Publications (2)13.53 Total impact
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Article: Tor1 regulates protein solubility in Saccharomyces cerevisiae.
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ABSTRACT: Accumulation of insoluble protein in cells is associated with aging and aging-related diseases, however the roles of insoluble protein in these processes remain uncertain. The nature and impact of changes to protein solubility during normal aging are less well understood. Using quantitative mass spectrometry, we identify 480 proteins that become insoluble during postmitotic aging in Saccharomyces cerevisiae and show that this ensemble of insoluble proteins is similar to those that accumulate in aging nematodes. SDS-insoluble protein is present exclusively in a nonquiescent subpopulation of postmitotic cells indicating an asymmetrical distribution of this protein. Additionally, we show that nitrogen starvation of young cells is sufficient to cause accumulation of a similar group of insoluble proteins. While many of the insoluble proteins identified are known to be autophagic substrates, induction of macroautophagy is not required for insoluble protein formation. However, genetic or chemical inhibition of the Tor1 kinase is sufficient to promote accumulation of insoluble protein. We conclude that TORC1 regulates accumulation of insoluble proteins via mechanisms acting upstream of macroautophagy. Our data indicate that the accumulation of proteins in an SDS-inoluble state in postmitotic cells represents a novel autophagic cargo preparation process that is regulated by the Tor1 kinase.Molecular biology of the cell 10/2012; · 5.98 Impact Factor -
Article: Proteomic analysis of age-dependent changes in protein solubility identifies genes that modulate lifespan.
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ABSTRACT: While it is generally recognized that misfolding of specific proteins can cause late-onset disease, the contribution of protein aggregation to the normal aging process is less well understood. To address this issue, a mass spectrometry-based proteomic analysis was performed to identify proteins that adopt sodium dodecyl sulfate (SDS)-insoluble conformations during aging in Caenorhabditis elegans. SDS-insoluble proteins extracted from young and aged C. elegans were chemically labeled by isobaric tagging for relative and absolute quantification (iTRAQ) and identified by liquid chromatography and mass spectrometry. Two hundred and three proteins were identified as being significantly enriched in an SDS-insoluble fraction in aged nematodes and were largely absent from a similar protein fraction in young nematodes. The SDS-insoluble fraction in aged animals contains a diverse range of proteins including a large number of ribosomal proteins. Gene ontology analysis revealed highly significant enrichments for energy production and translation functions. Expression of genes encoding insoluble proteins observed in aged nematodes was knocked down using RNAi, and effects on lifespan were measured. 41% of genes tested were shown to extend lifespan after RNAi treatment, compared with 18% in a control group of genes. These data indicate that genes encoding proteins that become insoluble with age are enriched for modifiers of lifespan. This demonstrates that proteomic approaches can be used to identify genes that modify lifespan. Finally, these observations indicate that the accumulation of insoluble proteins with diverse functions may be a general feature of aging.Aging cell 11/2011; 11(1):120-7. · 7.55 Impact Factor
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2012
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Buck Institute for Research on Aging
Novato, CA, USA
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