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Stella R. Evans, Carol L. Beck, Nancy J. Philp; A Role for mCLCA3 in the Mouse Retina. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3337.
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© ARVO (1962-2015); The Authors (2016-present)
The functional role of members of the CLCA (calcium-activated chloride channel) family continues to be debated. Once thought to function independently as ion channels, current studies suggest CLCAs may regulate calcium-activated chloride channels and some family members behave as adhesion molecules. mCLCA3 (Gob-5) and its human orthologue hCLCA1 are secreted family members involved in mucus secretion and play roles in pulmonary diseases such as asthma and cystic fibrosis. Analysis of Nrl-/- mouse retina by another group showed that mCLCA3 is upregulated 14-fold compared to wild-type (WT) by cDNA microarray analysis, and 44-fold by quantitative real-time PCR analysis. With Nrl-/- mice, all photoreceptors have a cone phenotype, with an absence of rods. We examined the expression of mCLCA3 in the WT and Nrl-/- mouse retina for clues about a role for mCLCA3 in cone function in the retina.
RT-PCR was utilized to determine the expression of mCLCA3 in the WT and Nrl-/- mouse retina and of hCLCA1 in human retina. The expression of mCLCA3 protein in WT mouse retina was also analyzed by Western blot and by immunohistochemical analysis of WT and Nrl-/- eye sections.
Our RT-PCR results confirm that mCLCA3 is upregulated in the Nrl-/- retina. mCLCA3 protein is present in the retina as confirmed by Western blot and immunohistochemical analysis. Immunohistochemistry also indicates that mCLCA3 colocalizes with the cone matrix sheath in WT and Nrl-/- mouse retina. We also found by RT-PCR that hCLCA1, the human orthologue, is expressed in the retina.
mCLCA3 may play a role in supporting cone function. This is suggested by the upregulation in Nrl-/- mouse retina as initially observed by microarray analysis and Q-PCR and as confirmed in this study by RT-PCR. It is unclear which retinal cell type expresses mCLCA3, but it is known that mCLCA3 is a secreted protein. mCLCA3 may be secreted from cones and support the function of the cone matrix sheath.
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