Diese Arbeit wird durch NIH GM085261 und ein Georgien Cancer Coalition Distinguished Scholar Award (zu YF) unterstützt.

<ol>
	<li>Fan, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=H1+linker+histones+are+essential+for+mouse+development+and+affect+nucleosome+spacing+in+vivo.">H1 linker histones are essential for mouse development and affect nucleosome spacing in vivo.</a> Mol. Cell Biol. 23, 4559-4572 (2003).</li><li>Woodcock, C. L., Skoultchi, A. I., Fan, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+linker+histone+in+chromatin+structure+and+function:+H1+stoichiometry+and+nucleosome+repeat+length.">Role of linker histone in chromatin structure and function: H1 stoichiometry and nucleosome repeat length.</a> Chromosome Res. 14, 17-25 (2006).</li><li>Shen, X., Gorovsky, M. 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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA-+chromatin-condensing+properties+of+rat+testes+H1a+and+H1t+compared+to+those+of+rat+liver+H1bdec;+H1t+is+a+poor+condenser+of+chromatin.">DNA- chromatin-condensing properties of rat testes H1a and H1t compared to those of rat liver H1bdec; H1t is a poor condenser of chromatin.</a> Biochemistry. 34, 15792-15801 (1995).</li><li>Orrego, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+affinity+of+mammalian+histone+H1+somatic+subtypes+for+DNA+and+chromatin.">Differential affinity of mammalian histone H1 somatic subtypes for DNA and chromatin.</a> BMC Biol. 5, 22-22 (2007).</li><li>Th'ng, J. P., Sung, R., Ye, M., Hendzel, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=H1+family+histones+in+the+nucleus.+Control+of+binding+and+localization+by+the+C-terminal+domain.">H1 family histones in the nucleus. Control of binding and localization by the C-terminal domain.</a> J. Biol. Chem. 280, 27809-27814 (2005).</li><li>Wang, Z. F., Sirotkin, A. M., Buchold, G. M., Skoultchi, A. I., Marzluff, W. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mouse+histone+H1+genes:+gene+organization+and+differential+regulation.">The mouse histone H1 genes: gene organization and differential regulation.</a> J. Mol. Biol. 271, 124-138 (1997).</li><li>Brown, D. T., Sittman, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+through+overexpression+and+tagging+of+the+variant+type+of+the+mouse+H1e+and+H1c+genes.">Identification through overexpression and tagging of the variant type of the mouse H1e and H1c genes.</a> J. Biol. Chem. 268, 713-718 (1993).</li><li>Fan, Y., Sirotkin, A., Russell, R. G., Ayala, J., Skoultchi, A. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Individual+somatic+H1+subtypes+are+dispensable+for+mouse+development+even+in+mice+lacking+the+H1(0)+replacement+subtype.">Individual somatic H1 subtypes are dispensable for mouse development even in mice lacking the H1(0) replacement subtype.</a> Mol. Cell. Biol. 21, 7933-7943 (2001).</li><li>Fan, Y., Skoultchi, A. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+analysis+of+H1+linker+histone+subtypes+and+their+functions+in+mice.">Genetic analysis of H1 linker histone subtypes and their functions in mice.</a> Methods Enzymol. 377, 85-107 (2004).</li><li>Heid, C. A., Stevens, J., Livak, K. J., Williams, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real+time+quantitative+PCR.">Real time quantitative PCR.</a> Genome Res. 6, 986-994 (1996).</li></ol>

Keine Interessenskonflikte erklärt.

Die Menge der hier vorgestellten Assays ermöglichen eine umfassende Analyse der Expression von Säugetier-Histon-Subtypen. Sorgfältig geplante und qRT-PCR-Assays bieten hochempfindliche und genaue Messungen der RNA-Nachrichten von Säugetier-Histon H1-Gene. Der kritische Teil qRT-PCR-Assays für Histon-Subtyp Gene ist die Herstellung von cDNA unter Verwendung von zufälligen Primers Reverse Transkription. mRNA der meisten Histone, einschließlich der meisten Gene H1, enthalten keine langen Poly-A-Schwanz in anderen ze...

