>Bir gün önce arıtma, 1 x 10 5 hücre/ml bir doku kültürü plaka RPMI hücreleri bölün. Konfluent State hücreleri tutarak kaçının. DC2.4 hücreleri son derece eksojen antijenleri yarı Konfluent devlet kadar dahil ama hızla bir aşırı birleşmesi durumunda ulaştıktan sonra yeteneği kaybetmek.</li>
	<li>Daha önce DC2.4 hücreleri yarı Konfluent, 250 µg/mL 1 x 10 6 hücre/mL için bOVA ekleyin ve 2-4 h için kuluçkaya 
	Not: aşağı akım deneyler sırasında tüm arabellekleri ve Kimyasalları 4 ° C'de aksi belirtilmediği sürece tutulur.</li>
</ol> 2. Microsomes hazırlanması <ol><li>DC2.4 hücreler yumuşak doku tabaktan bir yeni 50 mL konik tüp içine pipetting tarafından hasat.</li>
	<li>5 dk, 4 ° C için 1000 x g, santrifüj ve bOVA ile orta aspirasyon tarafından dikkatli bir şekilde çıkarın.</li>
	<li>DC2.4 hücrelerle iki kez PBS arabelleği (1.37 mM NaCl, 8.1 mM Na 2 HPO 4, 2.68 mM KCl, 1,47 mM KH 2 PO 4) tarafından Santrifüjü 1000 x g 5 min, 4 ° C için de 40 mL yıkayın ve süpernatant aspirasyon her zaman atın.</li>
	Homojenizasyon orta (0.25 M Sükroz, 1 mM EDTA, 10 mM HEPES-NaOH [pH 7.4]) ile 1/1000 hacmi proteaz inhibitörü kokteyller ve transfer resuspended DC2.4 <li>resuspend Pelet adım 2.3 içinde 1 - 2 mL (1/20-1/10 cilt kültür ortamının) hücreleri içine bir buz gibi Dounce homogenizer.</li>
	<li>Bozmaya resuspended DC2.4 hücreleri nazikçe tarafından 10-20 vuruş ile buz gibi Dounce homogenizer. 
	Not: buz üzerinde Dounce homogenizer bozulma adımı sırasında soğutmalı</li>
	<li>Yeni bir 15 mL konik tüp hücre kesintiye süspansiyon transfer.</li>
	<li>10 mL toplam 8-9 mL homojenizasyon orta ekleyin ve konik tüp 2000 g x ve 4 10 dk santrifüj kapasitesi ° C.</li>
	<li>Süpernatant kırılmamış hücreleri ve hücre çekirdeği kaldırmak için bir yeni 15 mL konik tüp aktarmak ve konik tüp 10 min 2.000 g x ve 4 için tekrar santrifüj kapasitesi ° C.</li>
	<li>İçine a yeni ultrasantrifüj tüp ve 100.000 g x ve 4 45 dk santrifüj süpernatant transfer ° C.</li>
	<li>Süpernatant Aspire edin ve yukarı ve aşağı microsome kesir aşağı akım deneyler için yapmak için birkaç kez çözüm pipetting tarafından dikkatle içinde homojenizasyon orta 1-2 mL 1/1000 birim proteaz inhibitörü kokteyller ile Pelet resuspend.</li>
	<li>Transfer microsome kesir bir yeni 5 mL yuvarlak alt tüpüne. 
	Not: bu adımdan sonra iodixanol yoğunluk gradient Santrifüjü üreticiye göre tarafından objektif microsomes zenginleştirmek mümkün &#39; s protokolü, non-spesifik microsomes kaldırmak için. Tepe fraksiyonları eksojen antijenleri için toplanan ve sonra arıtma (Adım 3) sonraki adıma tabi.</li>
</ol> 3. Microsomes arıtma bOVA ile geçiren ERAD <ol><li>Ekle 1/100 birim taze SA-manyetik boncuklar 5 mL. adımda 2.11 microsome kısmını yuvarlak alt tüp. 
	Not: bu adımdan önce microsome kesir contaminations belirsiz microsomes azaltmak için denetim manyetik boncuklar tarafından önceden temizlemek mümkün mü.</li>
	<li>Hafifçe karıştırın ve yavaş yavaş 30 dk için yuvarlak alt tüp 4'te döndürmek ° C.</li>
	<li>2-3 mL homojenizasyon orta 4 mL toplam yuvarlak alt tüp içine ekleyin ve hafifçe karıştırın.</li>
	<li>Yuvarlak alt tüp manyetik bir stand üzerine yerleştirin ve 4 ° C'de 10 dakika için kuluçkaya Veziküller için bağlı boncuk mıknatıs için ilgi vardır beri kahverengi mikro-boncuk mıknatıs için en yakın tüp duvar için yavaş yavaş birikir.</li>
	<li>Tüp ile dikkatli aspirasyon tarafından ilişkisiz veziküller kaldırmak için supernatants atmak kalan manyetik tribünde.</li>
	<li>Yıkama manyetik boncuklar veziküller homojenizasyon orta 5 mL ile iki kez için manyetik tarafından bağlı 4 ° C'de 10 dakika stand ve süpernatant her zaman dikkatli aspirasyon tarafından atın. 
	Not: Manyetik stand, arıtma centrifugations 10 dk, 2.000 x g de tarafından olmadan 4 ° C de mevcuttur.</li>
	<li>Manyetik boncuklar bağlı veziküller dikkatle içinde 100 µL homojenizasyon çevre için yukarı ve aşağı birkaç kez çözüm pipetting resuspend.</li>
