Significant and systematic expression differentiation in long-lived yeast strains.

Area of Science:

• Genomics
• Molecular Biology
• Aging Research

Background:

• Longevity regulation is conserved across eukaryotes, from yeast to mammals.
• Specific yeast mutants (sch9Δ, ras2Δ, tor1Δ) exhibit up to threefold extended chronological lifespan.
• Understanding the genetic and molecular mechanisms behind yeast lifespan extension is crucial.

Purpose of the Study:

• To dissect the molecular mechanisms underlying lifespan extension in yeast mutants.
• To identify key biological pathways and cellular activities affected in long-lived yeast strains.
• To correlate gene expression changes with observed lifespan extension.

Main Methods:

• Gene expression profiling of long-lived yeast mutants (sch9Δ, ras2Δ, tor1Δ) and wild type using Affymetrix Yeast2.0 arrays.
• Application of sub-array normalization and median-polishing summarization for accurate expression analysis.
• Statistical inference integrating expression data with Gene Ontology, KEGG pathways, and protein cellular localization for biological activity assessment.

Main Results:

• Long-lived yeast strains exhibit lower overall transcriptional activity.
• Down-regulation of the TCA cycle and oxidative phosphorylation pathways observed.
• Up-regulation of glycolysis/gluconeogenesis and a reduction in mitochondrial activities were noted.
• Specific alterations, like reduced mitosis-related activity in ras2Δ, were identified.

Conclusions:

• Modification of energy metabolism pathways, including ribosomal protein activity (down-regulated mitochondrial, up-regulated cytosolic), is directly linked to yeast lifespan extension.
• These findings provide a functional genomics perspective on aging, potentially refining the free radical theory in Saccharomyces cerevisiae.