Roles Of Chromosome Acetylation And Deacetylation In Hsp Gene Expression In Drosophila

Heat shock proteins (HSP) are a family of important proteins, which participate in many physiological processes in vivo, such as cell growth, development, differentiation, gene transcription, protein synthesis, fold and transport, etc. The regulation of hsp gene transcription is an elaborated and complex process, including the regulation of basic transcription and inducible transcription. It is a good model for the study on the regulation of eukaryotic gene transcription.In eukaryotes, the acetylation of histones was discovered many years ago. In the recent decade, more and more attention has been paid to the roles of acetylation in transcription regulation. The mechanisms of acetylation in transcription regulation are unclear, and the role of the acetylation in hsp gene transcription regulation is still a disputed issue. The study on the relationship between the acetylation and hsp gene transcription regulation will help us in understanding the mechanisms of eukaryotic transcription regulation.In this thesis, we studied the effects of acetylation on hsp gene transcription regulation in Drosophila melanogaster, in an attempt to disclose the mechanisms of the acetylation in hsp gene inducible transcription, at both the molecular and the chromosomal levels. The main results and conclusions are as followings.1, The histone deacetylase inhibitors were used to feed the larve of the fly, and then the polytene chromosomes were observed under the microscope. The results indicated that the histone deacetylase inhibitors had effects on the morphology of the polytene chromosomes. It is suggested that the acetytion has effects not only on the molecular interaction but also on the structure of the chromosomes.2, The hsp gene transcription was quantitatively determined by RT-PCR. Based on this result, it is concluded that the change of acetylation level at the loci of hsp, mediated by histone deacetylase inhibitors, exertsimportant functions in hsp gene transcription.3, After immunolabeling with anti acelated-lysine monoclonal antibody on the polytene chromosomes of heat shocked flies, fluorescence signals were detected at the hsp loci. Combined with the results of histone deactylase inhibitor, it is suggested that histone acetylation plays an important role in hsp gene transcription regulation.4, Compared the influence of two histone deacetylase inhibitors on the hsp70 gene transcription, after changing the time and the concentration of the inhibitors, we found the mechanism of the two histone deaceylase inhibitors is different.5, Histone acetyltransferase gene yGcnS and histone deacetylase gene yRpd3 were cloned and expressed, which has laid down a foundation for studying chromosome remodeling in vitro.6, We used Gcn5 and Rpd3 genes as probes to detect the homologous sequences in Drosophila melanogaster by fluorescence in situ hybridization (FISH).This work has provided useful information for the localization and cloning of related histone acetyltransferase and histone deacetylase genes in Drosophila melanogaster.