	<li>Aşağı akım deneyler için saf microsome olarak yeni bir microtube resuspended veziküller transfer. 
	Not: Genellikle, 5-20 µg proteinler 1 x 10 7 hücreleri içeren 50 µL microsome kesir ayrılmış olabilir.</li>
</ol> 4. Saf Microsomes analizini veziküller bağlı <ol><li>Resuspend manyetik boncuklar adım 3.8 TNE arabellek 100-200 µL tarafından (20 mM Tris-HCl pH 7.4, 150 mM NaCl, 0,5 M EDTA, %1 Nonidet P-40) 1/1000 birim proteaz inhibitörü kokteyller ile homojenizasyon orta yerine.</li>
	<li>Lysate 4.1 adımından yeni bir 1.5 mL microtube transfer.</li>
	<li>Üretici başına BCA tahlil kit kullanarak adım 4.2 protein konsantrasyonu belirlemek &#39; s protokolü. 
	Not: Genellikle 5-10 µL 4.2 adımından lysate protein konsantrasyonu belirlemek için yeterlidir.</li>
	<li>Lysate adım 4.2 (2 µg gümüş boyama için protein ve protein Western Blot için 10 µg) yeni mikrotüpler transfer.</li>
	<li>1 SDS jel-yükleme arabellek x 95 ° C ve kaynatın proteinleri ısı bloğunda mikrotüpler koymak (100 mM Tris-HCl pH 6.8, 200 mM dithiothreitol, % 4 SDS, %0,2 bromophenol mavi, % 20 gliserol) 5 dakika süreyle</li>
	<li>Mikrotüpler 21,500 g x ve 4 10 dk santrifüj kapasitesi ° C. toplamak supernatants yeni mikrotüpler çözünmez kesirler kaldırmak için.</li>
	<li>Adım 4.6 (2 µg) standart SD-sayfa tarafından çözümlenen proteinleri analiz.</li>
	<li>Protein bantları gümüş boyama kullanarak boyama gümüş tarafından kit üreticinin görselleştir &#39; s protokolü.</li>
	<li>Adım 4.6 (10 µg) standart SD-sayfa ve Western Blot tarafından çözümlenen proteinleri analiz. Üreticinin reaktif (SA-HRP) kullanmak &#39; s protokol ve fluorography tarafından görselleştirmek.</li>
</ol> 5. Vitro Sulandırma bOVA kullanarak saf Microsomes ERAD Ubiquitination <ol><li>Transfer saf microsomes (5-10 µg protein) adım 3.8 Retikülosit lysate (RL), % 50 hacmi ile reaksiyon arabellek (50 mM Tris pH 7.4, 3 mM ATP, 0,5 mM MgCl x 1 2) ve 0 pM 2 bayrak öğesini Ubikuitin yeni bir microtube içinde. 20-40 µL bu deneyin son birimdir.</li>
	<li>Incubate microtube 2 h 37 ° c 
	Not: ubiquitinated bOVA 5.12 adımda miktarı Western Blot tarafından tespit etmek için çok küçük ise, MG132 10 µM veya lactacystin proteasomes tarafından ubiquitinated bOVA işlenmesini engellemek için 2 µM ekleyin.</li>
	<li>Buz üzerinde microtube yerleştirerek reaksiyonu durdurmak</li>
	<li>Microsomes 500 µL TNE arabellek proteaz inhibitörü kokteyller hacmi 1/1.000 ile ekleyerek çözümlemek.</li>
	<li>Microtube 21,50, 10 dk santrifüj kapasitesig ve 4 x 0 ° c ubiquitinated bOVA DC2.4 in vitro ubiquitination tahlil önce içeren çözünmez kesirler kaldırmak için yeni bir microtube içine supernatants toplamak.</li>
	<li>Süpernatant için yeni bir microtube transfer ve yeni SA-manyetik boncuklar (genellikle 5 µL supernatants 500 µL için) 1/100 birim ekleme.</li>
	<li>Hafifçe karıştırın ve 4'te microtube 30 dk için yavaş yavaş döndürmek ° C.</li>
	<li>Microtube 21,500 g x ve 4 10 dk santrifüj kapasitesi ° C. atma süpernatant bOVA ve ubiquitinated bOVA kurtarmak için aspirasyon tarafından bağlı SA-manyetik boncuklar ile.</li>
	<li>21,500 g x ve 4 10 dk aralıklarla tarafından iki kez toplanan SA-manyetik boncuklar TNE arabelleği 1 mL ile yıkayın ° C. atma süpernatant her zaman aspirasyon.</li>
	<li>Arabellek arıtılmış proteinler tarafından SA-manyetik boncuklar gidermek için bir ısı blokta 95 ° C'de 5 min için yükleme SDS jel x 1 SA-manyetik boncuklar kaynatın.</li>
	<li>Microtube 21,500 g x ve 4 10 dk santrifüj kapasitesi ° C. çözünmez kesirler kaldırmak için yeni bir microtube supernatants toplamak.</li>
	<li>Standart SD-sayfa ve Western Blot proteinler için bağlı SA-manyetik boncuklar analiz. Antikorlar (Anti-bayrak, anti-multi-Ub ve anti-fare IgG-HRP) ve reaktif (SA-HRP) üreticisidir &#39; s Protokolü ve fluorography tarafından görüntülenmiştir.</li>
</ol>

