This work was supported by National Institutes of Health grant R01DK080971 and Juvenile Diabetes Research Foundation grant 37-2009-44. We also appreciate support received from the UCSD Pediatric Diabetes Research Center (PDRC).

1. Transfection of HEK293 Layer
<ol>
	<li>Prepare HEK293 cell medium by adding to 500 ml bottles of DMEM (with 4.5 g/ml glucose and phenol red and without glutamine): 50 ml FBS, 5 ml 100X penicillin/streptomycin solution, 5 ml 100x L-glutamine solution and 500 &mu;l amphotericin B.</li>
	<li>Plate out HEK293 cells in a 24-well plate using 0.5 ml of HEK293 media per well. Ensure that the cells are spread evenly across the bottom of the plate.</li>
	<li>When HEK293 cells reach 100% confluency, transfect with 0.8 &mu;g of...

<ol>
	<li>Kelly, C., McClenaghan, N. H., Flatt, P. R. <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+islet+structure+and+cellular+interactions+in+the+control+of+insulin+secretion.">Role of islet structure and cellular interactions in the control of insulin secretion.</a> Islets. 3, 41-47 (2011).</li><li>Konstantinova, I., 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=EphA-Ephrin-A-mediated+beta+cell+communication+regulates+insulin+secretion+from+pancreatic+islets.">EphA-Ephrin-A-mediated beta cell communication regulates insulin secretion from pancreatic islets.</a> Cell. 129, 359-370 (2007).</li><li>Jain, R., Lammert, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-cell+interactions+in+the+endocrine+pancreas.">Cell-cell interactions in the endocrine pancreas.</a> Diabetes Obes. Metab. 11, 159-167 (2009).</li><li>Poitout, V., Olson, L. K., Robertson, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin-secreting+cell+lines:+classification,+characteristics+and+potential+applications.">Insulin-secreting cell lines: classification, characteristics and potential applications.</a> Diabetes Metab. 22, 7-14 (1996).</li><li>Craig, A. M., Graf, E. R., Linhoff, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+to+build+a+central+synapse:+clues+from+cell+culture.">How to build a central synapse: clues from cell culture.</a> Trends in Neurosciences. 29, 8-20 (2006).</li><li>Scheiffele, P., Fan, J., Choih, J., Fetter, R., Serafini, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroligin+expressed+in+nonneuronal+cells+triggers+presynaptic+development+in+contacting+axons.">Neuroligin expressed in nonneuronal cells triggers presynaptic development in contacting axons.</a> Cell. 101, 657-669 (2000).</li><li>Abderrahmani, A., 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=Neuronal+traits+are+required+for+glucose-induced+insulin+secretion.">Neuronal traits are required for glucose-induced insulin secretion.</a> FEBS Lett. 565, 133-138 (2004).</li><li>Lowe, A. W., Madeddu, L., Kelly, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endocrine+secretory+granules+and+neuronal+synaptic+vesicles+have+three+integral+membrane+proteins+in+common.">Endocrine secretory granules and neuronal synaptic vesicles have three integral membrane proteins in common.</a> The Journal of Cell Biology. 106, 51-59 (1988).</li><li>Suckow, A. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+neurexin,+neuroligin,+and+their+cytoplasmic+binding+partners+in+the+pancreatic+beta-cells+and+the+involvement+of+neuroligin+in+insulin+secretion.">Expression of neurexin, neuroligin, and their cytoplasmic binding partners in the pancreatic beta-cells and the involvement of neuroligin in insulin secretion.</a> Endocrinology. 149, 6006-6017 (2008).</li><li>Suckow, A. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcellular+neuroligin-2+interactions+enhance+insulin+secretion+and+are+integral+to+pancreatic+beta+cell+function.">Transcellular neuroligin-2 interactions enhance insulin secretion and are integral to pancreatic beta cell function.</a> The Journal of Biological Chemistry. 287, 19816-19826 (2012).</li><li>Kohnert, K. D., Hehmke, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+suspensions+of+pancreatic+islet+cells:+a+comparison+of+methods.">Preparation of suspensions of pancreatic islet cells: a comparison of methods.</a> J. Biochem. Biophys. Methods. 12, 81-88 (1986).</li><li>Qi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+pancreatic+islet+isolation:+Part+I:+digestion+and+collection+of+pancreatic+tissue.">Human pancreatic islet isolation: Part I: digestion and collection of pancreatic tissue.</a> J. Vis. Exp. (27), e1125 (2009).</li><li>Qi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+pancreatic+islet+isolation:+Part+II:+purification+and+culture+of+human+islets.">Human pancreatic islet isolation: Part II: purification and culture of human islets.</a> J. Vis. Exp. (27), e1343 (2009).</li><li>Szot, G. L., Koudria, P., Bluestone, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+pancreatic+islet+isolation.">Murine pancreatic islet isolation.</a> J. Vis. Exp. (7), e255 (2007).</li><li>Zmuda, E. J., Powell, C. A., Hai, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+murine+islet+isolation+and+subcapsular+kidney+transplantation.">A method for murine islet isolation and subcapsular kidney transplantation.</a> J. Vis. Exp. (50), e2096 (2011).</li><li>Hauge-Evans, A. C., Squires, P. E., Persaud, S. J., Jones, 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=Pancreatic+beta-cell-to-beta-cell+interactions+are+required+for+integrated+responses+to+nutrient+stimuli:+enhanced+Ca2++and+insulin+secretory+responses+of+MIN6+pseudoislets.">Pancreatic beta-cell-to-beta-cell interactions are required for integrated responses to nutrient stimuli: enhanced Ca2+ and insulin secretory responses of MIN6 pseudoislets.</a> Diabetes. 48, 1402-1408 (1999).</li><li>Spiess, Y., Smith, M. A., Vale, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superfusion+of+dissociated+pancreatic+islet+cells+attached+to+Cytodex+beads.">Superfusion of dissociated pancreatic islet cells attached to Cytodex beads.</a> Diabetes. 31, 189-193 (1982).</li><li>Pham, P. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transient+gene+expression+in+HEK293+cells:+peptone+addition+posttransfection+improves+recombinant+protein+synthesis.">Transient gene expression in HEK293 cells: peptone addition posttransfection improves recombinant protein synthesis.</a> Biotechnol. Bioeng. 90, 332-344 (2005).</li><li>Thomas, P., Smart, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HEK293+cell+line:+a+vehicle+for+the+expression+of+recombinant+proteins.">HEK293 cell line: a vehicle for the expression of recombinant proteins.</a> J. Pharmacol. Toxicol. Methods. 51, 187-200 (2005).</li><li>Maurisse, R., 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=Comparative+transfection+of+DNA+into+primary+and+transformed+mammalian+cells+from+different+lineages.">Comparative transfection of DNA into primary and transformed mammalian cells from different lineages.</a> BMC Biotechnol. 10, 9 (2010).</li></ol>

