Purpose: To elucidate the function of type II collagen in the development and diseases of the eye by analyzing the temporospatial expression of the long (IIA) and short (IIB) isoforms of type II collagen in the normal and transgenic Dell mice.
Methods: Normal and Dell transgenic embryos harboring a deletion mutation in the pro alpha 1 (II) collagen chain were studied from day 10.5 of embryonic development up to day 10 postpartum. Northern and in situ hybridizations and RNase protection assays were used to study the developmental and temporospatial expression of type II collagen isoforms.
Results: Expression of type II collagen mRNAs was observed at all developmental stages with maximum expression at 16.5 days of embryonic development. RNase protection analyses confirmed that both wild type and transgene-derived mRNAs underwent similar alternative splicing of exon 2 in the eye. By in situ hybridization, both isoforms were observed in the cornea, sclera, vitreous, ganglion cell layer of retina, developing ciliary body-iris, and in the retinal pigment epithelium-Bruch's membrane as well as in the lens and conjunctiva. Differences were observed between eyes of Dell mice and of control subjects in the levels and temporal expression patterns of type II collagen mRNA, which resulted in structural abnormalities in histologic analysis.
Conclusions: Widespread expression of type II collagen mRNAs in ocular structures suggests an important role for type II collagen in structural development of the eye. As the expression patterns observed correspond to structural abnormalities in the eyes of Dell mice, the current results offer a promising basis for further development of mouse models for arthroophthalmopathies.