Document Type

Thesis

Date of Award

12-2014

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Biology

First Advisor

Professor Shishir Shishodia

Abstract

DNA methylation is an epigenetic mechanism involved in gene expression regulation. Astronauts are constantly being exposed to different stress factors, which include radiation, microgravity and confinement. These environmental stressors are understood to increase bone loss, decrease muscle mass and reduce immune function. Our objective is to investigate the hypothesis that modeled microgravity induces gene expression through epigenetic changes. Abnormal epigenetic events have been reported in human diseases like cancers and immunological disorders. The purpose of this study was to determine whether modeled microgravity induces these epigenetic changes by examining the expression of the proteins known to regulate gene expression specifically the DNA Methyltransferases (DNMT1, DNMT3a and DNMT3b) and Histone Deacetylase (HDAC1) as a first step towards future in vivo and in vitro studies in preventing senescence and apoptosis in astronauts. Proteins were extracted from mouse monocytes exposed to normal and simulated microgravity conditions with and without the demethylating agent 5-aza-2-deoxycytidine (DAC) and protein expression was examined x to see if our protein of interest after DAC treatment increased when compared to that of untreated cells. Cells were Media was changed every 24 to 48 hours and observed to ensure proper morphology of cells as well as ensure cell survival. DNA demethylation will be carried out using DAC in the presence and absence of microgravity. Western blot analysis was carried out on whole cell protein extracts using specific primary antibodies for DNMTl, DNMT3a/3b and HDACl. All DNMT and HDAC were detected in cells grown in normal gravity while those cells exposed to SMG showed decreased DNMT and HDAC expression in cells exposed to simulated microgravity conditions. Alternatively, cells exposed to both simulated microgravity and DAC showed increased levels ofDNMT3a and DNMT3b but significantly less DNMTI and HDAC proteins

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