Validation And Preliminary Study On Function Of Aging Related Proteins Of Human Colonic Epithelium

Colon is an important human organ and its epithelium plays a central role in many physiological functions including digestion, secretion and defense. The aging process of human colonic epithelium involves a slow decline in physiological vigor and an increasing susceptibility to age-related diseases, especially, colon cancer. Screening aging related proteins will help to elucidate the physiological state and functions of colonic epithelium comprehensively and systematically at molecular level. In order to provide scientific bases for postponing the aging process of colonic epithelium, diagnosing and treating aging related colon diseases, it is necessary to investigate the aging mechanism of the colonic epithelium.In previous study, 2-DE reference map of human colonic epithelium was established and 17 aging related proteins were identified by MS through comparative proteomic analysis of colonic epithelium between young and old men.These proteins could be associated with the aging of human colonic epithelium. On base of former results, real-time quantitative RT-PCR and/or immunohistochemistry were used to determine the differential expression levels of four proteins including 40S ribosomal protein SA, EF-Tu, Rhodanese and Rackl. Secondly, a model of NIH/3T3 cell senescence was induced by D-gal, three proteins was analyzed by western-blot in the senescent cell. The effect of Rackl on NIH/3T3 cell senescence was analyzed through suppressing Rackl expression by Rackl small interfering RNA (siRNA).The main results were described as follows:1) Comparing with old people, the expression of EF-Tu, Rhodanese and Rackl were declined and 40S ribosomal protein was overexpressed in the colonic epithelium of young people. The results were identical with the proteome analysis.2) A senescent model of NIH/3T3 cell was established successfully. The expression of EF-Tu and Rhodanese was declined in the senescent cell.This suggested the alteration could be associated with cell senescence in vitro.3) Rackl expression was suppressed successfully by Rackl small interfering RNA (siRNA).The suppression of Rackl could promote senescence ofNIH/3T3.In this study, it showed that 40S ribosomal protein SA, EF-Tu, Rhodanese and Rack1 were aging related proteins of colonic epithelium; The change that the expression of EF-Tu and Rhodanese was declined could be associated with cell senescence in vitro; The suppression of Rackl could promote cell senescence. These data provide useful information for the study of colonic epithelial physiology and its aging mechanism.