このプロジェクトの資金は、再生医療のためのカリフォルニア工科大学によって提供した。

1. Lentivirus production, harvest, and freezing
<ol>
	<li>Consult your institutional safety official before beginning this protocol, and follow their recommended safety guidelines.</li>
	<li>Day 1. Start with healthy, rapidly growing 293T cells to produce virus. Plate the cells at 5 x 106 
	cells per 10 cm plate. Use antibiotic-free 293T medium (high-glucose DMEM with 10% FBS and 4 mM L-glutamine) for virus production.</li>
	<li>Day 2. In the late afternoon, transfect 293T cells as follows (numbers given are for one 10 cm plate). 
	Let all reagents warm up to room temperature. Pipette 375 &mu;l OptiMEM into a microcentrifuge tube, then add 25 &mu;l 
	Fugene HD. Do not allow undiluted Fugene to contact the surface of the tube.</li>
	<li>In a microcentrifuge tube, mix:
		<ul>
			<li>5 &mu;g transfer plasmid (Slc7a1, target vector, or fluorescent control vector)</li>
			<li>3.75 &mu;g packaging plasmid (pCMV-dR8.91 or psPax2)</li>
			<li>1.25 &mu;g envelope plasmid (pMD2.G for pantropic, pHCMV-EcoEnv for ecotropic)</li>
			<li>serum-free OptiMEM to 100 &mu;l</li>
		</ul>
	</li>
	<li>Combine the two tubes and incubate the mixture 20-30 minutes at room temperature.</li>
	<li>Change the medium on the 293T cells to 10 ml fresh antibiotic-free 293T medium. Add the Fugene/plasmid mix 
	drop-wise to the plate and incubate overnight at 37&deg;C, 5% CO2.</li>
	<li>Day 3. Change medium on the 293T cells to 10 ml fresh antibiotic-free 293T medium. Be gentle, 
	because 293T cells adhere only loosely and can slough off by media pipetted too forcefully onto the 
	monolayer. Incubate for two days in a humidified incubator for virus production.</li>
	<li>Day 5. Harvest virus and filter with a 0.45 mm low protein binding filter. Use immediately or dispense 
	into single-use aliquots and freeze at -80&deg;C. Frozen pantropic and ecotropic virus should be re-titered after it has 
	been stored for six months and one month, respectively.</li>
	<li>Titer the virus as follows, using cells that are relatively amenable to transduction. Transduce cells with fluorescent control virus overnight using serial dilutions (e.g. 1:10, 1:100, 1:1000) in fresh medium with 6 &mu;g/ml PB. Change to fresh medium the next day. Allow the cells two days after transduction to begin expressing the fluorescent protein, then determine the fraction of transduced cells by FACS. Calculate the titer in transforming units (TU) per ml, based on dilutions that yield &lt; 15% transduction to minimize multiple transduction events. 
	<img src="/files/ftp_upload/2822/2822eq1.jpg" alt="Equation 1" />
	</li>
</ol>
2. Transduction of human target cells with murine retrovirus receptor Slc7a1
<ol>
	<li>Select a multiplicity of infection (MOI) = 2 to ensure that most cells will be transduced. For target cells that are resistant to transduction such as HDFs, a higher MOI will be required; we dilute the viral supernatant only 1:2 to achieve transduction of a majority of the cells.</li>
	<li>Transduce target cells overnight with viral supernatant diluted in fresh culture medium with 6 &mu;g/ml PB, which increases transduction by enhancing electrostatic interaction between the virus and target cell.1 Ideally one should use a minimal volume of virus, such as 1 ml for a 35 mm plate, because diffusion is a limiting factor in transduction efficiency. </li>
	<li>Culture cells for at least 48 hours after removing virus before transducing them with ecotropic virus, in order to ensure sufficient expression of the Slc7a1 receptor.</li>
	<li>(Optional) It is possible to use blasticidin to select for stably transduced cells expressing Slc7a1, if desired. A blasticidin kill curve should be generated in advance to determine the lowest effective concentration, generally between 2 &#x2013; 10 &mu;g/ml, that kills all untransduced target cells in 7 days. About 2 days after removing the Slc7a1 virus, switch the transduced cells to medium containing blasticidin. Culture the cells in blasticidin-containing medium for 7 days, at which point all remaining cells will stably express the retrovirus receptor at which point they can be transduced with ecotropic virus as well as banked for future use as a stable Slc7a1-expressing line.</li>
</ol>
3. Polymer complex titration to determine toxicity
<ol>
	<li>Day 1. Plate cells at 5000 cells/well in a 96-well plate, allowing at least triplicate wells for each experimental group. Include untransduced cells in complete medium to provide a baseline value for healthy cells, as well as samples consisting of cells in serum-free medium to induce growth arrest as a control. In parallel, plate cells in an appropriate format (such as a 24-well plate) for microscopic or FACS-based analysis of transduction efficiency in each experimental condition.</li>
	<li>Day 2. Transduce cells in plates set up for both the MTT and FACS analyses with virus encoding GFP, at an MOI of 0.5 to transduce ~40% of target cells. Test varied concentrations of CS/PB (e.g. 50, 100, 200, 400, 600, and 800 mg/ml of each component), as well as 6 &mu;g/ml PB, to determine optimal amounts. Generate polymer complexes as described in Part 4, below.</li>
	<li>Day 3. Remove virus-containing medium and replace with fresh medium. Return the plates to a humidified incubator.</li>
	<li>Day 5. Analyze FACS plate to determine the transduction efficiency with each polymer concentration. </li>
	<li>Day 6. Remove the medium from all wells of the MTT plate and replace with 100 &mu;l MTT solution (1 mg/ml MTT in complete medium). Culture for three hours in a humidified incubator to allow MTT to be reduced in the mitochondria of metabolically active cells.</li>
	<li>Remove MTT solution and replace with 200 ml MTT solvent (0.1 N HCl, 0.1% Igepal CA-630 in isopropanol). </li>
	<li>Incubate for two hours at room temperature or until all of the purple MTT formazan precipitate is dissolved. Read the absorbance on a microplate reader at 570 nm, subtracting the background reading at 690 nm. </li>
	<li>Select the optimal polymer concentration that produces maximum enhancement of transduction, as determined by FACS, with minimal effect on metabolic activity, as determined by MTT. For HDFs, we selected 100 &mu;g/ml CS/PB based on the data shown in the Representative Results, below.</li>
</ol>
4. Ecotropic transduction with polymer complexation
