Ubp1 ifade plazmid pCG001 nazik Tıbbi Araştırma John Curtin Okulu&#39;nda Rohan Baker tarafından sağlanmıştır. Bu çalışma Dimes Araştırma Bursu 1-FY2011 Mart Dimes, Basil O&#39;Connor Başlangıç ​​Akademik Araştırma Ödülü # 5-FY20 ve NSF KARİYER Ödülü 0.746.796 Mart tarafından finanse edildi.

1. Gerinim Mühendislik İş Akışı <ol><li> Dizileri kodlama (a) bir zar-yerelleştirme dizisi, (b) bir hızla olgunlaşan floresan protein ve bir ilgi ve protein (örneğin, bir transkripsiyon faktörü) ile çerçeve (c) bir proteaz tanıma sekansı, N-terminalinde. Ekleme Biz Tsr-Venüs muhabiri 2 hedef membran kullanılan ve ifade bakteriyofaj λ repressör CI protein moleküllerinin sayısını saymak için Ubikitin proteaz tanıma dizisi (Ub) için erimiş. Biz bölgenin kodlama CI yabani tip değiştirilmesi ve E. içine yapı birleştiren, füzyon proteini Tsr-Venus-UB-CI inşa nasıl Detayları λ Red 3 rekombinasyon kullanılarak coli kromozomu, ref ayrıntılı olarak tarif edilmektedir. 1. </li><li> Sıralanmasıyla tüm değişiklikler doğrulayın. </li><li> Bir plazmid kodlama ilgi flüoresan raportör proteini eksprese eden ve bir yük içine yukarıda kullanılan tanıma dizisi için spesifik bir proteaz Dönüşümütranslasyonel füzyon. Bu C-terminal artığı ubikitin 4 hemen sonra parçalayarak proteaz Ubp1 kullanılmıştır. </li></ol> 2. Kültür Hücreler ve örnek hazırlayın <ol><li> Biri E. seçin taze streaked agar plağından ilgi coli kolonisi 1 ml M9 minimal medya içine 5 1X MEM amino asitler ve uygun antibiyotik ile desteklenmiş. İstenen sıcaklıkta bir çalkalayıcı içinde inkübe yeterince uzun ulaşmak için OD 600&gt; 1.0 (600 nm de optik yoğunluk). </li><li> OD 600 = 0.02 için uygun antibiyotik ile 1 ml taze M9 ortama kültürü seyreltin. Uygun bir sıcaklıkta bir çalkalayıcı içinde inkübe edin. Düşük sıcaklık büyümesi için gerekli olmadığını Ilk hücre yoğunluğunda artış olabilir. </li><li> OD 600 = 0.2-0.3 (37 OD 600 bir başlangıç ​​hücre kültürü ile ° C = 0.02, bu 3-4 saat sürer), agaroz jel pedi (adım 3) hazırlarken başladığınızda. </li><li> Zaman OD hücreleri görüntüleme için hazır <sub&gt; 600 = 0.3-0.4. </li><li> 1,5 ml mikrosantrifüj tüpü, bir benchtop mikrosantrifüj 1 dakika boyunca 10,000 x g&#39;de santrifüj içine 1 ml İnkübe kültürü aktarın. </li><li> Süpernatantı atın ve 1 ml taze M9 orta ekleyin ve pelet hafifçe tekrar süspansiyon haline getirin. </li><li> 1 dakika boyunca 10,000 x g&#39;de santrifüjleyin. </li><li> 1.6 ve 1.7 adımları tekrarlayın. Süpernatantı atın. </li><li> Yavaşça 1 ml M9 medyada tekrar süspansiyon haline getirin. Timelapse görüntüleme için düşük hücre yoğunlukları sağlamak üzere 100-kat için - hücreler direkt olarak mikroskop görüntüleme ya da seyreltilmiş 10 için de kullanılabilir. Düşük hücre yoğunlukları uzatılmış timelapse görüntüleme için önemli olduğunu unutmayın. Görüntüleme odası (adım 4) deneme sırasında mühürlenir. Hücrelerin üstel büyüme nedeniyle, yüksek başlangıç ​​hücre konsantrasyonları anlamlı floresan protein olgunlaşması azaltılması ve hücre büyümesini etkileyen, jel pedi uzun süreli büyüme sonra odasının içindeki oksijeni tüketebilir. </li></ol> 3. Agaroz Çözüm hazırlayın <ol><li> 10-20 mg tartılır1,5 ml mikrosantrifüj tüpe düşük erime sıcaklığına