Abstract
Purpose:
To advance our understanding how the outer eye interacts with its environment, we asked which cellular receptors are expressed in the cornea, focusing on identification of G protein-coupled receptors (GPCRs) and other genes related to G protein signaling.
Methods:
Total RNA was isolated from the mouse cornea and subjected to next-generation sequencing using Illumina platform. The data was analyzed by CuffLinks and TopHat software. Gene expression was confirmed by RT-PCR. Cellular localization of transcripts was analyzed by in situ hybridization using high-resolution RNAscope technology. Immunohistochemistry was used to identify some cell types.
Results:
Mouse cornea transcriptome contained more than 45 million reads representing over 10,000 gene transcripts. We identified more than 150 GPCR gene transcripts, of which more than 100 were putative olfactory receptors (Olfr’s). RT-PCR analysis confirmed the presence of several other related genes, including olfactory marker protein (OMP) and the heterotrimeric G protein associated with olfaction, Gaolf. In situ hybridization showed that mRNA for OMP, Gaolf and possibly some Olfrs were found in epithelial cells of the cornea. One of Olfrs, Olfr558, was present primarily in vessels of the eye that were also stained with antibodies against alpha-smooth muscle actin, indicating expression in arterioles. The location of mRNA suggests that Olfr558 is expressed in endothelial cells. In addition to corneal epithelium, Gaolf was also present in the ganglion and inner nuclear layers of the retina.
Conclusions:
Several species of mRNA encoding putative olfactory receptors and related genes are expressed in the mouse cornea and other parts of the eye indicating that they may play a role in detection of chemicals in the eye environment.
Keywords: 533 gene/expression •
480 cornea: basic science •
714 signal transduction