<table border="1"><tbody><tr><td> Name des Reagenzes </td><td> Firma </td><td> Katalog-Nummer </td></tr><tr><td> RNase Zap </td><td> Applied Biosystems </td><td> AM9780 </td></tr><tr><td> Trizolreagenz </td><td> Invitrogen </td><td> 15596-018 </td></tr><tr><td> SuperScriptIII </td><td> Invitrogen </td><td> 18080-051 </td></tr><tr><td> Absolutem Ethanol </td><td> Fisher Scientific </td><td> BP2818-4 </td></tr><tr><td> IQ SYBR Green </td><td> Bio-Rad </td><td> 170-8880 </td></tr><tr><td> RNeasy Mini Kit </td><td> Qiagen </td><td> 74104 </td></tr><tr><td> Ich Deoxyribonuclease </td><td> Sigma </td><td> AMP-D1 </td></tr><tr><td> Microseal 96-well PCR-Platte </td><td> Bio-Rad </td><td> MSP-9605 </td></tr><tr><td> Microseal &#39;B&#39; Klebedichtungen </td><td> Bio-Rad </td><td> MSB-1001 </td&gt; </tr><tr><td> Saccharose </td><td> Agros Organics </td><td> AC40594 </td></tr><tr><td> Dinatriumhydrogenphosphat Heptahydrat (Na 2 HPO 4 · 7H 2 O) </td><td> Fisher Scientific </td><td> BP332 </td></tr><tr><td> Natriumchlorid (NaCl) </td><td> Amerikanischen Bioanalytische </td><td> AB01915 </td></tr><tr><td> Heptahydrat Natriumdihydrogenphosphat (NaH 2 PO 4 · 7H2O) </td><td> Fisher Scientific </td><td> BP-330 </td></tr><tr><td> HEPES </td><td> Fisher Scientific </td><td> BP310 </td></tr><tr><td> Kompletter Mini-Proteinase-Inhibitor Cocktail Tablette </td><td> Roche Applied Science </td><td> 11836153001 </td></tr><tr><td> EDTA </td><td> Sigma </td><td> E-5134 </td></tr><tr><td> Phenylmethansulfonylfluorid (PMSF) </td><td> Amerikanischen Bioanalytische </td><td> AB01620 </td></tr><tr><td> Nonidet-40 (NP-40) </td&gt; <td> Amerikanischen Bioanalytische </td><td> AB01425 </td></tr><tr><td> Kaliumchlorid (KCl) </td><td> Fisher Scientific </td><td> BP366 </td></tr><tr><td> Tris [hydroxymethyl aminomethan] </td><td> Amerikanischen Bioanalytische </td><td> AB02000 </td></tr><tr><td> Magnesiumchlorid (MgCl2) </td><td> Fisher Scientific </td><td> BP214 </td></tr><tr><td> Schwefelsäure (H2SO4) </td><td> VWR </td><td> VW3648-3 </td></tr><tr><td> Ammoniumhydroxid (NH 4 OH) </td><td> Agros Organics </td><td> AC42330 </td></tr><tr><td> Bradford-Protein-Assay </td><td> Bio-Rad </td><td> 500-0001 </td></tr><tr><td> Acetonitril </td><td> EMD </td><td> AX0145-1 </td></tr><tr><td> Trifluoressigsäure (TFA) </td><td> JTBaker </td><td> 9470-01 </td></tr></tbody></table>