<ol>
	<li>Prepare sterile-filtered stock solutions of PB and chondroitin sulfate at 20 mg/ml in water. Aliquot and store at -20&deg;C.</li>
	<li>Pipette viral supernatant into a microcentrifuge tube and dilute to the desired final concentration (e.g. MOI of 2) with fresh culture medium. Add equal volumes of PB and chondroitin sulfate (concentrations determined in step 3 above) in succession, flicking the tube to mix after each addition. The viral mixture will immediately become cloudy as precipitates form. Incubate the viral mixture at room temperature for 5 minutes to allow complex formation.</li>
	<li>Remove media from the receptor-expressing target cells, replace with the viral mix, and incubate overnight at 37&deg;C, 5% CO2. After removing the viral mix, wash the surface of the cells twice with PBS to aid in removing viral complexes. Complete removal is not necessary; we have observed no adverse effects on cell health from residual polymer complexes.</li>
</ol>
5. Verifying specificity of ecotropic transduction
<ol>
	<li>When producing ecotropic virus for the first time, it is prudent from a safety perspective to verify that the virus is unable to transduce unmodified human cells. Transduce human cells with ecotropic lentivirus at relatively high concentration (only a 1 to 2-fold dilution of viral supernatant in fresh medium) overnight with 6 &mu;g/ml PB or optimized CS/PB concentration. </li>
	<li>Remove virus-containing medium and replace with fresh medium. After incubating cells for 2 days, validate transgene expression by FACS using fluorescent vectors and/or by RT-PCR with transgene-specific primers.</li>
</ol>
6. Representative results:
Fig. 1A shows the lentivirus production process, and Fig. 1B shows transduction of human cells with ecotropic lentivirus, including pre-transduction with murine retrovirus receptor Slc7a1. For titering virus, we use a human rhabdomyosarcoma cell line stably transduced with Slc7a1 (Slc-hRMS). When using fluorescent control vectors to monitor transduction efficiency, we routinely achieve > 90% transduction efficiency of Slc-hRMS with ecotropic virus, as shown in Fig. 2A and 2B. Transduction rates of HDFs are generally lower because the cells have not been blasticidin-selected for receptor expression (Fig. 2C). Titers of ecotropic lentivirus are generally 10-20% of VSV-pseudotyped virus when measured on Slc-hRMS (Fig. 2D).
One freeze-thaw cycle reduces titer of ecotropic virus by 16 - 3%, equal to titer loss during a single freeze-thaw cycle of VSV-pseudotyped virus (p > 0.05). Contrary to previous reports,2 we observe no positive effect on virus titer from flash freezing in dry ice. Rather, we achieve higher post-thaw titers of either pseudotype by simply placing tubes of virus into a -80&deg;C freezer (data not shown). 
The MTT viability assay allows sensitive detection of growth arrest in target cells. Transduction with virus plus concentrations of CS/PB up to 800 &mu;g/ml has no effect on HDF metabolism (Fig. 3A). Exposure to CS/PB without virus also has no toxic effect on cells (data not shown). FACS analysis of HDFs transduced with virus plus various concentrations of CS/PB shows enhancement of transduction compared to PB alone (Fig. 3B). The maximum enhancement occurs at 100 &mu;g/ml CS/PB (Fig. 3C), several-fold lower than previously reported values.3 Thus, it is important to optimize conditions for any given target cell type.
Complexation with CS/PB enhances the observed titer roughly 3-fold in Slc-hRMS (Fig. 4A, p &lt; 0.01). In practice, this yields a greater effect on transduction efficiency at low virus concentrations than at higher concentrations (Fig. 4B), which is most likely due to multiply transduced cells and receptor saturation at higher virus concentrations.
Transduction with ecotropic virus is specific for cells expressing murine retrovirus receptor. When transducing unmodified human cells with ecotropic virus, we have not observed fluorescence greater than the untransduced background whether using PB or CS/PB, as shown in Fig. 5A. Microscopically, HDFs show no transduction in the absence of receptor (Fig. 5B) while pre-transduction with receptor results in fluorescent cells (Fig. 5C).
<img src="/files/ftp_upload/2822/2822fig1.jpg" alt="Figure 1" /> 
Figure 1. Schematic view of (A) the virus production process and (B) transduction of human cells with murine retrovirus receptor followed by ecotropic lentivirus.
<img src="/files/ftp_upload/2822/2822fig2.jpg" alt="Figure 2" /> 
Figure 2. High-efficiency transduction of human cells with ecotropic lentivirus encoding GFP. Cells were pre-transduced with murine retrovirus receptor Slc7a1. (A) Human rhabdomyosarcoma cell line blasticidin-selected for Slc7a1 (Slc-hRMS), transduced (blue) or untransduced (pink) with GFP. (B) Fluorescent micrograph of ecotropic-transduced Slc-hRMS (4X). (C) HDFs transduced (blue) and untransduced (pink) with ecotropic GFP lentivirus; cells were transduced with Slc7a1 two days prior to ecotropic transduction. (D) Titer of VSV-G pseudotyped and ecotropic lentivirus, measured on Slc-hRMS.
<img src="/files/ftp_upload/2822/2822fig3.jpg" alt="Figure 3" /> 
Figure 3. Optimizing chondroitin sulfate/polybrene (CS/PB) concentrations in human dermal fibroblasts. (A) Viability of HDFs measured by MTT assay after transduction in the presence of PB only or with varied concentrations of CS/PB. (B) Enhancement of transduction efficiency in HDFs by different concentrations of CS/PB, measured by FACS. (C) Quantification of transduction enhancement, showing that maximum transduction occurs at 100 &mu;g/ml CS/PB.
<img src="/files/ftp_upload/2822/2822fig4.jpg" alt="Figure 4" /> 
Figure 4. Effect of 400 &mu;g/ml CS/PB on transduction of Slc-hRMS with ecotropic lentivirus. (A) Titer enhancement, and (B) fold change in transduction rate compared to 6 &mu;g/ml polybrene alone.
<img src="/files/ftp_upload/2822/2822fig5.jpg" alt="Figure 5" /> 
Figure 5. Lack of ecotropic transduction of HDFs in the absence of murine retrovirus receptor Slc7a1. (A) FACS plot of BJ human fibroblasts, untransduced (pink) or transduced (blue) with ecotropic GFP lentivirus in both cases in the absence of receptor Slc7a1. BJ human fibroblasts transduced with ecotropic GFP lentivirus, without (B) and with (C) pre-transduction with receptor Slc7a1 (4X).

