Abstract
Background We previously reported that vascular smooth muscle cells ( VSMC s) from spontaneously hypertensive rats ( SHR s) show the increased expression of complement 3 (C3) and the synthetic phenotype. We targeted the SHR C3 gene (C3 knockout [C3 KO] SHRs ) by the zinc finger gene editing method. In the current study, we investigated the mechanisms underlying the increased expression of C3 and the role of endogenous C3 in the synthetic phenotype of SHR VSMC s in comparison to cells from Wistar-Kyoto ( WKY) rats and C3 KO SHR s. Methods and Results Nonmuscle myosin heavy chain staining of aortas from SHR s at 1 day after birth was stronger in comparison to WKY rats and C3 KO SHR s. DNA synthesis in VSMC s from SHR s was significantly higher in comparison to WKY rats and C3 KO SHR s. Immunohistochemical staining of renin and liver X receptor α in VSMC s from SHR s was stronger in comparison to WKY rats and C3 KO SHR s. The expression of renin, Krüppel-like factor 5, and liver X receptor α proteins in VSMC s from SHR s was significantly higher in comparison to WKY rats and C3 KO SHR s. The expression of synthetic phenotype markers osteopontin, matrix gla, and l-caldesmon, growth factors transforming growth factor-β1 and platelet-derived growth factor-A, transcription factors Krüppel-like factor 5 and liver X receptor α, and angiotensinogen mRNA s in VSMC s from SHR s was significantly higher in comparison to WKY rats and C3 KO SHR s. The expression of miR-145 mRNA in VSMC s from SHR s was suppressed in comparison to cells from WKY rats. miR-145 inhibitor significantly increased the expression of C3 in VSMC s from WKY rats, but not in cells from SHR s. Conclusions These findings indicate that the increased C3 with the suppression of miR-145 induces the synthetic phenotype through Krüppel-like factor 5 and the activation of the renin-angiotensin system through liver X receptor α in VSMC s from SHR s.