Departments of IIEP- Research and Teaching Institute, Critical Care Medicine and Cardiology, Hospital Israelita Albert Einstein, São Paulo, SP, Brazil.
Departments of IIEP- Research and Teaching Institute, Critical Care Medicine and Cardiology, Hospital Israelita Albert Einstein, São Paulo, SP, Brazil.
Atherosclerosis. 2017 Oct;265:14-21. doi: 10.1016/j.atherosclerosis.2017.07.028. Epub 2017 Jul 29.
Obesity and diabetes potentiate vascular calcification by increasing vascular smooth muscle cells osteoblastic differentiation mediated by the transcription factor Msx2 and bone morphogenetic protein-2 signaling. However, Bmp-2/Msx2 crosstalk to induce VSMC osteogenic phenotype transition and calcification is poorly understood in diabetes. We aimed to investigate mechanisms underlying Bmp-2-driven VSMC osteogenic differentiation and calcification in leptin-deficient ob/ob mice.
We incubated VSMC from ob/ob mice and wild type C57BL/6 littermates with or without Bmp-2. We used loss-of-function experiments to investigate the role of Msx2 in Bmp-2-induced ob/ob VSMC osteochondrogenic differentiation and calcification by transfecting Msx2 siRNA into VSMC.
Baseline ob/ob VSMC and aorta showed increased Msx2, Runx2, alkaline phosphatase mRNA and protein expression, which further increased in Bmp-2-incubated ob/ob VSMC, therefore augmenting ob/ob VSMC calcification in comparison to wild type VSMC. Accordingly, signaling pathways to induce VSMC osteogenic differentiation, such as Smad1/5 phosphorylation increased in ob/ob versus wild type aorta. In comparison to wild type VSMC, Msx2 siRNA transfected VSMC decreased Bmp-2-dependent osteochondrogenic differentiation response by abrogating Msx2, Runx2, Alpl expression in ob/ob but not in wild type VSMC. Nonetheless, Msx2 inhibition did not decrease calcification in Bmp-2 stimulated ob/ob VSMC in vitro.
Our data support a crucial role of Msx2 for ob/ob VSMC osteochondrogenic differentiation, however, Msx2 signaling alone is not sufficient for ob/ob VSMC calcification after Bmp-2 stimulation in vitro. These findings can be translated into novel perspectives for the understanding of the mechanisms and to provide therapeutic targets underlying vascular calcification in type 2 diabetes.
肥胖和糖尿病通过增加血管平滑肌细胞成骨分化来增强血管钙化，这种分化是由转录因子 Msx2 和骨形态发生蛋白-2 信号介导的。然而，Bmp-2/Msx2 相互作用以诱导 VSMC 成骨表型转变和钙化在糖尿病中尚未得到充分理解。我们旨在研究瘦素缺乏型 ob/ob 小鼠中 Bmp-2 驱动 VSMC 成骨分化和钙化的机制。
我们将 ob/ob 小鼠和野生型 C57BL/6 同窝仔鼠的 VSMC 与或不与 Bmp-2 一起孵育。我们使用失活功能实验通过将 Msx2 siRNA 转染到 VSMC 中来研究 Msx2 在 Bmp-2 诱导的 ob/ob VSMC 成软骨分化和钙化中的作用。
基础状态下，ob/ob VSMC 和主动脉显示出增加的 Msx2、Runx2、碱性磷酸酶 mRNA 和蛋白表达，这些表达在 Bmp-2 孵育的 ob/ob VSMC 中进一步增加，因此与野生型 VSMC 相比，增加了 ob/ob VSMC 的钙化。相应地，诱导 VSMC 成骨分化的信号通路，如 Smad1/5 磷酸化在 ob/ob 主动脉中比野生型增加。与野生型 VSMC 相比，Msx2 siRNA 转染的 VSMC 通过在 ob/ob 而非野生型 VSMC 中消除 Msx2、Runx2、Alpl 表达，减少了 Bmp-2 依赖性成软骨分化反应。尽管如此，在体外刺激 Bmp-2 时，Msx2 抑制并未减少 ob/ob VSMC 的钙化。
我们的数据支持 Msx2 对 ob/ob VSMC 成软骨分化的关键作用，然而，在体外刺激 Bmp-2 后，仅 Msx2 信号不足以引起 ob/ob VSMC 的钙化。这些发现可以为理解 2 型糖尿病中血管钙化的机制和提供治疗靶点提供新的视角。
