Extracellular Matrix and Outflow Resistance

细胞外基质和流出阻力

• 批准号: 7985508
• 负责人: Kate E Keller
• 金额: $ 26.95万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7985508
• 关键词: Affect; Aging; Anterior; Aqueous Humor; Area; Attenuated; Back; Binding; Biological; Blindness; C-terminal; Cell surface; Cells; Cellular Structures; Cleaved cell; Complex; Confocal Microscopy; Data; Development; Disease; Disintegrins; Endosomes; Enzymes; Event; Extracellular Matrix; Extracellular Matrix Degradation; Extracellular Space; Eye; Genes; Glaucoma; Goals; Homeostasis; Human; Hyaluronan; Hyaluronidase; Immunofluorescence Immunologic; Investigation; Lead; Life; MMP2 gene; Matrix Metalloproteinases; Messenger RNA; Metalloproteases; Modeling; Molecular; Pathway interactions; Patients; Peptide Hydrolases; Perfusion; Physiologic Intraocular Pressure; Physiological; Primary Open Angle Glaucoma; Process; Proteoglycan; RNA Interference; Recombinants; Recycling; Resistance; Reverse Transcriptase Polymerase Chain Reaction; Role; Series; Site; Structure; Symptoms; Testing; Time; Trabecular meshwork structure; Work; aqueous; aqueous humor flow; base; cell growth regulation; cell type; extracellular; gene synthesis; human MMP14 protein; inhibitor/antagonist; mRNA Transcript Degradation; novel; pressure; public health relevance; response; uptake; versican

DESCRIPTION (provided by applicant): Glaucoma is a common blinding disease that affects over 66 million people worldwide and is frequently associated with elevated intraocular pressure (IOP). However, a homeostatic mechanism to adjust elevated IOP must exist since less than 10% of people develop glaucoma. Elevated IOP is caused by increased resistance to aqueous humor outflow through the trabecular meshwork (TM). When TM cells are subjected to sustained elevated IOP, they initiate remodeling of the extracellular matrix (ECM) by releasing specific proteinases including matrix metalloproteinases (MMPs). ECM turnover produces a new, reduced resistance to allow greater aqueous humor outflow through the TM and decrease IOP. Examination of the molecules involved in remodeling, their proteolytic targets and modes and sites of action is critical in order for us to understand how IOP is adjusted. Our long-term goal is to determine the molecular mechanisms by which elevated IOP is homeostatically adjusted in normal eyes. The goal of this current proposal is to further elucidate the function of two ECM components, ADAMTS4 and hyaluronan, and their roles in IOP homeostasis. ADAMTS4 (A Disintegrin and Metalloproteinase with Thrombospondin motifs) is a proteolytic enzyme that degrades ECM components in the TM. ADAMTS4 increases outflow facility in anterior segment perfusion culture suggesting a role for ADAMTS4 in normal homeostatic responses to elevated IOP. Here, we propose a working model whereby ADAMTS4 is activated at specialized cellular structures, then cleaves its target molecules and is internalized into the cell in endosomes. These endosomes may be recycled to the cell surface to release active ADAMTS4 back into the ECM. We will investigate how ADAMTS4 is proteolytically activated and its cellular fate following activation in TM cells. Hyaluronan concentrations in TM decrease during aging and in POAG, which may be due to decreased synthesis, increased degradation or increased cellular hyaluronan uptake. Recently, three genes involved in hyaluronan synthesis and six genes responsible for hyaluronan degradation have been identified and we will investigate their mRNA levels in response to pressure. We will also determine how decreased hyaluronan concentration affects outflow facility in anterior segment perfusion culture. Finally, the effects of hyaluronan concentration on ADAMTS4/MMP expression, localization and/or activation in TM cells will be determined. Investigation into the molecular mechanisms by which ADAMTS4 and hyaluronan are regulated in the TM will provide new information on the complex series of events that leads to homeostatic adjustment of IOP. Studying the molecular details of normal IOP homeostasis should facilitate development of novel therapies targeted at reducing IOP in glaucoma patients. PUBLIC HEALTH RELEVANCE: Glaucoma is a leading cause of vision loss, affecting approximately 67 million people worldwide, but the underlying cause(s) of this disease is poorly understood. Current treatments for glaucoma are directed toward treating the symptoms but not the cause of the disease. This study focuses on understanding how glaucoma develops at the molecular level and thus may facilitate development of new therapies targeted at reducing elevated intraocular pressure.

描述（由申请人提供）：青光眼是一种常见的致盲性疾病，影响全球超过6600万人，通常与眼内压（IOP）升高相关。然而，必须存在调节升高的IOP的稳态机制，因为少于10%的人发展为青光眼。眼压升高是由于对通过小梁网（TM）流出的房水的阻力增加所致。当TM细胞经受持续升高的IOP时，它们通过释放包括基质金属蛋白酶（MMP）的特异性蛋白酶来启动细胞外基质（ECM）的重塑。ECM周转产生新的、降低的阻力，以允许更多的房水通过TM流出并降低IOP。检查参与重塑的分子、其蛋白水解靶点和作用模式和位点对于我们了解IOP是如何调节的至关重要。我们的长期目标是确定正常眼内眼压升高的分子机制。本研究的目的是进一步阐明两种ECM成分ADAMTS 4和透明质酸的功能及其在IOP稳态中的作用。 ADAMTS 4（具有血小板反应蛋白基序的去整合素和金属蛋白酶）是降解TM中的ECM组分的蛋白水解酶。ADAMTS 4增加眼前节灌注培养中的流出设施，表明ADAMTS 4在对升高的IOP的正常稳态反应中的作用。在这里，我们提出了一个工作模型，其中ADAMTS 4在专门的细胞结构中被激活，然后切割其靶分子并内化到细胞的内体中。这些内体可以再循环到细胞表面以将活性ADAMTS 4释放回ECM中。我们将研究ADAMTS 4是如何被蛋白水解激活的，以及它在TM细胞中激活后的细胞命运。TM和POAG中透明质酸浓度在老化过程中降低，这可能是由于合成减少、降解增加或细胞透明质酸摄取增加。最近，三个基因参与透明质酸的合成和六个基因负责透明质酸的降解已被确定，我们将研究其mRNA水平的压力。我们还将确定透明质酸浓度降低如何影响眼前节灌注培养的流出功能。最后，将确定透明质酸浓度对TM细胞中ADAMTS 4/MMP表达、定位和/或活化的影响。 对TM中ADAMTS 4和透明质酸调节的分子机制的研究将提供关于导致IOP稳态调节的复杂系列事件的新信息。研究正常IOP稳态的分子细节应有助于开发针对青光眼患者降低IOP的新疗法。 公共卫生相关性：青光眼是视力丧失的主要原因，影响全球约6700万人，但对这种疾病的根本原因知之甚少。目前青光眼的治疗方法是针对治疗症状，而不是疾病的原因。这项研究的重点是了解青光眼如何在分子水平上发展，从而可能促进新的治疗方法的发展，以降低眼压升高。