KLF4 inhibited the senescence-associated secretory phenotype in ox-LDL-treated endothelial cells via PDGFRA/NAMPT/mitochondrial ROS
Haoran Ding , Jing Tong , Hao Lin , Fan Ping, Tongqing Yao , Zi Ye , Jiapeng Chu , Deqiang Yuan , Kangwei Wang , Xuebo Liu, Fei Chen
ABSTRACT
Background: Inflammation is one of the significant consequences of ox-LDL-induced endothelial cell (EC) dysfunction. The senescence-associated secretory phenotype (SASP) is a critical source of inflammation factors.
However, the molecular mechanism by which the SASP is regulated in ECs under ox-LDL conditions remains unknown.
Results: The level of SASP was increased in ox-LDL-treated ECs, which could be augmented by KLF4 knockdown whereas restored by KLF4 knock-in. Furthermore, we found that KLF4 directly promoted PDGFRA transcription and confirmed the central role of the NAPMT/mitochondrial ROS pathway in KLF4/PDGFRA-mediated inhibition of SASP. Animal experiments showed a higher SASP HFD-fed mice, compared with normal feed (ND)-fed mice, and the endothelium of EC-specific KLF4-/- mice exhibited a higher proportion of SA-β-gal-positive cells and lower PDGFRA/NAMPT expression.
Conclusions: Our results revealed that KLF4 inhibits the SASP of endothelial cells under ox-LDL conditions through the PDGFRA/NAMPT/mitochondrial ROS.
Methods: Ox-LDL-treated ECs and HFD-fed mice were used as endothelial senescence models in vitro and in vivo. SA-β-gal stain, detection of SAHF and the expression of inflammatory factors determined SASP and senescence of ECs. The direct interaction of KLF4 and PDGFRA promotor was analyzed by EMSA and fluorescent dual luciferase reporting analysis.
Western blotting analysis of KLF4 protein expression in the intima ofEC KLF4-/- mice.Western blotting analysis of p21 protein expressiorin HUVECs after KLF4 expression is altered (n=5).; Western blottinganalysis ofPAI-2 and uPA protein expression in HUVECs(n-5).