agaroz. </li><li> % 3 agaroz çözüm yapmak antibiyotik vermeden uygun miktarda M9 minimal orta ekleyin. </li><li> 70, 30 dakika için agaroz çözelti ısıtılır ° C, çözelti tamamen eritilmiş ve homojen olmasını sağlamak için ters tüp eritir. Jel pedi bu noktada (adım 4) dökülecek veya sıcaklık 50 ° C&#39;ye düşmüş ve daha sonra kullanmak için birkaç saat tutulabilir. </li></ol> 4. Odası Jel Tampon hazırlayın <ol><li> Görüntüleme öncesinde yaklaşık 50 dakika su ile bir Microaqueduct slayt durulayın. </li><li> Bir kapak cam temizliği (6 açıklandığı gibi zaten sıkı bir temizleme yöntemi ile) ve basınçlı hava ile üfleme steril su ve kuru ile slayt Microaqueduct tutunuz. </li><li> Bu uygulamalar için modifiye edilebilir Microaqueduct sürgüyle (arasında cam tarafında giriş ve çıkışları kapsayan, böylece Microaqueduct slayt üzerinde lastik bir contahangi medya) numune içinden perfüze edilmiştir. Microaqueduct slaydın merkezine 50 ul agaroz çözeltisi (adım 3) uygulanır. </li><li> Temiz, kuru cam kapak ile agaroz çözüm ekleyin. </li><li> Agaroz çözelti 30 dakika boyunca oda sıcaklığında bekletilir. </li><li> Bu arada, (adım 2), bir hücre örneği hazırlamak. </li><li> Dikkatle jel ped üst cam kapak soyulabilir. Jel yastığı başına 1.0 ul yıkanmış hücre kültürü ekleyin. Jel pedi tarafından absorbe edilecek kültür için ~ 2 dakika bekleyin. O kadar uzun beklemek değil önemli olduğunu jel pedi overdries, ama yeterince uzun hücrelerinin düzgün jel pedi uyduğunu. İdeal bekleme süresi sıcaklık ve nem ile değişir. </li><li> Beklerken, başka precleaned cam kapak kurulayın. </li><li> Cam kapak ve Microaqueduct slayt iyi hizalanmış olduğunu kontrol ettikten yeni cam kapak ile örnek örtün. </li><li> Üreticinin yönergelerini izleyerek sıcaklık kontrollü iklim odasında birleştirin.Şimdi mikroskobu (adım 5) görüntüleme için kullanılabilir. </li></ol> 5. Görüntüleme ve Timelapse Filmler kazanılması <ol><li> Üreticinin talimatlarına (örneğin lazer deney öncesi ~ 0.5 saat süreyle ısınmış gerekebilir) takiben lazer ve mikroskop açın. </li><li> Mikroskop sahne yazısına monte odasına kilitleyin. Büyüme oda sıcaklığı ve 37 ° C ya da istenen diğer büyüme sıcaklıkta amaç ısıtıcı ayarlayın. </li><li> Oda sıcaklığının üzerinde görüntüleme, odak ya da jel pedi genellikle ilk sıcaklık kayması sonra ~ 15 dakika için önemli ölçüde sürüklenir. Uygulamada, ilgi alanları bulmak ve bir deney için gerekli görüntüleme komut dosyalarını değiştirmek için bu kez kullanın. </li><li> Mikroskop hücreleri bulun ve önceden tanımlanmış ve hizalanmış görüntüleme bölgede bu merkezleme sonra her hücrenin konumunu kaydetmek. Birden fazla hücre Her görüntü alımından zaman penceresinde görüntülenebilir. M üzerinde timelapse görüntüleme içinherhangi kuşaklar, diğer koloniler büyüme sırasında görüntüleme bölge girmeyecek şekilde görüntülü hücreleri başlangıçta yüz, en az birkaç mikron ile diğer hücrelerinden ayrılan olduğundan emin olun. </li><li> Böylece lazer uyarma yoğunluğunu ayarlayın ki 6 poz içindeki hemen hemen tüm floresan molekülü photobleach (Şekil 5). </li><li> , Otomatik bir görüntü dosyası / günlük, Şekil 3 &#39;de açıklanan deneysel akışı algoritması kullanılarak veri timelapse elde kullanılması. </li></ol>

