Chronic β-Cell Depolarization Impairs β-Cell Identity by Disrupting a Network of Ca 2+-Regulated Genes

Diabetes. 2017 Aug;66(8):2175-2187. doi: 10.2337/db16-1355. Epub 2017 May 26.

Abstract

We used mice lacking Abcc8, a key component of the β-cell KATP-channel, to analyze the effects of a sustained elevation in the intracellular Ca2+ concentration ([Ca2+]i) on β-cell identity and gene expression. Lineage tracing analysis revealed the conversion of β-cells lacking Abcc8 into pancreatic polypeptide cells but not to α- or δ-cells. RNA-sequencing analysis of FACS-purified Abcc8-/- β-cells confirmed an increase in Ppy gene expression and revealed altered expression of more than 4,200 genes, many of which are involved in Ca2+ signaling, the maintenance of β-cell identity, and cell adhesion. The expression of S100a6 and S100a4, two highly upregulated genes, is closely correlated with membrane depolarization, suggesting their use as markers for an increase in [Ca2+]i Moreover, a bioinformatics analysis predicts that many of the dysregulated genes are regulated by common transcription factors, one of which, Ascl1, was confirmed to be directly controlled by Ca2+ influx in β-cells. Interestingly, among the upregulated genes is Aldh1a3, a putative marker of β-cell dedifferentiation, and other genes associated with β-cell failure. Taken together, our results suggest that chronically elevated β-cell [Ca2+]i in Abcc8-/- islets contributes to the alteration of β-cell identity, islet cell numbers and morphology, and gene expression by disrupting a network of Ca2+-regulated genes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / physiology
  • Calcium / metabolism
  • Calcium Signaling / genetics*
  • Cell Adhesion / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Lineage / genetics
  • Cell Polarity*
  • Gene Expression / genetics*
  • Gene Expression Regulation / genetics*
  • Insulin-Secreting Cells / cytology
  • Insulin-Secreting Cells / metabolism*
  • KATP Channels / genetics
  • Mice
  • Pancreatic Polypeptide-Secreting Cells / physiology
  • S100 Calcium Binding Protein A6
  • S100 Calcium-Binding Protein A4 / metabolism
  • S100 Proteins / metabolism
  • Sulfonylurea Receptors / deficiency

Substances

  • Abcc8 protein, mouse
  • Ascl1 protein, mouse
  • Basic Helix-Loop-Helix Transcription Factors
  • Cell Cycle Proteins
  • KATP Channels
  • S100 Calcium Binding Protein A6
  • S100 Calcium-Binding Protein A4
  • S100 Proteins
  • S100a4 protein, mouse
  • S100a6 protein, mouse
  • Sulfonylurea Receptors
  • Calcium