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モロニーマウス白血病ウイルス（MLV）とその受容体のmSlc7a1に基づいて組換えエコトロピックgammaretrovirusよく研究し、広く利用されていますが、マウス細胞に導入遺伝子を提供するために20年以上に渡って使用されたこと。エコトロピックgammaretrovirusは、ヒトの細胞に癌遺伝子を提供するために最近でも使用されています。細胞のリプログラミングの文脈で、人間の癌遺伝子を保有する両種性ウイルスの発生を避けるためにmSlc7a1の使用は十分に確立されている4,5しかし、レンチウイルスはgammaretrovirus上の大きな利点を提供します。レンチウイルスプレインテグレーション複合体ができるため、難治性の細胞集団、多くの場合、再プログラミングのための望ましい目標である6を含む主要な細胞を、形質導入における非分裂細胞の伝達7 レンチウイルスは、ウイルスのトロピズム、毒性、およびその他のプロパティ8 MLV -シュードエコトロピックのレンチウイルスはマウス細胞、9を形質導入するために使用されているが、ほとんどヒト細胞で使用されていないを変更するためにMLVを含むさまざまな疑似型の数十、、で生産されている。10そこで、ヒトの細胞に細胞の初期化因子を含む、既知または疑われる癌遺伝子を、提供するために、安全で効果的なコスト、および高効率車両としてMLV -シュードエコトロピックレンチウイルスの使用を提案する。 それは、このプロトコルが完全にパントロピックレンチウイルスを生成して使用する必要性を排除しないことに注意することは重要であり、むしろ、このプロトコルは、癌に関連したウイルスで自己接種可能性から研究者を絶縁、パントロピックウイルスからがん遺伝子（s）を分離。タンパク質のmSlc7a1とそのヒト相同体のhSlc7a1は遍在11はアンフォトロピックウイルスに組み込むための比較的低リスクのmSlc7a1を作る、知られている腫瘍形成またはレシピエント細胞の選択的な増殖優位性を付与する能力がないとアミノ酸トランスポーターを発現している。この追加ステップは、必要な生物学的安全性レベルの専用のウイルスまたは組織培養施設を欠いている研究室で特に有用である。 いくつかの状況でそれは完全に直接標的細胞へのプラスミドSlc7a1をトランスフェクトすることによりパントロピックウイルスの使用を排除することも可能ですが、この技術の有用なターゲットとなる多くの細胞はまた、トランスフェクションに難治性です。別の方法として、ブラストサイジン選択して細胞をSlc7a1 -形質分離する能力は、VSV - Gシュードタイプレンチウイルスはエコトロピックウイルスが多数のため、これらの細胞を形質導入する日常的に使用することができる後に受容体発現細胞のストックを生成するために一度だけ使用できることを意味します実験。研究者は関係なく、常にその親和性は、任意のレンチウイルスを操作するためのそれらの機関の安全ガイドラインに従ってください。 このプロトコルで実現さエコトロピックウイルスの力価は、以前の研究と一致で、一般的にVSV -偽型ウイルス、パントロピックウイルスの力価の10-20％、より適度に低くなる。9これらの力価が安定してSlc7a1で形質導入ヒト細胞で測定したので、下エコトロピックウイルスのための観察力価は、標的細胞の受容体遺伝子の多様な発現に部分的に原因である可能性があります。それにもかかわらず、我々のプロトコルに到達ウイルス力価は、いくつかのケースでは、ほとんどのアプリケーションにとっては十分以上であり、細胞の大部分の伝達につながる&gt;細胞の90％。 遠心分離ベー​​スの手法は一般的にウイルス粒子を濃縮するために使用されます。しかしながら、遠心分離は、数時間を必要とする感染性エアロゾルを生成し、ウイルス粒子の大幅な損失につながることができる。12を別の方法として、CS / PBとの複合体がウイルス親和性を変化させることなく伝達を強化するために使用することができる。3このメソッドは急速である（5分ほぼ観測された力価を3倍にしながら、（10 mlのウイルス当たり0.03ドル））と安価。特別な機器や独自の試薬 ​​は不要、と我々は他の細胞株での前作との契約で、CS / PBにHDFSの曝露後に最小の急性毒性を観察している。このプロトコルの13つの潜在的な欠点がいくつか微視的に見えるポリマーの複合体が付着することです。文化の中で数日間のための細胞。我々は、これらの複合体は、細胞への公然と毒性はないが、細胞のプロセスで、より微妙な影響を与えることがあるという可能性を排除できない。 ここでは、安全かつ効率的に発癌因子とヒトの細胞を形質導入するための方法論を記載している。このアプローチでは、iPS細胞を含む癌遺伝子と幹細胞生物学を研究に大変有用であるはず。

