Glucocorticoids, ocular hypertension, and glaucoma

描述(由申请者提供)：青光眼是美国和世界范围内视力受损和失明的主要原因。然而，青光眼发生的分子机制却知之甚少。使用抗炎性糖皮质激素(GCs)可导致眼压升高和青光眼易感人群。这些“类固醇反应者”罹患原发性开角型青光眼(POAG)的风险更高。几乎所有的POAG患者都是类固醇反应者。GC诱导的高眼压和青光眼在临床上类似于POAG，GC对小梁网络(TM)的影响与POAG发生的许多分子和生化变化相似，小梁网络(TM)是负责调节房水流出(从而调节眼压)的组织。糖皮质激素受体(GR)的两个主要亚型介导GC的生物学反应。GRA是一种配体激活的转录因子，GRB是GC活性的主要负调控因子。我们最近发现，与正常TM(NTM)细胞相比，青光眼TM(GTM)细胞的GRB水平非常低，这使得GTM细胞更容易受到GCs的青光眼影响。我们的总体假设是：(A)在正常的TM细胞中，GR？？的高表达导致GC抵抗，而GR？的低水平表达，如在GTM中发现的那样，导致青光眼的GC反应性增强和眼压升高，以及(B)GR？；活性和表达受特定剪接蛋白的调节，并通过特定的重要蛋白移位到细胞核。以下特定目标将解决和检验这一假说：(1)研究剪接蛋白的表达和/或活性改变是否调节GR？；在青光眼背景下TM中的表达；(2)描述GR？和GR？；在正常和青光眼TM中调节GC敏感性的作用；以及(3)评估GR？是否调节GC诱导的高眼压；GR？在体外灌流培养的小鼠眼前节和体内的表达。这项研究首次探索了选择性剪接和核移位在TM中的作用，将开发两种新的GC诱导的高眼压模型，并将为GC诱导的高眼压、类固醇青光眼和POAG的发病机制提供更好的见解。

DESCRIPTION (provided by applicant): Glaucoma is a leading cause of visual impairment and blindness in the US and worldwide. However, the molecular mechanisms responsible for the development of glaucoma are poorly understood. The use of anti-inflammatory glucocorticoids (GCs) can cause elevated intraocular pressure (IOP) and glaucoma in susceptible individuals. These "steroid responders" are at higher risk for developing primary open-angle glaucoma (POAG). Almost all POAG patients are steroid responders. GC-induced ocular hypertension and glaucoma is clinically similar to POAG, and GC effects on the trabecular meshwork (TM), the tissue responsible for regulating aqueous humor outflow (and therefore IOP), mimic many of the molecular and biochemical changes that occur in POAG. Two major isoforms of the glucocorticoid receptor (GR) mediate GC biological responsiveness. GRa is a ligand activated transcription factor and GRb is a dominant negative regulator of GC activities. We recently found that glaucomatous TM (GTM) cells have very low levels of GRb compared to normal TM (NTM) cells, which makes GTM cells much more susceptible to the glaucomatous effects of GCs. Our overall hypothesis is that: (a) high expression of GR?; in normal TM cells leads to GC resistance, and low levels of GR?; expression, as found in GTM, leads to enhanced GC responsiveness and elevated IOP in glaucoma and (b) GR?; activity and expression are regulated by specific splicesome proteins and by translocation to the nucleus via specific importins. The following specific aims will address and test this hypothesis: (1) to investigate whether altered expression and/or activity of splicesome proteins regulate GR?; expression in the TM in the context of glaucoma, (2) to delineate the role of differential trafficking of GR?; and GR?; in regulating GC sensitivity in the normal and glaucomatous TM, and (3) to evaluate whether GC-induced ocular hypertension is regulated by GR?; expression in ex vivo perfusion cultured anterior segments as well as in vivo in mice. This research explores for the first time the roles of alternative splicing and nuclear translocation in the TM, will develop 2 new models of GC-induced ocular hypertension as well as will provide better insights into the pathogenesis of GC-induced ocular hypertension, steroid glaucoma, and POAG.