Abstract
Abstract: :
Purpose: To examine the regional distribution of CLC chloride channels in the rabbit lens epithelium with emphasis on CLC-2 and –3, moieties putatively involved in volume regulation. Methods: Reverse transcription-polymerase chain reaction (RT-PCR) was performed using CLC-gene specific primers (CLC1-7) on isolated regions of the rabbit lens that included the entire epithelium (including equator), the epithelia from the anterior-polar and equatorial regions, as separate fractions, and the superficial equatorial fibers. Immunohistochemical assays used two specific anti-CLC-2 polyclonal antibodies, against the C-terminus region of CLC-2, on lens fixed cryosections. Monoclonal antibodies against Na+-K+-ATPase and the tight-junction associated protein ZO1 served as markers for the basolateral and apical membranes respectively. Results: RT-PCR analysis revealed the expression of CLC-2, -3, -5, -6 and –7 in the entire lens epithelium. Message for CLC-2 and CLC-3 was found in both the anterior-polar and equatorial epithelial regions. CLC-3 mRNA transcript was clearly obtained from the superficial equatorial fibers, whereas that of CLC-2 was barely detectable. Immunofluorescent microscopy observations showed that the CLC-2 antibodies positively labeled the anterior-plus-equatorial epithelial surface, with higher fluorescence along the apical aspect. Conclusions: The lens epithelium exhibits various members of the CLC family, whereas the superficial equatorial fibers markedly express the CLC-3 form. In the epithelium, CLC-2 appears predominately situated within the apical membrane.
Keywords: immunohistochemistry • ion channels • molecular biology