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Cell Type-specific Gene Expression Profiling in the Mouse Liver
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Cell Type-specific Gene Expression Profiling in the Mouse Liver

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The COP9 signalosome is a repressor of replicative stress responses and polyploidization in the regenerating liver

Martina Panattoni1, Laura Maiorino, Anna Lukacs

  • 1Leukocyte Biology Unit, Ospedale San Raffaele Scientific Institute, Milano, Italy.

Hepatology (Baltimore, Md.)
|January 24, 2014
PubMed
Abstract

Insights

The COP9 signalosome (CSN) subunit COPS5 is crucial for preventing replicative stress in regenerating liver cells. Its absence triggers cell cycle arrest and apoptosis, highlighting CSN

Area of Science:

  • Cellular Biology
  • Molecular Oncology
  • DNA Replication

Background:

  • Aberrant DNA replication triggers a cellular stress response, normally preventing uncontrolled proliferation.
  • The COP9 signalosome (CSN) regulates cullin ring ligases (CRLs) and is vital for cell cycle control.
  • CSN inactivation in tissues leads to cell cycle arrest and death, but its role in differentiated hepatocytes is unclear.

Purpose of the Study:

  • To investigate the role of COPS5, a CSN catalytic subunit, in cell cycle reentry of differentiated hepatocytes.
  • To understand the consequences of COPS5 ablation in the liver during regeneration.

Main Methods:

  • Conditional ablation of COPS5 in mouse liver.
  • Analysis of regenerating livers lacking COPS5.
  • Investigating the effects of c-Myc overexpression in COPS5-null hepatocytes.

Main Results:

  • COPS5 deficiency in regenerating livers induced significant replicative stress.
  • This stress activated a CDKN2A-dependent program, causing cell cycle arrest, polyploidy, and apoptosis.
  • These effects were mimicked by c-Myc overexpression in COPS5-null hepatocytes.

Conclusions:

  • CSN inactivation in regenerating livers leads to cell cycle arrest and apoptosis, potentially via proto-oncogene and DNA replication control.
  • Overexpression of CSN in hepatocellular carcinoma may contribute to pathogenesis.
  • COPS5 is essential for preventing replicative stress and maintaining genomic stability in hepatocytes.

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