<table border="1"><tbody><tr><th>試薬の名前</th><th>会社</th><th>カタログ番号</th><th>コメント</th></tr><tr><td> pLenti6/UbC/mSlc7a1 </td><td> Addgene </td><td> 17224 </td><td>マウスMLV受容体</td></tr><tr><td> pMD2.G </td><td> Addgene </td><td> 12259 </td><td> VSV - Gエンベロープ</td></tr><tr><td>のpCMV - dR8.91 </td><td> D. Trono演習14 </td><td></td><td>パッケージングプラスミド（等価なプラスミドpsPax2がAddgeneから入手可能です、猫。番号12260） </td></tr><tr><td> pHCMV - EcoEnv </td><td> Addgene </td><td> 15802 </td><td>エコトロピック封筒</td></tr><tr><td> FUGW </td><td> Addgene </td><td> 14883 </td><td> GFPコントロールプラスミド</td></tr><tr><td> OPTIMEM </td><td>インビトロジェン</td><td> 31985 </td><td></td></tr><tr><td>トランスフェHD </td><td>ロッシュ</td><td> 04 709 705 001 </td><td></td></tr><tr><td>ヘキサジメトリンブロマイド（ポリブレン） </td><td>シグマアルドリッチ</td><td> H9268 </td><td></td></tr><tr><td>サメの軟骨からのコンドロイチン硫酸ナトリウム塩</td><td>シグマアルドリッチ</td><td> C4384 </td><td></td></tr><tr><td>ブラストサイジンS </td><td>フィッシャー</td><td> BP 2647100 </td><td></td></tr><tr><td> Methylthiazolyldiphenyl -テトラゾリウムブロマイド（MTT） </td><td>シグマアルドリッチ</td><td> M2128 </td><td></td></tr><tr><td> IGEPAL CA - 630 </td><td>シグマアルドリッチ</td><td> I3021 </td><td></td></tr></tbody></table>

transduction of human cells with polymer-complexed ecotropic lentivirus for enhanced biosafety