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L., Kyritsis, C., Tamp&#233;, R., Cresswell, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+phagosomes+in+dendritic+cells+form+a+cellular+compartment+sufficient+for+cross+presentation+of+exogenous+antigens.">Early phagosomes in dendritic cells form a cellular compartment sufficient for cross presentation of exogenous antigens.</a> Proc Natl Acad Sci U S A. 100 (22), 12889-12894 (2003).</li><li>Saveanu, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IRAP+identifies+an+endosomal+compartment+required+for+MHC+class+I+cross-presentation.">IRAP identifies an endosomal compartment required for MHC class I cross-presentation.</a> Science. 325 (5937), 213-217 (2009).</li><li>Zehner, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+translocon+protein+Sec61+mediates+antigen+transport+from+endosomes+in+the+cytosol+for+cross-presentation+to+CD8(+)+T+cells.">The translocon protein Sec61 mediates antigen transport from endosomes in the cytosol for cross-presentation to CD8(+) T cells.</a> Immunity. 42 (5), 850-863 (2015).</li></ol>

Yazarlar ifşa gerek yok.

CP önceki çalışmalarda, immünfloresan mikroskobu16,30,31,32tarafından geç endosome veya ER kısıtlı alana eklenen eksojen antijenleri birikmiş. Hücresel yuvası Sükroz veya iodixanol yoğunluk gradient Santrifüjü kullanarak tanımlandığı gibi bu ERAD benzeri taşıma ve işleme eksojen antijenleri ER veya geç endosome, bu özel alanlarda yapılmaktadır olduğunu tahmin edilme...

MHC ı molekülleri ile kısa antijenik peptidler sitozol1Ubikuitin-proteasome sistemi tarafından işlenen endojen antijenleri türetilen tüm çekirdekli hücrelerin yüzeyinde ifade. İşlendikten sonra antijenik peptidler endoplazmik retikulum (ER) Lümen DOKUNUN peptid taşıyıcı tarafından taşınmaktadır. ER Lümen peptid yükleme ve doğru katlanır MHC ben karmaşık bir dizi belirli chaperones yardım. Molekülleri bu dizi acil servis merkezi a bölme için yükleme MHC ben2peptid olduğunu belirten peptid-yükleme karmaşık (PLC) denir. Yükleme, peptid MHC sonra ben moleküller hücre yüzeyine taşınır ve bir anahtar edinilmiş bağışıklık sistemi olarak kendini işaretleri ve etkinleştirir CD8+ sitotoksik T lenfositler (CTL) kanser hücreleri veya enfeksiyöz ajanlar algılamaya tarafından antijenik rolü peptidler olmayan kendine proteinler3.
Hücreleri (APC) sunulması antijen, eksojen antijenleri üzerinden antijenik peptidler de sunulan MHC ben esas olarak yapılan4,5,6,7,8 üzerinden CP, dışarı DCs9,10,11tarafından. CP esastır saf CD8+ T aktivasyonu için hem de hücreleri ve bellek CD8+ T hücreleri içine CTL'ler12,13Anti-bulaşıcı ve anti-tumoral ve immün tolerans bakım ihracı, kendi kendine oyunculuk saf T hücreleri14,15. CP moleküler mekanizmaları henüz ayrıntılı olarak tarif edilebilir ancak CP edinilmiş bağışıklık sisteminde birçok önemli rol oynar. Eksojen antijenleri ve acil servis ve endosome hem de lokalize ERAD, eksojen antijenleri ERAD benzeri işleme ve16 yükleme peptid acil servise endosome taşınmaktadır düşündüren tarafından işlenmiş olan CP önceki çalışmaların ortaya . Ancak, CP peptid yüklenmesini serviste değil ama da Ayrıca ER (şekil 1)17,18 farklı özelliklere sahip çok klasik olmayan endositik bölmeleri, gerçekleştirilir biriken kanıtlar gösteriyor ,19,20,21. Antijenik peptid öncüleri bozulma aminopeptidaz yüksek faaliyet tarafından önlemek için bu klasik olmayan endositik bölmeleri (şekil 1) proksimal bölgede22 sitozol, işleme ve peptid CP içinde yükleme oluşur. Endositik bu bölmeleri karakterizasyonu tartışmalı olmasına rağmen bu yerde eksojen antijenlere başka hiçbir varolan belirli moleküller vardır.
ERAD özellikle misfolded proteinler ER kaldırır hücresel bir yoludur. ERAD yolu misfolded proteinler retrogradely sitoplazma için ER membran aracılığıyla taşınır ve ubiquitin-proteasome sistemi23,24,25tarafından işlenen. Proteinler gibi büyük moleküllerin lipid bilayer ile taşınmaktadır zaman, bu moleküller Derlin ER26ve Tom karmaşık içinde karmaşık ve Tim ve Sec61 karmaşık gibi bir translocon kompleksi olarak adlandırılan bir moleküler aparatı ile başarılı mitokondri27. Ne zaman exogenously eklendi antijenleri ER membran taşınır, lipid bilayer ile translocons, Sec61 kompleksi gibi kompleks içinde nüfuz gerekir. Burada açıklanan yöntemi endositik salonlar için işaretleyici olarak bu zarı delici moleküller kullanarak hedeflenen vezikül saf.
Burada açıklanan yöntemi eksojen bir antijen DC benzeri hücre satırı DC2.428 ve biotinylated ovalbumin (bOVA) kullanarak yeni bir vezikül arıtma protokoldür. Endositik bölmeleri streptavidin (SA) tarafından saf-membran-Penetran bOVA bir üreticisi kullanarak manyetik boncuklar. Bu saf microsome, bazı exogenously bOVA hala membran kesirler korundu ama dışında microsome ve sonra ubiquitinated taşınan ve işlenen ekledi vitro29. Bu saf microsome ERAD ve karmaşık yükleme peptid için hem de ER yerleşik proteinler endositik yuvası özel proteinler yer alan; hücresel yuvası CP29potansiyel endositik yuvası olduğunu düşündüren. Bu iletişim kuralı eksojen antijenleri türüne bağlı değildir ve ayrıca diğer DC alt kümeleri ve DCs hassas moleküler mekanizması için yeterli CP netleştirmek için diğer hücre tipleri, endotel hücreleri, makrofajlar ve B hücreleri gibi için geçerlidir.