expression analysis of mammalian linker-histone subtypes

Histon H1 bindet an den Nukleosomen Kernteilchen und Linker-DNA, die Erleichterung Faltung von Chromatin in Struktur höherer Ordnung. H1 ist für Säugetier-Entwicklung ein wesentlicher und reguliert die Genexpression in vivo 2-4. Unter den hoch konservierte Histon-Proteine ​​ist die Familie von H1 Linker Histonen die heterogene Gruppe. Es gibt 11 H1-Subtypen bei Säugetieren, die differentiell während der Entwicklung und in verschiedenen Zelltypen geregelt sind. Diese H1 Subtypen umfassen 5 somatischen H1s (H1a-e), der Ersatz H1 0, 4 Keimzellen spezifische H1 Subtypen und H1x 5. Das Vorhandensein von mehreren H1 Subtypen, die DNA-Bindungsaffinität und Chromatin Verdichtung Fähigkeit unterscheiden 6-9 bietet eine zusätzliche Modulation der Chromatinstruktur Funktion. Somit ist die quantitative Analyse der Expression einzelnen H1 Subtypen, sowohl von mRNA und Proteinen, zum besseren Verständnis der Regulation der höheren erforderlichenchromosomaler Struktur und Funktion. Hier beschreiben wir eine Reihe von Tests zur Analyse der Expression von einzelnen H1 Subtypen (1) ausgebildet ist. mRNA-Expression von verschiedenen Genen H1 Variante wird durch eine Reihe von hochempfindlichen und quantitative RT-PCR (qRT-PCR)-Assays, die schneller, genauer und erfordern viel weniger Proben im Vergleich zu der alternativen Ansatz der Northern-Blot-Analyse gemessen. Anders als die meisten anderen zellulären mRNA-Einträge, fehlt mRNAs für die meisten Histone, einschließlich der Mehrheit der Gene H1, eine lange polyA-Schwanz, aber auch eine Stamm-Schleifen-Struktur am 3&#39;-untranslatierten Region (UTR) 10. Daher werden cDNAs aus Gesamt-RNA durch reverse Transkription unter Verwendung von Zufallsprimern statt Oligo-dT-Primer hergestellt. Echtzeit PCR mit Primern, die an jedem H1 Subtypen (Tabelle 1) werden durchgeführt, um eine möglichst quantitative Messung der mRNA-Spiegel von einzelnen H1-Subtyp zu erhaltens. Die Expression von Housekeeping-Gene werden als Steuerelemente für Normalisierung analysiert. Die relative Häufigkeit der Proteine ​​des H1-Subtyp und Histone wird durch Umkehrphasen-Hochleistungs-Flüssigchromatographie (RP-HPLC)-Analyse von Gesamt Histone aus Säugerzellen 11-13 extrahiert wurde. Die HPLC-Methode und Elution hier beschriebenen Bedingungen geben optimale Trennungen von Maus H1-Subtypen. Durch die Quantifizierung der HPLC-Profil, berechnen wir den relativen Anteil der einzelnen Subtypen H1 H1 innerhalb der Familie, sowie Bestimmung der H1 um Nukleosomen-Verhältnis in den Zellen.

Watch this Scientific Journal Video about Expression Analysis of Mammalian Linker-histone Subtypes at JoVE.com

Expression Analysis of Mammalian Linker-histone Subtypes

Wir beschreiben eine Reihe von Tests zur Expression von H1 Linker Histonen zu analysieren. mRNA einzelner Gene H1 werden quantitativ durch zufällige Primer basieren reverse Transkription durch real-time PCR gefolgt gemessen, während Protein Quantifizierung der H1-Histone durch HPLC-Analyse erreicht wird.

Expressionsanalyse von Säugetier-Linker-Histon-Subtypen

Linker histone H1 binds to the nucleosome core particle and linker DNA, facilitating folding of chromatin into higher order structure.  H1 is essential ...

expression-analysis-of-mammalian-linker-histone-subtypes

Research

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Biology

13.7K Aufrufe.  Georgia Institute of Technology. Wir beschreiben eine Reihe von Tests zur Expression von H1 Linker Histonen zu analysieren. mRNA einzelner Gene H1 werden quantitativ durch zufällige Primer basieren reverse Transkription durch real-time PCR gefolgt gemessen, während Protein Quantifizierung der H1-Histone durch HPLC-Analyse erreicht wird.

