Genes determining cellular senescence in yeast

Abstract

Methods of isolating mutant yeast cells with increased life span, as well as mutant yeast cells isolated by the methods, are disclosed. Also described are methods of identifying agents which increase life span of yeast cells, and methods of isolating genes which affect senescence in organisms.

1 .- 10 . (cancelled)  
     
     
         11 . The protein encoded by a mutant SIR4 gene, consisting essentially of a SIR4 gene having a stop at codon 1237.  
     
     
         12 . A protein comprising a region which is homologous to the SUN domain region, said SUN domain region consisting essentially of an amino acid sequence selected from the group consisting of: a) amino acid 236 through amino acid 451 of SEQ ID NO. 2; b) amino acid 123 through amino acid 338 of SEQ ID NO. 12; and c) amino acid 211 through amino acid 426 of SEQ ID NO. 14.  
     
     
         13 . A method of evaluating a gene that affects lifespan, the method comprising 
 providing a first yeast cell which has an altered capacity for mitotic division relative to a second yeast cell;    crossing the first and second yeast cell to produce progeny cells; and    evaluating co-segregation of the altered capacity for mitotic division and a trait other than capacity for mitotic division, wherein co-segregation of the altered capacity for mitotic division and the trait indicates the trait as a phenotype correlating with lifespan.    
     
     
         14 . The method of  claim 13  wherein the trait other than capacity for mitotic division relates to a phenotype selected from the group consisting of: enhanced stress survival, growth to higher saturation density than the cells provided in (a), heat shock resistance, starvation resistance, paraquat resistance, and caffeine resistance.  
     
     
         15 . A method of identifying a gene that modulates lifespan or capacity for mitotic divisions, the method comprising: 
 providing a mutant yeast cell characterized by a first lifespan or capacity for mitotic divisions;    introducing a heterologous nucleic acid into the yeast cell to provide a modified, mutant yeast cell; and    evaluating whether the heterologous nucleic acid alters lifespan or divisional capacity of the modified, mutant yeast cell.    
     
     
         16 . The method of  claim 15  wherein the mutant cell is defective in a SIR gene.  
     
     
         17 . The method of  claim 15  wherein the heterologous nucleic acid comprises a mammalian sequence that alters lifespan or divisional capacity of the modified, mutant yeast cell.  
     
     
         18 . An isolated nucleic acid comprising a gene that complements a mutant yeast cell, wherein (i) the mutant yeast cell is characterized by a first lifespan or capacity for mitotic divisions, (ii) the first lifespan or capacity for mitotic divisions differs from a wildtype lifespan or divisional capacity of a wildtype cell, and (iii) presence of the gene in the mutant yeast cell alters the lifespan or divisional capacity of the mutant cell from the first lifespan or capacity for mitotic divisions.  
     
     
         19 . A method of evaluating a gene, the method comprising: 
 providing a nucleic acid that comprises a test gene that is homologous to a lifespan-associated gene selected from the group consisting of: SIR4, UTH1, NCA3, SAG1, PUMILIO, YGL023, D13645, and D43951;    providing a yeast cell characterized by a first lifespan or divisional capacity,    introducing the nucleic acid into the yeast cell to provide a modified yeast cell,    expressing the test gene in the modified yeast cell,    evaluating the modified yeast cell for lifespan or divisional capacity or a phenotype correlated with lifespan; and    comparing the lifespan or the divisional capacity or the correlated phenotype as evaluated for the modified yeast cell to a corresponding evaluation of the yeast cell, not modified by the nucleic acid.    
     
     
         20 . The method of  claim 19  wherein the test gene is selected from the group consisting of: SIR4, UTH1, NCA3, SAG1, PUMILIO, YGL023, D13645, and D43951.  
     
     
         21 . The method of  claim 19  wherein yeast cell has a genetic alteration relative to a wildtype cell or a naturally-occurring cell.  
     
     
         22 . The method of  claim 21  wherein the genetic alteration is an alteration to a SIR4 gene.