Structure, chromosomal location, and tissue-specific expression of the mouse opticin gene

PURPOSE. To determine the structure, location, and tissue-specific expressi on of the mouse opticin gene (Optc) and to compare expression in the eye wi th that of Prelp, collagen TI, and collagen IX. METHODS. Expressed sequence tags (ESTs) to mouse opticin were identified an d the full-length sequence obtained after PCR reactions using a 15-day-post conception (dpc) whole-mouse embryo cDNA. library. The mouse chromosomal lo calization of Optc was determined by radiation hybrid mapping and its genom ic structure determined using an Optc-containing BAC clone. Tissue-specific expression of opticin, PRELP, collagen II, and collagen IX mRNAs was inves tigated by in situ hybridization and by dot blot hybridization for opticin. RESULTS. The Optc gene was localized to mouse chromosome I at 74.3 cM and c onsisted of seven exons spanning 10 kb. The Optc gene was less than 4 kb fr om the Prelp gene. In situ hybridization localized opticin mRNA exclusively to the presumptive ciliary body during development and to the nonpigmented ciliary epithelium of the adult mouse eye. Expression of Prelp was also de tected in the nonpigmented ciliary epithelium of the adult eye. However, ex pression of collagen types II and IX was detected largely in the developing mouse eye, with type IX expression confined primarily to the presumptive c iliary body. CONCLUSIONS. The Optc, Prelp, and fibromodulin (Fmod) genes form a cluster on mouse chromosome 1. Opticin may represent a marker for ciliary body diff erentiation. Continued expression of opticin in the adult mouse eye suggest s functions other than that of putative regulator of vitreous collagen fibr illogenesis.