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Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae
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Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae

Published on: July 9, 2013

Accelerated aging and failure to segregate damaged proteins in Sir2 mutants can be suppressed by overproducing the

Nika Erjavec1, Lisa Larsson, Julie Grantham

  • 1Department of Cell and Molecular Biology, Göteborg University, 413 90 Göteborg, Sweden.

Genes & Development
|October 3, 2007
PubMed

Insights

Oxidatively damaged proteins accumulate with yeast cell age. A Sir2p-dependent mechanism retains these damaged protein aggregates in mother cells, ensuring progeny rejuvenation.

Area of Science:

  • Cellular senescence
  • Protein quality control
  • Aging research

Background:

  • Oxidatively damaged proteins, specifically carbonylated proteins, increase with replicative age in yeast mother cells.
  • These damaged proteins are linked to cellular aging and dysfunction.
  • Understanding the mechanisms of damage segregation is crucial for aging research.

Purpose of the Study:

  • To investigate the role of protein aggregates and chaperones in the asymmetric segregation of damaged proteins during yeast cell division.
  • To elucidate the involvement of Sir2p (Sirtuin 2) in retaining damaged proteins in the mother cell.
  • To explore the relationship between Hsp104p (Heat Shock Protein 104) and Sir2p in maintaining cellular quality control and preventing aging.

Main Methods:

  • Analysis of carbonylated protein levels in relation to yeast replicative age.
  • Immunofluorescence microscopy to visualize protein aggregates containing Hsp104p.
  • Genetic manipulation, including gene deletions (e.g., sir2Δ, hsp104Δ) and gene overproduction.
  • Assessment of damage asymmetry during cytokinesis.
  • Monitoring of chaperone (Hsp104p, Hsp70s) damage levels and protein aggregate rescue rates.
  • Treatment with drugs that inhibit damage segregation.

Main Results:

  • Carbonylated proteins associate with Hsp104p-containing aggregates.
  • Sir2p-dependent retention of these aggregates in progenitor cells establishes damage asymmetry.
  • Hsp104p deletion disrupts damage asymmetry.
  • Hsp104p overproduction partially restores damage retention in sir2Δ mutants.
  • Hsp104p and Hsp70s show increased damage and slower aggregate rescue in sir2Δ cells.
  • Hsp104p overproduction suppresses the accelerated aging phenotype of sir2Δ cells.
  • Inhibition of damage segregation accelerates aging, confirming the role of spatial quality control.

Conclusions:

  • Functional chaperones, particularly Hsp104p, associated with protein aggregates are essential for establishing damage asymmetry.
  • Sir2p plays a critical role in the retention of damaged protein aggregates in mother cells, contributing to progeny rejuvenation.
  • Spatial quality control mechanisms, involving chaperone-mediated aggregate handling and segregation, are vital for preventing cellular aging and ensuring longevity.

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