We have nothing to disclose.

The coculture method described here provides an effective way to determine the physiological importance of specific beta-cell-surface, transmembrane proteins, and specifically of their extracellular domains. By culturing beta cells or insulinoma cells (such as the INS-1 cells employed here) in contact with HEK293 cells displaying a protein of interest on the cell surface, experiments can be designed to determine the effects of extracellular protein-protein interactions without directly disturbing the intracellular milieu...

We describe here a method to facilitate investigations of how the extracellular domains of specific transmembrane proteins affect insulin secretion. The method probes the effects of interactions of the protein of interest with proteins (or possibly other molecules) on the pancreatic beta-cell surface. The method allows investigations of how cell-surface proteins expressed by beta cells or by other neighboring cells (e.g. endothelial cells, neurons, pancreatic alpha cells) affect beta-cell function through transcellular interactions (i.e. through interactions with interaction partners on the surface of adjacent beta cells).
The cellular plasma membrane contains a complex array of structural and functional proteins serving as bridges to the extracellular environment. By formation of transcellular connections or by initiation of plastic signaling events, interactions between cell-surface proteins can help coordinate the function of neighboring cells. Pancreatic beta cells are clustered together within the pancreatic islets and act in a coordinated fashion to maintain glucose homeostasis1. As revealed, for example, by the importance of extracellular EphA-ephrinA and neuroligin-2 interactions in the regulation of glucose-stimulated insulin secretion, it is becoming ever more clear that increased knowledge of the extracellular interactions occurring between proteins on the surfaces of adjacent beta cells will be of great importance for gaining a full understanding of insulin secretion, beta cell functional maturation and the maintenance of glucose homeostasis1-3. The goal of the method described here is to enable investigations of the effects on beta cell function of transcellular interactions involving specific transmembrane or otherwise-cell-surface-associated proteins. By co-culturing beta cells with HEK293 cells transfected with different expression constructs, the effects on beta cell function of different cell-surface proteins or mutated variants thereof can be efficiently probed. This is accomplished without having to transfect the beta cells themselves.
Elucidation of the roles of particular transcellular interactions by knockdown, knockout or overexpression studies in cultured beta cells or in vivo necessitates direct perturbation of beta-cell mRNA and protein expression, potentially affecting beta cell health and/or function in ways that could confound analyses of the effects of specific extracellular interactions. These approaches also alter levels of the intracellular domains of the targeted proteins and, further, do not allow effects due to interactions between proteins on or in the same cell to be distinguished from the effects of transcellular interactions. Here, a method for determining the effect of specific transcellular interactions on the insulin secreting capacity and responsiveness of beta cells is described. This method is applicable to insulin-secreting beta-cell lines, such as INS-1 cells4, and to dissociated primary rodent or human beta cells. It is based on coculture models developed by neurobiologists, who found that exposure of cultured neurons to specific neuronal proteins expressed on HEK293 (or COS) cell layers could identify proteins that drive synapse formation5,6. Given the parallels between the secretory machinery of neuronal synapses and of beta cells, we reasoned that beta-cell function and functional maturation might be driven by similar transcellular interactions7-9. In order to probe these interactions, we developed the system described herein in which beta cells are cocultured on a layer of HEK293 cells expressing a protein of interest10. This system allows the beta-cell cytoplasm to remain untouched while extracellular protein-protein interactions are manipulated.

