HTRA1-Dependent Cell Cycle Proteomics

The HTRA1 gene encoding an evolutionary conserved protein quality-control factor can be epigenetically silenced or inactivated by mutation under pathologic conditions such as cancer. Recent evidence suggests that the loss of HTRA1 function causes multiple phenotypes, including the acceleration of cell growth, delayed onset of senescence, centrosome amplification, and polyploidy, suggesting an implication in the regulation of the cell cycle. To address this model, we performed a large-scale proteomics study to correlate the abundance of proteins and HTRA1 levels in various cell cycle phases using label-free-quantification mass spectrometry. These data indicate that the levels of 4723 proteins fluctuated in a cell-cycle-dependent manner, 2872 in a HTRA1-dependent manner, and 1530 in a cell-cycle- and HTRA1-dependent manner. The large number of proteins affected by the modulation of HTRA1 levels supports its general role in protein homeostasis. Moreover, the detected changes in protein abundance, in combination with pull-down data, implicate HTRA1 in various cell cycle events such as DNA replication, chromosome segregation, and cell-cycle-dependent apoptosis. These results highlight the wide implications of HTRA1 in cellular physiology.HTRA1基因（HTRA1）编码一种进化保守的蛋白质质量控制因子（protein quality-control factor），在癌症等病理条件下，可通过表观遗传沉默或突变失活。近期研究表明，HTRA1功能丧失会引发多种表型，包括细胞生长加速、衰老起始延迟、中心体扩增以及多倍体，提示其参与细胞周期调控。为验证该模型，本研究开展了大规模蛋白质组学研究，采用无标记定量质谱（label-free-quantification mass spectrometry）技术，分析不同细胞周期时相中的蛋白质丰度与HTRA1水平的相关性。数据显示，共有4723种蛋白质的丰度呈细胞周期依赖性波动，2872种呈HTRA1依赖性变化，另有1530种同时受细胞周期与HTRA1调控。受HTRA1水平调控的蛋白质数量众多，佐证了其在蛋白质稳态（protein homeostasis）中的普遍调控作用。此外，结合下拉实验（pull-down）数据与检测到的蛋白质丰度变化，提示HTRA1参与DNA复制、染色体分离、细胞周期依赖性凋亡等多种细胞周期事件。本研究结果凸显了HTRA1在细胞生理过程中的广泛调控意义。