Serie: Expression Analysis of Mammalian Linker-histone Subtypes

Bacterial Gene Expression Analysis Using Microarrays

Bakterielle Gene Expression Analysis Using Microarrays

Forschung

Biologie

The Preparation of Primary Hematopoietic Cell Cultures From Murine Bone Marrow for Electroporation

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell  electroporation system and Gene Pulser  electroporation buffer were specifically developed to transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells.This video demonstrates how to establish primary hematopoietic cell cultures from murine bone marrow, and then prepare them for electroporation in the MXcell system. We begin by isolating femur and tibia. Bone marrow from both femur and tibia are then harvested and cultures are established. Cultured bone marrow cells are then transfected and analyzed.

This procedure describes how to establish primary hematopoietic cell cultures from murine bone marrow and is followed by transfection using the Gene Pulser MXCell electroporation system.

Die Herstellung von primären hämatopoetischen Zellkulturen aus Knochenmark der Maus für die Elektroporation

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Staining of Proteins in Gels with Coomassie G-250 without Organic Solvent and Acetic Acid

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents (Methanol, Ethanol or 2-Propanol) and acetic acid are used for fixation, staining and destaining of proteins in a gel after SDS-PAGE. To speed up the procedure, heating the staining solution in the microwave oven for a short time is frequently used. This usually results in evaporation of toxic or hazardous Methanol, Ethanol or 2-Propanol and a strong smell of acetic acid in the lab which should be avoided due to safety considerations. In a protocol originally published in two patent applications by E.M. Wondrak (US2001046709 (A1), US6319720 (B1)), an alternative composition of the staining solution is described in which no organic solvent or acid is used. The CBB is dissolved in bidistilled water (60-80mg of CBB G-250 per liter) and 35 mM HCl is added as the only other compound in the staining solution. The CBB staning of the gel is done after SDS-PAGE and thorough washing of the gel in bidistilled water. By heating the gel during the washing and staining steps, the process can be finished faster and no toxic or hazardous compunds are evaporating. The staining of proteins occurs already within 1 minute after heating the gel in staining solution and is fully developed after 15-30 min with a slightly blue background that is destained completely by prolonged washing of the stained gel in bidistilled water, without affecting the stained protein bands.

A short protocol for protein staining with Coomassie Brilliant Blue (CBB) G-250 in polyacrylamide gels is described without using organic solvents or acetic acid as in the classical staining procedures with CBB.

Färbung von Proteinen in Gelen mit Coomassie G-250 ohne organische Lösungsmittel und Essigsäure

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

Mit dem Gene Pulser MXcell Elektroporation System zur Primary Cells mit hohem Wirkungsgrad zu transfizieren

Pulse-chase Analysis of N-linked Sugar Chains from Glycoproteins in Mammalian Cells

Attachment of the Glc3Man9GlcNAc2 precursor oligosaccharide to nascent polypeptides in the ER is a common modification for secretory proteins. Although this modification was implicated in several biological processes, additional aspects of its function are emerging, with recent evidence of its role in the production of signals for glycoprotein quality control and trafficking. Thus, phenomena related to N-linked glycans and their processing are being intensively investigated. Methods that have been recently developed for proteomic analysis have greatly improved the characterization of glycoprotein N-linked glycans. Nevertheless, they do not provide insight into the dynamics of the sugar chain processing involved. For this, labeling and pulse-chase analysis protocols are used that are usually complex and give very low yields. We describe here a simple method for the isolation and analysis of metabolically labeled N-linked oligosaccharides. The protocol is based on labeling of cells with [2-3H] mannose, denaturing lysis and enzymatic release of the oligosaccharides from either a specifically immunoprecipitated protein of interest or from the general glycoprotein pool by sequential treatments with endo H and N-glycosidase F, followed by molecular filtration (Amicon). In this method the isolated oligosaccharides serve as an input for HPLC analysis, which allows discrimination between various glycan structures according to the number of monosaccharide units comprising them, with a resolution of a single monosaccharide. Using this method we were able to study high mannose N-linked oligosaccharide profiles of total cell glycoproteins after pulse-chase in normal conditions and under proteasome inhibition. These profiles were compared to those obtained from an immunoprecipitated ER-associated degradation (ERAD) substrate. Our results suggest that most NIH 3T3 cellular glycoproteins are relatively stable and that most of their oligosaccharides are trimmed to Man9-8GlcNAc2. In contrast, unstable ERAD substrates are trimmed to Man6-5GlcNAc2 and glycoproteins bearing these species accumulate upon inhibition of proteasomal degradation.

