GPCR Kinase-2 in TNFalpha Signaling in Macrophages

巨噬细胞是参与许多炎性疾病发病机制的重要免疫细胞， 包括动脉粥样硬化，并且是动脉粥样硬化病变中的主要免疫细胞之一。除了 巨噬细胞在摄取血管壁中修饰的脂蛋白后成为泡沫细胞， 通过产生细胞因子与动脉粥样硬化斑块形成相关的炎症反应， 趋化因子和生长因子。这些试剂进一步影响更多单核细胞和其他细胞的化学吸引力。 免疫细胞以及深刻地影响平滑肌细胞和内皮细胞的功能， 附近因此，巨噬细胞在动脉粥样硬化形成的所有阶段，包括脂肪条纹中发挥重要作用 到晚期斑块并最终导致斑块破裂。因此，了解生化机制， 巨噬细胞生物学受哪种调节是非常关键的。初步数据显示，巨噬细胞 生物学由G蛋白偶联受体激酶-2（GRK 2）调节。GRK 2是丝氨酸/苏氨酸激酶， 由于其在β-肾上腺素能受体磷酸化中的作用而被发现。有证据表明肿瘤 坏死因子-β 1（TNF-α）诱导的NF-κ BB信号传导以及随之而来的巨噬细胞生物学是至关重要的 通过与NFκ B B信号传导抑制剂相互作用和潜在磷酸化，受GRK 2调节 也就是I， B，􀀁这些结果表明，这种激酶在巨噬细胞生物学中具有新的重要作用， 因此在动脉粥样硬化的发病机制中。这项建议的目的是进一步扩大我们的 初步发现，并检查GRK 2调节巨噬细胞生物学的机制， 重要的是，还测试GRK 2的缺失是否影响动脉粥样硬化的病理生理学。总的假设是 GRK 2与NFB激酶的相互作用和磷酸化调节TNF α诱导的NF B信号传导，􀀃 炎症介质的产生和巨噬细胞的存活/凋亡，因此，GRK 2起作用， 在动脉粥样硬化的发病机制中起关键作用。为了验证这一假设，我们将检查以下内容 具体目标：1.描述GRK-2调节TNFα诱导的NFκ B B通路的机制， 巨噬细胞2.检查GRK 2在巨噬细胞中的TNF α信号传导中的功能相关性。􀀁3.确定 骨髓细胞特异性GRK 2缺失是否影响LDLR敲除小鼠动脉粥样硬化的发病机制。 综上所述，我们的研究应该提供重要的机制洞察TNFα信号在巨噬细胞 以及鉴定慢性炎性疾病治疗中的潜在治疗靶点

Macrophages are important immune cells involved in the pathogenesis of many inflammatory diseases, including atherosclerosis and are one of the major immune cells in the atherosclerotic lesions. In addition to becoming foam cells upon uptake of modified lipoproteins in the vessel walls, macrophages also mediate the inflammatory responses that are associated with atherosclerotic plaque formation by producing cytokines, chemokines and growth factors. These agents further influence chemoattraction of more monocytes and other immune cells as well as profoundly affect the functions of smooth muscle cells and endothelial cells that are in the vicinity. Therefore, macrophages play an essential role in all stages of atherogenesis including fatty streaks to advanced plaques and eventually to plaque rupture. Thus, understanding the biochemical mechanisms by which macrophage biology is regulated is highly critical. Preliminary data demonstrates that macrophage biology is regulated by G-protein coupled receptor kinase-2 (GRK2). GRK2 is a serine/threonine kinase that was discovered for its role in the phosphorylation of 􀀂-adrenergic receptors. Evidence indicates that tumor necrosis factor-􀀁(TNF􀀁)-induced NF􀀃B signaling, and the consequent macrophage biology are critically regulated by GRK2, via interaction with, and potentially phosphorylation of the inhibitor of NF􀀃B signaling namely I􀀃B􀀁. These results suggest a novel and significant role for this kinase in macrophage biology and therefore in the pathogenesis of atherosclerosis. The objective of this proposal is to further expand on our preliminary findings and examine the mechanisms by which GRK2 regulates macrophage biology and importantly, also test if, loss of GRK2 affects the pathophysiology of atherosclerosis. The overall hypothesis is that GRK2 interaction with and phosphorylation of I􀀃B􀀁regulates TNF􀀁-induced NF􀀃B signaling, inflammatory mediator production, and macrophage survival/apoptosis and therefore, GRK2 plays a crucial role in the pathogenesis of atherosclerosis. To test this hypothesis we will examine the following specific aims: 1. Describe the mechanisms by which GRK-2 regulates TNF􀀁-induced NF􀀃B pathway in macrophages. 2. Examine the functional relevance of GRK2 in TNF􀀁signaling in macrophages. 3. Determine whether myeloid cell-specific loss of GRK2 affects the pathogenesis of atherosclerosis in LDLR knockout mice. Taken together, our studies should provide important mechanistic insight into TNF􀀁signaling in macrophages as well as identify potential therapeutic targets in the treatment of chronic inflammatory diseases