Abstract
Abstract: :
Purpose: The connective tissue growth factor (CTGF) gene is an early inducible gene encoding a member of the CNN family of cysteine-rich secretory proteins which regulate proliferation and extracellular matrix production. We hypothesize that CTGF may have an important role in the physiological regulation of outflow facility and in the pathophysiology of increased intraocular pressure. To explore this hypothesis, we evaluated regulation of CTGF expression in TM cells. Methods: The expression and distribution of CTGF was determined by PCR and Western blot analysis in HTM and SC cells and in TM tissue. To study the regulation of CTGF gene expression by different physiological factors in TM cells, quantitative RT-PCR analysis was performed using ß-actin as an internal control. Results: PCR analysis of cDNA libraries generated from HTM and SC cells and TM tissue and sequencing of PCR products confirmed expression of CTGF transcripts in all samples analyzed. Western blot analysis of cell lysates obtained from TM and SC cells using two different polyclonal antibodies raised against CTGF, demonstrated the presence of high molecular weight (56 kDa) CTGF. The presence of CTGF (56 kDa) was also confirmed in human aqueous humor by Western blot analysis. Immuohistochemical analysis of human eye tissue cryosections revealed CTGF staining in ciliary muscle and in TM, JCT and SC. In preliminary studies, serum starved (24 hours) human TM cells treated for 4 hours with serum, TGF-ß (20 nM), dexamethasone (5 µM), thrombin (5 U/ml) or lysophosphatidic acid (LPA, 20 µM) demonstrated a robust induction of CTGF by TGF-ß, serum and thrombin, and moderate induction by LPA and dexamethasone. Conclusion: CTGF expression in outflow pathway tissues and cells, and its upregulation in TM cells by serum factors, TGF-ß, dexamethasone, thrombin and LPA, suggest that CTGF may be involved in the regulation of aqueous outflow resistance by influencing extracellular matrix production and its reorganization.
Keywords: 503 outflow: trabecular meshwork • 403 extracellular matrix • 417 gene/expression