Name: differentiated mouse adipocytes in primary culture: a model of insulin resistance
Uploaded: 2023-02-17T14:00:00
Description: Watch this Scientific Journal Video about Differentiated Mouse Adipocytes in Primary Culture: A Model of Insulin Resistance at JoVE.com

We thank Daniel Mondrag&#243;n, Antonio Prado, Fernando L&#243;pez-Barrera, Mart&#237;n Garc&#237;a-Serv&#237;n, Alejandra Castilla, and Mar&#237;a Antonieta Carbajo for their technical assistance, and Jessica Gonzalez Norris for critically editing the manuscript. This protocol was supported by Consejo Nacional de Ciencia y Tecnolog&#237;a de M&#233;xico (CONACYT), Fondo Sectorial de Investigacio&#769;n para la Educacio&#769;n&#160;Grant 284771 (to Y.M.).

All rodent experiments were approved by the Bioethics Committee of the Institute of Neurobiology of the UNAM, protocol number 075.
1. Isolation of mouse adipocyte precursor cells
<ol>
	<li>Euthanize 8-10-week-old male C57BL/6 mice (e.g., by CO2&#160;inhalation and subsequent cervical dislocation) (four animals per isolation). Disinfect the mice by rubbing with 70% ethanol and obtain the adipose tissue immediately after sacrifice. 
	NOTE: After the euthanasia ...

<ol>
	<li>Elmus, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+signaling+and+insulin+resistance.">Insulin signaling and insulin resistance.</a> Journal of Investigative Medicine. 61 (1), 11-14 (2013).</li><li>Kasuga, M., Zick, Y., Blithe, D. L., Crettaz, M., Kahn, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+stimulates+tyrosine+phosphorylation+of+the+insulin+receptor+in+a+cell-free+system.">Insulin stimulates tyrosine phosphorylation of the insulin receptor in a cell-free system.</a> Nature. 298 (5875), 667-669 (1982).</li><li>Kasuga, M., Karlsson, F. A., Kahn, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+stimulates+the+phosphorylation+of+the+95,000-dalton+subunit+of+its+own+receptor.">Insulin stimulates the phosphorylation of the 95,000-dalton subunit of its own receptor.</a> Science. 215 (4529), 185-187 (1982).</li><li>Taniguchi, C. M., Emanuelli, B., Kahn, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+nodes+in+signalling+pathways:+insights+into+insulin+action.">Critical nodes in signalling pathways: insights into insulin action.</a> Nature Reviews Molecular Cell Biology. 7 (2), 85-96 (2006).</li><li>Insulin Resistance. StatPearls Available from: <a target="_blank" href="https://www.ncbi.nlm.nih.gov/books/NBK507839/">https://www.ncbi.nlm.nih.gov/books/NBK507839/</a> (2021)</li><li>Petersen, M. C., Shulm, G. 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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+does+obesity+cause+diabetes.">Why does obesity cause diabetes.</a> Cell Metabolism. 34 (1), 11-20 (2022).</li><li>Lo, K., 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=Analysis+of+in+vitro+insulin-resistance+models+and+their+physiological+relevance+to+in+vivo+diet-induced+adipose+insulin+resistance.">Analysis of in vitro insulin-resistance models and their physiological relevance to in vivo diet-induced adipose insulin resistance.</a> Cell Reports. 5 (1), 259-270 (2013).</li><li>Asterholm, I. W., 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=Adipocyte+inflammation+is+essential+for+healthy+adipose+tissue+expansion+and+remodeling.">Adipocyte inflammation is essential for healthy adipose tissue expansion and remodeling.</a> Cell Metabolism. 20 (1), 103-118 (2014).</li><li>Hotamisligil, G. S., Murray, D. L., Choy, L. N., Spiegelman, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+necrosis+factor+alpha+inhibits+signaling+from+the+insulin+receptor.">Tumor necrosis factor alpha inhibits signaling from the insulin receptor.</a> Proceedings of the National Academy of Sciences. 91 (11), 4854-4858 (1994).</li><li>Ruan, H., Hacohen, N., Golub, T. R., Parijs, L. V., Lodish, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+necrosis+factor-&#945;+suppresses+adipocyte-specific+genes+and+activates+expression+of+preadipocyte+genes+in+3T3-L1+adipocytes.+Nuclear+factor-&#954;B+activation+by+TNF-&#945;+is+obligatory.">Tumor necrosis factor-&#945; suppresses adipocyte-specific genes and activates expression of preadipocyte genes in 3T3-L1 adipocytes. Nuclear factor-&#954;B activation by TNF-&#945; is obligatory.</a> Diabetes. 51 (5), 1319-1336 (2002).</li><li>Boucher, J., Kleinridders, A., Kahn, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+receptor+signaling+in+normal+and+insulin-resistant+states.">Insulin receptor signaling in normal and insulin-resistant states.</a> Cold Spring Harbor Perspectives in Biology. 6 (1), 009191 (2014).</li><li>Hotamisligil, G. S., 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=IRS-1-mediated+inhibition+of+insulin+receptor+tyrosine+kinase+activity+in+TNF-alpha-+and+obesity-induced+insulin+resistance.">IRS-1-mediated inhibition of insulin receptor tyrosine kinase activity in TNF-alpha- and obesity-induced insulin resistance.</a> Science. 271 (5249), 665-668 (1996).</li><li>Copps, K. D., White, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+insulin+sensitivity+by+serine/threonine+phosphorylation+of+insulin+receptor+substrate+proteins+IRS1+and+IRS2.">Regulation of insulin sensitivity by serine/threonine phosphorylation of insulin receptor substrate proteins IRS1 and IRS2.</a> Diabetologia. 55 (10), 2565-2582 (2012).</li><li>Gassmann, M., Grenacher, B., Rohde, B., Vogel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+western+blots:+pitfalls+of+densitometry.">Quantifying western blots: pitfalls of densitometry.</a> Electrophoresis. 30 (11), 1845-1855 (2009).</li><li>Skurk, T., Hauner, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+culture+of+human+adipocyte+precursor+cells:+expansion+and+differentiation.">Primary culture of human adipocyte precursor cells: expansion and differentiation.</a> Methods in Molecular Biology. 806, 215-226 (2012).</li><li>Hausman, D. B., Park, H. J., Hausman, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+culture+of+preadipocytes+from+rodent+white+adipose+tissue.">Isolation and culture of preadipocytes from rodent white adipose tissue.</a> Methods in Molecular Biology. 456, 201-219 (2008).</li><li>Macotela, Y., 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=Intrinsic+differences+in+adipocyte+precursor+cells+from+different+white+fat+depots.">Intrinsic differences in adipocyte precursor cells from different white fat depots.</a> Diabetes. 61 (7), 1691-1699 (2012).</li><li>Rodeheffer, M. S., Birsoy, K., Friedman, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+white+adipocyte+progenitor+cells+in+vivo.">Identification of white adipocyte progenitor cells in vivo.</a> Cell. 135 (2), 240-249 (2008).</li><li>Hausman, D. B., DiGirolamo, M., Bartness, T. J., Hausman, G. J., Martin, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biology+of+white+adipocyte+proliferation.">The biology of white adipocyte proliferation.</a> Obesity Reviews. 2 (4), 239-254 (2001).</li><li>Kirkland, I. M., Tchkonia, T., Pirtskhalava, T., Han, J., Karagiannides, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adipogenesis+and+aging:+does+aging+make+fat+go+MAD.">Adipogenesis and aging: does aging make fat go MAD.</a> Experimental Geronotology. 37 (6), 757-767 (2002).</li><li>Guo, W., 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=Aging+results+in+paradoxical+susceptibility+of+fat+cell+progenitors+to+lipotoxicity.">Aging results in paradoxical susceptibility of fat cell progenitors to lipotoxicity.</a> American Journal of Physiology. Endocrinology and Metabolism. 292 (4), 1041-1051 (2007).</li><li>Ruan, H., Hacohen, N., Golub, T. R., Van Parijs, L., Lodish, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=F.Tumor+necrosis+factor-a+suppresses+adipocyte-specific+genes+and+activatesexpression+of+preadipocyte+genes+in+3T3-L1+adipocytes:+nuclear+factor-kappaB+activation+by+TNF-a+is+obligatory.">F.Tumor necrosis factor-a suppresses adipocyte-specific genes and activatesexpression of preadipocyte genes in 3T3-L1 adipocytes: nuclear factor-kappaB activation by TNF-a is obligatory.</a> Diabetes. 51 (5), 1319-1336 (2002).</li><li>Jager, J., Gre &#769;meaux, T., Cormont, M., Le Marchand-Brustel, Y., Tanti, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interleukin-1b-induced+insulin+resistance+in+adipocytes+throughdown-regulation+of+insulin+receptor+substrate-1+expression.">Interleukin-1b-induced insulin resistance in adipocytes throughdown-regulation of insulin receptor substrate-1 expression.</a> Endocrinology. 148 (1), 241-251 (2007).</li><li>Rotter, V., Nagaev, I., Smith, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interleukin-6+(IL-6)+induces+insulinresistance+in+3T3-L1+adipocytes+and+is,+like+IL-8+and+tumor+necrosis+factor-a,overexpressed+in+human+fat+cells+from+insulin-resistant+subjects.">Interleukin-6 (IL-6) induces insulinresistance in 3T3-L1 adipocytes and is, like IL-8 and tumor necrosis factor-a,overexpressed in human fat cells from insulin-resistant subjects.</a> The Journal of Biological Chemistry. 278 (46), 45777-45784 (2003).</li><li>Isidor, M. 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This paper provides a method for studying insulin resistance that uses primary adipocytes in culture treated with TNF-&#945;. This model has the advantage that primary adipocytes can be cultured under defined conditions for long periods of time with a tight control of cellular environmental factors26. The assay duration is 15-20 days, although variations in the percentage of differentiated adipocytes can occur between experiments. Primary adipocytes have advantages over cell lines since they have ...

