Role of X-ray-induced transcripts in adaptive responses following X-rays: Progress report -- year 2.

摘要

The overall goal of this proposal is to clone low dose X-ray-induced genes via molecular biology cloning techniques. From previous data, certain human cells can clearly carry out adaptive survival responses (ASRs) following ionizing radiation. Research goals are to better understand how some human cells can establish ASRs, and why other cells fail to do so. The author has been successful at identifying several genes whose expressions are altered during the establishment of, and actual processes occurring in, the adaptive response of U1-Mel cells. He will, in the next year or so, investigate the kinetics of expression of these genes, and whether or not other environmental stresses affect the expressions of these genes via Northern blot analyses. Finally, he will begin to investigate the function(s) of these genes within the cell, either under normal conditions of growth or following X-irradiation, using antisense expression technologies. Antisense RNA analyses and DNA repair endpoints (i.e., survival recovery, alkaline/neutral filter elutions, and PFGE) will be combined to examine the effects of specific gene (open quotes)knock out(close quotes) experiments on ASRs in those human cells which demonstrate this response. The authors is constructing mammalian expression vectors containing cyclin A, cyclin B, p53, or xip5, and xip12 (when full-length cDNAs are available) in the (open quotes)sense(close quotes) orientation to overexpress these genes in human cells which did not demonstrate ASRs, such as HTB-152 or a variety of other human fibroblasts. Since many of the xips identified by 2-D gel electrophoresis were cell cycle regulated, the factors turning them on or off within a normal cell cycle may be clearly related to the events occurring in human cells following a genetic insult.