幹と腫瘍細胞生物学の研究は、多くの場合、検査技師のための主要な安全性の問題を上げる、もしくはそれが疑われる癌遺伝子とヒト細胞のウイルスの伝達を必要とする。彼らは非分裂細胞を含む多くの細胞型を、形質導入できるため、そのような一般的に使用されるVSV - Gシューのようなパントロピックレンチウイルスは、遺伝子機能を研究するための貴重なツールです。しかし、研究者は、より高い生物学的安全性レベルの処理要件と安全性の問題に起因する癌遺伝子をエンコードするパントロピックウイルスの生産と遠心分離を回避する場合があります。 c - MycおよびSV40ラージT抗原を含むいくつかの強力な癌遺伝子は、誘導多能性幹細胞（IPSC）の生産を高めることが知られている。他のすべての既知のIPSC誘導遺伝的変化（OCT​​4、SOX2、KLF4、NANOG、LIN28、および機能のp53の損失）も癌へのリンクを持っている、だけでなく、比較的高い安全性の懸念から、それらを作る。 これらの癌に関連したウイルスが細胞のリプロ​​グラミングと多能性を研究する上で有用であるが、それらが安全に使用する必要があります。これらの生物学的安全性の問題に対処するために、我々は、コスト削減と簡便な操作で追加の重点を置いて、エコトロピックレンチウイルスによるヒト細胞の形質導入のための方法を示しています。我々は、受容体発現ヒト細胞は、このアプローチの有効性を検証、ウイルスに暴露の90％以上を形質導入する十分に高い力価を持つエコトロピックレンチウイルスを生産している。 レンチウイルスは、多くの場合、超遠心分離によって濃縮されますが、このプロセスには数時間かかりますし、人間の生物医学研究者への感染性エアロゾルを生成することができます。別の方法として、ウイルス粒子は、より安全にコンドロイチン硫酸とポリブレン（CS / PB）との複合体によって細胞上に沈降することができます。この手法は、安定的に無視できる追加の時間とコストで、マウスレトロウイルス受容体を発現する細胞で3倍にする機能的なウイルスの力価を増加させる。ヒト皮膚線維芽細胞（HDFS）の形質導入は、最大限そのポリマー濃度は、目的の標的細胞のタイプのために滴定する必要が示唆し、以前に癌細胞株で報告された最適値に比べ約4倍低いCS / PB濃度を用いて強化されています。そこで、新たな細胞タイプにおけるポリマーの毒性のアッセイにmethylthiazolyldiphenyl -テトラゾリウムブロマイド（MTT）の使用について説明します。私たちは、最小限の急性毒性を示す、ポリマーの錯体形成またはポリブレン（PB、6μg/ ml）での標準用量のいずれかを使用してウイルスの導入後HDFSの同等の生存率を観察。 このプロトコルでは、我々は生物学的安全性のリスクを低減し、伝達率を増加させる、ヒト細胞における癌遺伝子の過剰発現のためのエコトロピックレンチウイルスの使用を説明します。我々はまた、ウイルス粒子のエアロゾル形成遠心分離を回避しながら、伝達を強化するためにポリマーの錯体化の使用を示します。

Watch this Scientific Journal Video about Transduction of Human Cells with Polymer-complexed Ecotropic Lentivirus for Enhanced Biosafety at JoVE.com

Transduction of Human Cells with Polymer-complexed Ecotropic Lentivirus for Enhanced Biosafety

レンチウイルスは、遺伝子機能を探索するための貴重な研究ツールですが、研究者は、既知または疑われる癌遺伝子をコードしてパントロピックレンチウイルスの産生を回避する場合があります。別の方法として、我々はエコトロピック受容体mSlc7a1を表現するように修正ヒト細胞でのエコトロピックレンチウイルスの使用のためのより安全なプロトコルを提示する。

強化されたバイオセーフティのためのポリマー複合エコトロピックレンチウイルスによるヒト細胞のトランスダクション

Stem and tumor cell biology studies often require viral transduction of human cells with known or suspected oncogenes, raising major safety issues for ...

transduction-human-cells-with-polymer-complexed-ecotropic-lentivirus

Research

JoVE Journal

Biology

15.0K ビュー.  University of California, Davis. レンチウイルスは、遺伝子機能を探索するための貴重な研究ツールですが、研究者は、既知または疑われる癌遺伝子をコードしてパントロピックレンチウイルスの産生を回避する場合があります。別の方法として、我々はエコトロピック受容体mSlc7a1を表現するように修正ヒト細胞でのエコトロピックレンチウイルスの使用のためのより安全なプロトコル?...

ビデオ: Transduction of Human Cells with Polymer-complexed Ecotropic Lentivirus for Enhanced Biosafety

Detection of Protein Ubiquitination

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of three enzymes. They include ubiquitin-activating enzyme E1, ubiquitin-conjugating enzyme E2, and ubiquitin ligase E3. Unlike to E1 and E2, E3 ubiquitin ligases display substrate specificity. On the other hand, numerous deubiquitylating enzymes have roles in processing polyubiquitinated proteins. Ubiquitination can result in change of protein stability, cellular localization, and biological activity. Mutations of genes involved in the ubiquitination/deubiquitination pathway or altered ubiquitin system function are associated with many different human diseases such as various types of cancer, neurodegeneration, and metabolic disorders. The detection of altered or normal ubiquitination of target proteins may provide a better understanding on the pathogenesis of these diseases. &nbsp;Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro. These protocols are also useful to detect other ubiquitin-like small molecule modification such as sumolyation and neddylation.

