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Precise expression of Fis1 is important for glucose responsiveness of beta cells

Schultz, Julia; Waterstradt, Rica; Kantowski, Tobias; Rickmann, Annekatrin; Reinhardt, Florian; Sharoyko, Vladimir LU ; Mulder, Hindrik LU ; Tiedge, Markus and Baltrusch, Simone (2016) In Journal of Endocrinology 230(1). p.81-91
Abstract

Mitochondrial network functionality is vital for glucose-stimulated insulin secretion in pancreatic beta cells. Altered mitochondrial dynamics in pancreatic beta cells are thought to trigger the development of type 2 diabetes mellitus. Fission protein 1 (Fis1) might be a key player in this process. Thus, the aim of this study was to investigate mitochondrial morphology in dependence of beta cell function, after knockdown and overexpression of Fis1. We demonstrate that glucose-unresponsive cells with impaired glucose-stimulated insulin secretion (INS1-832/2) showed decreased mitochondrial dynamics compared with glucose-responsive cells (INS1-832/13). Accordingly, mitochondrial morphology visualised using MitoTracker staining differed... (More)

Mitochondrial network functionality is vital for glucose-stimulated insulin secretion in pancreatic beta cells. Altered mitochondrial dynamics in pancreatic beta cells are thought to trigger the development of type 2 diabetes mellitus. Fission protein 1 (Fis1) might be a key player in this process. Thus, the aim of this study was to investigate mitochondrial morphology in dependence of beta cell function, after knockdown and overexpression of Fis1. We demonstrate that glucose-unresponsive cells with impaired glucose-stimulated insulin secretion (INS1-832/2) showed decreased mitochondrial dynamics compared with glucose-responsive cells (INS1-832/13). Accordingly, mitochondrial morphology visualised using MitoTracker staining differed between the two cell lines. INS1-832/2 cells formed elongated and clustered mitochondria, whereas INS1-832/13 cells showed a homogenous mitochondrial network. Fis1 overexpression using lentiviral transduction significantly improved glucose-stimulated insulin secretion and mitochondrial network homogeneity in glucose-unresponsive cells. Conversely, Fis1 downregulation by shRNA, both in primary mouse beta cells and glucose-responsive INS1-832/13 cells, caused unresponsiveness and significantly greater numbers of elongated mitochondria. Overexpression of FIS1 in primary mouse beta cells indicated an upper limit at which higher FIS1 expression reduced glucose-stimulated insulin secretion. Thus, FIS1 was overexpressed stepwise up to a high concentration in RINm5F cells using the RheoSwitch system. Moderate FIS1 expression improved glucose-stimulated insulin secretion, whereas high expression resulted in loss of glucose responsiveness and in mitochondrial artificial loop structures and clustering. Our data confirm that FIS1 is a key regulator in pancreatic beta cells, because both glucosestimulated insulin secretion and mitochondrial dynamics were clearly adapted to precise expression levels of this fission protein.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Fission protein 1, Glucose-stimulated insulin secretion, Mitochondrial dynamics, Pancreatic beta cells
in
Journal of Endocrinology
volume
230
issue
1
pages
11 pages
publisher
Society for Endocrinology
external identifiers
  • scopus:84980000676
  • wos:000379880200012
ISSN
0022-0795
DOI
10.1530/JOE-16-0111
language
English
LU publication?
yes
id
2db4c595-1b99-437c-994c-74ed407016a9
date added to LUP
2016-08-15 11:29:27
date last changed
2017-02-05 04:52:06
@article{2db4c595-1b99-437c-994c-74ed407016a9,
  abstract     = {<p>Mitochondrial network functionality is vital for glucose-stimulated insulin secretion in pancreatic beta cells. Altered mitochondrial dynamics in pancreatic beta cells are thought to trigger the development of type 2 diabetes mellitus. Fission protein 1 (Fis1) might be a key player in this process. Thus, the aim of this study was to investigate mitochondrial morphology in dependence of beta cell function, after knockdown and overexpression of Fis1. We demonstrate that glucose-unresponsive cells with impaired glucose-stimulated insulin secretion (INS1-832/2) showed decreased mitochondrial dynamics compared with glucose-responsive cells (INS1-832/13). Accordingly, mitochondrial morphology visualised using MitoTracker staining differed between the two cell lines. INS1-832/2 cells formed elongated and clustered mitochondria, whereas INS1-832/13 cells showed a homogenous mitochondrial network. Fis1 overexpression using lentiviral transduction significantly improved glucose-stimulated insulin secretion and mitochondrial network homogeneity in glucose-unresponsive cells. Conversely, Fis1 downregulation by shRNA, both in primary mouse beta cells and glucose-responsive INS1-832/13 cells, caused unresponsiveness and significantly greater numbers of elongated mitochondria. Overexpression of FIS1 in primary mouse beta cells indicated an upper limit at which higher FIS1 expression reduced glucose-stimulated insulin secretion. Thus, FIS1 was overexpressed stepwise up to a high concentration in RINm5F cells using the RheoSwitch system. Moderate FIS1 expression improved glucose-stimulated insulin secretion, whereas high expression resulted in loss of glucose responsiveness and in mitochondrial artificial loop structures and clustering. Our data confirm that FIS1 is a key regulator in pancreatic beta cells, because both glucosestimulated insulin secretion and mitochondrial dynamics were clearly adapted to precise expression levels of this fission protein.</p>},
  author       = {Schultz, Julia and Waterstradt, Rica and Kantowski, Tobias and Rickmann, Annekatrin and Reinhardt, Florian and Sharoyko, Vladimir and Mulder, Hindrik and Tiedge, Markus and Baltrusch, Simone},
  issn         = {0022-0795},
  keyword      = {Fission protein 1,Glucose-stimulated insulin secretion,Mitochondrial dynamics,Pancreatic beta cells},
  language     = {eng},
  number       = {1},
  pages        = {81--91},
  publisher    = {Society for Endocrinology},
  series       = {Journal of Endocrinology},
  title        = {Precise expression of Fis1 is important for glucose responsiveness of beta cells},
  url          = {http://dx.doi.org/10.1530/JOE-16-0111},
  volume       = {230},
  year         = {2016},
}