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

Acta Physiol (Oxf). 2015 Apr;213(4):882-92. doi: 10.1111/apha.12460. Epub 2015 Feb 15.


Aim: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Keywords: Scn3a; exocytosis; insulin secretion; microRNA; patch-clamp; voltage-dependent channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium
  • Electrophysiological Phenomena
  • Gene Expression Regulation / physiology*
  • Glucose / metabolism
  • Glucose / pharmacology
  • Insulin / metabolism
  • Islets of Langerhans / metabolism*
  • Mice
  • Mice, Knockout
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction
  • Voltage-Gated Sodium Channels / genetics
  • Voltage-Gated Sodium Channels / metabolism*


  • Insulin
  • MicroRNAs
  • Mirn375 microRNA, mouse
  • Voltage-Gated Sodium Channels
  • Glucose
  • Calcium