Insulin is an anabolic hormone produced by pancreatic islet &#946;-cells and the key regulator of glucose and lipid metabolism. Among its many functions, insulin regulates glucose uptake, glycogen synthesis, gluconeogenesis, protein synthesis, lipogenesis, and lipolysis1. The initial molecular signal after insulin interaction with its receptor (IR) is the activation of the intrinsic tyrosine protein kinase activity of IR2, resulting in its autophosphorylation3&#160;and the subsequent activation of a family of proteins known as insulin receptor substrates (IRS), which binds to adaptor proteins leading to activation of a cascade of protein kinases4. Insulin activates two main signaling pathways: phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT)&#160;and Ras-mitogen-activated protein kinase (MAPK). The former constitutes a major branch point or node4,5&#160;for the activation of numerous downstream effectors involved in diverse physiological functions, including the regulation of fuel homeostasis, whereas the latter regulates cell growth and differentiation4,6. Insulin actions ultimately depend on the cell type and physiological context7.
One of the main insulin-responsive metabolic tissues is the adipose tissue. White adipose tissue is the most abundant type of fat in humans and rodents, distributed within subcutaneous fat (between the skin and muscles) and visceral fat (around the organs in the abdominal cavity). Given their large volume, adipocytes or fat cells are the most abundant cell type in adipose tissue. These fat cells can be brown/beige (thermogenic), pink (in the mammary gland), and white8,9. White adipocytes keep the main energy reserves in the body in the form of triglycerides, an insulin-dependent process. Insulin promotes glucose transport and lipogenesis, while it inhibits lipolysis or lipid breakdown7,10. It also facilitates the differentiation of preadipocytes into adipocytes&#160;&#8212; the mature fat-storing cells11.
Insulin resistance occurs when a normal insulin level produces an attenuated biological response, resulting in compensatory hyperinsulinemia12. Insulin resistance is a condition associated with overweight and obesity5, that when combined leads to type 2 diabetes (T2D) and other metabolic diseases13. Hyperinsulinemia compensates insulin resistance in peripheral tissues to maintain normal blood glucose levels14. However, eventual &#946;-cell loss or exhaustion, together with exacerbated insulin resistance, leads to elevated blood glucose levels consistent with T2D5. Therefore, insulin resistance and hyperinsulinemia can contribute to the development of obesity-derived metabolic diseases15. Furthermore, obesity may cause chronic low-grade local inflammation promoting insulin resistance in adipose tissue15,16,17. In addition, obesity-derived alterations in adipose tissue, such as fibrosis, inflammation, and reduced angiogenesis and adipogenesis, lead to lower adiponectin serum levels (an insulin sensitizer) and increased secretion of factors such as plasminogen activator inhibitor 1 (PAI-1), free fatty acids, and exosomes into the bloodstream, exacerbating insulin resistance17.
Many aspects underlying insulin resistance remain unknown. In vitro and in vivo models have been developed to study the mechanisms mediating insulin resistance in major target tissues, including adipose tissue. The advantage of in vitro models is that researchers have more control of the environmental conditions and can evaluate insulin resistance in specific cell types. Particularly, adipocyte precursor cells (APCs) have the individual phenotype of the donor tissue, which might reflect physiology better than adipocyte cell lines. A main factor inducing insulin resistance in vitro is tumor necrosis factor-&#945; (TNF-&#945;). TNF-&#945; is a proinflammatory cytokine secreted by adipocytes and macrophages in adipose tissue18. While it is required for proper adipose tissue remodeling and expansion19, long-term exposure to TNF-&#945; induces insulin resistance in adipose tissue in vivo and in adipocytes in vitro20. Chronic TNF-&#945; treatment of several cell types leads to increased serine phosphorylation of both IR and IRS-1, thereby promoting decreased tyrosine phosphorylation21. Increased phosphorylation of IRS-1 on serine residues inhibits the IR tyrosine kinase activity and may be one of the key mechanisms by which chronic TNF-&#945; treatment impairs insulin action22,23. TNF-&#945; activates pathways involving the serine/threonine kinase inhibitor of nuclear factor &#312;B kinase &#946; (IKK&#946;) and c-Jun N terminal kinase (JNK)24. JNK induces a complex proinflammatory transcriptional program but also directly phosphorylates IRS-16.
Understanding the pathogenesis of insulin resistance has become increasingly important to guide the development of future therapies against T2D. APCs have proven to be an excellent model for the study of fat cell biology, including the sensitivity and resistance to insulin, and for identifying the intrinsic properties of adipocytes independent of the systemic environment. APCs can be easily obtained from different adipose depots, and under the appropriate conditions, differentiated into mature adipocytes. With this method, direct effects on insulin resistance/sensitivity can be evaluated in adipocytes.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1. Isolation mouse adipocyte precursor cells</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ACK lysing buffer&#160;</td>
			<td>LONZA</td>
			<td>10-548E</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Biotin Microbeads&#160;</td>
			<td>Miltenyi</td>
			<td>130-090-485</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-CD31</td>
			<td>eBioscience</td>
			<td>13-0311-85</td>
			<td></td>
		</tr>
		<tr>
			<td>AutoMACS Pro Separator</td>
			<td>Miltenyi</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Basement membrane matrix (matrigel)</td>
			<td>Corning</td>
			<td>354234</td>
			<td></td>
		</tr>
		<tr>
			<td>bFGF</td>
			<td>Sigma</td>
			<td>F0291</td>
