Insulin-like growth factor-binding protein-5-induced laminin gamma1 transcription requires filamin A

J Biol Chem. 2010 Apr 23;285(17):12925-34. doi: 10.1074/jbc.M109.061754. Epub 2010 Feb 18.

Abstract

Insulin-like growth factor-binding protein-5 (IGFBP-5) has IGF-1-independent intranuclear effects that are poorly defined. Treatment of cells with IGFBP-5 induces migration, prevents apoptosis, and leads to increased laminin subunit transcription. Similarly, filamin A (FLNa), an actin-binding protein that participates in cell attachment, plays important additional roles in signal transduction and modulation of transcriptional responses. In this report, we show that IGFBP-5 leads to dephosphorylation of FLNa with subsequent FLNa cleavage. Following cleavage, there is enhanced recruitment of Smad3/4 to a C-terminal FLNa fragment with nuclear translocation and subsequent binding to the promoter region of the laminin gamma1 (lamc1) gene. FLNa knockdown prevents IGFBP-5-mediated increases in lamc1 transcription. These data indicate that IGFBP-5 induces formation of a FLNa-based nuclear shuttle that recruits transcription factors and regulates transcription of IGFBP-5 target genes. These studies provide new insights into the mechanisms whereby IGFBP-5 and FLNa exert intranuclear effects.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Active Transport, Cell Nucleus / drug effects
  • Active Transport, Cell Nucleus / physiology
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Cell Movement / drug effects
  • Cell Movement / physiology
  • Cell Nucleus / metabolism*
  • Cells, Cultured
  • Contractile Proteins / metabolism*
  • Filamins
  • Insulin-Like Growth Factor Binding Protein 5 / metabolism
  • Insulin-Like Growth Factor Binding Protein 5 / pharmacology*
  • Laminin / biosynthesis*
  • Microfilament Proteins / metabolism*
  • Phosphorylation / drug effects
  • Phosphorylation / physiology
  • Protein Structure, Tertiary
  • Rats
  • Signal Transduction / drug effects*
  • Signal Transduction / physiology
  • Smad3 Protein / metabolism
  • Smad4 Protein / metabolism
  • Transcription, Genetic / drug effects*
  • Transcription, Genetic / physiology

Substances

  • Contractile Proteins
  • Filamins
  • Insulin-Like Growth Factor Binding Protein 5
  • Laminin
  • Microfilament Proteins
  • Smad3 Protein
  • Smad3 protein, rat
  • Smad4 Protein
  • Smad4 protein, rat
  • laminin gamma 1