| In the past decades, alterations in the morphology, cytoskeleton and cell cycle have been observed in cells in vitro under microgravity conditions. But the underlying mechanisms are not absolutely identified yet. Our previous study on proteomic and microRNA expression profiles of zebrafish (Danio rerio) embryos exposed to simulated-microgravity has demonstrated a serial of microgravity-sensitive molecules. Centrosomal protein of135kDa (CEP135) was found down-regulated in proteomic study, but the mRNA expression level was up-regulated in zebrafish embryos after simulated-microgravity, indicating there must be some post-transcriptional modifications occurred.Based on these interesting findings, expression and regulation of cep135under simulated microgravity condition were studied in this thesis. Full-length cDNA of cep135gene was firstly cloned from ZF4cells. The sequence was analyzed and the phylogenetic tree was constructed based on the similarity to other species. In zebrafish embryos and ZF4cells exposed to simulated-microgravity, the mRNA expression level of cep135was significantly increased, while the protein level was significantly decreased, tested by RT-qPCR and western blot method, respectively. Meanwhile, the expression of dre-miR-22a was significantly increased in simulated-microgravity ZF4cells. Additionally, by means of dre-miR-22a overexpression in ZF4cells and dual-luciferase system assay in Hela cells, cep135is demonstrated to be a direct target of dre-miR-22a.In this thesis, zebrafish cep135gene was firstly cloned, which will surely contribute to new gene annotation in this animal model. Studies on expression and regulation of cepl35under simulated microgravity condition will provide explanations for the dramatic effects of microgravity. Besides, cep135is firstly identified to be a direct target of dre-miR-22a. |
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