Differential expression of neuroendocrine-specific protein in form-deprived chick eyes.

PURPOSE To identify genes that are highly expressed in form-deprived retina-retinal pigment epithelium-choroid tissues. Neuroendocrine-specific proteins were found to be highly expressed. METHODS mRNAs enriched in retina-retinal pigment epithelium-choroid tissues from 3-, 7-, and 14-day form-deprived chick eyes were isolated by differential display technique with cDNA library screening. Neuroendocrine-specific protein A and C were cloned in control and form-deprived eyes. mRNA and protein levels, with respective regional localizations, were examined by Northern blot, Western blot, and immunohistochemical analyses, respectively. RESULTS The isolated clone included an insert with a sequence homologous to both chick neuroendocrine-specific proteins A and C. The increases in mRNA and protein levels were confirmed by Northern and Western blot analyses, respectively. Immunohistochemical localization of neuroendocrine-specific proteins A and C was detected in the layer of photoreceptor inner segments, presumably in the cone cells. Northern blot analysis using negative lenses showed that levels of neuroendocrine-specific protein A and C mRNAs were not altered using negative lenses. CONCLUSIONS The expression of both neuroendocrine-specific proteins A and C mRNAs in cone photoreceptor cells was upregulated within 14 days of form deprivation, but not in response to negative spectacle lenses. These data suggest that the increase in induction of neuroendocrine-specific proteins is not a secondary consequence of ocular elongation or myopic refraction. Induction of neuroendocrine-specific proteins in form-deprived eyes may be causally related to the development of myopia or may be an unrelated effect of form deprivation.