Nuclear PLCs affect insulin secretion by targeting PPARγ in pancreatic β cells

Roberta Fiume, Giulia Ramazzotti, Irene Faenza, Manuela Piazzi, Alberto Bavelloni, Anna Maria Billi, Lucio Cocco

Research output: Contribution to journalArticlepeer-review

Abstract

Type 2 diabetes is a heterogeneous disorder caused by concomitant impairment of insulin secretion by pancreatic β cells and of insulin action in peripheral target tissues. Studies with inhibitors and agonists established a role for PLC in the regulation of insulin secretion but did not distinguish between effects due to nuclear or cytoplasmic PLC signaling pathways that act in a distinct fashion. We report that in MIN6 β cells, PLCβ1 localized in both nucleus and cytoplasm, PLCδ4 in the nucleus, and PLCγ1 in the cytoplasm. By silencing each isoform, we observed that they all affected glucose-induced insulin release both at basal and high glucose concentrations. To elucidate the molecular basis of PLC regulation, we focused on peroxisome proliferator-activated receptor-γ (PPARγ), a nuclear receptor transcription factor that regulates genes critical to β-cell maintenance and functions. Silencing of PLCβ1 and PLCδ4 resulted in a decrease in the PPARγ mRNA level. By means of a PPARγ- promoter-luciferase assay, the decrease could be attributed to a PLC action on the PPARγ-promoter region. The effect was specifically observed on silencing of the nuclear and not the cytoplasmic PLC. These findings highlight a novel pathway by which nuclear PLCs affect insulin secretion and identify PPARγ as a novel molecular target of nuclear PLCs.

Original languageEnglish
Pages (from-to)203-210
Number of pages8
JournalFASEB Journal
Volume26
Issue number1
DOIs
Publication statusPublished - Jan 2012

Keywords

  • Diabetes
  • Phosphoinositides
  • PLCβ1
  • PLCδ4

ASJC Scopus subject areas

  • Biochemistry
  • Biotechnology
  • Genetics
  • Molecular Biology

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