Browsing by Subject "cross-linked actin networks"
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Item Exploring Trabecular Meshwork Molecular Pathogenic Mechanisms In Primary Open Angle Glaucoma And Glucocorticoid Induced Glaucoma(2016-08-01) Bermudez, Jaclyn Y.; Clark, Abbot F.; Mao, Weiming; Singh, MeharvanIn a normal functioning eye, the aqueous humor, a fluid secreted by the ciliary body, drains through the trabecular meshwork (TM), a multilayered tissue in the anterior segment of the eye. The TM is the initial site of damage in glaucoma. Damaged TM results in higher aqueous humor outflow resistance and causes elevated IOP, the latter of which leads to optic nerve damage. Numerous clinical studies have shown that lowering IOP can prevent neuronal damage and slow/stop the progression of the disease. In the glaucomatous TM (GTM), there is excessive extracellular matrix protein deposition, cytoskeletal changes and altered cell function. The transforming growth factor β (TGFβ) pathway is activated by TGFβ2 which has been found to be more abundant in the GTM. Additionally, formation of cross-linked actin networks (CLANs) in the GTM is increased compared to non-glaucoma TM. Primary open angle glaucoma (POAG), glucocorticoid-induced glaucoma (GIG) and glucocorticoid-induced ocular hypertension (GCOHT), share similar pathophysiologies. GC-OHT differs from POAG in that about 40% of the population develops GC-OHT after topical treatment with glucocorticoids however, the mechanism that differentiates steroid responders from non-responders is unknown. In our studies we have explored trabecular meshwork molecular pathogenic mechanisms that are responsible for the disease pathology. We have studied epigenetics as a regulatory mechanism for increasing TGFβ2 expression. We have also used proteomics to determine proteins that are associated with CLANs. Lastly, we studied genes that are differentially expressed in glucocorticoid responders versus non-responders in our bovine model of GC-OHT. Overall, our research has enhanced our understanding of the TM and the molecular mechanisms that play a role in glaucoma. We hope to use this information to find new disease modifying therapies.Item Identification of Actin Binding Proteins Associated with Cross-Linked Actin Networks(2006-12-01) Mills, Christy E.; Clark, Abbot F.; Yorio, Thomas; Wordinger, Robert J.Mills, Christy E., Identification of Actin Binding Proteins Associated with Cross-Lined Actin Networks. Master of Science (Pharmacology and Neuroscience), December 2006, 95 pp., 9 tables, 16 figures, references, 122 titles. Glucocorticoid therapy can leady to ocular hypertension and glaucoma. The purpose of this study is to examine mechanisms contributing to increased intraocular pressure using tissue culture models of steroid-induced ocular hypertension through identification of specific actin-binding proteins associated with cross-linked actin network (CLANs). Human trabecular meshwork ™ cells were cultured to confluence and treated with dexamethasone or vehicle for 14 days. Total RNA was extracted for gene expression analysis to confirm steroid-induced expression of actin binding proteins in human TM cells. Western blots confirmed expression of actin binding proteins and demonstrated the specificity of selected antibodies. Fluorescence microscopy of treated TM cells showed cytoskeleton rearrangements from linear actin stress fibers to cross-linked actin networks and the position of candidate proteins in relation to CLANs. Dexamethasone treatment of TM cells altered the expression of actin-associated proteins that may be important in the formation of CLANs and increased outflow resistance.Item TGFβ Signaling and the Formation of Cross-Linked Actin Networks (CLANs) in Human Trabecular Meshwork Cells(2016-05-01) Montecchi-Palmer, Michela; Clark, Abbot F.; Mao, Weiming; Ghorpade, AnujaGlaucoma is the leading cause of irreversible vision loss and blindness worldwide. One of the major risk factors for glaucoma is increased intraocular pressure (IOP); however there is little understanding of the initial causes of abnormal IOP. Actin cytoskeletal rearrangements known as cross-linked actin networks (CLANs) form at a higher incidence in the glaucomatous trabecular meshwork (TM) cells compared to non-glaucomatous TM cells. The incidence of CLANs is believed to increase the stiffness of TM cells and TM tissue, thereby increasing aqueous humor (AH) outflow resistance and IOP. Even though these actin formations are known to be present, the actual cause of their formation has not yet been elucidated. CLANs can be induced by either transforming growth factor-β2 (TGFβ2) or glucocorticoids such as Dexamethasone (Dex). The primary focus of this research is the TGFβ2 induced CLAN formation and the TGFβ pathways leading to these cytoskeletal rearrangements. Primary human TM cell culture was used to identify whether the Smad or non-Smad TGFβ pathways are the primary path to TGFβ2 induced CLAN formation by testing the ability of various inhibitors to prevent and resolve TGFβ2 induced CLANs. The results of this research will be a novel and critical source of information in the development of therapeutic strategies for the treatment of elevated IOP and glaucoma, and possibly a better understanding of additional factors contributing to the onset of this sight threatening disease.