MSX2-WNT SIGNALING IN CARDIOVASCULAR CALCIFICATION

描述（申请人提供）：动脉硬化是以动脉壁增厚、硬化并失去弹性为特征的慢性疾病状态。动脉粥样硬化、Monckeberg's内侧钙化硬化和小动脉硬化是动脉硬化的三种组织病理学类型。随着年龄的增长、糖耐量下降、糖尿病和高血压，导管动脉变得越来越硬化，失去了远端组织灌注顺畅所必需的顺应性。血管几何形状的改变，以及纤维化、交联和矿化引起的血管基质材料特性的改变，都会损害Windkessel的生理机能。动脉硬化，即内侧钙化硬化，是导致2型糖尿病（T2DM）患者下肢截肢的重要因素。更好地了解控制动脉纤维化、钙化和依从性的信号通路将导致减少动脉硬化疾病负担的新策略。最近的数据表明，Wnt/ 2- catenin信号和Wnt7 /LRP6相互作用在血管钙化和组织纤维化中起重要作用——TNF-、BMP2-和Msx2-激活的成骨矿化的下游。因此，本提案的具体目的是：目的1：“利用SM22- Cre（+）、Ctnnb1（flox/+）、Ctnnb1(flox/+)，建立细胞自主血管平滑肌细胞（VSMC） 2-连环蛋白作用对糖尿病动脉硬化血管钙化和壁纤维化的贡献；LDLR（-/-）小鼠作为研究模型。”我们测试了VSMC 2-catenin信号的基因下调是否会改变糖尿病动脉硬化的发生和进展，包括LDLR-/-小鼠饮食诱导的LE血流量减少。目的2：“利用糖尿病SM22- Cre（+）、LRP6（fl/fl）、LRP6（fl/fl）、LRP6和mx2 - wnt信号在心血管钙化过程中的促钙化作用，研究VSMC LRP6表达在介导mx2 - wnt信号的促钙化作用中的作用。LDLR（-/-）小鼠作为研究模型。”LRP6通过2-catenin和nfatc介导的转录介导wnt7依赖性成骨和纤维化信号。在此目的中，我们在体内确定VSMC LRP6在糖尿病动脉硬化血管钙化启动中的细胞自主作用，以及对饮食诱导的主动脉成骨基因程序激活的影响。这些目标的结果将为降低VSMC 2-catenin水平和LRP6信号作为改善血管钙化的潜在治疗策略提供生理学依据和验证，从而降低II型糖尿病患者的下肢截肢风险

DESCRIPTION (provided by applicant): Arteriosclerosis is the chronic disease state characterized by thickening and hardening of arterial walls with loss of elasticity. Atherosclerosis, Monckeberg's medial calcific sclerosis, and arteriolosclerosis are the three histopathologic types of arteriosclerosis. With advancing age, impaired glucose tolerance, diabetes, and hypertension, the conduit arteries become increasingly arteriosclerotic, losing compliance necessary for smooth distal tissue perfusion. This Windkessel physiology is impaired by changes in vascular geometry, and by changes in vascular matrix material properties arising from fibrosis, cross-linking and mineralization. Arteriosclerosis- viz., medial calcific sclerosis - has emerged as a particularly important contributor to lower extremity (LE) amputation risk in type II diabetes (T2DM). A better understanding of signaling pathways that control arterial fibrosis, calcification, and compliance will lead to new strategies for diminishing arteriosclerotic disease burden. Recent data identify Wnt/ 2 -catenin signaling and Wnt7 /LRP6 interactions as important in vascular calcification and tissue fibrosis -- down-stream of TNF-, BMP2-, and Msx2- activated osteogenic mineralization. Thus, the specific aims of this proposal are: Aim 1: "To establish the contributions of cell-autonomous vascular smooth muscle cell (VSMC) 2-catenin actions to vascular calcification and mural fibrosis in diabetic arteriosclerosis, using SM22- Cre(+);Ctnnb1(flox/+);LDLR(-/-) mice as a model for study." We test whether genetic down- regulation of VSMC 2-catenin signaling alters initiation and progression of diabetic arteriosclerosis, including diet-induced reductions in LE blood flow in the LDLR-/- mouse. Aim 2: "To examine the role of VSMC LRP6 expression in mediating the pro-calcific actions of Msx2-Wnt signaling during cardiovascular calcification, using diabetic SM22- Cre(+);LRP6(fl/fl);LDLR(-/-) mice as a model for study." LRP6 mediates Wnt7-dependent osteogenic and fibrotic signals in culture via 2-catenin and NFATc-mediated transcription. In this aim, we determine in vivo the cell-autonomous roles of VSMC LRP6 to the initiation of vascular calcification in diabetic arteriosclerosis in vivo, and the impact upon diet-induced activation of aortic osteogenic gene programs. The outcomes of these aims will provide physiological rationale and validation for reducing VSMC 2-catenin levels and LRP6 signaling as a potential therapeutic strategy to ameliorate vascular calcification -- and thus reduce lower extremity amputation risk in type II diabetes