			<td>Growth factor</td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>Equitech-Bio, Inc.</td>
			<td>BAC63-1000</td>
			<td></td>
		</tr>
		<tr>
			<td>CD45 Monoclonal Antibody (30-F11) - Biotin&#160;</td>
			<td>eBioscience</td>
			<td>13-0451-85</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase, Type 1</td>
			<td>Worthington Biochem</td>
			<td>LS004197</td>
			<td></td>
		</tr>
		<tr>
			<td>Dexamethasone</td>
			<td>Sigma</td>
			<td>D1756</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>GIBCO</td>
			<td>12800017</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM low glucose</td>
			<td>GIBCO</td>
			<td>31600-034</td>
			<td></td>
		</tr>
		<tr>
			<td>EGF</td>
			<td>Peprotech</td>
			<td>315-09</td>
			<td>Growth factor</td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>GIBCO</td>
			<td>26140-079</td>
			<td></td>
		</tr>
		<tr>
			<td>ITS mix</td>
			<td>Sigma</td>
			<td>I3146</td>
			<td></td>
		</tr>
		<tr>
			<td>L-ascorbic acid 2-phosphate</td>
			<td>Sigma</td>
			<td>A8960</td>
			<td></td>
		</tr>
		<tr>
			<td>LIF</td>
			<td>Millipore</td>
			<td>ESG1107</td>
			<td>Growth factor</td>
		</tr>
		<tr>
			<td>Linoleic acid-albumin</td>
			<td>Sigma</td>
			<td>L9530</td>
			<td></td>
		</tr>
		<tr>
			<td>MCDB 201 medium</td>
			<td>Sigma</td>
			<td>M6770</td>
			<td></td>
		</tr>
		<tr>
			<td>Normocin</td>
			<td>InvivoGen</td>
			<td>ant-nr-2</td>
			<td></td>
		</tr>
		<tr>
			<td>PDGF-BB&#160;</td>
			<td>Peprotech</td>
			<td>315-18</td>
			<td>Growth factor</td>
		</tr>
		<tr>
			<td>Peniciline-Streptomycine</td>
			<td>BioWest</td>
			<td>L0022-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Pre-Separation Filters (70 &#181;m)</td>
			<td>Miltenyi</td>
			<td>130-095-823</td>
			<td></td>
		</tr>
		<tr>
			<td>Purified Rat Anti-Mouse CD16 / CD32&#160;</td>
			<td>BD Pharmingen</td>
			<td>553142</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA&#160;</td>
			<td>GIBCO</td>
			<td>25300062</td>
			<td></td>
		</tr>
		<tr>
			<td>2. Adipocyte differentiation and insulin resistance induction</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>3-Isobutyl-1-methylxanthine [IBMX]</td>
			<td>Sigma</td>
			<td>I5879</td>
			<td>Differentiation cocktail</td>
		</tr>
		<tr>
			<td>BMP4</td>
			<td>R&#38;D Systems</td>
			<td>5020-BP-010</td>
			<td>Differentiation cocktail</td>
		</tr>
		<tr>
			<td>Dexamethasone</td>
			<td>Sigma</td>
			<td>D1756</td>
			<td>Differentiation cocktail</td>
		</tr>
		<tr>
			<td>Insulin</td>
			<td>Sigma</td>
			<td>I9278</td>
			<td></td>
		</tr>
		<tr>
			<td>Rosiglitazone</td>
			<td>Cayman</td>
			<td>71742</td>
			<td>Differentiation cocktail</td>
		</tr>
		<tr>
			<td>TNF&#945;</td>
			<td>R&#38;D Systems</td>
			<td>210-TA-005&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>3. Evaluation of insulin signaling pathway by western blot</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-beta tubulin antibody</td>
			<td>Abcam</td>
			<td>ab6046</td>
			<td></td>
		</tr>
		<tr>
			<td>Bromophenol blue</td>
			<td>BioRad</td>
			<td>161-0404</td>
			<td>Laemmli buffer</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma</td>
			<td>E5134</td>
			<td>RIPA buffer</td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma</td>
			<td>E4378</td>
			<td>RIPA buffer</td>
		</tr>
		<tr>
			<td>FluorChem E system</td>
			<td>ProteinSimple</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma</td>
			<td>G6279</td>
			<td>Laemmli buffer</td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Sigma</td>
			<td>G7126</td>
			<td>Running and Transfer buffer</td>
		</tr>
		<tr>
			<td>Igepal</td>
			<td>Sigma</td>
			<td>I3021</td>
			<td>RIPA buffer</td>
		</tr>
		<tr>
			<td>2- mercaptoethanol</td>
			<td>Sigma</td>
			<td>M3148</td>
			<td>Laemmli buffer</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>JT Baker</td>
			<td>907007</td>
			<td>Transfer buffer</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>JT Baker</td>
			<td>3624-05</td>
			<td>TBS-T</td>
		</tr>
		<tr>
			<td>NaF</td>
			<td>Sigma</td>
			<td>77F-0379</td>
			<td>RIPA buffer</td>
		</tr>
		<tr>
			<td>NaOH&#160;</td>
			<td>JT Baker</td>
			<td>3722-19</td>
			<td></td>
		</tr>
		<tr>
			<td>Na4P2O7</td>
			<td>Sigma</td>
			<td>114F-0762</td>
			<td>RIPA buffer</td>
		</tr>
		<tr>
			<td>Na3VO4</td>
			<td>Sigma</td>
			<td>S6508</td>
			<td>RIPA buffer</td>
		</tr>
		<tr>
			<td>Nitrocellulose membrane&#160;</td>
			<td>BioRad</td>
			<td>1620112</td>
			<td></td>
		</tr>
		<tr>
			<td>Nonfat dry milk</td>
			<td>BioRad</td>
			<td>1706404</td>
			<td>Blocking solution</td>
		</tr>
		<tr>
			<td>Prestained protein standard&#160;</td>
			<td>BioRad</td>
			<td>1610395</td>
			<td></td>
		</tr>
		<tr>
			<td>Protease inhibitor cocktail&#160;</td>
			<td>Sigma</td>
			<td>P8340-5ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Peroxidase AffiniPure Donkey Anti-Rabbit IgG (H+L)&#160;</td>
			<td>Jackson ImmunoResearch</td>
			<td>711-035-132</td>
			<td></td>
		</tr>
		<tr>
			<td>Phospho- Insulin Receptor &#946;&#160;</td>
			<td>Cell signaling</td>
			<td>3024</td>
			<td></td>
		</tr>
		<tr>
			<td>Phospho-Akt (Ser473) Antibody</td>
			<td>Cell signaling</td>
			<td>9271</td>
			<td></td>
		</tr>
		<tr>
			<td>Phospho-IRS1 (Tyr608) antibody</td>
			<td>Millipore</td>
			<td>9432</td>
			<td></td>
		</tr>
		<tr>
			<td>Saccharose&#160;</td>
			<td>JT Baker</td>
			<td>407205</td>
			<td>RIPA buffer</td>
		</tr>
		<tr>
			<td>SDS</td>
			<td>BioRad</td>
			<td>1610302</td>
			<td>Running and laemmli buffer</td>
		</tr>
		<tr>
			<td>SuperSignal West Pico PLUS Chemiluminescent Substrate</td>
			<td>Thermo Scientific</td>
			<td>34577</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris-base</td>
			<td>Promega</td>
			<td>H5135</td>
			<td>Running, transfer and laemmli buffer</td>
		</tr>
		<tr>
			<td>Tris-HCl</td>
			<td>JT Baker</td>
			<td>4103-02</td>
			<td>RIPA buffer - TBS</td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>Sigma</td>
			<td>P1379</td>
			<td>TBS-T</td>
		</tr>
	</tbody>
</table>

