Homologous but not heterologous contact increases the insulin secretion of individual pancreatic B-cells.
To assess whether and how specifically contact influences the functioning of differentiated cells, we have studied the secretion of adult pancreatic B-cells as a function of aggregation to either homologous B-cells or other heterologous endocrine islet cell types, all present in a mixed cell suspension. Using an immunological plaque assay for insulin, we have quantitated the proportion of single and aggregated B-cells inducing the formation of a hemolytic plaque (a reflection of the size of the secreting cell population) and the area of these plaques (a reflection of the hormonal output of individual cells or aggregates) after a 30-min stimulation by 16.7 mM glucose. By taking into account the number of B-cells within the aggregates, we have calculated from these data the insulin output on a per B-cell basis. We show here that the homologous contact between companion B-cells promotes the recruitment of secreting B-cells and increases their individual secretion of insulin twofold over that of single B-cells. By contrast, heterologous B- to non-B-cell contact was not effective in enhancing the recruitment of secreting B-cells and in promoting their individual secretion. These findings show that a highly differentiated cell function, such as insulin secretion, is controlled specifically by homologous cell to cell contacts.
Bosco
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D
Institute of Histology and Embryology, University of Geneva Medical School, Switzerland.
Orci
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Meda
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P
D000818:Animals; D002448:Cell Adhesion; D002450:Cell Communication; D005947:Glucose / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects
D007328:Insulin; D005947:Glucose