<table><tbody><tr><td>RPMI 1640</td><td>gibco by life technologies</td><td>11875-093</td><td></td></tr><tr><td>Fetal bovine serum</td><td>Equitech bio</td><td>SFB30</td><td></td></tr><tr><td>Sodium pyruvate</td><td>gibco by life technologies</td><td>11360-070</td><td></td></tr><tr><td>MEM non-essential amino acids</td><td>gibco by life technologies</td><td>11140-050</td><td></td></tr><tr><td>HEPES</td><td>gibco by life technologies</td><td>15630-080</td><td></td></tr><tr><td>2-mercaptoethanol</td><td>gibco by life technologies</td><td>21985-023</td><td></td></tr><tr><td>L-glutamine</td><td>gibco by life technologies</td><td>25030-164</td><td></td></tr><tr><td>Penisicillin-Sreptomycin</td><td>gibco by life technologies</td><td>15140-122</td><td></td></tr><tr><td>DMEM</td><td>gibco by life technologies</td><td>12100-46</td><td></td></tr><tr><td>OVA</td><td>SIGMA</td><td>A5503</td><td></td></tr><tr><td>Biotin-protein labelling kit</td><td>Thermo Fisher Scientific</td><td>F6347</td><td></td></tr><tr><td>MG-132</td><td>Santa Cruz Biotechnology</td><td>201270</td><td></td></tr><tr><td>lactacystin</td><td>SIGMA</td><td>L6785</td><td></td></tr><tr><td>Dounce homogenizer</td><td>IUCHI</td><td>131703</td><td></td></tr><tr><td>protease inhibitor cocktails</td><td>SIGMA</td><td>P8340</td><td></td></tr><tr><td>iodixanol</td><td>Cosmo bio</td><td>1114542</td><td></td></tr><tr><td>SA-magnetic beads</td><td>New England Biolabs</td><td>201270</td><td></td></tr><tr><td>control magnetic beads</td><td>Chemagen</td><td>M-PVA012</td><td></td></tr><tr><td>magnetic stand</td><td>BD Biosciences</td><td>552311</td><td></td></tr><tr><td>BCA protein assay kit</td><td>Thermo Fisher Scientific</td><td>23225</td><td></td></tr><tr><td>silver staining kits</td><td>Cosmo bio</td><td>423413</td><td></td></tr><tr><td>Reticulocyte Lysate</td><td>Promega</td><td>1730714</td><td></td></tr><tr><td>Flag-tagged ubiquitin</td><td>SIGMA</td><td>U5382</td><td></td></tr><tr><td>anti-ovalbumin (OVA,mouse)</td><td>Antibody Shop</td><td>HYB 094-06</td><td></td></tr><tr><td>ant-multi-ubiquitin (mouse)</td><td>MBL</td><td>D058&amp;minus;3</td><td></td></tr><tr><td>anti-Flag (mouse)</td><td>SIGMA</td><td>F3165</td><td></td></tr><tr><td>trypsin</td><td>SIGMA</td><td>85450C</td><td></td></tr></tbody></table>

purification of the membrane compartment for endoplasmic reticulum-associated degradation of exogenous antigens in cross-presentation

Dendritik hücreler (DC) işleme ve MHC sınıf (MHC) üzerine içselleştirilmiş eksojen antijen sunan son derece yetenekli ben moleküller olarak da bilinen çapraz-sunum (CP). CP çalış önemli bir rol sadece saf CD8 uyarılması+ T hücreleri ve bellek CD8+ T hücreleri için bulaşıcı ve tümör bağışıklığı ama aynı zamanda kendiliğinden hareket inactivation saf T hücreleri tarafından T hücre anerji veya T hücre silme. Her ne kadar aydınlatılmamıştır için CP kritik moleküler mekanizması kalır, biriken kanıtlar eksojen antijenleri endoplazmik retikulum ilişkili bozulması ile (ERAD) klasik olmayan ihracat sonra endositik işlenir gösterir bölmeleri. Çünkü eksojen antijenlere başka hiçbir belirli moleküler işaretleri vardı yakın zamana kadar bu endositik bölmeleri karakterizasyonu sınırlıydı. Burada açıklanan endositik bu bölmeleri arıtma için izin verir yeni bir vezikül yalıtım Protokolü yöntemidir. Bu saf microsome kullanarak, biz ERAD benzeri taşıma, ubiquitination ve eksojen antijen vitro, işlenmesi Ubikuitin-proteasome sistemi ihracat bundan sonra eksojen antijen işleme düşündüren yeniden düzenlendi hücresel bölme. Bu iletişim kuralı daha fazla CP moleküler mekanizması netleştirmek için diğer hücre tipleri için uygulanabilir.

