Purpose
Ocular surface is continuously exposed to tear components as well as xenobiotics and commensal and pathogenic microorganisms. To advance our understanding how the outer eye interacts with its environment, we asked which cellular receptors are expressed on the ocular surface, focusing on identification of genes encoding G protein-coupled receptors (GPCRs).
Methods
Total RNA was isolated from mouse cornea and conjunctiva and subjected to next-generation sequencing using Illumina platform. The data was analyzed by CuffLinks and TopHat software packages. Gene expression was confirmed by RT-PCR using total or poly-adenylated RNA obtained from independent cornea and conjunctiva preparations. Cellular localization of transcripts was analyzed by in situ hybridization using RNAscope technology on paraffin-embedded slices of mouse eyes.
Results
We performed directional RNA deep sequencing, utilizing Epicenter library preparation kit to generate more than 45 million reads representing over 10,000 transcripts. We identified more than 150 GPCR gene transcripts, of which more than 100 were putative olfactory receptors (Olfr’s). Our RT-PCR analyses confirmed the presence of several GPCR and G protein transcripts, including the G protein associated with olfaction, Golf. In contrast, a number of control genes, such as insulin or rhodopsin did no show significant expression. In situ hybridization showed that mRNA for Olfr558 was present primarily in basal epithelial cells of cornea and conjunctiva.
Conclusions
Several species of mRNA encoding putative olfactory receptors are expressed on the mouse OS.
Keywords: 675 receptors: pharmacology/physiology •
480 cornea: basic science •
533 gene/expression