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Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols
12:02

Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols

Published on: June 6, 2017

Nuclear insulin receptor substrate-1 activates promoters of cell cycle progression genes

A Wu1, J Chen, R Baserga

  • 1Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA.

Oncogene
|August 19, 2007
PubMed

Insights

Insulin receptor substrate-1 (IRS-1) moves into cell nuclei, activating genes like c-myc and cyclin D1, which promotes cell growth and cancer. This nuclear IRS-1 function is crucial for cell cycle gene regulation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • Insulin receptor substrate-1 (IRS-1) is a key docking protein for insulin and IGF-1 receptors.
  • IRS-1 signaling is implicated in cell proliferation, survival, transformation, and cancer development.

Purpose of the Study:

  • To investigate the role of nuclear IRS-1 in regulating gene expression.
  • To elucidate the mechanism by which IRS-1 influences rDNA, c-myc, and cyclin D1 promoter activity.

Main Methods:

  • Chromatin immunoprecipitation (ChIP) to assess IRS-1 promoter occupancy.
  • Analysis of promoter activity in response to IGF-1 stimulation.
  • Use of mutant IRS-1 protein lacking the phosphotyrosine-binding (PTB) domain.

Main Results:

  • IRS-1 translocates to the nucleus and occupies rDNA, c-myc, and cyclin D1 promoters in an IGF-1-dependent manner.
  • Nuclear translocation of IRS-1 is essential for activating these promoters.
  • Activation of c-myc and cyclin D1 by nuclear IRS-1 does not require PI3-kinase activity and depends on the PTB domain.

Conclusions:

  • Nuclear IRS-1 directly activates cell cycle-related genes, including c-myc and cyclin D1.
  • This novel nuclear function of IRS-1 contributes to its role in cell transformation and cancer.
  • The mechanism involves direct promoter occupancy and is independent of canonical PI3-kinase signaling.

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