CP moleküler mekanizması aydınlatmak için nerede eksojen antijenleri ERAD benzeri taşıma ve işleme tabi hücresel kompartmanlarda tanımlamak gereklidir. Gözlemler immünfloresan mikroskopi veya elektron mikroskobu nerede eksojen antijenleri16,17,18,19birikmiş hücresel yuvası tespit ederken, 30</su...

Watch this Scientific Journal Video about Purification of the Membrane Compartment for Endoplasmic Reticulum-associated Degradation of Exogenous Antigens in Cross-presentation at JoVE.com

Purification of the Membrane Compartment for Endoplasmic Reticulum-associated Degradation of Exogenous Antigens in Cross-presentation

Burada açıklanan nerede eksojen antijenleri endoplazmik retikulum ilişkili düşmesine çapraz-sunum tarafından işlenen hücresel kompartmanlarda arıtma için izin verir yeni bir vezikül yalıtım Protokolü yöntemidir.

Membran yuvası arıtma için çapraz-sunudaki eksojen antijenleri endoplazmik retikulum ilişkili bozulma

Dendritic cells (DCs) are highly capable of processing and presenting internalized exogenous antigens upon major histocompatibility class (MHC) I ...

purification-membrane-compartment-for-endoplasmic-reticulum

Universidad de Cartagena UDEC

Research

JoVE Journal

Immunology and Infection

8.2K Görüntüleme.  Takasaki University of Health and Welfare. Burada açıklanan nerede eksojen antijenleri endoplazmik retikulum ilişkili düşmesine çapraz-sunum tarafından işlenen hücresel kompartmanlarda arıtma için izin verir yeni bir vezikül yalıtım Protokolü yöntemidir.

Video: Purification of the Membrane Compartment for Endoplasmic Reticulum-associated Degradation of Exogenous Antigens in Cross-presentation

Purification and Aggregation of the Amyloid Precursor Protein Intracellular Domain

Amyloid precursor protein (APP) is a type I transmembrane protein associated with the pathogenesis of Alzheimer's disease (AD). APP is characterized by a large extracellular domain and a short cytosolic domain termed the APP intracellular domain (AICD). During maturation through the secretory pathway, APP can be cleaved by proteases termed &alpha;, &beta;, and &gamma;-secretases1. Sequential proteolytic cleavage of APP with &beta; and &gamma;-secretases leads to the production of a small proteolytic peptide, termed A&beta;, which is amyloidogenic and the core constituent of senile plaques. The AICD is also liberated from the membrane after secretase processing, and through interactions with Fe65 and Tip60, can translocate to the nucleus to participate in transcription regulation of multiple target genes2,3. Protein-protein interactions involving the AICD may affect trafficking, processing, and cellular functions of holo-APP and its C-terminal fragments. We have recently shown that AICD can aggregate in vitro, and this process is inhibited by the AD-implicated molecular chaperone ubiquilin-14. Consistent with these findings, the AICD has exposed hydrophobic domains and is intrinsically disordered in vitro5,6, however it obtains stable secondary structure when bound to Fe657. We have proposed that ubiquilin-1 prevents inappropriate inter- and intramolecular interactions of AICD, preventing aggregation in vitro and in intact cells4. While most studies focus on the role of APP in the pathogenesis of AD, the role of AICD in this process is not clear. Expression of AICD has been shown to induce apoptosis8, to modulate signaling pathways9, and to regulate calcium signaling10. Over-expression of AICD and Fe65 in a transgenic mouse model induces Alzheimer's like pathology11, and recently AICD has been detected in brain lysates by western blotting when using appropriate antigen retrieval techniques12. To facilitate structural, biochemical, and biophysical studies of the AICD, we have developed a procedure to produce recombinantly large amounts of highly pure AICD protein. We further describe a method for inducing the in vitro thermal aggregation of AICD and analysis by atomic force microscopy. The methods described are useful for biochemical, biophysical, and structural characterization of the AICD and the effects of molecular chaperones on AICD aggregation.

A method for large-scale purification of the APP intracellular domain (AICD) is described. We also describe methodology to induce in vitro AICD aggregation and visualization by atomic force microscopy. The methods described are useful for biochemical/structural characterization of the AICD and the effects of molecular chaperones on its aggregation.

Amiloid prekürsör protein intrasellüler Domain saflaştırılması ve toplama

Amyloid precursor protein (APP) is a type I transmembrane protein associated with the pathogenesis of Alzheimer's disease (AD). APP is characterized by a ...

Tıp

Mitochondria-associated ER Membranes (MAMs) and Glycosphingolipid Enriched Microdomains (GEMs): Isolation from Mouse Brain

