节律基因Period2对紫外线损伤细胞的研究

发布时间：2019-01-11 09:41

【摘要】： 紫外线是引起DNA损伤常见的物理因素。根据日光中紫外线波长的不同，可将其分为3种：UVA(315—400nm)、UVB(280—315nm)和UVC(200—280nm)。其中UVC较前两者造成的DNA损伤重一些。过量的紫外线照射皮肤可诱发皮肤癌。近日节律广泛存在于生物体内，其周期在24小时左右，故称为近日节律(circadian rhythm)。人体的许多生理、生化参数均有近日节律的特点，如睡眠一觉醒、体温、血压、心率等，均表现出明显的近日节律。 Period2是近日节律基因家族的重要一员。研究发现，Period2和肿瘤的发生发展有密切的关系。本实验室发现，Period2过表达能够减轻γ射线对细胞的损伤作用，降低细胞对γ射线的敏感性。紫外线也能够引起细胞的损伤，其机制可能与γ射线引起DNA破坏类似。据此推测，Period2基因可能在紫外线引起细胞损伤方面有一定的作用。本文首先诱导体外培养的细胞产生近日节律，在Period2表达处于峰值和谷值的时候给与紫外线照射。流式细胞术、克隆形成实验和彗星电泳实验的结果发现，不同组细胞的凋亡率、细胞周期分布和细胞的生长能力具有显著性的差异。然后，，将Period2真核表达质粒转染入体外培养细胞中，增加细胞的Period2表达。发现Period2高表达的细胞与对照组细胞相比，紫外线引起的凋亡率、细胞周期分布和细胞的生长能力改变具有显著性的差异。紫外线照射可引起DNA的单链断裂、双链断裂及环丁烷嘧啶二聚体形成，这种损伤可经DNA修复系统进行修复。通过彗星实验，提示Period2基因过表达有抑制紫外线DNA损伤并促进DNA修复的作用。
[Abstract]:Ultraviolet radiation (UV) is a common physical factor causing DNA damage. According to the wavelength of ultraviolet light, it can be divided into three kinds of: UVA (315-400nm), UVB (280-315nm and UVC (200-280nm). The DNA damage caused by UVC was more serious than that caused by the former two. Excessive ultraviolet radiation can induce skin cancer. Circadian rhythm exists widely in organisms and its cycle is about 24 hours, so it is called circadian (circadian rhythm). Many physiological and biochemical parameters of the human body are characterized by circadian rhythm, such as sleep arousal, body temperature, blood pressure, heart rate and so on. Period2 is an important member of the circadian gene family. The study found that Period2 has a close relationship with tumorigenesis and development. Our laboratory found that overexpression of Period2 can attenuate the damage of 纬-ray and decrease the sensitivity of cells to 纬-ray. UV can also cause cell damage, which may be similar to 纬-ray-induced DNA damage. It is suggested that Period2 gene may play a role in ultraviolet-induced cell damage. In this study, cells were induced to produce circadian rhythms and were exposed to ultraviolet light at peak and valley levels of Period2 expression. The results of flow cytometry clone formation assay and comet electrophoresis showed that there were significant differences in apoptosis rate cell cycle distribution and cell growth ability between different groups. Then, the eukaryotic expression plasmid of Period2 was transfected into cultured cells in vitro to increase the expression of Period2. It was found that there were significant differences in the apoptosis rate, cell cycle distribution and cell growth ability between the cells with high expression of Period2 and those of the control group. Ultraviolet irradiation can cause single strand break, double strand break and formation of cyclobutane pyrimidine dimer in DNA. This damage can be repaired by DNA repair system. Comet assay suggested that overexpression of Period2 gene could inhibit the damage of ultraviolet DNA and promote the repair of DNA.
【学位授予单位】：四川大学
【学位级别】：硕士
【学位授予年份】：2007
【分类号】：R363

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