Reduced expression of the insulin receptor in mouse insulinoma (MIN6) cells reveals multiple roles of insulin signaling in gene expression, proliferation, insulin content, and secretion

Mitsuru Ohsugi, Corentin Gras-Méneur, Yiyong Zhou, Ernesto Bernal-Mizrachi, James D. Johnson, Dan S. Luciani, Kenneth S. Polonsky, M. Alan Permutt

Research output: Contribution to journalArticle

71 Scopus citations

Abstract

The role of insulin signaling in pancreatic β cells has become increasingly apparent. Stably transformed insulinoma cell lines (MIN6) were created with small interfering RNA resulting in the reduction of insulin receptor (IR) expression up to 80% (insulin receptor knockdown, IRKDΔ80). Functionally perturbed IR signaling was confirmed with the absence of insulin-stimulated insulin receptor substrate 1 tyrosine phosphorylation. Additionally, Akt phosphorylation was reduced and responded poorly to glucose stimulation. Gene expression profiling revealed that reduced IR expression was associated with alterations in expression of > 1,500 genes with diverse functions. IRKD cells exhibited low rate of proliferation due to delay in transition from G0/G1 to S phase, whereas susceptibility to apoptosis did not differ from that of control cells. Insulin content was reduced in proportion to the reduction of IR. IRKD cells maintained glucose responsiveness as measured by NAD(P)H generation, whereas Ca2+ responses and insulin secretion were enhanced. IRKDΔ80 and control cells were treated with glucose (25 mM) or insulin (100 nM) for 45 min, and gene expression profiles were assessed. Transcriptional activation of several hundred early response genes common to both glucose and insulin stimulation was observed in control cells. In IRKDΔ80 cells, insulin failed to activate any genes as anticipated. Importantly, glucose stimulation of gene expression in IRKDΔ80 cells showed that most genes previously activated by glucose were no longer activated, suggesting a major autocrine/paracrine effect of insulin on glucose-regulated gene expression. On the other hand, there were a number of glucose-regulated genes in the IRKDΔ80 cells that were not previously observed in control cells, suggesting a feedback regulation of insulin signaling on glucose-regulated gene expression. These results demonstrate important roles of the insulin receptor in islet β cell gene expression and function and may serve to elucidate molecular defects in animal models with diminished β cell insulin signaling.

Original languageEnglish (US)
Pages (from-to)4992-5003
Number of pages12
JournalJournal of Biological Chemistry
Volume280
Issue number6
DOIs
StatePublished - Feb 11 2005

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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