Molecular evidence that human ocular ciliary epithelium expresses components involved in phototransduction

Here we report the expression, in the human ocular ciliary epithelium and i n a human nonpigmented (NPE) ciliary epithelial cell line, of genes usually restricted to cone and rod photoreceptor cells of the retina. By RT-PCR an d DNA sequencing we identified the expression of rhodopsin and components l inked to its deactivation, including rhodopsin kinase, recoverin, and visua l arrestin. We also detected the expression of transducin (T-alpha), phosph odiesterase (PDE-alpha), and cGMP-gated channel alpha -subunits. Cultured N PE cells responded to treatment with phorbol ester by enhancing the express ion of rhodopsin mRNA three-to fourfold. Indirect immunofluorescence of the intact ciliary epithelium with monoclonal antibodies (MAbs) against rhodop sin, rhodopsin kinase, and visual arrestin revealed labeling preferentially restricted to the NPE cells. Furthermore, Western blot analysis of whole l ysates from the pars plicata region of the human ciliary epithelium with MA bs demonstrated immunochemical cross-reactivity with proteins of molecular mass similar to rhodopsin (36 kDa), rhodopsin kinase (64 to 66 kDa), and ar restin (48-52 kDa) from the human retina. These results provide the first m olecular evidence that components of a non-visual phototransduction pathway are expressed in the human ocular NPE ciliary epithelium, which may be lin ked to circadian entrainment tasks. (C) 2001 Academic Press.