Control of Trabecular Meshwork Cytoskeleton

描述（由申请人提供）：本资助的长期目标是确定如何控制avb3整合素信号机制，以开发控制青光眼吞噬和流出设施的治疗靶点。青光眼导致视网膜神经节细胞不可逆转的丧失，全世界约有6700万人患有青光眼。它们通常与眼内压（IOP）水平升高有关，这是由于房水从小梁网（TM）流出减少所致。肌动蛋白细胞骨架是一个重要的调控机制。它控制着一些关键的生物过程，包括维持正常的流出设施，包括收缩，吞噬和基质沉积。整合素在调节细胞凋亡的过程中起着核心作用

DESCRIPTION (provided by applicant): The long-term objective of this grant is to identify how to control avb3 integrin signaling mechanisms in order to develop therapeutic targets to control phagocytosis and outflow facility in glaucoma. The glaucomas, which lead to irreversible loss of retinal ganglion cells, affect approximately 67 million people worldwide. They are commonly associated with elevated levels of intraocular pressure (IOP) due to a reduction in aqueous humor outflow from the trabecular meshwork (TM). One of the major factors that have emerged as an important regulatory mechanism for outflow facility is the actin cytoskeleton. It controls a number of key biological processes involved in maintaining normal outflow facility including contractility, phagocytosis, and matrix deposition. Integrins play a central role in regulating the activity of actin cytoskeleton and our studies suggest that dysregulation of the avb3 integrin may be responsible for some of changes observed during glaucoma including decreased phagocytosis and outflow facility. We propose that this integrin may be chronically activated in glaucoma, especially steroid induced glaucoma during a process called inside-out signaling. Inside-out signaling occurs when a secondary stimulus such as dexamethasone induces the expression, or binding, of intracellular proteins to the cytoplasmic tails of the integrin subunits This binding triggers the active conformation of the integrin. Once this integrin is activated, it would cause a decrease in phagocytosis and outflow facility by triggering a Rac1/Trio pathway that prevents phagocytosis. We plan to test this hypothesis by using an activating antibody to induce the active conformation of avb3 integrin or viral vectors to overexpress an activated avb3 integrin in porcine organ cultured anterior segments. We then plan to determine if expression of this activated avb3 integrin causes a decrease in phagocytosis and outflow facility. We also plan to determine if the Rac1/Trio pathway utilized by avb3 integrin to decrease phagocytosis is involved in the decrease in outflow facility and how dexamethasone treatment causes the activation of the avb3 integrin. Finally, we plan to determine if increases in outflow facility following steroid treatment correlate with the levels of avb3 integrin expression in the TM. These studies should show whether b3 integrin signaling pathway(s) could be involved in steroid induced glaucoma and identify sites along the pathway that we can target to increase outflow facility in the diseased eye.