differentiated mouse adipocytes in primary culture: a model of insulin resistance

Insulin resistance is a reduced effect of insulin on its target cells, usually derived from decreased insulin receptor signaling. Insulin resistance contributes to the development of type 2 diabetes (T2D) and other obesity-derived diseases of high prevalence worldwide. Therefore, understanding the mechanisms underlying insulin resistance is of great relevance. Several models have been used to study insulin resistance both in vivo and in vitro; primary adipocytes represent an attractive option to study the mechanisms of insulin resistance and identify molecules that counteract this condition and the molecular targets of insulin-sensitizing drugs. Here, we have established an insulin resistance model using primary adipocytes in culture treated with tumor necrosis factor-&#945; (TNF-&#945;).
Adipocyte precursor cells (APCs), isolated from collagenase-digested mouse subcutaneous adipose tissue by magnetic cell separation technology, are differentiated into primary adipocytes. Insulin resistance is then induced by treatment with TNF-&#945;, a proinflammatory cytokine that reduces the tyrosine phosphorylation/activation of members of the insulin signaling cascade. Decreased phosphorylation of insulin receptor (IR), insulin receptor substrate (IRS-1), and protein kinase B (AKT) are quantified by western blot. This method provides an excellent tool to study the mechanisms mediating insulin resistance in adipose tissue.