<ol>
	<li>Hensel, Z., Feng, H. D., Han, B., Hatem, C., Wang, J., Xiao, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stochastic+expression+dynamics+of+transcription+factor+revealed+by+single-molecule+noise+analysis.">Stochastic expression dynamics of transcription factor revealed by single-molecule noise analysis.</a> Nat. Struct. Mol. Biol. 19, 797-802 (2012).</li><li>Yu, J., Xiao, J., Ren, X., Lao, K., Xie, X. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+Gene+Expression+in+Live+Cells,+One+Protein+Molecule+at+a+Time.">Probing Gene Expression in Live Cells, One Protein Molecule at a Time.</a> Science. 311, 1600-1603 (2006).</li><li>Datsenko, K. A., Wanner, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-step+inactivation+of+chromosomal+genes+in+Escherichia+coli+K-12+using+PCR+products.">One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products.</a> Proc. Nat. Acad. Sci. U.S.A. 97, 6640-6645 (2000).</li><li>Tobias, J. W., Varshavsky, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cloning+and+Functional+Analysis+of+the+Ubiquitin-specific+Protease+Gene+UBP1+of+Saccharomyces+cerevisiae.">Cloning and Functional Analysis of the Ubiquitin-specific Protease Gene UBP1 of Saccharomyces cerevisiae.</a> J. Biol. Chem. 266, 12021-12028 (1991).</li><li>Sambrook, J., Russell, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Molecular Cloning: A Laboratory Manual. , A2.2 (2001).</li><li>Xiao, J., Elf, J., Li, G., Yu, J., Xie, X. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+gene+expression+in+living+cells+at+the+single-molecule+level.">Imaging gene expression in living cells at the single-molecule level.</a> Single Molecules: a laboratory manual. , 149-169 (2007).</li><li>Nagai, T., 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=A+variant+of+yellow+fluorescent+protein+with+fast+and+efficient+maturation+for+cell-biological+applications.">A variant of yellow fluorescent protein with fast and efficient maturation for cell-biological applications.</a> Nat. Biotechnol. 20, 87-90 (2002).</li><li>Stagaman, G., Forsyth, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bright-field+microscopy+of+semitransparent+objects.">Bright-field microscopy of semitransparent objects.</a> J. Opt. Soc. Am. A. 5, 648-659 (1988).</li><li>Tobias, J. W., Shrader, T. E., Rocap, G., Varshavsky, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+N-end+rule+in+bacteria.">The N-end rule in bacteria.</a> Science. 254, 1374-137 (1991).</li></ol>

Biz hiçbir açıklama yok.

CoTrAC yöntemi geleneksel N-veya C-terminali floresan proteini füzyon proteini etkinliği bozabilir diğer proteinlerin üretimini ölçmek için yaygın olabilir. CoTrAC stratejisi mevcut yöntemler üzerinde üç benzersiz avantajlara sahiptir. İlk olarak, eş-translasyonel füzyon flüoresan raportör molekülü, gerçek zamanlı olarak protein üretim doğru sayımı izin veren, ilgilenilen proteinin her bir molekül için üretilmiş olmasını sağlar. İkincisi, membran hedefli muhabiri Tsr-Venüs çok düşü...

<table border="1"><tbody><tr><td> Reaktif Adı </td><td> Şirket </td><td> Katalog numarası </td><td> Yorumlar (isteğe bağlı) </td></tr><tr><td> Agaroz (Düşük erime sıcaklığı) </td><td> Lonza </td><td> 50100 </td><td></td></tr><tr><td> Milli-Q H2O </td><td></td><td></td><td></td></tr><tr><td> 5 x M9 tuzlan </td><td></td><td></td><td> Aşağıda tarif 9&#39;da tarif edildiği gibi </td></tr><tr><td> % 20 glikoz </td><td></td><td></td><td></td></tr><tr><td> MgSO4 </td><td></td><td></td><td></td></tr><tr><td> CaCl2 </td><td></td><td></td><td></td></tr><tr><td> 50 x MEM amino asit solüsyonu </td><td> Invitrogen </td><td> 11130-051 </td><td></td></tr><tr><td> Sıcaklık Kontrollü BüyümeBölme Sahne adaptörü </td><td> Bioptechs </td><td> -2 FCS </td><td></td></tr><tr><td> Amaç Isıtıcı </td><td> Bioptechs </td><td> Model mikroskop objektif bağlıdır </td><td></td></tr><tr><td> Slayt Microaqueduct </td><td> Bioptechs </td><td> 130119-5 </td><td></td></tr><tr><td> Mikro kapağı gözlük </td><td> VWR </td><td> 40CIR-1 </td><td> Kaynağı zor olabilir; Bioptechs adresinden de bulunabilir </td></tr><tr><td> Cam / slayt conta Kapak </td><td> Bioptechs </td><td> FCS2 0,75 mm </td><td></td></tr><tr><td> Floresan Mikroskop </td><td> Çeşitli </td><td> Örnek kurulum: Tutarlı Innova 308C Argon iyon lazer, Olympus IX-81 mikroskop, Olympus PlanApo 100X NA 1.45 hedefi, Metamorph yazılım </td><td> Lazer uyarma, otomatik xyz aşamasında, komut dosyası görüntüleme ve otofokus yeteneğine otomasyon yazılımı, resolvin yeteneğine optik olmalıg tek floresan proteinleri </td></tr><tr><td> EM-CCD Kamera </td><td> Çeşitli </td><td> Örnek kurulum: Andor Ixon DU-898 </td><td> Arka plan üstüne tek floresan proteinleri tespit etmek için yeterince düşük gürültü olmalı </td></tr></tbody></table>

