Monocyte Differentiation and Mac-1-Regulated Forkhead

描述（由申请人提供）：炎症在动脉粥样硬化和再狭窄的血管损伤中起重要作用。血管细胞之间的粘附相互作用协调了这种炎症反应。我们集中在白细胞整合素Mac-1（CD 11b/CD 18），确定这种粘附受体作为动脉损伤后新生内膜增厚的分子决定因素。这使我们假设Mac-1的“由外向内”信号可能启动了促进血管炎症的基因程序。我们已经克隆了一种新的叉头转录因子（Mac-1调节叉头，MFH），使用差异显示PCR，是下调Mac-1集群相比，非集群单核细胞。MFH作为已知调节单核细胞分化的基因（包括PU.1和c-fms）的转录抑制物起作用，并且过表达MFH在体外防止巨噬细胞样分化。该提议的中心假设是Mac-1参与通过调节新型叉头转录抑制因子的表达来协调单核细胞分化信号，从而调节血管炎症并最终调节损伤后的新生内膜增厚。我们的具体目标是：（1）确定MFH调节转录活性的能力的分子机制，并表征Mac-1对MFH调节的性质;（2）确定在体外和体内操纵MFH表达对单核细胞分化的影响;和（3）检查逆转录病毒骨髓干细胞过表达MFH对动脉损伤后巨噬细胞积聚和新生内膜增厚的影响。本提案中概述的实验应阐明Mac-1信号在单核细胞分化中的作用及其在血管损伤中的重要性。了解单核细胞分化的分子机制将提供必要的见解，制定抗炎策略，调节动脉粥样硬化，再狭窄和移植动脉病的血管损伤。

DESCRIPTION (provided by applicant): Inflammation plays an essential role in vascular injury in atherosclerosis and restenosis. Adhesive interactions between vascular cells orchestrate this inflammatory response. We have focused on the leukocyte integrin Mac-1 (CD11b/CD18), identifying this adhesive receptor as a molecular determinant of neointimal thickening after arterial injury. This led us to hypothesize that "outside-in" signaling by Mac-1 may initiate a gene program that promotes vascular inflammation. We have cloned a novel forkhead transcription factor (Mac-l-regulated forkhead, MFH) using differential display PCR that is down-regulated in Mac-1 clustered compared to non-clustered monocytic cells. MFH functions as a transcriptional repressor of genes known to regulate monocyte differentiation, including PU.1 and c-fms, and over-expressing MFH prevents macrophage-like differentiation in vitro. The central hypothesis of this proposal is that Mac-1 engagement orchestrates monocyte differentiation signals by regulating the expression of a novel forkhead transcription repressor, thereby modulating vascular inflammation and ultimately neointimal thickening after injury. Our specific aims are: (1) to define the molecular mechanism of MFH's ability to modulate transcriptional activity and to characterize the nature of MFH regulation by Mac-1; (2) to determine the effect of manipulating MFH expression on monocyte differentiation in vitro and in vivo; and (3) to examine the effect of retroviral bone marrow stem cell over-expression of MFH on macrophage accumulation and neointimal thickening after arterial injury. The experiments outlined in this proposal should clarify the role of Mac-1 signaling in monocyte differentiation and its importance in vascular injury. Understanding the molecular mechanisms of monocyte differentiation will provide insights necessary to develop anti-inflammatory strategies for modulating vascular injury in atherosclerosis, restenosis, and transplant arteriopathy.