蛋白酶体激活因子BLM10/PA200的转录调控机制研究

Proteasome activator Blm10/PA200 plays critical roles in the regulation of ribosome biogenesis, DNA repair and acetylation-dependent degradation of core histones during spermatogenesis. Despite mounting evidence indicating its significant cellular functions, BLM10/PA200 transcriptional regulation remains largely unknown. Our research has been focusing on the transcriptional regulation of proteasome activator Blm10/PA200 as long term studies. We discovered that there are two conserved binding sites for transcription factors, Crt1, and Rpn4 on the promoter region of BLM10/PA200. Crt1 inhibits the transcription of BLM10 by binding to the predicted binding site of Crt1. Deletion of Rpn4 completely blocks the BLM10 transcription activation in response to DNA damage. All these indicate that the repressor Crt1 and the activator Rpn4 co-regulate BLM10 transcription in response to DNA damage. In this study, we will systemically investigate the mechanisms of BLM10/PA200 transcriptional regulation, and will lay the foundations for better understand the physiological roles of Blm10/PA200.

蛋白酶体激活因子Blm10/PA200直接参与精子发生及DNA损伤修复过程中组蛋白降解，且该过程依赖于组蛋白乙酰化修饰。另外，Blm10/PA200在体细胞代谢，线粒体损伤及凋亡等过程中发挥重要作用。然而，BLM10/PA200的转录调控机制仍不清楚。该申请的前期结果显示，在BLM10基因非编码调控区存在Crt1及Rpn4两个转录因子的结合位点；Crt1结合在BLM10启动子区域中被预测的Crt1结合位点上，并显著抑制BLM10基因表达调控序列的转录活性；Rpn4的缺失下调BLM10基因的转录水平，且抑制DNA损伤诱导的BLM10基因转录上调；提示Crt1及Rpn4可能分别作为BLM10/PA200的转录激活因子及抑制因子共同调节其转录活性。本项目将系统阐明蛋白酶体激活因子BLM10/PA200基因转录调控机制，为进一步揭示蛋白酶体激活因子Blm10/PA200更广泛的生理功能奠定基础。

细胞衰老与DNA损伤，蛋白酶体活性减弱，组蛋白缺失及表观遗传的改变密切相关。蛋白酶体激活因子Blm10/PA200直接参与精子发生及DNA损伤修复过程中组蛋白降解，且该过程依赖于组蛋白乙酰化修饰。另外，BLM10/PA200在体细胞代谢，线粒体损伤及凋亡等过程中发挥重要作用。然而，BLM10/PA200的转录调控机制仍不清楚。本项目发现，在衰老过程中Blm10/PA200的蛋白水平降低是引起衰老过程中蛋白酶体活性降低的主要原因，而衰老过程反过来刺激Blm10进一步发生转录。在Blm10基因非编码调控区存在Crt1及Rpn4两个转录因子的结合位点，Crt1抑制BLM10基因的转录活性，而Rpn4促进BLM10基因的转录水平。与Rpn4敲除相反，Crt1的缺失能够增强DNA损伤刺激下的Blm10的转录水平，减弱衰老过程中组蛋白的水平，延长酵母的复制性寿命。这些结果不仅阐明了蛋白酶体激活因子BLM10/PA200基因转录调控机制，还说明细胞可以通过上调Blm10的转录而拮抗衰老过程，这为研究衰老及衰老相关的疾病机制奠定基础。