miR-542-3p调控BMP7通路在老龄VSMC向成骨样表型转化中作用及机制研究

The vascular calcification was severe along with the age increase gradually, but the mechanism is not completely clear.The osteoblast-like phenotypic transformation of vascular smooth muscle cells(VSMC) was thought to be the key link of vascular calcification. We have found that the expression of miR-542-3p was significantly down regulated in VSMC by aging, which lead to lose the function of contractile phenotype of VSMC, and at the same time to accelerate osteoblast-like phenotypic transformation of VSMC, but the mechanism is not clear. Bioinformatics predicted that the BMP7 is potential target genes of miR-542-3p, which showed a negative correlation of the expression level of miR-542-3p and BMP7 in VSMC. Previous studies suggested that the BMP7 may accelerate the osteoblast-like phenotypic transformation of VSMC by downstream effectors Jagged1 and/or Runx2.Thus the hypothesis was put forward that the lower expression of miR-542-3p in aging VSMC, could induce up-regulation expression of BMP7, and then promote the osteoblast-like phenotypic transformation of VSMC. This project intends to clarify the effect and mechanism of BMP7 regulated by miR-542-3p on osteoblast-like phenotypic transformation of VSMC induced by aging through induced VSMC calcification model and aging ApoE-/- mice model of vascular calcification, expect to perfect the molecular mechanisms of vascular calcification by aging, and provide a new thinking for clinical prevention and treatment of vascular calcification in the elderly.

血管钙化随年龄增加逐渐加重，但增龄促血管钙化的机制尚不完全清楚。目前认为VSMC向成骨样表型转化是血管钙化的关键环节。我们研究发现miR-542-3p在老龄VSMC中显著下调，致VSMC收缩表型丧失，同时促进VSMC向成骨样表型转化，但机制不清。生物信息学预测BMP7是miR-542-3p潜在靶基因，VSMC中miR-542-3p表达水平与BMP7负相关。既往研究提示BMP7可能通过下游效应分子Jagged1和/或Runx2促VSMC向成骨样表型转化。因而提出假说：老龄VSMC中miR-542-3p减少，导致BMP7表达上调，从而促VSMC向成骨样表型转化。本项目拟利用VSMC诱导钙化模型和老龄ApoE-/-小鼠血管钙化模型，阐明miR-542-3p调控BMP7通路在老龄VSMC向成骨样表型转化中作用及机制。通过本项目有望完善老龄促血管钙化的分子机制，为临床防治老年人血管钙化提供新的思路。

血管钙化随年龄增加逐渐加重，但增龄促血管钙化的机制尚不完全清楚。目前认为VSMC向成骨样表型转化是血管钙化的关键环节。此次主要研究老龄VSMC中miR-542-3p减少靶向上调BMP7，从而促VSMC向成骨样表型转化及钙化的作用及机制。研究结果明确了老龄下调Mir-542-3p，可通过靶向调控BMP7促VSMC向成骨样表型转化及钙化，具体包括：1.老龄VSMC中miR-542-3p表达显著降低; 2. miR-542-3p抑制β-磷酸甘油诱导的幼龄VSMC钙化; 3.验证了miR-542-3p可靶向调节BMP7; 4.BMP7逆转mir-542-3p对VSMC向成骨表型转化的抑制作用。相关内容发表 SCI 论文2 篇。另外，还成功构建高脂饮食喂养老龄ApoE-/-小鼠血管钙化动物模型，并检测了不同年龄小鼠血管壁成骨表型标记物表达差异。生物合成了硫化镉（CdS）纳米颗粒用于核酸及过氧化氢检测。重要结果和关键数据：MicroArray及qRT-PCR方法比较了不同年龄VSMC中260个microRNAs表达差异，荧光素酶报告基因检测系统证实BMP7为Mir-542-3p靶基因，检测了VSMC成骨表型相关因子及细胞钙化指标。并且在这一研究基础上，深入研究BMP7调控VSMC成骨样表型转化的机制，发现BMP7不直接抑制VSMC Jagged1表达，但可抑制内皮细胞Jagged1表达，提示BMP7有可能通过内皮细胞-平滑肌细胞间对话调节VSMC的成骨样表型转化。Jagged1在调控VSMC向成骨表型转化中扮演何种角色，内皮-平滑肌细胞对话调节通过何种介质完成，值得进一步研究明确。综上所述，此次研究完善了老龄促血管钙化的分子机制，而且有望为临床防治老年人血管钙化提供新的思路。