single-molecule imaging of gene regulation in vivo using cotranslational activation by cleavage (cotrac)

Bu görüntü ile yarılması ile bir floresan mikroskobu yöntem, CO-translasyonel Aktivasyon (CoTrAC) proteinin işlevi dalgalanmayla olmaksızın tek molekül hassas canlı hücrelerde protein moleküllerinin üretimini açıklar. Bu yöntem, bu mümkün ardışık beş dakikalık bir zaman pencereleri sırasında bir hücre tarafından üretilen protein moleküllerinin sayısını saymak mümkün kılar. Bu canlı hücrelerde tek floresan protein molekülleri tespit etmek için yeterince hassas olan ~ 0,5 1 kW / cm 2, lazer uyarma güç yoğunluğuna sahip bir floresan mikroskop gerektirir. Bir zar hedefleme sırası, bir hızlı-olgunlaşma, sarı floresan protein ve bir proteaz tanıma sekansı: bu yöntemde kullanılan flüoresan raportör üç parçadan oluşur. Raportör Çevrimsel ilgi çeken bir proteinin N-terminusunda için eritilerek birleştirilir. Hücreler bir sıcaklık kontrollü mikroskop sahnede yetiştirilir. Her beş dakikada, hücrelerin içindeki floresan molekülü (ve daha sonra eş görüntülü) floresans görüntüleri analiz ederek unted ve sadece yeni tercüme proteinler sonraki ölçüm sayılan böylece sonradan photobleached. Bu yöntem sonucunda floresans görüntüler, her bir görüntü floresan noktalar tespit tek hücreleri atayarak ve ardından hücre soylarının hücreleri atayarak analiz edilebilir. Belirli bir hücreye bir zaman penceresi içinde üretilen proteinlerin sayısı tek flüoresan moleküllerinin ortalama yoğunluk tarafından lekelerin entegre floresan yoğunluğu bölünmesiyle hesaplanır. Bu tek bir 5 dakikalık bir zaman pencereleri içinde 0-45 molekül aralığında ifade seviyelerini ölçmek için bu yöntem kullanılır. Bu yöntem bize λ repressör CI ifadesi gürültü ölçmek için etkin ve sistem biyolojisi diğer birçok potansiyel uygulamalar vardır.

Λ repressör CI üretim takip bir CoTrAC deneyden elde Tipik sonuçlar Şekiller 4 ve 5 &#39;de gösterilmiştir. Bu deneyde, 12 koloniler 5 dakika aralıklarla görüntülenmiştir. Her zaman noktasında, koloni birinci autofocused edildi ve görüntüleme bölge içinde merkezi. Sonraki odaklı / merkezli pozisyonu saklanan ve aydınlık görüntü elde edildi. Evresi hücrelerin (faz-kontrast veya diferansiyel girişim kontrast (DIC) optik olmadan bisecting düzlemine aydınlık oda...

Watch this Scientific Journal Video about Single-molecule Imaging of Gene Regulation In vivo Using Cotranslational Activation by Cleavage CoTrAC at JoVE.com

Single-molecule Imaging of Gene Regulation In vivo Using Cotranslational Activation by Cleavage CoTrAC

Bu görüntü ile yarılması ile bir floresan mikroskobu yöntem, CO-translasyonel Aktivasyon (CoTrAC), proteinin işlevi dalgalanmayla olmaksızın tek molekül hassas canlı hücrelerde protein moleküllerinin üretimini açıklar. Bu yöntem, bir transkripsiyon faktörü, λ repressör CI stokastik ifade dinamik takip etmek için kullanılmıştır<sup&gt; 1</sup&gt;.

