Smad3 is necessary for transforming growth factor-beta2 induced ocular hypertension in mice

Colleen M. McDowell, Holly E. Tebow, Robert J. Wordinger, Abbot F. Clark

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

TGFβ2 induces extracellular matrix (ECM) remodeling and alters the cytoskeleton by both the canonical Smad and non-canonical signaling pathways. TGFβ2 regulates the expression of ECM proteins in trabecular meshwork (TM) cells, increases intraocular pressure (IOP) in an exvivo perfusion organ culture model, and induces ocular hypertension in rodent eyes. A necessary step in the canonical Smad signaling pathway is phosphorylation of receptor protein Smad3 by the TGF-β receptor complex. The purpose of this study was to determine whether TGFβ2 signals invivo through the canonical Smad signaling pathway in the TM using Smad3 knockout (KO) mice. Ad5.hTGFβ2226/228 (2.5×107pfu) was injected intravitreally into one eye of homozygous (WT), heterozygous (HET), and homozygous (KO) 129-Smad3tm1Par/J mice (n=9-10 mice/group), with the uninjected contralateral eye serving as the control. IOP measurements were taken using a rebound tonometer. To test the effect of TGFβ2 signaling on the ECM, fibronectin expression was determined by immunohistochemistry and qPCR analysis. Transduction of the TM with viral vector Ad5.hTGFβ2226/228 caused a statistically significant difference in IOP exposure between Smad3 genotypes: WT, 187.7±23.9mmHg*day (n=9); HET, 95.6±24.5mmHg*day (n=9); KO, 52.8±25.2mmHg*day (n=10); (p<0.05 WT versus HET, p<0.01 WT versus KO). Immunohistochemistry and qPCR analysis showed that Ad5.hTGFβ2226/228 increased fibronectin expression in the TM of WT mice (2.23±0.24 fold) compared to Smad3 KO mice (0.99±0.19 fold), p<0.05. These results demonstrate Smad3 is a necessary signaling protein for TGFβ2-induced ocular hypertension and fibronectin deposition in the TM.

Original languageEnglish
Pages (from-to)419-423
Number of pages5
JournalExperimental eye research
Volume116
DOIs
StatePublished - Nov 2013

Keywords

  • Glaucoma
  • Mouse model
  • Ocular hypertension
  • TGFβ2 signaling
  • Trabecular meshwork

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