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MiR-335 overexpression impairs insulin secretion through defective priming of insulin vesicles

Salunkhe, Vishal A. LU ; Ofori, Jones K. LU ; Gandasi, Nikhil R.; Salö, Sofia A.; Hansson, Sofia; Andersson, Markus E. LU ; Wendt, Anna LU ; Barg, Sebastian LU ; Esguerra, Jonathan L.S. LU and Eliasson, Lena LU (2017) In Physiological Reports 5(21).
Abstract

MicroRNAs contribute to the maintenance of optimal cellular functions by fine-tuning protein expression levels. In the pancreatic β-cells, imbalances in the exocytotic machinery components lead to impaired insulin secretion and type 2 diabetes (T2D). We hypothesize that dysregulated miRNA expression exacerbates β-cell dysfunction, and have earlier shown that islets from the diabetic GK-rat model have increased expression of miRNAs, including miR-335- 5p (miR-335). Here, we aim to determine the specific role of miR-335 during development of T2D, and the influence of this miRNA on glucose-stimulated insulin secretion and Ca2+-dependent exocytosis. We found that the expression of miR-335 negatively correlated with secretion... (More)

MicroRNAs contribute to the maintenance of optimal cellular functions by fine-tuning protein expression levels. In the pancreatic β-cells, imbalances in the exocytotic machinery components lead to impaired insulin secretion and type 2 diabetes (T2D). We hypothesize that dysregulated miRNA expression exacerbates β-cell dysfunction, and have earlier shown that islets from the diabetic GK-rat model have increased expression of miRNAs, including miR-335- 5p (miR-335). Here, we aim to determine the specific role of miR-335 during development of T2D, and the influence of this miRNA on glucose-stimulated insulin secretion and Ca2+-dependent exocytosis. We found that the expression of miR-335 negatively correlated with secretion index in human islets of individuals with prediabetes. Overexpression of miR-335 in human KndoC- (βH\ and in rat INS-1 832/13 cells (OE335) resulted in decreased glucose-sti- mulated insulin secretion, and OE335 cells showed concomitant reduction in three exocytotic proteins: SNAP25, Syntaxin-binding protein 1 (STXBPl), and synaptotagmin 11 (SYTll). Single-cell capacitance measurements, complemented with TIRF microscopy of the granule marker NPY-mEGFP demonstrated a significant reduction in exocytosis in OE335 cells. The reduction was not associated with defective docking or decreased Ca2+ current More likely, it is a direct consequence of impaired priming of already docked granules. Earlier reports have proposed reduced granular priming as the cause of reduced first-phase insulin secretion during prediabetes. Here, we show a specific role of miR-335 in regulating insulin secretion during this transition period. Moreover, we can conclude that miR-335 has the capacity to modulate insulin secretion and Ca2+-dependent exocytosis through effects on granular priming.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Beta cell, Exocytosis, Insulin secretion, MicroRNA, Patch-clamp, SNAP25, STXBP1, TIRF, Type 2 Diabetes
in
Physiological Reports
volume
5
issue
21
publisher
John Wiley & Sons
external identifiers
  • scopus:85033675346
  • wos:000415351500008
ISSN
2051-817X
DOI
10.14814/phy2.13493
language
English
LU publication?
yes
id
8d6ca497-b160-4ab3-bf73-832bf8b7ec9e
date added to LUP
2017-11-28 07:51:32
date last changed
2018-05-06 04:38:25
@article{8d6ca497-b160-4ab3-bf73-832bf8b7ec9e,
  abstract     = {<p>MicroRNAs contribute to the maintenance of optimal cellular functions by fine-tuning protein expression levels. In the pancreatic β-cells, imbalances in the exocytotic machinery components lead to impaired insulin secretion and type 2 diabetes (T2D). We hypothesize that dysregulated miRNA expression exacerbates β-cell dysfunction, and have earlier shown that islets from the diabetic GK-rat model have increased expression of miRNAs, including miR-335- 5p (miR-335). Here, we aim to determine the specific role of miR-335 during development of T2D, and the influence of this miRNA on glucose-stimulated insulin secretion and Ca<sup>2+</sup>-dependent exocytosis. We found that the expression of miR-335 negatively correlated with secretion index in human islets of individuals with prediabetes. Overexpression of miR-335 in human KndoC- (βH\ and in rat INS-1 832/13 cells (OE335) resulted in decreased glucose-sti- mulated insulin secretion, and OE335 cells showed concomitant reduction in three exocytotic proteins: SNAP25, Syntaxin-binding protein 1 (STXBPl), and synaptotagmin 11 (SYTll). Single-cell capacitance measurements, complemented with TIRF microscopy of the granule marker NPY-mEGFP demonstrated a significant reduction in exocytosis in OE335 cells. The reduction was not associated with defective docking or decreased Ca<sup>2+</sup> current More likely, it is a direct consequence of impaired priming of already docked granules. Earlier reports have proposed reduced granular priming as the cause of reduced first-phase insulin secretion during prediabetes. Here, we show a specific role of miR-335 in regulating insulin secretion during this transition period. Moreover, we can conclude that miR-335 has the capacity to modulate insulin secretion and Ca<sup>2+</sup>-dependent exocytosis through effects on granular priming.</p>},
  articleno    = {e13493},
  author       = {Salunkhe, Vishal A. and Ofori, Jones K. and Gandasi, Nikhil R. and Salö, Sofia A. and Hansson, Sofia and Andersson, Markus E. and Wendt, Anna and Barg, Sebastian and Esguerra, Jonathan L.S. and Eliasson, Lena},
  issn         = {2051-817X},
  keyword      = {Beta cell,Exocytosis,Insulin secretion,MicroRNA,Patch-clamp,SNAP25,STXBP1,TIRF,Type 2 Diabetes},
  language     = {eng},
  month        = {11},
  number       = {21},
  publisher    = {John Wiley & Sons},
  series       = {Physiological Reports},
  title        = {MiR-335 overexpression impairs insulin secretion through defective priming of insulin vesicles},
  url          = {http://dx.doi.org/10.14814/phy2.13493},
  volume       = {5},
  year         = {2017},
}