We recently discovered that sperm production in the nematode Caenorhabditis elegans reduces male lifespan, and that mutations in the spermatogenesis-defective gene, spe-26, can increase average lifespan 35 to 100% (Van Voorhies, 1992, Nature in press). Thus this gene has the largest effect on lifespan of any gene so far identified in C. elegans. The gene has been cloned, and both wild-type and mutant genes have been completely sequenced. This proposal is to extend and utilize these findings to learn more about how sperm production and the spe-26 gene influence aging, and to take advantage of the cloned spe-26 gene to extend life-span by transformation of worms with altered spe-26 clones. C. elegans has many advantages for genetic analysis of the fundamental causes of aging, including short generation time, ease of culture, homozygous wild-type strain, detailed knowledge of its development, sophisticated genetics, small genome with an extensive genetic map and nearly complete physical map, and methods for gene tagging and for DNA transformation. Thus it is well suited for analysis of either Longevity Assurance Genes, that normally act to increase lifespan, or Aging Genes, like spe-26, that must be mutated to increase lifespan.
The specific aims of this proposal are as follows. (l) Determine if the lifespan increase caused by spe-26 mutations is mediated solely by their effect on spermatogenesis or if the phenotypes are distinct functions of the same gene. This will be done by characterization of additional mutations and analysis of the sequences responsible for tissue specific gene regulation. (2) Increase the lifespan of wild-type C. elegans by creating transgenic strains that disrupt the normal spe-26 gene by transformation with DNA constructs encoding either spe-26 antisense RNA or dominant negative mutant proteins. This is the most important experiment in terms of the goals of the """"""""Genetic and Molecular Basis of Longevity"""""""" program because it would demonstrate that lifespan can be increased by disrupting a normal aging gene in a transgenic animal, a model that could be applied to humans. (3) Find genes similar in function to spe-26 in other organisms by searching for genes similar in sequence. This will be done by low stringency hybridization and PCR amplification with spe-26 primers to see if spe-26 homologues can be found in other animals including mammals. (4) Determine if other mutations affecting spermatogenesis alter C. elegans lifespan. We will take advantage of our laboratory's more than 50 spermatogenesis-defective genes ordered into a developmental pathway to see exactly when during spermatogenesis and under control of which genes does lifespan become reduced. This proposal is directly relevant to human health because fundamental mechanisms of aging may be found and mammalian and human homologues of spe-26 may be identified, and, most importantly, because establishing that lifespan can be increased by transgenic disruption of aging genes will be a model for potential human therapy.
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