Intracellular organelles are highly dynamic structures with varying shape and composition, which are subjected to cell-specific intrinsic and extrinsic cues. Their membranes are often juxtaposed at defined contact sites, which become hubs for the exchange of signaling molecules and membrane components1,2,3,4. The inter-organellar membrane microdomains that are formed between the endoplasmic reticulum (ER) and the mitochondria at the opening of the IP3-sensitive Ca2+ channel are known as the mitochondria associated-ER membranes or MAMs4,5,6. The protein/lipid composition and biochemical properties of these membrane contact sites have been extensively studied particularly in relation to their role in regulating intracellular Ca2+ 4,5,6. The ER serves as the primary store of intracellular Ca2+, and in this capacity regulates a myriad of cellular processes downstream of Ca2+ signaling, including post-translational protein folding and protein maturation7. Mitochondria, on the other hand, maintain Ca2+ homeostasis, by buffering cytosolic Ca2+ concentration thereby preventing the initiation of apoptotic pathways downstream of Ca2+ unbalance4,8. The dynamic nature of the MAMs makes them ideal sites to dissect basic cellular mechanisms, including Ca2+ signaling and regulation of mitochondrial Ca2+ concentration, lipid biosynthesis and transport, energy metabolism and cell survival 4,9,10,11,12. Several protocols have been described for the purification of these microdomains from liver tissue and cultured cells13,14. 
	Taking previously published methods into account, we have adapted a protocol for the isolation of mitochondria and MAMs from the adult mouse brain. To this procedure we have added an extra purification step, namely a Triton X100 extraction, which enables the isolation of the glycosphingolipid enriched microdomain (GEM) fraction of the MAMs. These GEM preparations share several protein components with caveolae and lipid rafts, derived from the plasma membrane or other intracellular membranes, and are proposed to function as gathering points for the clustering of receptor proteins and for protein&#x2013;protein interactions4,15.

Mitochondria-associated ER Membranes MAMs and Glycosphingolipid Enriched Microdomains GEMs: Isolation from Mouse Brain

This procedure illustrates how to isolate from the adult mouse brain the mitochondria-associated ER membranes or MAMs and the glycosphingolipid-enriched microdomain fractions from MAMs and mitochondrial preparations.

Mitokondri ilişkili ER Membranlar (MAM) ve Glycosphingolipid zenginleştirilmiştir Microdomains (GEM&#39;lerle): Fare Beyin izolasyon

Intracellular organelles are highly dynamic structures with varying shape and composition, which are subjected to cell-specific intrinsic and extrinsic ...

Nörobilim

Reconstitution of Msp1 Extraction Activity with Fully Purified Components

As the center for oxidative phosphorylation and apoptotic regulation, mitochondria play a vital role in human health. Proper mitochondrial function depends on a robust quality control system to maintain protein homeostasis (proteostasis). Declines in mitochondrial proteostasis have been linked to cancer, aging, neurodegeneration, and many other diseases. Msp1 is a AAA+ ATPase anchored in the outer mitochondrial membrane that maintains proteostasis by removing mislocalized tail-anchored proteins. Using purified components reconstituted into proteoliposomes, we have shown that Msp1 is necessary and sufficient to extract a model tail-anchored protein from a lipid bilayer. Our simplified reconstituted system overcomes several of the technical barriers that have hindered detailed study of membrane protein extraction. Here, we provide detailed methods for the generation of liposomes, membrane protein reconstitution, and the Msp1 extraction assay.

Here, we present a detailed protocol for reconstitution of Msp1 extraction activity with fully purified components in defined proteoliposomes.

Msp1 Ayıklama Etkinliğinin Tamamen Saflaştırılmış Bileşenlerle Yeniden Uzlaştırılması

As the center for oxidative phosphorylation and apoptotic regulation, mitochondria play a vital role in human health. Proper mitochondrial function ...

Biyokimya

Spontaneous Formation and Rearrangement of Artificial Lipid Nanotube Networks as a Bottom-Up Model for Endoplasmic Reticulum

We present a convenient method to form a bottom-up structural organelle model for the endoplasmic reticulum (ER). The model consists of highly dense lipidic nanotubes that are, in terms of morphology and dynamics, reminiscent of ER. The networks are derived from phospholipid double bilayer membrane patches adhering to a transparent Al2O3 substrate. The adhesion is mediated by Ca2+ in the ambient buffer. Subsequent depletion of Ca2+ by means of BAPTA/EDTA causes retraction of the membrane, resulting in spontaneous lipid nanotube network formation. The method only comprises phospholipids and microfabricated surfaces for simple formation of an ER model and does not require the addition of proteins or chemical energy (e.g., GTP or ATP). In contrast to the 3D morphology of the cellular endoplasmic reticulum, the model is two-dimensional (albeit the nanotube dimensions, geometry, structure, and dynamics are maintained). This unique in vitro ER model consists of only a few components, is easy to construct, and can be observed under a light microscope. The resulting structure can be further decorated for additional functionality, such as the addition of ER-associated proteins or particles to study transport phenomena among the tubes. The artificial networks described here are suitable structural models for the cellular ER, whose unique characteristic morphology has been shown to be related to its biological function, whereas details regarding formation of the tubular domain and rearrangements within are still not completely understood. We note that this method uses Al2O3 thin-film-coated microscopy coverslips, which are commercially available but require special orders. Therefore, it is advisable to have access to a microfabrication facility for preparation.

Solid-supported, protein-free, double phospholipid bilayer membranes (DLBM) can be transformed into complex and dynamic lipid nanotube networks and can serve as 2D bottom-up models of the endoplasmic reticulum.

Kendiliğinden oluşumu ve endoplazmik retikulum için aşağıdan yukarıya Model olarak yapay Lipid nanotüp ağların düzenlenmesi

We present a convenient method to form a bottom-up structural organelle model for the endoplasmic reticulum (ER). The model consists of highly dense ...

