Regulated laminin-332 expression in human islets of Langerhans

Armanet M., Wojtusciszyn A., Morel P., Parnaud G., Rousselle P., Sinigaglia C., Berney T., Bosco D.The FASEB Journal, 2009

In this article, the authors show that LN-332 is expressed in isolated human islets with labeling confined to endocrine cells. Labeling in isolated islets is granular but don’t colocalize with hormone secretory granules. LN- 332 is most abundant in cultured islets compared to freshly isolated islets and is found in a culture medium, which suggests that it is secreted by islets. When islets are exposed to interleukin (IL)-1B, expression and secretion of LN-332 increase compared to control. Inhibition of phosphatidylinositol 3-kinase (PI3-K) activity, inhibited culture and IL-1B-induced LN-332 expression in islets. These results show that LN-332, known to have some beneficial effect on B-cells in vitro, is produced and secreted by endocrine islet cells and is up-regulated by stress conditions such as culture and IL-1-exposure. Altogether, their observations can be considered as prerequisites necessary to hypothesize that the in vitro effect of LN-332 on B-cell secretion, viability, and replication is of physiological relevance as well.