Gen Yönetmelik Tek molekül Görüntüleme<em&gt; In vivo</em&gt; Dilinim tarafından Cotranslational Aktivasyon (CoTrAC) kullanma

We describe a fluorescence microscopy method, Co-Translational Activation by Cleavage (CoTrAC) to image the production of protein molecules in live cells ...

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JoVE Journal

Biology

Single-molecule Imaging of Gene Regulation In vivo Using Cotranslational Activation by Cleavage (CoTrAC)

9.8K Görüntüleme.  Johns Hopkins University School of Medicine. Bu görüntü ile yarılması ile bir floresan mikroskobu yöntem, CO-translasyonel Aktivasyon (CoTrAC), proteinin işlevi dalgalanmayla olmaksızın tek molekül hassas canlı hücrelerde protein moleküllerinin üretimini açıklar. Bu yöntem, bir transkripsiyon faktörü, λ repressör CI stokastik ifade dinamik takip etmek için kullanılmıştır 1.

Video: Single-molecule Imaging of Gene Regulation In vivo Using Cotranslational Activation by Cleavage CoTrAC

Single-Molecule Imaging of Nuclear Transport

The utility of single molecule fluorescence microscopy approaches has been proven to be of a great avail in understanding biological reactions over the last decade. The investigation of molecular interactions with high temporal and spatial resolutions deep within cells has remained challenging due to the inherently weak signals arising from individual molecules. Recent works by Yang et al. demonstrated that narrow-field epifluorescence microscopy allows visualization of nucleocytoplasmic transport at the single molecule level. By the single molecule approach, important kinetics, such as nuclear transport time and efficiency, for signal-dependent and independent cargo molecules have been obtained. Here we described a protocol for the methodological approach with an improved spatiotemporal resolution of 0.4 ms and 12 nm. The improved resolution enabled us to capture transient active transport and passive diffusion events through the nuclear pore complexes (NPC) in semi-intact cells. We expect this method to be used in elucidating other binding and trafficking events within cells.

Single molecule microscopy approch provided novel insights into nuclear transport.

Tek Molekül Görüntüleme Nükleer Ulaştırma

The utility of single molecule fluorescence microscopy approaches has been proven to be of a great avail in understanding biological reactions over the ...

Biyoloji

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c

Apoptosis, or programmed cell death, is a conserved and highly regulated pathway by which cells die1. Apoptosis can be triggered when cells encounter a wide range of cytotoxic stresses. These insults initiate signaling cascades that ultimately cause the release of cytochrome c from the mitochondrial intermembrane space to the cytoplasm2. The release of cytochrome c from mitochondria is a key event that triggers the rapid activation of caspases, the key cellular proteases which ultimately execute cell death3-4.
The pathway of apoptosis is regulated at points upstream and downstream of cytochrome c release from mitochondria5. In order to study the post-mitochondrial regulation of caspase activation, many investigators have turned to direct cytoplasmic microinjection of holocytochrome c (heme-attached) protein into cells6-9. Cytochrome c is normally localized to the mitochondria where attachment of a heme group is necessary to enable it to activate apoptosis10-11. Therefore, to directly activate caspases, it is necessary to inject the holocytochrome c protein instead of its cDNA, because while the expression of cytochrome c from cDNA constructs will result in mitochondrial targeting and heme attachment, it will be sequestered from cytosolic caspases. Thus, the direct cytosolic microinjection of purified heme-attached cytochrome c protein is a useful tool to mimic mitochondrial cytochrome c release and apoptosis without the use of toxic insults which cause cellular and mitochondrial damage.
In this article, we describe a method for the microinjection of cytochrome c protein into cells, using mouse embryonic fibroblasts (MEFs) and primary sympathetic neurons as examples. While this protocol focuses on the injection of cytochrome c for investigations of apoptosis, the techniques shown here can also be easily adapted for microinjection of other proteins of interest.

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c

In this protocol, we describe the direct cytoplasmic microinjection of cytochrome c protein into fibroblasts and primary sympathetic neurons. This technique allows for the introduction of cytochrome c protein into the cytoplasm of cells and mimics the release of cytochrome c from mitochondria, which occurs during apoptosis.

Sitokrom Sitoplazmik Mikroenjeksiyon Apoptoz aktivasyonu C</em

Apoptosis, or programmed cell death, is a conserved and highly regulated pathway by which cells die1.  Apoptosis can be triggered when cells encounter a ...

