Overexpression of c1q/tumor necrosis factor-related protein-3 promotes phosphate-induced vascular smooth muscle cell calcification both in vivo and in vitro.

OBJECTIVE: Vascular calcification is highly correlated with increased cardiovascular morbidity and mortality. C1q/tumor necrosis factor-related protein-3 (CTRP3) is a newly identified adipokine that plays important roles in cardiovascular system. Here, we investigated the role of CTRP3 in vascular calcification and its underlying mechanism. APPROACH AND
RESULTS: Adenine-induced chronic renal failure rat model was used to mimic the process of arterial medial calcification. The level of CTRP3 was elevated in serum and abdominal aorta of chronic renal failure rats. Periadventitial gene delivery of CTRP3 significantly accelerated the calcification of abdominal aorta and arterial ring. In cultured vascular smooth muscle cells (VSMCs), CTRP3 increased β-glycerophosphate-induced calcium deposition and alkaline phosphatase activity. Although CTRP3 alone was not sufficient to induce calcification in VSMCs, it upregulated the expression of osteogenic marker genes including runt-related transcription factor 2 (Runx2), bone morphogenetic protein 2, and osteopontin. CTRP3 further enhanced β-glycerophosphate-induced downregulation of smooth muscle α-actin and smooth muscle 22α, while augmenting osteogenic marker expression in VSMCs induced by β-glycerophosphate. In contrast, knockdown of CTRP3 in VSMCs potently suppressed β-glycerophosphate-induced calcification. Mechanistically, knockdown of Runx2 inhibited CTRP3-promoted VSMC calcification. CTRP3 increased extracellular signal-regulated kinase 1/2 phosphorylation and reactive oxygen species production. Preincubation with U0126, an extracellular signal-regulated kinase 1/2 upstream kinase inhibitor, had no effect on CTRP3-induced reactive oxygen species production. However, pretreatment with N-acetyl-l-cysteine, a reactive oxygen species scavenger, suppressed CTRP3-induced extracellular signal-regulated kinase 1/2 phosphorylation. Both N-acetyl-l-cysteine and U0126 significantly inhibited CTRP3-induced upregulation of Runx2 and calcified nodule formation.
CONCLUSIONS: CTRP3 promotes vascular calcification by enhancing phosphate-induced osteogenic transition of VSMC through reactive oxygen species-extracellular signal-regulated kinase 1/2-Runx2 pathway.