Referenced in: none

Automatically associated channels: Nav1.3

Title: Modulation of microRNA-375 expression alters voltage-gated Na(+) channel properties and exocytosis in insulin-secreting cells.

Authors: V A Salunkhe, J L S Esguerra, J K Ofori, I G Mollet, M Braun, M Stoffel, A Wendt, L Eliasson

Journal, date & volume: Acta Physiol (Oxf), 2015 Apr , 213, 882-92

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25627423

Abstract
MiR-375 has been implicated in insulin secretion and exocytosis through incompletely understood mechanisms. Here we aimed to investigate the role of miR-375 in the regulation of voltage-gated Na(+) channel properties and glucose-stimulated insulin secretion in insulin-secreting cells.MiR-375 was overexpressed using double-stranded mature miR-375 in INS-1 832/13 cells (OE375) or downregulated using locked nucleic acid (LNA)-based anti-miR against miR-375 (LNA375). Insulin secretion was determined using RIA. Exocytosis and ion channel properties were measured using the patch-clamp technique in INS-1 832/13 cells and beta-cells from miR-375KO mice. Gene expression was analysed by RT-qPCR, and protein levels were determined by Western blot.Voltage-gated Na(+) channels were found to be regulated by miR-375. In INS-1 832/13 cells, steady-state inactivation of the voltage-gated Na(+) channels was shifted by approx. 6 mV to a more negative membrane potential upon down-regulation of miR-375. In the miR-375 KO mouse, voltage-gated Na(+) channel inactivation was instead shifted by approx. 14 mV to a more positive membrane potential. Potential targets differed among species and expression of suggested targets Scn3a and Scn3b in INS-1 832/13 cells was only slightly moderated by miR-375. Modulation of miR-375 levels in INS-1-832/13 cells did not significantly affect insulin release. However, Ca(2+) dependent exocytosis was significantly reduced in OE375 cells.We conclude that voltage-gated Na(+) channels are regulated by miR-375 in insulin-secreting cells, and validate that the exocytotic machinery is controlled by miR-375 also in INS-1 832/13 cells. Altogether we suggest miR-375 to be involved in a complex multifaceted network controlling insulin secretion and its different components.