Over the last few years, the increased prevalence of obesity and T2D has prompted an intense search for the mechanisms mediating insulin resistance in adipose tissue. With the protocol described here, APCs can be differentiated into mature adipocytes to evaluate insulin resistance and sensitivity. Once the APCs reach confluence, it takes 10 days to complete their differentiation into mature adipocytes and their TNF-&#945;-mediated induction of insulin resistance (Figure 1).
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Watch this Scientific Journal Video about Differentiated Mouse Adipocytes in Primary Culture: A Model of Insulin Resistance at JoVE.com

Differentiated Mouse Adipocytes in Primary Culture: A Model of Insulin Resistance

This protocol describes the isolation of mouse preadipocytes from subcutaneous fat, their differentiation into mature adipocytes, and the induction of insulin resistance. Insulin action is evaluated by the phosphorylation/activation of members of the insulin signaling pathway through western blot. This method allows direct determination of insulin resistance/sensitivity in primary adipocytes.

Insulin resistance is a reduced effect of insulin on its target cells, usually derived from decreased insulin receptor signaling. Insulin resistance ...

Insulin resistance can be evaluated in primary adipocytes, allowing the study of donors under different physiopathological contexts, such as lean versus obese, or cells from different fat depos. Primary adipocytes retain many of their intrinsic properties and can be cultured under defined conditions for a long period of time, with a tight control of cellular environmental factors. To start the differentiation process, cells must be at 80%confluence.If differentiation starts at a lower or higher confluence, cells will differentiate less or lose their differentiation capacity. After sacrificing the animal, disinfect the mice by rubbing with 70%ethanol. Dissect the inguinal subcutaneous adipose tissue from each mouse and collect it in a 15-milliliter conical tube, containing 15 milliliters of type one collagenase solution on ice.Cut the adipose tissue into small pieces with sterile surgical scissors and digest the samples by incubation with type one collagenase solution at 37 degrees Celsius in an orbital shaker at 150 RPM for 30 minutes. Check the digestion every 10 minutes to ensure it works, and to prevent over digestion. Filter using a 200-micrometer mesh syringe to eliminate the tissue not digested with collagenase, and pass the filter over the edge of the tube to drain as many cells as possible into the solution.Add 15 milliliters of cold DMEM 1%BSA to stop digestion, and centrifuge at 400 G for 10 minutes at four degrees Celsius. Aspirate the top layer containing mature adipocytes and most of the liquid layer. Add 20 milliliters of cold PBS 2%FBS to it and resuspend the pellet.After centrifuging again for five minutes, remove the supernatant by aspirating the upper layer to eliminate the remaining adipocytes and fat. Resuspend the pellet in one milliliter of ACK lysing buffer. Incubate on ice for five minutes.Add 10 milliliters of PBS 2%FBS and mix it. After centrifuging for five minutes and aspirating the supernatant, resuspend the pellet in 200 microliters of anti-FC solution. Incubate on ice for five minutes and transfer the cell suspension to a five-milliliter tube that fits into the pre-chilled racks of a magnetic cell separator.After centrifuging for five minutes and eliminating the supernatant, add 200 microliters of the mixture of CD 31 monoclonal antibody biotin and CD 45 monoclonal antibody biotin to it. Mix well and incubate on ice for 15 minutes. Then add 400 microliters of PBS 2%FBS and centrifuge again at 400 G for five minutes at four degrees Celsius.Aspirate the supernatant and incubate it in 100 microliters of anti-biotin microbeads for 15 minutes on ice. Add 400 microliters of PBS 2%FBS and centrifuge again at 400 G for five minutes at four degrees Celsius, as shown previously. After discarding the supernatant, resuspend the pellet in 350 microliters of PBS 2%FBS.To remove the cell aggregates, or large particles, from the single cell-suspensions with a 70-micrometer pre-separation filter, activate the filter with 100 microliters of PBS 2%FBS. Pass the cell suspension through the filter, and collect it in a clean tube. Then wash the filter with 100 microliters of PBS 2%FBS.To perform magnetic separation of cells using the negative separation strategy, place the sample in position A of the chilled rack and two empty tubes in positions B and C to recover the non-labeled and labeled cells. Then load the washing buffer and running buffer into the corresponding bottles. In the separation section, select the number of samples to be separated and select the deplete protocol.Press run and start the separation. At the end of the program, recover the unlabeled cells. Next, coat a 12-well plate with basement membrane matrix by adding 400 microliters of 2.5%basement membrane matrix to cover the entire surface of each well.Remove the excess solution and let the plate dry inside the laminar flow hood for at least one hour. After centrifuging for five minutes and discarding the supernatant, resuspend the pellet in 500 microliters of growth medium. Seed the adipocyte precursor cells, or APCs, in one well of the 12-well plate previously coated with 2.5%basement membrane matrix.Incubate at 37 degrees Celsius in a 5%carbon dioxide atmosphere, and change the medium every 48 hours until the cells reach 80%confluence. After removing the medium completely, wash the cells with 350 microliters of PBS 2%FBS. Harvest the cells with 350 microliters of 0.05%tripsin EDTA for two minutes at 37 degrees Celsius, and add two milliliters of growth medium.Collect the cells in a new 50-milliliter conical tube and centrifuge at 400 G for five minutes. Passage the APCs to 12-well plates, previously coated with 2.5%basement membrane matrix, and incubate at 37 degrees Celsius with 5%carbon dioxide. Change the medium every 48 hours until cells reach 80%confluence.At 80%confluence, aspirate off any growth medium and replace it with 500 microliters of differentiation medium, containing 3.3 nanomolar bone morphogenetic protein in each well. After 48 hours, replace the medium with 500 microliters per well differentiation medium, and the differentiation cocktail. Remove the medium 72 hours later and add 100 nanomolar of insulin in 500 microliters of fresh differentiation medium.48 hours later, induce insulin resistance with four nanograms per milliliter of tumor necrosis factor alpha, or TNF alpha. Aspirate off any differentiation medium and replace it with 500 microliters of simple medium 2%FBS with TNF alpha. After incubating for 24 hours, add four nanograms per milliliter of TNF alpha in a simple medium 0%FBS.Activate the insulin signaling pathway 24 hours later by adding 100 nanomolar insulin and incubate for 15 minutes at 37 degrees Celsius in a 5%carbon dioxide atmosphere, as shown earlier. After incubation, remove the medium and wash with 500 microliters of PBS, include a control well without the insulin treatment. Extract protein and measure the phosphorylation of insulin-signaling markers by Western blot.Subcutaneous adipocyte precursor cells at 80%confluence prior to inducing differentiation in the 12-well culture plates, and primary adipocytes after seven days of inducing differentiation are shown in this figure. The insulin resistance induced by TNF alpha in subcutaneous primary adipocytes was demonstrated by decreased insulin-induced phosphorylation of insulin receptor, insulin receptor substrate one, and protein kinase B or AKT. The membrane was probed with anti-phosphorylated insulin receptor, anti-phosphorylated insulin receptor substrate one, anti-phosphorylated AKT, and anti-beta tubulin was used as a loading control.The signal was visualized with chemiluminescence detection. The representative blots and the quantification from three independent experiments are shown here. When attempting this procedure, one thing that needs to be taken care of is that the induction of insulin resistance with TNF alpha is with 2%FBS for 24 hours and with 0%FBS for the last 24 hours.

