白内障是导致人类失明的主要原因，HSF4突变可引起先天性和年龄相关性白内障，但其突变引起白内障的分子病理机制尚不清楚。在前期工作中，我们首先发现HSF4：在细胞核中组成性地形成核内小体，与p53共定位，通过Co-IP和GST pull-down验证了其和p53直接相互作用；抑制DNA复制和细胞增殖；调控细胞核降解关键酶DLAD表达；用morpholino抑制其表达可致斑马鱼产生类似白内障表型。我们认为HSF4在晶状体发育和分化过程中起着调节中枢作用。本项目将在前期工作的基础上，通过体外和体内实验，深入研究HSF4在启动晶状体纤维细胞分化、调控特异结构蛋白表达，以及调控DLAD和纤维细胞去核化的分子机制，揭示HSF4调控晶状体细胞分化和发育过程的中枢作用，以及p53与HSF4的协同调控作用。本项目如顺利实施，不仅有助于理解晶状体细胞分化的精妙调控过程，还可能揭示白内障发病的新的分子病理机制。

Cataract is the most common cause for vision loss in humans. HSF4 mutations lead to both congenital and age-related cataract. However, the mechanism by which HSF4 mutations cause cataract remains elusive. In the previous studies, we provide the first evidences to show that HSF4 forms constitutive nuclear bodies, organizes p53 distribution, interacts with p53 in the nuclei of human lens epithelial cells; HSF4 inhibits lens epithelial cell proliferation by inhibiting DNA replication; regulates expression of DLAD, which is responsible for denucleation of lens fiber cells; and knockdown of HSF4 expression in zebrafish resulted in cataract-like phenotype in the fish lens. These sets of data lend credence to our hypothesis that HSF4 is a pivotal factor regulating lens differentiation. Here we will perform serials experiments, both in vitro and in vivo, to test this theory. We will investigate HSF4's pivotal role regulating lens differentiation through several mechanisms: First, If HSF4 inhibit lens epithelial cell proliferation and regulate fiber cell differentiation by activating the G1/S checkpoint? Second, how do HSF4 mutations disrupted its regulation in lens structural protein expression? Third, how does HSF4 regulate expression of DLAD and control denucleation of lens fiber cells? In addition, we will design experiments to test if HSF4 exerts the above functions through synergistic action with p53? Our studies will find novel pathway control lens differentiation and development, and for the first time, reveal the molecular mechanisms regarding how HSF4 mutations cause cataract.