Transforming growth factor-beta2 induces synthesis and secretion of endothelin-1 in human trabecular meshwork cells. Journal Article

Authors: Von Zee, C. L.; Langert, K. A.; Stubbs, E. B., Jr
Article Title: Transforming growth factor-beta2 induces synthesis and secretion of endothelin-1 in human trabecular meshwork cells.
Abstract: PURPOSE: Analysis of aqueous humor from patients with primary open-angle glaucoma (POAG) revealed marked increases in the content of endothelin-1 (ET-1) and transforming growth factor-beta (TGF-beta). We determined the consequences of TGF-beta signaling on ET-1 expression and secretion by human trabecular meshwork (TM) cells. METHODS: Primary or transformed (NTM5 and GTM3) human TM cells conditioned in serum-free media were incubated in the absence or presence of TGF-beta1 or -beta2. Relative changes in preproendothelin (ppET)-1 mRNA content and secreted ET-1 peptide were quantified by real-time PCR and ELISA, respectively. In some experiments, TGF-beta or ET-1 receptor antagonists, or Rho G-protein inhibitors, were evaluated for effects on TGF-beta signaling. Filamentous actin organization was visualized by phalloidin. RESULTS: Primary or transformed human TM cells cultured in the presence of TGF-beta1 or -beta2 exhibit a marked (>8-fold) increase in ppET-1 mRNA content compared to vehicle controls. Coincubation with SB-505124, an inhibitor of TGFbetaRI/ALK-5 signaling, prevented TGF-beta-mediated ppET-1 mRNA expression. In contrast, coincubation with ET(A) (BQ-123) or ET(B) (BQ-788) receptor antagonists had no effect on TGF-beta-mediated ppET-1 mRNA expression. TGF-beta1 and -beta2 each elicited a robust (>7-fold) secretion of ET-1 while enhancing stress fiber organization. Inhibition of Rho signaling attenuated TGF-beta-mediated increases in ppET-1 mRNA content, ET-1 secretion, and stress fiber organization. CONCLUSIONS: TGF-beta, signaling through the TGFbetaRI/ALK-5 receptor, elicits marked increases in ET-1 mRNA content and ET-1 secretion from cultured primary or transformed human TM cells. Elevated levels of TGF-beta2 present in AH of POAG patients may elevate intraocular pressure, in part, by eliciting aberrant Rho G-protein dependent cell contraction, and increasing ET-1 synthesis and secretion, in human TM cells.
Journal Title: Investigative ophthalmology visual science
Volume: 53
Issue: 9
ISSN: 1552-5783
Publisher: Unknown  
Journal Place: United States
Date Published: 2012
Start Page: 5279
End Page: 5286
Language: English
Notes: ID: 12581; Record Owner: From MEDLINE, a database of the U.S. National Library of Medicine.; Status: MEDLINE; Publishing Model: Journal available in: Electronic Citation processed from: Internet; NLM Journal Code: gwi, 7703701; CAS Registry/EC Number/Name of Substance: 0 (2-(5-benzo(1,3)dioxol-5-yl-2-tert-butyl-3H-imidazol-4-yl)-6-methylpyridine hydrochloride). 0 (Actins). 0 (Benzodioxoles). 0 (Endothelin-1). 0 (Imidazoles). 0 (Pyridines). 0 (RNA, Messenger). 0 (Recombinant Proteins). 0 (Transforming Growth Factor beta2). 75330-75-5 (Lovastatin).; Electronic Date of Publication: 20120807; Entry Date: 20121024