Regulation of connective tissue growth factor expression in the aqueous humor outflow pathway.
OBJECTIVE
Connective Tissue Growth Factor (CTGF) is an inducible secretory protein known to regulate proliferation and extracellular matrix production in various cell types. We hypothesize that CTGF plays a critical role in the physiological regulation of aqueous humor outflow through the trabecular meshwork (TM) by influencing extracellular matrix synthesis and organization.


METHODS
To determine the expression of CTGF in tissues of the aqueous outflow pathway, cells obtained from human TM and Schlemm's Canal (SC) were analyzed by PCR and western blot analysis. To understand the regulation of CTGF expression in TM cells, TM cells were either treated with various physiologic factors or subjected to cyclical stretch prior to analysis of CTGF expression by RT-PCR and western blot analysis. To study the effect of increased intraocular pressure on CTGF production, we perfused porcine eyes at high pressure (50 mm Hg) for 5 h, followed by analysis of CTGF expression by RT-PCR and western blotting.


RESULTS
Treatment of human TM cells treated with either serum or transforming growth factor-beta 1 led to a robust stimulation, compared to thrombin, lysophosphatidic acid (LPA), and dexamethasone, which elicited a relatively moderate induction of CTGF expression. Both high pressure perfusion and mechanical stretch were associated with increases in the levels of CTGF at the protein and transcript levels.


CONCLUSIONS
This study demonstrates that CTGF expression in TM cells is modulated by several physiological agonists and by increased ocular pressure and mechanical stretch. These results suggest that the regulation of CTGF expression within tissues of the outflow pathway may play a role in the homeostasis of intraocular pressure, possibly by modulation of ECM production in these tissues.
Chudgar
Saumil M
SM
Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA. chudg001@mc.duke.edu <chudg001@mc.duke.edu>
Deng
Peifeng
P
Maddala
Rupalatha
R
Epstein
David L
DL
Rao
P Vasantha
PV
D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism*; D001769:Blood; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor; D003907:Dexamethasone / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D007429:Intraocular Pressure; D008246:Lysophospholipids / Q000494:pharmacology; D010477:Perfusion; D011312:Pressure; D012333:RNA, Messenger / Q000378:metabolism; D013314:Stress, Mechanical; D013552:Swine; D013917:Thrombin / Q000494:pharmacology; D014129:Trabecular Meshwork / Q000166:cytology / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
C526317:CCN2 protein, human; D005938:Glucocorticoids; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; D055513:Connective Tissue Growth Factor; D003907:Dexamethasone; D013917:Thrombin; C032881:lysophosphatidic acid