Analysis of Cyp11a1 null on apoptosis of developing mice retina

• Main Authors: Jui-Chen Lee, 李芮甄
• Other Authors: 胡孟君
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/64329164957401629711

碩士 === 國立臺灣大學 === 生理學研究所 === 98 === Neuroactive steroids can be synthesized de novo in the nervous system that influence the brain development and many neurophysiological functions. It’s recording that neurosteroids such as progesterone and estrogen could protect neuron cells from apoptosis. Retina is a target of steroids, and it also could produce neurosteroids like pregnenolone. DHEA/DEHAS, 17β-oestradiol and 3α5βS reduced the cell death in retinal excitotoxicity. However, pregnenolone sulfate increased the NMDA-induced excitotoxic retinal cell death. In this study, we utilize knockout mice disrupted with Cyp11a1, the key gene controlling steroidogenesis, to explore the role of steroids in retina apoptosis. Cyp11a1 null mice lack the synthesis of steroids and die about postnatal 6 days. By 5 day of age, Cyp11a1 null mice gained 25% less weight than their wild-type and heterozygote littermates. Expression of Cyp11a1 mRNA could not be detected in Cyp11a1 KO mice. Additionally, we generated SCC-Cre transgenic mice, in which the human CYP11A1 promoter drives Cre expression. Cre recombinase activity was detected in retina at postnatal day 5, indicating CYP11A1 promoter is functional in mouse retina. We used TUNEL assay to investigate the apoptosis in retina of WT and KO mice. On postnatal day 5, the majority of the apoptotic cells detected by TUNEL assay were observed in the inner nuclear layer of retina. The number of TUNEL positive cells in the retina of Cyp11a1 null mice was significant reduced when compared with their wild-type littermates. It indicated that apoptosis of retina was decreased in the condition of steroids deficiency. To understand the molecular pathway, we analyzed the expression of procaspase-3 and Bcl-2 in WT and KO retina. The protein levels of Bcl-2 in KO retina were significantly increased compared with WT. The protein levels of procaspase-3 in KO retina were higher than those in WT, suggesting that caspase-3 activity was reduced. Therefore, caspase-3 and Bcl2 could be involved in the steroid-mediated retinal apoptosis.