Ubiquitination is a key posttranslational modification carried out by a set of three enzymes. Mutations of genes involved in this modification are associated with many different human diseases. Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro.

タンパク質のユビキチン化の検出

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of ...

生物学

Generation of Induced Pluripotent Stem Cells by Reprogramming Mouse Embryonic Fibroblasts with a Four Transcription Factor, Doxycycline Inducible Lentiviral Transduction System

Using a defined set of transcription factors and cell culture conditions, Yamanaka and colleagues demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc, and Klf4 is capable of inducing pluripotency in mouse fibroblasts.1 Subsequent reports have demonstrated the utility of the doxycycline (DOX) inducible lentiviral delivery system for the generation of both primary and secondary iPS cells from a variety of other adult mouse somatic cell types.2,3
Induced pluripotent stem (iPS) cells are similar to embryonic stem (ES) cells in morphology, proliferation and ability to induce teratoma formation. Both types of cell can be used as the pluripotent starting material for the generation of differentiated cells or tissues in regenerative medicine.4-6 iPS cells also have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction.
Here we demonstrate the protocol for reprogramming mouse embryonic fibroblast (MEF) cells with the Stemgent DOX Inducible Mouse TF Lentivirus Set. We also demonstrate that the Stemgent DOX Inducible Mouse TF Lentivirus Set is capable of expressing each of the four transcription factors upon transduction into MEFs thereby inducing a pluripotent stem cell state that displays the pluripotency markers characteristic of ES cells.

The Stemgent Dox Inducible Mouse TF Lentivirus Set can reprogram mouse embryonic fibroblasts (MEFs) to induced pluripotent stem (iPS) cells. Here we demonstrate the protocol for DOX-inducible expression of mouse reprogramming transcription factors Oct4, Sox2, Klf4 and c-Myc to generate iPS colonies that express common mES pluripotency markers.

4つの転写因子とマウス胚線維芽細胞を再プログラムすることによって誘導多能性幹細胞の生成、ドキシサイクリンは、レンチウイルス伝達系の誘導性

Using a defined set of transcription factors and cell culture conditions, Yamanaka and colleagues demonstrated that retrovirus-mediated delivery and ...

Lentivirus Production

RNA interference (RNAi) is a system of gene silencing in living cells. In RNAi, genes homologous in sequence to short interfering RNAs (siRNA) are silenced at the post-transcriptional state. Short hairpin RNAs, precursors to siRNA, can be expressed using lentivirus, allowing for RNAi in a variety of cell types. Lentiviruses, such as the Human Immunodeficiency Virus, are capable to infecting both dividing and non-dividing cells. We will describe a procedure which to package lentiviruses. Packaging refers to the preparation of competent virus from DNA vectors. Lentiviral vector production systems are based on a 'split' system, where the natural viral genome has been split into individual helper plasmid constructs. This splitting of the different viral elements into four separate vectors diminishes the risk of creating a replication-capable virus by adventitious recombination of the lentiviral genome. Here, a vector containing the shRNA of interest and three packaging vectors (p-VSVG, pRSV, pMDL) are transiently transfected into human 293 cells. After at least a 48-hour incubation period, the virus containing supernatant is harvested and concentrated. Finally, virus titer is determined by reporter (fluorescent) expression with a flow cytometer.

To make lentiviruses, DNA vectors are transfected into human 293 cells. After harvest and concentrating the supernatant, virus titer is determined by fluorescence expression with a flow cytometer.

レンチウイルスの生産

RNA interference (RNAi) is a system of gene silencing in living cells. In RNAi, genes homologous in sequence to short interfering RNAs (siRNA) are ...

Generation of Induced Pluripotent Stem Cells by Reprogramming Human Fibroblasts with the Stemgent Human TF Lentivirus Set

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing the pluripotent state in mouse fibroblasts.1 The same group also reported the successful reprogramming of human somatic cells into induced pluripotent stem (iPS) cells using human versions of the same transcription factors delivered by retroviral vectors.2 Additionally, James Thomson et al. reported that the lentivirus-mediated co-expression of another set of factors (Oct4, Sox2, Nanog and Lin28) was capable of reprogramming human somatic cells into iPS cells.3
iPS cells are similar to ES cells in morphology, proliferation and the ability to differentiate into all tissue types of the body. Human iPS cells have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction. The generation of patient-specific iPS cells circumvents an important roadblock to personalized regenerative medicine therapies by eliminating the potential for immune rejection of non-autologous transplanted cells.
Here we demonstrate the protocol for reprogramming human fibroblast cells using the Stemgent Human TF Lentivirus Set. We also show that cells reprogrammed with this set begin to show iPS morphology four days post-transduction. Using the Stemolecule Y27632, we selected for iPS cells and observed correct morphology after three sequential rounds of colony picking and passaging. We also demonstrate that after reprogramming cells displayed the pluripotency marker AP, surface markers TRA-1-81, TRA-1-60, SSEA-4, and SSEA-3, and nuclear markers Oct4, Sox2 and Nanog.

