Genetic mutations in heat shock factor 4 (Hsf4) is associated with both congenital and age-related cataracts. Hsf4 regulates lens development through its ability to both activate and inhibit transcription. Previous studies suggested Hsf4 is involved in modulating cellular senescence depending on p21^cip1 and p27 ^kip1 expression in MEF cells. Here, we found that Hsf4 acts as a suppressor of p21^cip1 expression and plays an anti-senescence role during lens development. Knocking out Hsf4 facilitated UVB-induced cellular senescence in mouse lens epithelial cells (mLECs). p21^cip1 was upregulated at both the mRNA and protein levels in HSF4^−/− mLECs under control and UVB-treated conditions, and knockdown of p21^cip1 by siRNA alleviated UVB-induced cellular senescence. HSF4 directly bound to the p21^cip1 promoter and increased H3K27m3 levels at the p21^cip1 proximal promoter region by recruiting the methyltransferase EZH2. In animal models, p21^cip1 was gradually upregulated in wild-type mouse lenses with increasing age, while Hsf4 levels decreased. We generated a Hsf4 mutant mice line (Hsf4^del-42) which displayed obvious congenital cataract phenotype. The expression of p21^cip1 and senescence-associated cytokines were induced in the cataractous lenses of Hsf4^del-42 mice. H3K27m3 and EZH2 levels decreased in p21^cip1 promoters in the lenses of Hsf4^del-42 mice. The SA-β-Gal activities were positive in lens epithelia of aged Hsf4^null zebrafish compared to wild-type lenses. p21^cip1 and senescence-associated cytokines levels were also upregulated in lenses of Hsf4^null zebrafish. Accordingly, we propose that HSF4 plays a protective role in lens epithelial cells against cellular senescence during lens development and aging, partly by fine-tuning p21^cip1 expression.

热休克因子 4 ( Hsf4 ) 的基因突变与先天性和年龄相关性白内障有关。Hsf4 通过其激活和抑制转录的能力来调节晶状体发育。以前的研究表明 Hsf4 参与调节细胞衰老，这取决于MEF 细胞中p21 ^cip1和 p27 ^{kip1 的}表达。在这里，我们发现 Hsf4 作为 p21 ^cip1表达的抑制因子，并在晶状体发育过程中发挥抗衰老作用。敲除Hsf4促进了 UVB 诱导的小鼠晶状体上皮细胞 (mLEC) 的细胞衰老。p21 ^cip1在 HSF4 ^-/-的 mRNA 和蛋白质水平上均上调在控制和 UVB 处理条件下的 mLEC，以及通过 siRNA敲低 p21 ^cip1减轻了 UVB 诱导的细胞衰老。HSF4 直接与 p21 ^cip1启动子结合，并通过募集甲基转移酶 EZH2增加 p21 ^cip1近端启动子区域的H3K27m3 水平。在动物模型中，p21 ^cip1在野生型小鼠晶状体中随着年龄的增长逐渐上调，而 Hsf4 水平下降。我们生成了一个 Hsf4 突变小鼠系 (Hsf4 ^del-42 )，其显示出明显的先天性白内障表型。在 Hsf4 ^del-42白内障晶状体中诱导p21 ^cip1和衰老相关细胞因子的表达老鼠。Hsf4 ^del-42小鼠晶状体中 p21 ^cip1启动子的H3K27m3 和 EZH2 水平降低。与野生型晶状体相比，老年 Hsf4^无效斑马鱼的晶状体上皮中的 SA-β-Gal 活性呈阳性。在 Hsf4^无效斑马鱼的晶状体中，p21 ^cip1和衰老相关细胞因子水平也上调。因此，我们建议 HSF4 在晶状体上皮细胞中发挥保护作用，防止晶状体发育和衰老过程中的细胞衰老，部分是通过微调 p21 ^cip1表达。