DEVELOPMENTAL EXPRESSION OF A TYPE-II COLLAGEN BETA-GALACTOSIDASE FUSION GENE IN TRANSGENIC MICE

The correct temporal and spatial expression of the type II collagen ge ne is believed to be important for normal development and growth of th e skeleton and the eye, i.e., tissues where the protein product is pre dominantly found. To study transcriptional activation of type II colla gen gene in skeletal and nonskeletal tissues we produced transgenic mi ce carrying murine pro alpha 1(II) collagen/beta-galactosidase fusion gene constructs, The expression of the fusion gene was found to depend on the presence of intron 1 sequences: constructs with most of intron I deleted failed to reveal any beta-galactosidase activity confirming the important role of regulatory sequences within intron 1 of the gen e. High-level expression of the functional construct was clearly confi ned to cartilaginous tissues but transient low-level expression was al so observed in extraskeletal locations, such as the developing brain a nd the notochord. The results demonstrate that the regulatory elements in the pro alpha 1(II) collagen/beta-galactosidase fusion gene constr uct confer both temporal and spatial specificity indistinguishable fro m that of the endogenous pro alpha 1(II) collagen gene as determined b y the presence of the corresponding mRNA by in situ hybridization. Fur thermore the beta-galactosidase activity correlated well with the prog ression of chondrogenesis as seen by staining of whole mouse embryos w ith Alizarin red S and Alcian blue in the hybrid mouse strain used for microinjections. The transgenic mouse line produced should prove usef ul for studies on various aspects of chondrogenesis. Furthermore, the data shows that the regulatory elements present in the construct are s ufficient for targetting the expression of other genes in cartilage. ( C) 1995 Wiley-Liss, Inc.