We demonstrate the protocol for the generation of induced pluripotent stem cells from human somatic cells using lentivirus-mediated delivery of the human factors Oct4, Sox2, Nanog, and Lin28. Pluripotency was confirmed by morphology and the presence of embryonic stem (ES) cell-specific markers.

StemgentヒトTFのレンチセットでヒト線維芽細胞を再プログラムすることによって誘導多能性幹細胞の生成

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing ...

Differentiation of Embryonic Stem Cells into Oligodendrocyte Precursors

Oligodendrocytes are the myelinating cells of the central nervous system. For regenerative cell therapy in demyelinating diseases, there is significant interest in deriving a pure population of lineage-committed oligodendrocyte precursor cells (OPCs) for transplantation. OPCs are characterized by the activity of the transcription factor Olig2 and surface expression of a proteoglycan NG2. Using the GFP-Olig2 (G-Olig2) mouse embryonic stem cell (mESC) reporter line, we optimized conditions for the differentiation of mESCs into GFP+Olig2+NG2+ OPCs. In our protocol, we first describe the generation of embryoid bodies (EBs) from mESCs. Second, we describe treatment of mESC-derived EBs with small molecules: (1) retinoic acid (RA) and (2) a sonic hedgehog (Shh) agonist purmorphamine (Pur) under defined culture conditions to direct EB differentiation into the oligodendroglial lineage. By this approach, OPCs can be obtained with high efficiency (&gt;80%) in a time period of 30 days. Cells derived from mESCs in this protocol are phenotypically similar to OPCs derived from primary tissue culture. The mESC-derived OPCs do not show the spiking property described for a subpopulation of brain OPCs in situ. To study this electrophysiological property, we describe the generation of spiking mESC-derived OPCs by ectopically expressing NaV1.2 subunit. The spiking and nonspiking cells obtained from this protocol will help advance functional studies on the two subpopulations of OPCs.

We describe a small molecule-based protocol for differentiation of mouse embryonic stem cells into oligodendrocyte precursor cells (OPCs). This protocol generates Olig2+NG2+ OPCs with high efficiency by 30 days of differentiation. We also describe a method to generate "spiking" OPCs that can fire action potentials.

オリゴデンドロサイト前駆体に胚性幹細胞の分化

Oligodendrocytes are the myelinating cells of the central nervous system. For regenerative cell therapy in demyelinating diseases, there is significant ...

Proteomic Sample Preparation from Formalin Fixed and Paraffin Embedded Tissue

Preserved clinical material is a unique source for proteomic investigation of human disorders. Here we describe an optimized protocol allowing large scale quantitative analysis of formalin fixed and paraffin embedded (FFPE) tissue. The procedure comprises four distinct steps. The first one is the preparation of sections from the FFPE material and microdissection of cells of interest. In the second step the isolated cells are lysed and processed using 'filter aided sample preparation' (FASP) technique. In this step, proteins are depleted from reagents used for the sample lysis and are digested in two-steps using endoproteinase LysC and trypsin. 
After each digestion, the peptides are collected in separate fractions and their content is determined using a highly sensitive fluorescence measurement. Finally, the peptides are fractionated on 'pipette-tip' microcolumns. The LysC-peptides are separated into 4 fractions whereas the tryptic peptides are separated into 2 fractions. In this way prepared samples allow analysis of proteomes from minute amounts of material to a depth of 10,000 proteins. Thus, the described workflow is a powerful technique for studying diseases in a system-wide-fashion as well as for identification of potential biomarkers and drug targets.

Archival formalin fixed and paraffin embedded (FFPE) clinical samples are valuable material for investigation of diseases. Here we demonstrate a sample preparation workflow allowing in-depth proteomic analysis of microdissected FFPE tissue.

ホルマリン固定からプロテオミクスサンプル調製およびパラフィン包埋組織

Preserved clinical material is a unique source for proteomic investigation of human disorders. Here we describe an optimized protocol allowing large scale ...

Efficient Generation Human Induced Pluripotent Stem Cells from Human Somatic Cells with Sendai-virus

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs include modeling pathogenesis of human genetic diseases, autologous cell therapy after gene correction, and personalized drug screening by providing a source of patient-specific and symptom relevant cells. However, there are several hurdles to overcome, such as eliminating the remaining reprogramming factor transgene expression after human iPSCs production. More importantly, residual transgene expression in undifferentiated human iPSCs could hamper proper differentiations and misguide the interpretation of disease-relevant in vitro phenotypes. With this reason, integration-free and/or transgene-free human iPSCs have been developed using several methods, such as adenovirus, the piggyBac system, minicircle vector, episomal vectors, direct protein delivery and synthesized mRNA. However, efficiency of reprogramming using integration-free methods is quite low in most cases.
Here, we present a method to isolate human iPSCs by using Sendai-virus (RNA virus) based reprogramming system. This reprogramming method shows consistent results and high efficiency in cost-effective manner.