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Telomerase is a specialized reverse transcriptase1 that adds short DNA repeats, called telomeres, to the 3' end of linear chromosomes2 that serve to protect them from end-to-end fusion and degradation. Following DNA replication, a short segment is lost at the end of the chromosome3 and without telomerase, cells continue dividing until eventually reaching their Hayflick Limit4. Additionally, telomerase is dormant in most somatic cells5 in adults, but is active in cancer cells6 where it promotes cell immortality7.
The minimal telomerase enzyme consists of two core components: the protein subunit (TERT), which comprises the catalytic subunit of the enzyme and an integral RNA component (TER), which contains the template TERT uses to synthesize telomeres8,9. Prior to 2008, only structures for individual telomerase domains had been solved10,11. A major breakthrough in this field came from the determination of the crystal structure of the active12, catalytic subunit of T. castaneum telomerase, TcTERT1.
Here, we present methods for producing large quantities of the active, soluble TcTERT for structural and biochemical studies, and the reconstitution of the telomerase RNP complex in vitro for telomerase activity assays. An overview of the experimental methods used is shown in Figure 1.

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.

Active T. in vitro Sulandırma castaneum Telomeraz

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more ...

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the messagefor review see 1. However, it's now widely accepted that synonymous codon usage is the primary cause of non-uniform translational elongation rates1. Synonymous codons are not used with identical frequency. A bias exists in the use of synonymous codons with some codons used more frequently than others2. Codon bias is organism as well as tissue specific2,3. Moreover, frequency of codon usage is directly proportional to the concentrations of cognate tRNAs4. Thus, a frequently used codon will have higher multitude of corresponding tRNAs, which further implies that a frequent codon will be translated faster than an infrequent one. Thus, regions on mRNA enriched in rare codons (potential pause sites) will as a rule slow down ribosome movement on the message and cause accumulation of nascent peptides of the respective sizes5-8. These pause sites can have functional impact on the protein expression, mRNA stability and protein foldingfor review see 9. Indeed, it was shown that alleviation of such pause sites can alter ribosome movement on mRNA and subsequently may affect the efficiency of co-translational (in vivo) protein folding1,7,10,11. To understand the process of protein folding in vivo, in the cell, that is ultimately coupled to the process of protein synthesis it is essential to gain comprehensive insights into the impact of codon usage/tRNA content on the movement of ribosomes along mRNA during translational elongation.
Here we describe a simple technique that can be used to locate major translation pause sites for a given mRNA translated in various cell-free systems6-8. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA. The rationale is that at low-frequency codons, the increase in the residence time of the ribosomes results in increased amounts of nascent peptides of the corresponding sizes. In vitro transcribed mRNA is used for in vitro translational reactions in the presence of radioactively labeled amino acids to allow the detection of the nascent chains. In order to isolate ribosome bound nascent polypeptide complexes the translation reaction is layered on top of 30% glycerol solution followed by centrifugation. Nascent polypeptides in polysomal pellet are further treated with ribonuclease A and resolved by SDS PAGE. This technique can be potentially used for any protein and allows analysis of ribosome movement along mRNA and the detection of the major pause sites. Additionally, this protocol can be adapted to study factors and conditions that can alter ribosome movement and thus potentially can also alter the function/conformation of the protein.

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

A technique to identify translational pause sites on mRNA is described. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA, followed by the size analysis of the nascent chains using a denaturing gel electrophoresis.

Ribozom Bağlı Doğan Polipeptitler İzolasyonu<em&gt; In vitro</em&gt; MRNA boyunca Translasyonel Duraklat Siteleri Belirleme

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the ...

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway that polypeptide chain follows during co-translational folding to achieve its functional form is still an enigma. In order to understand this process and to determine the exact conformation of the co-translational folding intermediates, it is essential to develop techniques that allow the isolation of RNCs carrying nascent chains of predetermined sizes to allow their further structural analysis.
SecM (secretion monitor) is a 170 amino acid E. coli protein that regulates expression of the downstream SecA (secretion driving) ATPase in the secM-secA operon6. Nakatogawa and Ito originally found that a 17 amino acid long sequence (150-FSTPVWISQAQGIRAGP-166) in the C-terminal region of the SecM protein is sufficient and necessary to cause stalling of SecM elongation at Gly165, thereby producing peptidyl-glycyl-tRNA stably bound to the ribosomal P-site7-9. More importantly, it was found that this 17 amino acid long sequence can be fused to the C-terminus of virtually any full-length and/or truncated protein thus allowing the production of RNCs carrying nascent chains of predetermined sizes7. Thus, when fused or inserted into the target protein, SecM stalling sequence produces arrest of the polypeptide chain elongation and generates stable RNCs both in vivo in E. coli cells and in vitro in a cell-free system. Sucrose gradient centrifugation is further utilized to isolate RNCs.
The isolated RNCs can be used to analyze structural and functional features of the co-translational folding intermediates. Recently, this technique has been successfully used to gain insights into the structure of several ribosome bound nascent chains10,11. Here we describe the isolation of bovine Gamma-B Crystallin RNCs fused to SecM and generated in an in vitro translation system.

