April 2010
Volume 51, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2010
Sr Splicing Proteins: Key Players in Regulating Gr/grβ Ratio and Glucocorticoid Response in Trabecular Meshwork Cells
Author Affiliations & Notes
  • A. Jain
    Cell Biology and Anatomy,
    Univ of North Texas Health Science Ctr, Fort Worth, Texas
    North Texas Eye Research Institute, Fort Worth, Texas
  • R. J. Wordinger
    Cell Biology and Anatomy,
    Univ of North Texas Health Science Ctr, Fort Worth, Texas
    North Texas Eye Research Institute, Fort Worth, Texas
  • T. Yorio
    Pharmacology & Neuroscience,
    Univ of North Texas Health Science Ctr, Fort Worth, Texas
    North Texas Eye Research Institute, Fort Worth, Texas
  • A. F. Clark
    Cell Biology and Anatomy,
    Univ of North Texas Health Science Ctr, Fort Worth, Texas
    North Texas Eye Research Institute, Fort Worth, Texas
  • Footnotes
    Commercial Relationships  A. Jain, None; R.J. Wordinger, None; T. Yorio, None; A.F. Clark, None.
  • Footnotes
    Support  NIH Grant EY017374-01A1 to RJW, NIH Grant EY016242-01A1 to TY
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 3216. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      A. Jain, R. J. Wordinger, T. Yorio, A. F. Clark; Sr Splicing Proteins: Key Players in Regulating Gr/grβ Ratio and Glucocorticoid Response in Trabecular Meshwork Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3216.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Purpose: : Glucocorticoids (GCs) are commonly used anti-inflammatory agents, but can be associated with increased intraocular pressure that can lead to iatrogenic glaucoma. However, there is heterogeneity in this GC-induced ocular hypertension, with a subset of the population being "steroid responders". The GC receptor (GR) exists as two alternatively spliced isoforms, GRα and GRβ. GRβ has a unique C-terminal 9β exon and acts as a dominant negative regulator of GC activity. Knocking down GRβ enhances GC responsiveness in trabecular meshwork (TM) cells. Alternative mRNA splicing is mediated by spliceosomes, which include SR proteins (SRps). The purpose of our study was to determine whether SR proteins in TM regulate the differential expression of these two alternatively spliced isoforms of GR (GRα and GRβ).

Methods: : Putative binding sites for SRp20 and SRp40 in GR exon 9 that may regulate alternate splicing of GR were identified using Splicing Rainbow software. Quantitative RT-PCR and western immunoblotting were used to determine the differential expression of SRp20, SRp30c, and SRp40 in GTM3 and NTM5 cell lines. Over and under-expression of SRp20, SRp30c, and SRp40 via treatment with bombesin or by transfection with expression vectors or siRNAs were used to determine effects on GRα/GRβ ratios and dexamethasone (100 nM) response in TM cells. Dex responsiveness was determined using a GRE-luciferase reporter vector as well as western immunoblotting for fibronectin and myocilin.

Results: : Modulating the levels of SRp20, SRp30c, and SRp40 altered GRα/GRβ ratios in TM cells. Dex responsiveness correlated with the GRβ/GRα ratio. The bombesin peptide increased SRp30c expression, increased the GRβ/GRα ratio, and decreased Dex responsiveness in GTM-3 cells.

Conclusions: : Relative levels of SRp20, SRp30c, and SRp40 in TM cells control differential expression of the two alternatively spliced isoforms of GR and thereby regulate GC responsiveness. Different levels and/or activities of these SRps may account for differential GC sensitivity among the population.

Keywords: corticosteroids • trabecular meshwork • receptors 
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×