Biyomühendislik

Purification of the Sarco-Endoplasmic Reticulum Ca2+-ATPase from Rabbit Muscle

Some P-type ATPases, such as sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), are inherently labile membrane proteins that require specific physicochemical conditions during purification to obtain them with high purity and structural quality and in a catalytically active form. The disaccharide trehalose is a compatible solute that is synthesized and accumulated in high concentrations in the yeast cytoplasm to stabilize the membranes and proteins. The use of trehalose as an additive in the protocol for the purification of plasma membrane H+-ATPase results in a high-quality preparation, the hexameric structure of which is shown by biochemical analytical methods. Trehalose can, therefore, be used as a stabilizing additive for the purification of membrane proteins (P-ATPases). This protocol describes the modification of the classical protocol for SERCA purification by subjecting SERCA to centrifugation on a trehalose concentration gradient. The inclusion of this carbohydrate led to the purification of SERCA in a catalytically active form with high purity and, importantly, in a stable form. Partial biochemical characterization of the purified SERCA (SDS-PAGE, enzyme kinetics, FITC labeling, circular dichroism spectroscopy) showed that the enzyme is suitable for functional and structural studies. The use of trehalose in the purification protocol of P-type ATPases and other labile membrane (and cytosolic) proteins is suggested.

This protocol describes an improved SERCA purification method, which includes the disaccharide trehalose in the final centrifugation step. This carbohydrate stabilizes proteins under harsh conditions. The purified SERCA was catalytically active and displayed high purity, making it suitable for structural and functional studies.

Sarko-Endoplazmik Retikulum Ca2+-ATPazın Tavşan Kasından Saflaştırılması

Some P-type ATPases, such as sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), are inherently labile membrane proteins that require specific ...

Visualization of Endoplasmic Reticulum Localized mRNAs in Mammalian Cells

In eukaryotes, most of the messenger RNAs (mRNAs) that encode secreted and membrane proteins are localized to the surface of the endoplasmic reticulum (ER). However, the visualization of these mRNAs can be challenging. This is especially true when only a fraction of the mRNA is ER-associated and their distribution to this organelle is obstructed by non-targeted (i.e. "free") transcripts. In order to monitor ER-associated mRNAs, we have developed a method in which cells are treated with a short exposure to a digitonin extraction solution that selectively permeabilizes the plasma membrane, and thus removes the cytoplasmic contents, while simultaneously maintaining the integrity of the ER. When this method is coupled with fluorescent in situ hybridization (FISH), one can clearly visualize ER-bound mRNAs by fluorescent microscopy. Using this protocol the degree of ER-association for either bulk poly(A) transcripts or specific mRNAs can be assessed and even quantified. In the process, one can use this assay to investigate the nature of mRNA-ER interactions.

Here we describe a method to visualize endoplasmic reticulum-associated mRNAs in mammalian tissue culture cells. This technique involves the selective permeabilization of the plasma membrane with digitonin to remove cytoplasmic contents followed by fluorescent in situ hybridization to detect either bulk poly(A) mRNA or specific transcripts.

Memeli hücrelerinde endoplazmik retikulum lokalize mRNA&#39;ların görselleştirilmesi

In eukaryotes, most of the messenger RNAs (mRNAs) that encode secreted and membrane proteins are localized to the surface of the endoplasmic reticulum ...

Biyoloji

Visualization of Endoplasmic Reticulum Subdomains in Cultured Cells

The lipids and proteins in eukaryotic cells are continuously exchanged between cell compartments, although these retain their distinctive composition and functions despite the intense interorganelle molecular traffic. The techniques described in this paper are powerful means of studying protein and lipid mobility and trafficking in vivo and in their physiological environment. Fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) are widely used live-cell imaging techniques for studying intracellular trafficking through the exo-endocytic pathway, the continuity between organelles or subcompartments, the formation of protein complexes, and protein localization in lipid microdomains, all of which can be observed under physiological and pathological conditions. The limitations of these approaches are mainly due to the use of fluorescent fusion proteins, and their potential drawbacks include artifactual over-expression in cells and the possibility of differences in the folding and localization of tagged and native proteins. Finally, as the limit of resolution of optical microscopy (about 200 nm) does not allow investigation of the fine structure of the ER or the specific subcompartments that can originate in cells under stress (i.e. hypoxia, drug administration, the over-expression of transmembrane ER resident proteins) or under pathological conditions, we combine live-cell imaging of cultured transfected cells with ultrastructural analyses based on transmission electron microscopy.

We describe the imaging approaches we use to investigate the distribution and mobility of the transfected fluorescent proteins resident in the endoplasmic reticulum (ER) by means of the confocal imaging of living cells. We also ultrastructurally analyze the effect of their expression on the architecture of this subcellular compartment.

Kültür Hücrelerinin retikulum Subdomain&#39;ler Görselleştirme

The lipids and proteins in eukaryotic cells are continuously exchanged between cell compartments, although these retain their distinctive composition and ...

Cycloheximide Chase Analysis of Protein Degradation in Saccharomyces cerevisiae

Regulation of protein abundance is crucial to virtually every cellular process. Protein abundance reflects the integration of the rates of protein synthesis and protein degradation. Many assays reporting on protein abundance (e.g., single-time point western blotting, flow cytometry, fluorescence microscopy, or growth-based reporter assays) do not allow discrimination of the relative effects of translation and proteolysis on protein levels. This article describes the use of cycloheximide chase followed by western blotting to specifically analyze protein degradation in the model unicellular eukaryote, Saccharomyces cerevisiae (budding yeast). In this procedure, yeast cells are incubated in the presence of the translational inhibitor cycloheximide. Aliquots of cells are collected immediately after and at specific time points following addition of cycloheximide. Cells are lysed, and the lysates are separated by polyacrylamide gel electrophoresis for western blot analysis of protein abundance at each time point. The cycloheximide chase procedure permits visualization of the degradation kinetics of the steady state population of a variety of cellular proteins. The procedure may be used to investigate the genetic requirements for and environmental influences on protein degradation.

