Localization of endothelin-1 mRNA expression and immunoreactivityin the anterior segment of human eye: Expression of ETA and ETBreceptors

[摘要] Purpose: Endothelin-1 (ET-1), a potent vasoactive peptide, is animportant regulator of intraocular pressure. Actually, there is evidenceof a role for ET-1 in the pathogenesis of glaucoma. However, theexpression pattern of ET-1 and its receptors, ETA and ETB, in theanterior segment of human eye are not known. In the current study, wehave examined the expression and distribution of ET-1 as well as theexpression profile of ETA and ETB genes in the iris, ciliary muscle, andciliary processes of human eyes.Methods: Six normal human eyes with no history of eye diseases werefixed, embedded in paraffin and sectioned. Cellular localization of ET-1was identified by in situ hybridization and immunohistochemistry. Iris,ciliary processes, and ciliary muscles were dissected from six normalhuman eyes and quantitative real time RT-PCR was used to quantify theexpression of ETA and ETB.Results: In situ hybridization revealed the presence of ET-1transcripts in the iris, nonpigmented epithelial ciliary cells, andciliary muscle. Immunohistochemical studies showed that ET-1-likeimmmunoreactivity appeared in the same regions where ET-1 mRNA wasexpressed as well as in trabecular cells, inner and outer endothelialcells lining Schlemm's canal, corneal epithelial, and limbus cells.Quantitative real time RT-PCR demonstrated that the expression of ETAand ETB receptors is greatest in the iris, followed by ciliary muscleand ciliary processes.Conclusions: ET-1 and its receptors ETA and ETB are constitutivelyexpressed in the anterior segment of human eye. These results indicatethat ET-1 may play a physiological role in the regulation of intraocularpressure through its ETA and ETB receptors in human eye. In addition,ET-1 present in corneal epithelium and limbus may function in regulatingcell proliferation and/or differentiation.

[学科分类] 生物化学/生物物理