We describe a method for analysis of the alteration of N-linked glycans through the early life of glycoproteins after their biosynthesis in mammalian cells. This is achieved by pulse-chase analysis of metabolically labeled glycans, enzymatic release from glycoproteins and examination by HPLC.

Pulse-Chase-Analyse von N-verknüpften Zuckerketten von Glykoproteinen in Säugerzellen

Attachment of the Glc3Man9GlcNAc2 precursor oligosaccharide to nascent polypeptides in the ER is a common modification for secretory proteins. Although ...

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

Verwendung eines automatisierten Cell Counter zu Genexpressionsstudien Simplify: siRNA Knockdown von IL-4 abhängige Genexpression in Namalwalzellen

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

Analysis of DNA Double-strand Break (DSB) Repair in Mammalian Cells

DNA double-strand breaks are the most dangerous DNA lesions that may lead to massive loss of genetic information and cell death. Cells repair DSBs using two major pathways: nonhomologous end joining (NHEJ) and homologous recombination (HR). Perturbations of NHEJ and HR are often associated with premature aging and tumorigenesis, hence it is important to have a quantitative way of measuring each DSB repair pathway. Our laboratory has developed fluorescent reporter constructs that allow sensitive and quantitative measurement of NHEJ and HR. The constructs are based on an engineered GFP gene containing recognition sites for a rare-cutting I-SceI endonuclease for induction of DSBs. The starting constructs are GFP negative as the GFP gene is inactivated by an additional exon, or by mutations. Successful repair of the I-SceI-induced breaks by NHEJ or HR restores the functional GFP gene. The number of GFP positive cells counted by flow cytometry provides quantitative measure of NHEJ or HR efficiency.

Analysis of DNA Double-strand Break DSB Repair in Mammalian Cells

This article describes GFP-based fluorescence in vivo assays that separately quantify homologous recombination and nonhomologous end joining in mammalian cells.

Die Analyse der DNA-Doppelstrang Break (DSB) Reparatur in Säugerzellen

DNA double-strand breaks are the most dangerous DNA lesions that may lead to massive loss of genetic information and cell death.  Cells repair DSBs using ...

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying potassium (referred to as GIRK) channels, which are important for regulating the excitability of neurons. There are four different mammalian GIRK channel subunits (GIRK1-GIRK4) - we focus on GIRK2 because it forms a homotetramer. Stimulation of different types of G protein-coupled receptors (GPCRs), such as the muscarinic receptor (M2R), leads to activation of GIRK channels. Alcohol also directly activates GIRK channels. We will show how to mutate one amino acid by specifically changing one or more nucleotides in the cDNA for the GIRK channel. This mutated cDNA sequence will be amplified in bacteria, purified, and the presence of the point mutation will be confirmed by DNA sequencing. The cDNAs for the mutated and wild-type GIRK channels will be transfected into human embryonic kidney HEK293T cells cultured in vitro. Lastly, whole-cell patch-clamp electrophysiology will be used to study the macroscopic potassium currents through the ectopically expressed wild-type or mutated GIRK channels. In this experiment, we will examine the effect of a L257W mutation in GIRK2 channels on M2R-dependent and alcohol-dependent activation.

We will demonstrate how to study the effect of a single point mutation on the function of an ion channel.

Mutagenese und funktionale Analyse von Ionenkanälen heterolog in Säugerzellen exprimierten

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying ...

