In vivo role of focal adhesion kinase in regulating pancreatic β-cell mass and function through insulin signaling, actin dynamics, and granule trafficking

Diabetes. 2012 Jul;61(7):1708-18. doi: 10.2337/db11-1344. Epub 2012 Apr 12.

Abstract

Focal adhesion kinase (FAK) acts as an adaptor at the focal contacts serving as a junction between the extracellular matrix and actin cytoskeleton. Actin dynamics is known as a determinant step in insulin secretion. Additionally, FAK has been shown to regulate insulin signaling. To investigate the essential physiological role of FAK in pancreatic β-cells in vivo, we generated a transgenic mouse model using rat insulin promoter (RIP)-driven Cre-loxP recombination system to specifically delete FAK in pancreatic β-cells. These RIPcre(+)fak(fl/fl) mice exhibited glucose intolerance without changes in insulin sensitivity. Reduced β-cell viability and proliferation resulting in decreased β-cell mass was observed in these mice, which was associated with attenuated insulin/Akt (also known as protein kinase B) and extracellular signal-related kinase 1/2 signaling and increased caspase 3 activation. FAK-deficient β-cells exhibited impaired insulin secretion with normal glucose sensing and preserved Ca(2+) influx in response to glucose, but a reduced number of docked insulin granules and insulin exocytosis were found, which was associated with a decrease in focal proteins, paxillin and talin, and an impairment in actin depolymerization. This study is the first to show in vivo that FAK is critical for pancreatic β-cell viability and function through regulation in insulin signaling, actin dynamics, and granule trafficking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Animals
  • Calcium / metabolism
  • Caspase 3 / biosynthesis
  • Cell Survival
  • Exocytosis
  • Female
  • Focal Adhesion Kinase 1 / genetics
  • Focal Adhesion Kinase 1 / metabolism*
  • Glucose Intolerance / genetics
  • Insulin / genetics
  • Insulin / metabolism*
  • Insulin Resistance*
  • Insulin Secretion
  • Insulin-Secreting Cells / cytology
  • Insulin-Secreting Cells / metabolism*
  • MAP Kinase Signaling System
  • Male
  • Mice
  • Paxillin / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats
  • Talin / metabolism
  • Transport Vesicles / metabolism

Substances

  • Insulin
  • Paxillin
  • Talin
  • Focal Adhesion Kinase 1
  • Ptk2 protein, mouse
  • Proto-Oncogene Proteins c-akt
  • Casp3 protein, mouse
  • Caspase 3
  • Calcium