of work: Werner's Syndrome (WS) is a homozygous recessive disease characterized by early onset of many characteristics of normal aging, such as wrinkling of the skin, graying of the hair, cataracts, diabetes, and osteoporosis. The symptoms of WS begin to appear around the age of puberty, and most patients die before age 50. Because of the acceleration of aging in WS, the study of this disease will hopefully shed light on the degenerative processes that occur in normal aging. Cells from WS patients grow more slowly and senescence at an earlier population doubling than age-matched normal cells, possibly because these cells appear to lose the telomeric ends of their chromosomes at an accelerated rate. In general, WS cells have a high level of genomic instability, with increased amounts of DNA deletions, insertions, and rearrangements. These effects could potentially be the result of defects in DNA repair, replication, and/or recombination, although the actual biochemical defect remains unknown. The gene that is defective in WS, the WRN gene, has recently been identified and characterized as a helicase. Thus, the genetic evidence also points to a role for the WRN protein in some aspect of DNA metabolism. We are using several avenues to identify and characterize the biochemical defect in WS cells. WS cells appear to have a subtle defect in transcription-coupled repair, the highly efficient removal of lesions from the transcribed strand of active genes. We have taken various approaches to analysis of transcriptional capacity in Werners cells and extracts. We observe a defect which can be complemented by addition of purified werners protein. We are making purified WRN protein for use in a number of basic and complex biochemical assays. The protein has helicase activity and will unwind small and large DNa duplex constructs. The helicase activity is sensitive to a compound, distamycin, which is a DNA minor groove binder, and the helicase will work on blunt duplexes. We are currently characterizing the helicase activity and searching for proteins that will enhance it and thus may be interacting with the Werner helicase. Our ongoing and future studies will be directed towards elucidation of the causes of the accelerated aging phenotype in WS, with hope that this knowledge can also be applied to our current understanding of both the aging of cells and organisms in general.
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