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments (optional)</td>
		</tr>
		<tr>
			<td>pcDNA 3.3 vector/backbone</td>
			<td>Invitrogen</td>
			<td>K830001</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Lipofectamine 2000</td>
			<td>Invitrogen</td>
			<td>18324012</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Mediatech</td>
			<td>45001-312</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Pen/strep solution</td>
			<td>Mediatech</td>
			<td>45001-652-1</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Amphotericin B</td>
			<td>Mediatech</td>
			<td>45001-808-1/30</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>RPMI-1640</td>
			<td>Mediatech</td>
			<td>45001-404</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>D-PBS</td>
			<td>Mediatech</td>
			<td>45001-434</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Sodium Pyruvate</td>
			<td>Mediatech</td>
			<td>45001-710-1</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>2-Mercaptoethanol</td>
			<td>Invitrogen</td>
			<td>21985023</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Cell stripper</td>
			<td>Mediatech</td>
			<td>45000-668</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>T75 Flask</td>
			<td>BD</td>
			<td>1368065</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>16% Paraformaldehyde</td>
			<td>Electron Microscopy Sciences</td>
			<td>50980487</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>10X PBS</td>
			<td>Mediatech</td>
			<td>45001-130</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Mediatech</td>
			<td>MT35010CV</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>IBMX</td>
			<td>Sigma</td>
			<td>I5879-100MG</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>RIPA lysis buffer</td>
			<td>Sigma</td>
			<td>R0278</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

coculture analysis of extracellular protein interactions affecting insulin secretion by pancreatic beta cells

Interactions between cell-surface proteins help coordinate the function of neighboring cells. Pancreatic beta cells are clustered together within pancreatic islets and act in a coordinated fashion to maintain glucose homeostasis. It is becoming increasingly clear that interactions between transmembrane proteins on the surfaces of adjacent beta cells are important determinants of beta-cell function.
Elucidation of the roles of particular transcellular interactions by knockdown, knockout or overexpression studies in cultured beta cells or in vivo necessitates direct perturbation of mRNA and protein expression, potentially affecting beta-cell health and/or function in ways that could confound analyses of the effects of specific interactions. These approaches also alter levels of the intracellular domains of the targeted proteins and may prevent effects due to interactions between proteins within the same cell membrane to be distinguished from the effects of transcellular interactions.
Here a method for determining the effect of specific transcellular interactions on the insulin secreting capacity and responsiveness of beta cells is presented. This method is applicable to beta-cell lines, such as INS-1 cells, and to dissociated primary beta cells. It is based on coculture models developed by neurobiologists, who found that exposure of cultured neurons to specific neuronal proteins expressed on HEK293 (or COS) cell layers identified proteins important for driving synapse formation. Given the parallels between the secretory machinery of neuronal synapses and of beta cells, we reasoned that beta-cell functional maturation might be driven by similar transcellular interactions. We developed a system where beta cells are cultured on a layer of HEK293 cells expressing a protein of interest. In this model, the beta-cell cytoplasm is untouched while extracellular protein-protein interactions are manipulated. Although we focus here primarily on studies of glucose-stimulated insulin secretion, other processes can be analyzed; for example, changes in gene expression as determined by immunoblotting or qPCR.

Using the method described here, we have tested the effect of different variants of the protein neuroligin on insulin secretion. This complements our published work investigating the effect of neuroligin-2 on beta-cell function10. Figure 2, for example, depicts results obtained from coculturing INS-1 beta cells with HEK293 cells transfected to express a neuroligin isoform referred to here as NL-X. This experiment was designed to test the hypothesis that NL-X engages in transcellular interactio...

Watch this Scientific Journal Video about Coculture Analysis of Extracellular Protein Interactions Affecting Insulin Secretion by Pancreatic Beta Cells at JoVE.com

Coculture Analysis of Extracellular Protein Interactions Affecting Insulin Secretion by Pancreatic Beta Cells

Transcellular protein interactions are important determinants of pancreatic beta-cell function. Detailed here is a method&#x2014;adapted from a coculture model of synaptogenesis&#x2014;for investigating how specific transmembrane proteins influence insulin secretion. Transfected HEK293 cells express proteins of interest; beta cells do not need to be transfected or otherwise directly perturbed.

Interactions between cell-surface proteins help coordinate the function of neighboring cells. Pancreatic beta cells are clustered together within ...

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12.8K Görüntüleme.  University of California, San Diego. Transsellüler protein etkileşimleri pankreatik beta hücre fonksiyonu önemli belirleyicidir. Burada ayrıntılı bir yöntem uyarlanmış özel transmembran proteinler insülin salgılanmasını nasıl etkilediğini araştıran sinaptogenez-için bir kokültürü model. Transfekte edilmiş HEK293 hücreleri ilgili proteinlerin ifade eder; beta hücreleri transfekte edilmiş veya başka şekilde doğrudan tedirgin gerekmez.