KLF4 Protects Endothelial Cells against Senescence by Activating PDGF-BB/PDGFRA Pathway

Aims: To explore the role KLF4 plays in regulating senescence of endothelial cells and the specific mechanism of it. Main Methods: Human umbilical vein endothelial cells (HUVECs) were cultured with glucose or angiotensin (Ang) II to induce senescence. Expressions of KLF4, PDGF-BB, PDGFRA and PDGFRB in normal and senescent HUVECs were assessed by mRNA-seq and protein microarray. KLF4/PDGF-BB/PDGFRA axis then was affected using sh-RNA. Fluorescent dual luciferase reporting system and EMSA were used to determine if KLF4 directly promoted transcription of PDGF-BB/PDGFRA. Senescence of aortic wall in wild type C57BL/6 mice, STZ-induced diabetic mice fed with high-fat diet (HFD) and endothelial cells (ECs)- specific KLF4 knockout mice was assessed by SA-β-Gal staining. Key Findings: STZ-induced diabetes with high-fat diet and absence of endothelial KLF4 led to accelerated senescence of aortic vessel wall in mice. Whole mRNA-seq and protein microarray analysis revealed decreased expression of KLF4, PDGFBB, PDGFRA and PDGFRB in senescent HUVECs. Knock-in of KFL4, PDGF-BB or PDGFRA, but not PDGFRB, led to impaired senescence in glucose treated HUVECs, whereas knock-down of KLF4, PDGF-BB or PDGFRA directly accelerated senescence as revealed by greater proportion of positive SA-β-Gal staining, higher inflammatory factors level, more frequent G2/M cell cycle arrest and typical cellular nuclear senescent morphology. KLF4 directly promoted transcription activity of PDGF-BB/PDGFRA as revealed by fluorescent dual luciferase reporting system and EMSA. Incubation of HUVECs with PDGF-BB and PDGFRs vectors increased KLF4 expression. Significance: In diabetic mice models and glucose/Ang II-induced HUVECs, KLF4 protects endothelial cells against senescence by activating PDGF-BB/PDGFRA pathway