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Abstract #70147 Published in IGR 18-2
Vertebrate Lonesome Kinase Regulated Extracellular Matrix Protein Phosphorylation, Cell Shape and Adhesion in Trabecular Meshwork Cells
Maddala R; Skiba NP; Rao PVJournal of Cellular Physiology 2017; 232: 2447-2460
Glaucoma, a leading cause of irreversible blindness is commonly associated with elevated intraocular pressure (IOP) due to impaired aqueous humor (AH) drainage through the trabecular meshwork (TM). Although dysregulated production and organization of extracellular matrix (ECM) is presumed to increase resistance to AH outflow and elevate IOP by altering TM cell contractile and adhesive properties, it is not known whether regulation of ECM protein phosphorylation via the secretory vertebrate lonesome kinase (VLK) influences TM cellular characteristics. Here we tested this possibility. Experiments carried out in this study reveal that the 32 kDa protein is a prominent VLK isoform detectable in lysates and conditioned media (CM) of human TM cells. Increased levels of VLK were observed in CM of TM cells subjected to cyclic mechanical stretch, or treated with dexamethasone, TGF-β2 and TM cells expressing constitutively active RhoA GTPase. Downregulation of VLK expression in TM cells using siRNA decreased tyrosine phosphorylation (TyrP) of ECM proteins and focal adhesions, and induced changes in cell shape in association with reduced levels of actin stress fibers and phospho-paxillin. VLK was also demonstrated to regulate TGF-β2-induced TyrP of ECM proteins. Taken together, these results suggest that VLK secretion can be regulated by external cues, intracellular signal proteins and mechanical stretch, and VLK can in turn regulate TyrP of ECM proteins secreted by TM cells and control cell shape, actin stress fibers and focal adhesions. These observations indicate a potential role for VLK in homeostasis of AH outflow and IOP, and in the pathobiology of glaucoma. This article is protected by copyright. All rights reserved.
Department of Ophthalmology, Duke University School of Medicine, Durham, NC, 27710.
Full articleClassification:
2.5.1 Trabecular meshwork (Part of: 2 Anatomical structures in glaucoma > 2.5 Meshwork)
3.5 Molecular biology incl. SiRNA (Part of: 3 Laboratory methods)
3.6 Cellular biology (Part of: 3 Laboratory methods)