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Research

JoVE Journal

Biology

Primary Culture and Plasmid Electroporation of the Murine Organ of Corti. 

In all mammals, the sensory epithelium for audition is located along the spiraling organ of Corti that resides within the conch shaped cochlea of the inner ear (fig 1). Hair cells in the developing cochlea, which are the mechanosensory cells of the auditory system, are aligned in one row of inner hair cells and three (in the base and mid-turns) to four (in the apical turn) rows of outer hair cells that span the length of the organ of Corti. Hair cells transduce sound-induced mechanical vibrations of the basilar membrane into neural impulses that the brain can interpret. Most cases of sensorineural hearing loss are caused by death or dysfunction of cochlear hair cells.
An increasingly essential tool in auditory research is the isolation and in vitro culture of the organ explant 1,2,9. Once isolated, the explants may be utilized in several ways to provide information regarding normative, anomalous, or therapeutic physiology. Gene expression, stereocilia motility, cell and molecular biology, as well as biological approaches for hair cell regeneration are examples of experimental applications of organ of Corti explants.
This protocol describes a method for the isolation and culture of the organ of Corti from neonatal mice. The accompanying video includes stepwise directions for the isolation of the temporal bone from mouse pups, and subsequent isolation of the cochlea, spiral ligament, and organ of Corti. Once isolated, the sensory epithelium can be plated and cultured in vitro in its entirety, or as a further dissected micro-isolate that lacks the spiral limbus and spiral ganglion neurons. Using this method, primary explants can be maintained for 7-10 days. As an example of the utility of this procedure, organ of Corti explants will be electroporated with an exogenous DsRed reporter gene. This method provides an improvement over other published methods because it provides reproducible, unambiguous, and stepwise directions for the isolation, microdissection, and primary culture of the organ of Corti.

Primary Culture and Plasmid Electroporation of the Murine Organ of Corti.

This procedure describes a method for the isolation and culture of the murine organ of Corti with or without the spiral limbus and spiral ganglion neurons. We also demonstrate a method for the expression of an exogenous reporter gene in the organ of Corti explant by electroporation.

In all mammals, the sensory epithelium for audition is located along the spiraling organ of Corti that resides within the conch shaped cochlea of the ...

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Human cancer and response to therapy is better represented in orthotopic animal models. This paper describes the development of an orthotopic mouse model of ovarian cancer, treatment of cancer via oral delivery of drugs, and monitoring of tumor cell behavior in response to drug treatment in real time using in vivo imaging system. In this orthotopic model, ovarian tumor cells expressing luciferase are applied topically by injecting them directly into the mouse bursa where each ovary is enclosed. Upon injection of D-luciferin, a substrate of firefly luciferase, luciferase-expressing cells generate bioluminescence signals. This signal is detected by the in vivo imaging system and allows for a non-invasive means of monitoring tumor growth, distribution, and regression in individual animals. Drug administration via oral gavage allows for a maximum dosing volume of 10 mL/kg body weight to be delivered directly to the stomach and closely resembles delivery of drugs in clinical treatments. Therefore, techniques described here, development of an orthotopic mouse model of ovarian cancer, oral delivery of drugs, and in vivo imaging, are useful for better understanding of human ovarian cancer and treatment and will improve targeting this disease.

