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Abstract #5587 Published in IGR 2-1
Signal transduction mediated by adhesion of human trabecular meshwork cells to extracellular matrix
Zhou L; Cheng EL; Rege P; Yue BYJTExperimental Eye Research 2000; 70: 457-465
In this study the authors investigated the signaling event induced by adhesion of human trabecular meshwork (TM) cells to extracellular matrix (ECM) elements such as fibronectin. The role of tyrosine phosphorylation in adhesion was evaluated. A number of intracellular entities involved in the adhesion-mediated pathways were identified. For the experiments, human TM cells were seeded onto fibronectin- or polylysine (negative control)-coated plates. Fifteen, 30, 90 and 240 minutes after the seeding, cell lysates were collected. Immunoblotting analysis revealed that tyrosine phosphorylation occurred within 15 minutes of adhesion of TM cells to fibronectin and the level increased with time. The phosphotyrosyl proteins had molecular masses 25-220 kDa. A much lower level of tyrosine phosphorylation was observed when cells were plated on polylysine. Immunoprecipitation experiments indicated that the phosphotyrosine-containing proteins included focal adhesion kinase, paxillin, phosphatidylinositol 3-kinase and mitogen activated protein kinase. Within 30 minutes of adherence to fibronectin, human TM cells immunostained for paxillin and phosphotyrosine and exhibited prominent focal contacts. When treated with tyrosine kinase inhibitors genistein and herbimycin A and a protein kinase C (PKC) pseudosubstrate peptide inhibitor, cell adhesion to fibronectin was compromised and focal contact formation was limited. These results demonstrated that in human TM cells, tyrosine kinase was activated upon their adherence to fibronectin. PKC also appeared to play a role in modulation of the cell-matrix adhesion process. The current study provides insight into the signaling pathways that are linked to the ECM-induced events in TM cells. Elucidation of the hierarchy of signal responses may help develop strategies manipulating the cell-matrix interactions in the TM system.
Dr. L. Zhou, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago College of Medicine, 1855 West Taylor Street, Chicago, IL, USA. email: u24184@uic.edu
Classification:
2.5 Meshwork (Part of: 2 Anatomical structures in glaucoma)