We describe here a technique that is now routinely used to isolate stably bound ribosome nascent chain complexes (RNCs). This technique takes advantage of the discovery that a 17 amino acid long SecM "arrest sequence" can halt translation elongation in a prokaryotic (E. coli) system, when inserted into (or fused to the C-terminus) of virtually any protein.

Ribozom Ciltli Polipeptitler izole bir aracı olarak SECM Tutuklanma sırası kullanılarak

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway ...

Analysis of Global RNA Synthesis at the Single Cell Level following Hypoxia

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a particular transcriptional program in order to mount an appropriate and coordinated cellular response. The cell possesses several oxygen sensor enzymes that require molecular oxygen as cofactor for their activity. These range from prolyl-hydroxylases to histone demethylases. The majority of studies analyzing cellular responses to hypoxia are based on cellular populations and average studies, and as such single cell analysis of hypoxic cells are seldom performed. Here we describe a method of analysis of global RNA synthesis at the single cell level in hypoxia by using Click-iT RNA imaging kits in an oxygen controlled workstation, followed by microscopy analysis and quantification.&nbsp; Using cancer cells exposed to hypoxia for different lengths of time, RNA is labeled and measured in each cell. This analysis allows the visualization of temporal and cell-to-cell changes in global RNA synthesis following hypoxic stress.

We describe a technique for analysis of global RNA synthesis in hypoxia using imaging. Click-chemistry labeling of RNA has not previously been performed under hypoxia and allows visualization of global RNA changes at the single cell level. This approach complements the existing averaged RNA techniques, allowing direct visualization of cell-to-cell changes in global RNA synthesis.

Ününüz Aşağıdaki Tek Hücre Düzeyinde Küresel RNA Sentezi Analizi

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a ...

Demonstration of Proteolytic Activation of the Epithelial Sodium Channel (ENaC) by Combining Current Measurements with Detection of Cleavage Fragments

The described methods can be used to investigate the effect of proteases on ion channels, receptors, and other plasma membrane proteins heterologously expressed in Xenopus laevis oocytes. In combination with site-directed mutagenesis, this approach provides a powerful tool to identify functionally relevant cleavage sites. Proteolytic activation is a characteristic feature of the amiloride-sensitive epithelial sodium channel (ENaC). The final activating step involves cleavage of the channel&#8217;s &#947;-subunit in a critical region potentially targeted by several proteases including chymotrypsin and plasmin. To determine the stimulatory effect of these serine proteases on ENaC, the amiloride-sensitive whole-cell current (&#916;Iami) was measured twice in the same oocyte before and after exposure to the protease using the two-electrode voltage-clamp technique. In parallel to the electrophysiological experiments, a biotinylation approach was used to monitor the appearance of &#947;ENaC cleavage fragments at the cell surface. Using the methods described, it was demonstrated that the time course of proteolytic activation of ENaC-mediated whole-cell currents correlates with the appearance of a &#947;ENaC cleavage product at the cell surface. These results suggest a causal link between channel cleavage and channel activation. Moreover, they confirm the concept that a cleavage event in &#947;ENaC is required as a final step in proteolytic channel activation. The methods described here may well be applicable to address similar questions for other types of ion channels or membrane proteins.

Demonstration of Proteolytic Activation of the Epithelial Sodium Channel ENaC by Combining Current Measurements with Detection of Cleavage Fragments

Proteolytic activation of the epithelial sodium channel (ENaC) heterologously expressed in Xenopus laevis oocytes can be demonstrated by combining current measurements with a biotinylation approach to investigate the appearance of ion channel cleavage products at the cell surface. Functionally important cleavage sites can be identified by using site-directed mutagenesis.

Bölünme Fragmentlerin Algılama ile Akım Ölçümleri birleştiren tarafından Epitel Sodyum Kanalı (ENaC) proteolitik Aktivasyonunun gösteri

The described methods can be used to investigate the effect of proteases on ion channels, receptors, and other plasma membrane proteins heterologously ...

