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Versican splice variants in human trabecular meshwork and ciliary muscle
1Section on Aging and Ocular Disease, National Eye Institute, National Institutes of Health, Bethesda, MD, USA. xiujun.zhao@mssm.edu
Molecular Vision
|August 20, 2005
Summary
This study identifies four versican variants in ocular tissues, with V1 predominating in human trabecular meshwork (HTM) and ciliary muscle. TGF-beta treatment upregulates versican variants, particularly V0 and V2, in HTM cells.
Area of Science:
- Ophthalmology
- Molecular Biology
- Biochemistry
Background:
- Versican, a chondroitin sulfate proteoglycan, plays a role in regulating aqueous humor outflow and intraocular pressure.
- Four splice variants of versican (V0-V3) exist, differing in glycosaminoglycan (GAG) attachment domains.
- Versican is upregulated in human trabecular meshwork (HTM) cells upon transforming growth factor-beta (TGF-beta) stimulation.
Purpose of the Study:
- To investigate the presence and distribution of versican isoforms in ocular tissues and cultured cells.
- To analyze the differential expression patterns of versican variants in HTM and human ciliary muscle (HCM).
- To determine the effect of TGF-beta on versican variant expression in HTM cells.
Main Methods:
- Dissection of HTM and HCM tissues from healthy donor eyes.
- Establishment of primary cell cultures from HTM and HCM.
- Treatment of HTM cells with TGF-beta1 or TGF-beta2.
- Real-time PCR with SYBR Green for relative quantitation of versican variant gene expression.
Main Results:
- All four versican variants (V0-V3) were detected in ocular tissues and cultured cells.
- The V1 variant was most abundant in HTM and HCM tissues.
- In cultured HTM cells, V0 and V1 variants predominated, with V1 being more abundant than V0.
- TGF-beta treatment upregulated all versican variants in HTM cells, with the greatest increase observed in V0 and V2 forms.
Conclusions:
- This study is the first to report the presence of various versican forms in the anterior segment of the eye.
- The V1 variant, with extensive GAG domains, is the most prominent in HTM and HCM.
- Upregulation of GAG-rich versican variants in HTM cells under TGF-beta stimulation aligns with increased chondroitin sulfate levels observed in glaucoma.