Cycloheximide Chase Analysis of Protein Degradation in Saccharomyces cerevisiae

Protein abundance reflects the rates of both protein synthesis and protein degradation. This article describes the use of cycloheximide chase followed by western blotting to analyze protein degradation in the model unicellular eukaryote, Saccharomyces cerevisiae (budding yeast).

Protein Bozulması ve Siklohekzimid Chase Analizi<em&gt; Saccharomyces cerevisiae</em

Regulation of protein abundance is crucial to virtually every cellular process. Protein abundance reflects the integration of the rates of protein ...

The Endoplasmic Reticulum

The endoplasmic reticulum or ER makes up for more than half of the membranes in a cell and accounts for 10% of total cell volume. It is also the primary protein and lipid synthesis factory for most cell organelles, such as the Golgi apparatus, lysosomes, secretory vesicles, and the plasma membrane. Despite being the most extensive and functionally complex subcellular organelle, ER was the last to be discovered. After years of deliberation, Keith Porter and George Palade in the year 1954, produced the first high-resolution electron microscope images to affirm the presence of ER in the eukaryotic cell.
The ER membranes were identified as sites for protein synthesis and crucial for intracellular transport using radio-labeled and fluorescent-labeled amino acids. The isolation of ER is a tricky task as it forms an intricate mesh with other subcellular organelles. However, on cell homogenization, the disrupted ER membranes reseal into small closed vesicles called microsomes. These vesicles form a microsystem capable of sustaining all ER-related functions like protein and lipid synthesis, calcium signaling, and glycosylation. Subcellular fractionation is the best and often-used technique for the purification of these membranes. When separating using a sucrose gradient, the rough ER microsomes sediments at a higher density than smooth ER microsomes.
The ER network in a cell is dynamic. It is constantly shape-shifting along with the cytoskeleton to bolster mechanical support for the cell structure. Despite the distinct cisternae and tubule morphologies of the ER membrane, interconversion between the two is possible and is governed by the expression of membrane proteins. The ER network rearranges by tubule growth, retraction, and fusion of adjacent ER-ER membranes.
As mentioned above, the ER network is required for optimal overall cellular health. Disruption of ER morphology is linked to pathological conditions, including neurological disorders like Alzheimer&#39;s disease, hereditary spastic paraplegia, and viral infections like hepatitis C virus, and dengue virus.

Endoplazmik Retikulum

The endoplasmic reticulum or ER makes up for more than half of the membranes in a cell and accounts for 10% of total cell volume. It is also the primary ...

Education

JoVE Core

Hücre Biyolojisi

Unit 1

Endoplazmik Retikulum ve Peroksizomlarda Transmembran Taşıma

KEY TERMS AND CONCEPTS

ER Retrieval Pathway

In the secretory pathway, vesicles transport proteins from one cellular compartment to another in forward transport to deliver the protein to its correct location. Occasionally, misfolded proteins and incorrect proteins escape their original compartments, and a retrieval pathway is used to return the escaped proteins to their original compartment.
The ER uses many checkpoints to prevent the entry of incorrectly folded or a resident protein as cargo onto a transport vesicle. These mechanisms include cargo selectivity of the receptors, aggregation of functionally similar proteins, and retention sequences on resident proteins.
Biochemical studies characterizing the cargo-sorting receptors have shown that they are ligand-specific and bind only at specific pH (pH 5.0 in yeast and mammals). Functionally similar ER-resident can proteins aggregate to form large complexes that cannot be loaded onto transport vesicles, thus avoiding the accidental escape of these proteins from the organelle. Additionally, the membrane-spanning domain of several ER and Golgi proteins contain a retention sequence that marks these proteins for staying back in the ER, so receptors do not bind them.
If an ER-resident protein escapes these checkpoints and gets loaded onto a Golgi-bound vesicle, a specific amino acid sequence called a retrieval signal helps the protein get recognized and transported back to the ER. The receptors involved in retrieval mechanisms recognize the retrieval signals at the carboxyl terminus of soluble proteins of the ER and in the cytoplasmic domain of some ER and Golgi membrane proteins. The receptors selectively capture such proteins and package them in vesicles that transport them back to the ER.
Two well-characterized retrieval signals are the carboxy-terminal tetrapeptide KDEL and KKXX found in many ER lumen resident proteins. BiP, a molecular chaperone, plays a vital role in preventing the aggregation of misfolded proteins. Interaction between BiP and unfolded proteins is mediated by a substrate-binding domain and a nucleotide-binding domain for ATPase activity. KDEL receptor in the post-ER compartments such as ERGIC and Golgi binds with the carboxyl-terminal retrieval signal of BiP and returns BiP to the ER via COPI vesicles.

ER Alma Yolu

In the secretory pathway, vesicles transport proteins from one cellular compartment to another in forward transport to deliver the protein to its correct ...

Membran yuvası arıtma için çapraz-sunudaki eksojen antijenleri endoplazmik retikulum ilişkili bozulma

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Protein Bozulması ve Siklohekzimid Chase Analizi

Endoplazmik Retikulum

ER Alma Yolu