Studying DNA Looping by Single-Molecule FRET

Bending of double-stranded DNA (dsDNA) is associated with many important biological processes such as DNA-protein recognition and DNA packaging into nucleosomes. Thermodynamics of dsDNA bending has been studied by a method called cyclization which relies on DNA ligase to covalently join short sticky ends of a dsDNA. However, ligation efficiency can be affected by many factors that are not related to dsDNA looping such as the DNA structure surrounding the joined sticky ends, and ligase can also affect the apparent looping rate through mechanisms such as nonspecific binding. Here, we show how to measure dsDNA looping kinetics without ligase by detecting transient DNA loop formation by FRET (Fluorescence Resonance Energy Transfer). dsDNA molecules are constructed using a simple PCR-based protocol with a FRET pair and a biotin linker. The looping probability density known as the J factor is extracted from the looping rate and the annealing rate between two disconnected sticky ends. By testing two dsDNAs with different intrinsic curvatures, we show that the J factor is sensitive to the intrinsic shape of the dsDNA.

This study presents a detailed experimental procedure to measure looping dynamics of double-stranded DNA using single-molecule Fluorescence Resonance Energy Transfer (FRET). The protocol also describes how to extract the looping probability density called the J factor.

Tek Molekül FRET DNA döngü oluşturma incelenmesi

Bending of double-stranded DNA (dsDNA) is associated with many important biological processes such as DNA-protein recognition and DNA packaging into ...

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) maintain the turnover of all mature blood cell lineages. The coordination of the complex signals leading to specific HSC fates relies upon the interaction between HSCs and the intricate bone marrow microenvironment, which is still poorly understood[1-2].
We describe how by combining a newly developed specimen holder for stable animal positioning with multi-step confocal and two-photon in vivo imaging techniques, it is possible to obtain high-resolution 3D stacks containing HSPCs and their surrounding niches and to monitor them over time through multi-point time-lapse imaging. High definition imaging allows detecting ex vivo labeled hematopoietic stem and progenitor cells (HSPCs) residing within the bone marrow. Moreover, multi-point time-lapse 3D imaging, obtained with faster acquisition settings, provides accurate information about HSPC movement and the reciprocal interactions between HSPCs and stroma cells.
Tracking of HSPCs in relation to GFP positive osteoblastic cells is shown as an exemplary application of this method. This technique can be utilized to track any appropriately labeled hematopoietic or stromal cell of interest within the mouse calvarium bone marrow space.

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

The nature of the interactions between hematopoietic stem and progenitor cells (HSPCs) and bone marrow niches is poorly understood. Custom hardware modifications and a multi-step acquisition protocol allow the use of two-photon and confocal microscopy to image ex vivo labeled HSPCs homed within bone marrow areas, tracking interactions and movement.

Yetişkin Fare Kalvaryal Kemik İliği içinde Hematopoietik kök hücrelerin Vivo 4-Boyutlu Takip

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) ...

Parallel High Throughput Single Molecule Kinetic Assay for Site-Specific DNA Cleavage

Site-specific DNA cleavage (SSDC) is a key step in many cellular processes, and it is crucial to gene editing. This work describes a kinetic assay capable of measuring SSDC in many single DNA molecules simultaneously. Bead-tethered substrate DNAs, each containing a single copy of the target sequence, are prepared in a microfluidic flow channel. An external magnet applies a weak force to the paramagnetic beads. The integrity of up to 1,000 individual DNAs can be monitored by visualizing the microbeads under darkfield imaging using a wide-field, low magnification objective. Injecting of a restriction endonuclease, NdeI, initiates the cleavage reaction. Video microscopy is used to record the exact moment of each DNA cleavage by observing the frame in which the associated bead moves up and out of the focal plane of the objective. Frame-by-frame bead counting quantifies the reaction, and an exponential fit determines the reaction rate. This method allows collection of quantitative and statistically significant data on single molecule SSDC reactions in a single experiment.

A highly parallel method for measuring the site-specific cleavage of DNA at the single molecule level is described. This protocol demonstrates the technique using the restriction endonuclease NdeI. The method can easily be modified to study any process that results in site-specific DNA cleavage.

Siteye Özgü DNA Bölünmesi için Paralel Yüksek İş Kinetik Test

Site-specific DNA cleavage (SSDC) is a key step in many cellular processes, and it is crucial to gene editing. This work describes a kinetic assay capable ...