Here, we present our established method to reprogram human somatic cells into transgene-free human iPSCs with Sendai virus, which shows consistent outcome and enhanced efficiency.

仙台ウイルスのヒト体細胞からの効率的な次世代ヒューマン誘導多能性幹細胞

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs ...

Zinc-finger Nuclease Enhanced Gene Targeting in Human Embryonic Stem Cells

One major limitation with current human embryonic stem cell (ESC) differentiation protocols is the generation of heterogeneous cell populations.&#160;These cultures contain the cells of interest, but are also contaminated with undifferentiated ESCs, non-neural derivatives and other neuronal subtypes.&#160; This limits their use in in vitro and in vivo applications, such as in vitro modeling for drug discovery or cell replacement therapy. To help overcome this, reporter cell lines, which offer a means to visualize, track and isolate cells of interest, can be engineered.&#160;However, to achieve this in human embryonic stem cells via conventional homologous recombination is extremely inefficient.&#160;This protocol describes targeting of the Pituitary homeobox 3 (PITX3) locus in human embryonic stem cells using custom designed zinc-finger nucleases, which introduce site-specific double-strand DNA breaks, together with a PITX3-EGFP-specific DNA donor vector. Following the generation of the PITX3 reporter cell line, it can then be differentiated using published protocols for use in studies such as in vitro Parkinson&#8217;s disease modeling or cell replacement therapy.

Reporter cell lines offer a means to visualize, track and isolate cells of interest from heterogeneous populations.&#160;However, gene-targeting using conventional homologous recombination in human embryonic stem cells is extremely inefficient. Herein, we describe targeting CNS midbrain specific transcription factor PITX3 locus with EGFP using zinc-finger nuclease enhanced homologous recombination.

ヒト胚性幹細胞におけるターゲティングジンクフィンガーヌクレアーゼ遺伝子の強化

One major limitation with current human embryonic stem cell (ESC) differentiation protocols is the generation of heterogeneous cell ...

Fluorescence Imaging with One-nanometer Accuracy (FIONA)

Fluorescence imaging with one-nanometer accuracy (FIONA) is a simple but useful technique for localizing single fluorophores with nanometer precision in the x-y plane. Here a summary of the FIONA technique is reported and examples of research that have been performed using FIONA are briefly described. First, how to set up the required equipment for FIONA experiments, i.e., a total internal reflection fluorescence microscopy (TIRFM), with details on aligning the optics, is described. Then how to carry out a simple FIONA experiment on localizing immobilized Cy3-DNA single molecules using appropriate protocols, followed by the use of FIONA to measure the 36 nm step size of a single truncated myosin Va motor labeled with a quantum dot, is illustrated. Lastly, recent effort to extend the application of FIONA to thick samples is reported. It is shown that, using a water immersion objective and quantum dots soaked deep in sol-gels and rabbit eye corneas (&#62;200 &#181;m), localization precision of 2-3 nm can be achieved.

Fluorescence Imaging with One-nanometer Accuracy FIONA

Single fluorophores can be localized with nanometer precision using FIONA. Here a summary of the FIONA technique is reported, and how to carry out FIONA experiments is described.

ワンナノメートルの精度で蛍光イメージング（FIONA）

Fluorescence imaging with one-nanometer accuracy (FIONA) is a simple but useful technique for localizing single fluorophores with nanometer precision in ...

Optimal Lentivirus Production and Cell Culture Conditions Necessary to Successfully Transduce Primary Human Bronchial Epithelial Cells

In vitro culture of primary human bronchial epithelial (HBE) cells using air-liquid interface conditions provides a useful model to study the processes of airway cell differentiation and function. In the past few years, the use of lentiviral vectors for transgene delivery became common practice. While there are reports of transduction of fully differentiated airway epithelial cells with certain non-HIV pseudo-typed lentiviruses, the overall transduction efficiency is usually less than 15%. The protocol presented here provides a reliable and efficient method to produce lentiviruses and to transduce primary human bronchial epithelial cells. Using undifferentiated bronchial epithelial cells, transduction in bronchial epithelial growth media, while the cells attach, with a multiplicity of infection factor of 4 provides efficiencies close to 100%. This protocol describes, step-by-step, the preparation and concentration of high-titer lentiviral vectors and the transduction process. It discusses the experiments that determined the optimal culture conditions to achieve highly efficient transductions of primary human bronchial epithelial cells.

Primary human bronchial epithelial cells are difficult to transduce. This protocol describes the production of lentiviruses and their concentration as well as the optimal culture conditions necessary to achieve highly efficient transductions in these cells throughout differentiation to a pseudostratified epithelium.

正常に伝達する初代ヒト気管支上皮細胞に必要な最適なレンチウイルスの生産および細胞培養条件

In vitro culture of primary human bronchial epithelial (HBE) cells using air-liquid interface conditions provides a useful model to study the processes of ...