Initiation and Inhibition of Medial Artery Calcification

描述(由申请者提供)：我们的目标是了解动脉中膜钙化的启动和预防的分子机制。我们的工作假设是血液中含有一种内侧动脉钙化的致病因子(S)，并且这种血清核素在动脉中层弹力层中启动钙化的能力通常被钙化抑制物的相反作用所阻止，例如维生素K依赖的基质Gla蛋白(MGP)，这是一种由动脉中弹力层附近的平滑肌细胞分泌的抑制物。这种通过血液传播的内侧动脉钙化理论预测，当血清核素驱动的内侧动脉钙化的启动超过了MGP等抑制剂阻止这种钙化的能力时，体内就会发生钙化。我们的初步研究表明，血清含有一种有效的弹性蛋白钙化核蛋白，该试剂是一种55-150 kDa的蛋白质。我们的第一个目标是了解内侧动脉钙化的血清核因子，我们设计了实验来鉴定核因子，将重组核因子用于各种核因子结构-功能的研究，并在体内验证血清核因子活性驱动动脉钙化的假说。我们的第二个目标是了解决定大鼠中膜钙化程度的因素，我们设计了实验来测试骨吸收抑制剂预防尿毒症中膜钙化的能力，并在中膜钙化开始时阻止它的进展。我们还将确定华法林是否与尿毒症协同作用以加速中层钙化。我们的第三个目标是确定基质GLA蛋白正常情况下阻止内侧动脉钙化的分子机制。初步研究表明，MGP在器官培养中的动脉中高度表达，华法林在器官培养中导致中层钙化，而在培养液中添加MGP可以防止这种钙化。我们设计了利用动脉器官培养的实验，以确定MGP通常抑制内侧动脉钙化的机制；MGP结构与其作为钙化抑制剂的活性之间的关系；以及调节MGP表达和血管细胞磷酸化的因素。

DESCRIPTION (provided by applicant): Our goal is to understand the molecular mechanisms responsible for the initiation and prevention of calcification in the artery media. Our working hypothesis is that blood contains a causative agent(s) for medial artery calcification, and that the ability of this serum nucleator to initiate calcification in the elastic lamellae of the artery media is normally prevented by the opposing action of calcification inhibitors such as the vitamin K-dependent matrix Gla protein (MGP), an inhibitor which is secreted by smooth muscle cells adjacent to the elastic lamellae in the artery media. This blood borne theory of medial artery calcification predicts that calcification can occur in vivo whenever the initiation of medial calcification driven by the serum nucleator exceeds the capacity ofinhibitors such as MGP to prevent this calcification. Our initial study shows that serum contains a potent nucleator of elastin calcification, and that this agent is a 55-150kDa protein. Our first aim is to understand the serum nucleator of medial artery calcification, and we have designed experiments to identify the nucleator, to use recombinant nucleator in a variety of studies of nucleator structure-function, and to test the hypothesis that serum nucleator activity drives artery calcification in vivo. Our second aim is to understand the factors that determine the extent of medial calcification in the rat, and we have designed experiments to test the ability of bone resorption inhibitors to prevent medial calcification in uremia, and to arrest the progression of medial calcification once it has begun. We will also determine whether warfarin acts synergistically with uremia to accelerate medial calcification. Our third aim is to identify the molecular mechanisms by which medial artery calcification is normally prevented by matrix Gla protein. Pilot studies show that MGP is highly expressed by the artery in organ culture, that warfarin causes medial calcification in organ culture, and that addition of MGP to medium prevents this calcification. We have designed experiments using artery organ culture to determine the mechanisms by which MGP normally inhibits medial artery calcification; the relation between MGP structure and its activity as a calcification inhibitor; and the factors, which regulate MGP expression and phosphorylation by vascular cells.