Oxidized Low-Density Lipoprotein Promotes Osteoblastic Differentiation of Valvular Interstitial Cells through RAGE/MAPK

OBJECTIVES: We have previously shown that oxidized low-density lipoprotein (oxLDL) promotes the osteogenic differentiation of valvular interstitial cells (VICs) by inducing endoplasmic reticulum (ER) stress. We also demonstrated the detrimental role of the receptor for advanced glycation end products (RAGE) activation and signaling in the development and progression of aortic valve (AV) calcification. Here, we test the hypothesis that oxLDL may induce the osteoblastic differentiation of VICs via RAGE. METHODS: Cultured porcine aortic VICs were used in an in vitro model. The VICs were incubated with oxLDL for analysis, with and without RAGE siRNA. RESULTS: We found that oxLDL markedly increased the expression of RAGE, induced high levels of proinflammatory cytokine production and promoted the osteoblastic differentiation and calcification of VICs. oxLDL also induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) MAPK. However, these effects were found to be markedly suppressed by siRNA silencing of RAGE. CONCLUSIONS: Our data provide evidence that RAGE mediates oxLDL-induced activation of p38 and JNK MAPK and the osteogenic differentiation of VICs.