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Orthotopic animal models of ovarian cancer replicate better human disease and therefore enhance our understanding of cancer progression and tumor response to therapy. A mouse model receives an intrabursal injection of luciferase-expressing ovarian tumor cells. Treatment is administered via oral gavage. Tumor growth is monitored by in vivo imaging system.

Human cancer and response to therapy is better represented in orthotopic animal models.  This paper describes the development of an orthotopic mouse model ...

Isolation and Primary Culture of Rat Hepatic Cells

Primary hepatocyte culture is a valuable tool that has been extensively used in basic research of liver function, disease, pathophysiology, pharmacology and other related subjects. The method based on two-step collagenase perfusion for isolation of intact hepatocytes was first introduced by Berry and Friend in 1969 1 and, since then, has undergone many modifications. The most commonly used technique was described by Seglenin 1976 2. Essentially, hepatocytes are dissociated from anesthetized adult rats by a non-recirculating collagenase perfusion through the portal vein. The isolated cells are then filtered through a 100 &mu;m pore size mesh nylon filter, and cultured onto plates. After 4-hour culture, the medium is replaced with serum-containing or serum-free medium, e.g. HepatoZYME-SFM, for additional time to culture. These procedures require surgical and sterile culture steps that can be better demonstrated by video than by text. Here, we document the detailed steps for these procedures by both video and written protocol, which allow consistently in the generation of viable hepatocytes in large numbers.

Primary hepatocytes provide a valuable tool to evaluate biochemical, molecular, and metabolic functions in a physiologically relevant experimental system. We describe a reliable protocol for rat in situ liver perfusion, which consistently generates viable hepatocytes up to 1.0 &times; 108 cells per preparation with cell viability between 88 ~ 96%.

Primary hepatocyte culture is a valuable tool that has been extensively used in basic research of liver function, disease, pathophysiology, pharmacology ...

Isolation and Culture of Mouse Primary Pancreatic Acinar Cells

This protocol permits rapid isolation (in less than 1 hr) of murine pancreatic acini, making it possible to maintain them in culture for more than one week. More than 20 x 106 acinar cells can be obtained from a single murine pancreas. This protocol offers the possibility to independently process as many as 10 pancreases in parallel. Because it preserves acinar architecture, this model is well suited for studying the physiology of the exocrine pancreas in vitro in contrast to cell lines established from pancreatic tumors, which display many genetic alterations resulting in partial or total loss of their acinar differentiation.

In this publication, we describe a rapid and convenient procedure for isolating and culturing primary pancreatic acinar cells from the murine pancreas. This method constitutes a valuable approach to study the physiology of fresh primary normal/untransformed exocrine pancreatic cells.

This protocol permits rapid isolation (in less than 1 hr) of murine pancreatic acini, making it possible to maintain them in culture for more than one ...

A Video Protocol of Retroviral Infection in Primary Intestinal Organoid Culture

Lgr5-positive stem cells can be supplemented with the essential growth factors Egf, Noggin, and R-Spondin, which allows us to culture ever-expanding primary 3D epithelial structures in vitro. Both the architecture and physiological properties of these &#39;mini-guts&#39;, also called organoids, closely resemble their in vivo counterparts. This makes them an attractive model system for the small intestinal epithelium. Using retroviral transduction, functional genetics can now be performed by conditional gene overexpression or knockdown. This video demonstrates the procedure of organoid culture, the generation of retroviruses, and the retroviral transduction of organoids to assist phenotypic analysis of the small intestinal epithelium in vitro. This novel organotypic model system in combination with retroviral mediated gene expression provides a valuable tool for rapid analysis of gene function in vitro without the need of costly and time-consuming generation for transgenic animals.

This protocol explains primary Lgr5-positve organoid culture and the subsequent performance of retroviral transduction. This enables Cre-inducible overexpression or knockdown of the delivered transgene and allows functional studies to be carried out in the novel in vitro organotypic model system.

Lgr5-positive stem cells can be supplemented with the essential growth factors Egf, Noggin, and R-Spondin, which allows us to culture ever-expanding ...

Isolation and Primary Culture of Mouse Aortic Endothelial Cells

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an important model for cardiovascular disease research. This study demonstrates a simple method to isolate and culture endothelial cells from the mouse aorta without any special equipment. To isolate endothelial cells, the thoracic aorta is quickly removed from the mouse body, and the attached adipose tissue and connective tissue are removed from the aorta. The aorta is cut into 1 mm rings. Each aortic ring is opened and seeded onto a growth factor reduced matrix with the endothelium facing down. The segments are cultured in endothelial cell growth medium for about 4 days. The endothelial sprouting starts as early as day 2. The segments are then removed and the cells are cultured continually until they reach confluence. The endothelial cells are harvested using neutral proteinase and cultured in endothelial cell growth medium for another two passages before being used for experiments. Immunofluorescence staining indicated that after the second passage the majority of cells were double positive for Dil-ac-LDL uptake, Lectin binding, and CD31 staining, the typical characteristics of endothelial cells. It is suggested that cells at the second to third passages are suitable for in vitro and in vivo experiments to study the endothelial biology. Our protocol provides an effective means of identifying specific cellular and molecular mechanisms in endothelial cell physiopathology.

The vascular endothelial cells play a significant role in many important cardiovascular disorders. This article describes a simple method to isolate and expand endothelial cells from the mouse aorta without using any special equipment. Our protocol provides an effective means of identifying mechanisms in endothelial cell physiopathology.

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an ...

Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the Nucleoskeleton and Cytoskeleton (LINC complexes). These protein scaffolds span the nuclear envelope and connect the interior of the nucleus to components of the surrounding cytoplasmic cytoskeleton. LINC complexes consist of two evolutionary-conserved protein families, Sun proteins and Nesprins that harbor C-terminal molecular signature motifs called the SUN and KASH domains, respectively. Sun proteins are transmembrane proteins of the inner nuclear membrane whose N-terminal nucleoplasmic domain interacts with the nuclear lamina while their C-terminal SUN domains protrudes into the perinuclear space and interacts with the KASH domain of Nesprins. Canonical Nesprin isoforms have a variable sized N-terminus that projects into the cytoplasm and interacts with components of the cytoskeleton. This protocol describes the validation of a dominant-negative transgenic mouse strategy that disrupts endogenous SUN/KASH interactions in a cell-type specific manner. Our approach is based on the Cre/Lox system that bypasses many drawbacks such as perinatal lethality and cell nonautonomous phenotypes that are associated with germline models of LINC complex inactivation. For this reason, this model provides a useful tool to understand the role of LINC complexes during development and homeostasis in a wide array of tissues.

Nuclear envelope proteins play a central role in many basic biological processes and have been implicated in a variety of human diseases. This protocol describes a new Cre/Lox-based mouse model that allows for the spatiotemporal control of LINC complexes disruption.

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the ...

Glucose Uptake Measurement and Response to Insulin Stimulation in In Vitro Cultured Human Primary Myotubes

Skeletal muscle is the largest glucose deposit in mammals and largely contributes to glucose homeostasis. Assessment of insulin sensitivity of muscle cells is of major relevance for all studies dedicated to exploring muscle glucose metabolism and characterizing metabolic alterations. In muscle cells, glucose transporter type 4 (GLUT4) proteins translocate to the plasma membrane in response to insulin, thus allowing massive entry of glucose into the cell. The ability of muscle cells to respond to insulin by increasing the rate of glucose uptake is one of the standard readouts to quantify muscle cell sensitivity to insulin. Human primary myotubes are a suitable in vitro model, as the cells maintain many features of the donor phenotype, including insulin sensitivity. This in vitro model is also suitable for the test of any compounds that could impact insulin responsiveness. Measurements of the glucose uptake rate in differentiated myotubes reflect insulin sensitivity.
In this method, human primary muscle cells are cultured in vitro to obtain differentiated myotubes, and glucose uptake rates with and without insulin stimulation are measured. We provide a detailed protocol to quantify passive and active glucose transport rates using radiolabeled [3H] 2-deoxy-D-Glucose ([3H]2dG). Calculation methods are provided to quantify active basal and insulin-stimulated rates, as well as stimulation fold.

Glucose Uptake Measurement and Response to Insulin Stimulation in In Vitro Cultured Human Primary Myotubes

In this method, human primary muscle cells are cultured in vitro to obtain differentiated myotubes and glucose uptake rates are measured. We provide a detailed protocol to quantify rates in basal and insulin-stimulated states using radiolabeled [3H] 2-deoxy-D-Glucose.

Skeletal muscle is the largest glucose deposit in mammals and largely contributes to glucose homeostasis. Assessment of insulin sensitivity of muscle ...

Isolation and Culture of Primary Mouse Keratinocytes from Neonatal and Adult Mouse Skin

The keratinocyte (KC) is the predominant cell type in the epidermis, the outermost layer of the skin. Epidermal KCs play a critical role in providing skin defense by forming an intact skin barrier against environmental insults, such as UVB irradiation or pathogens, and also by initiating an inflammatory response upon those insults. Here we describe methods to isolate KCs from neonatal mouse skin and from adult mouse tail skin. We also describe culturing conditions using defined growth supplements (dGS) in comparison to chelexed fetal bovine serum (cFBS). Functionally, we show that both neonatal and adult KCs are highly responsive to high calcium-induced terminal differentiation, tight junction formation and stratification. Additionally, cultured adult KCs are susceptible to UVB-triggered cell death and can release large amounts of TNF upon UVB irradiation. Together, the methods described here will be useful to researchers for the setup of in vitro models to study epidermal biology in the neonatal mouse and/or the adult mouse.

Epidermal keratinocytes form a functional skin barrier and are positioned at the front line of host defense against external environmental insults. Here we describe methods for isolation and primary culture of epidermal keratinocytes from neonatal and adult mouse skin, and induction of terminal differentiation and UVB-triggered inflammatory response from keratinocytes.

The keratinocyte (KC) is the predominant cell type in the epidermis, the outermost layer of the skin. Epidermal KCs play a critical role in providing skin ...

A Tissue Culture Model of Estrogen-producing Primary Bovine Granulosa Cells

Ovarian granulosa cells (GC) are the major source of estradiol synthesis. Induced by the preovulatory luteinizing hormone (LH) surge, cells of the theca and, in particular, of the granulosa cell layer profoundly change their morphological, physiological, and molecular characteristics and form the progesterone-producing corpus luteum that is responsible for maintaining pregnancy. Cell culture models are essential tools to study the underlying regulatory mechanisms involved in the folliculo-luteal transformation. The presented protocol focuses on the isolation procedure and cryopreservation of bovine GC from small- to medium-sized follicles (&#60; 6 mm). With this technique, a nearly pure population of GC can be obtained. The cryopreservation procedure greatly facilitates time management of the cell culture work independent of a direct primary tissue (ovaries) supply. This protocol describes a serum-free cell culture model that mimics the estradiol-active status of bovine GC. Important conditions that are essential for a successful steroid-active cell culture are discussed throughout the protocol. It is demonstrated that increasing the plating density of the cells induces a specific response as indicated by an altered gene expression profile and hormone production. Furthermore, this model provides a basis for further studies on GC differentiation and other applications.

A long-term culture model of bovine granulosa cells under serum-free conditions is described. This model allows researchers to study the effects of diverse factors and conditions as different plating densities on the characteristics of estrogen-producing bovine granulosa cells.

Ovarian granulosa cells (GC) are the major source of estradiol synthesis. Induced by the preovulatory luteinizing hormone (LH) surge, cells of the theca ...