Analysis of mRNA Nuclear Export Kinetics in Mammalian Cells by Microinjection

In eukaryotes, messenger RNA (mRNA) is transcribed in the nucleus and must be exported into the cytoplasm to access the translation machinery. Although the nuclear export of mRNA has been studied extensively in Xenopus oocytes1 and genetically tractable organisms such as yeast2 and the Drosophila derived S2 cell line3, few studies had been conducted in mammalian cells. Furthermore the kinetics of mRNA export in mammalian somatic cells could only be inferred indirectly4,5. In order to measure the nuclear export kinetics of mRNA in mammalian tissue culture cells, we have developed an assay that employs the power of microinjection coupled with fluorescent in situ hybridization (FISH). These assays have been used to demonstrate that in mammalian cells, the majority of mRNAs are exported in a splicing dependent manner6,7, or in manner that requires specific RNA sequences such as the signal sequence coding region (SSCR) 6. In this assay, cells are microinjected with either in vitro synthesized mRNA or plasmid DNA containing the gene of interest. The microinjected cells are incubated for various time points then fixed and the sub-cellular localization of RNA is assessed using FISH. In contrast to transfection, where transcription occurs several hours after the addition of nucleic acids, microinjection of DNA or mRNA allows for rapid expression and allows for the generation of precise kinetic data.

Here we describe an assay that employs the power of microinjection coupled with fluorescent in situ hybridization in order to accurately measure the nuclear export kinetics of mRNA in mammalian somatic cells.

Die Analyse der mRNA Nuclear Export Kinetics in Säugerzellen durch Mikroinjektion

In eukaryotes, messenger RNA (mRNA) is transcribed in the nucleus and must be exported into the cytoplasm to access the translation machinery. Although ...

Analysis of Cell Cycle Position in Mammalian Cells

The regulation of cell proliferation is central to tissue morphogenesis during the development of multicellular organisms. Furthermore, loss of control of cell proliferation underlies the pathology of diseases like cancer. As such there is great need to be able to investigate cell proliferation and quantitate the proportion of cells in each phase of the cell cycle. It is also of vital importance to indistinguishably identify cells that are replicating their DNA within a larger population. Since a cell&prime;s decision to proliferate is made in the G1 phase immediately before initiating DNA synthesis and progressing through the rest of the cell cycle, detection of DNA synthesis at this stage allows for an unambiguous determination of the status of growth regulation in cell culture experiments.
DNA content in cells can be readily quantitated by flow cytometry of cells stained with propidium iodide, a fluorescent DNA intercalating dye. Similarly, active DNA synthesis can be quantitated by culturing cells in the presence of radioactive thymidine, harvesting the cells, and measuring the incorporation of radioactivity into an acid insoluble fraction. We have considerable expertise with cell cycle analysis and recommend a different approach. We Investigate cell proliferation using bromodeoxyuridine/fluorodeoxyuridine (abbreviated simply as BrdU) staining that detects the incorporation of these thymine analogs into recently synthesized DNA. Labeling and staining cells with BrdU, combined with total DNA staining by propidium iodide and analysis by flow cytometry1 offers the most accurate measure of cells in the various stages of the cell cycle. It is our preferred method because it combines the detection of active DNA synthesis, through antibody based staining of BrdU, with total DNA content from propidium iodide. This allows for the clear separation of cells in G1 from early S phase, or late S phase from G2/M. Furthermore, this approach can be utilized to investigate the effects of many different cell stimuli and pharmacologic agents on the regulation of progression through these different cell cycle phases.
In this report we describe methods for labeling and staining cultured cells, as well as their analysis by flow cytometry. We also include experimental examples of how this method can be used to measure the effects of growth inhibiting signals from cytokines such as TGF-&beta;1, and proliferative inhibitors such as the cyclin dependent kinase inhibitor, p27KIP1. We also include an alternate protocol that allows for the analysis of cell cycle position in a sub-population of cells within a larger culture5. In this case, we demonstrate how to detect a cell cycle arrest in cells transfected with the retinoblastoma gene even when greatly outnumbered by untransfected cells in the same culture. These examples illustrate the many ways that DNA staining and flow cytometry can be utilized and adapted to investigate fundamental questions of mammalian cell cycle control.

Determining the cell cycle position of a population of cells, or understanding how signals affect proliferation, can be readily measured by flow cytometry using this protocol. We report a simple experimental approach to staining cells and quantifying their position in the cell cycle.

Analyse des Zellzyklus Position in Säugerzellen

The regulation of cell proliferation is central to tissue morphogenesis during the development of multicellular organisms. Furthermore, loss of control of ...