Separable regulatory elements from pro-alpha 2 (XI) collagen gene drive distinct patterns of cartilage-specific expression in transgenic mice

How to build an inducible cartilage-specific transgenic mouse

Transgenic mice are used to study the roles of specific proteins in an intact living system. Use of transgenic mice to study processes in cartilage, however, poses some challenges. First of all, many factors involved in cartilage homeostasis and disease are also crucial factors in embryogenesis. Therefore, meddling with these factors often leads to death before birth, and mice who do survive cannot be considered normal. The build-up of cartilage in these mice is altered, making it nearly impossible to truly interpret the role of a protein in adult cartilage function.An elegant way to overcome these limitations is to make transgenic mice time- and tissue-specific, there by omitting side-effects in tissues other than cartilage and during embryology. This review discusses the potential building blocks for making an inducible cartilage-specific transgenic mouse. We review which promoters can be used to gain chondrocyte-specificity - all chondrocytes or a specific subset thereof - as well as different systems that can be used to enable inducibility of a transgene.

A 1,064 bp fragment from the promoter region of the Col11a2 gene drives lacZ expression not only in cartilage but also in osteoblasts adjacent to regions undergoing both endochondral and intramembranous ossification in mouse embryos

We isolated a 1,064 bp promoter fragment that extended from the 3'-end of the adjacent gene for retinoic X receptor-beta to beyond the most clearly defined start site of the mouse Col11a2 gene. The fragment was then joined to a beta-galactosidase gene and used to prepare transgenic mice. Three independent lines of transgenic mice were generated. The reporter beta-galactosidase gene was expressed in essentially all cartilaginous tissues in 15.5-day-old mouse embryos. In addition, the construct was expressed in osteoprogenitors within developing periosteum and in osteoblasts within mineralized bone. This pattern of expression was evident during both endochondral and intramembranous bone formation. Therefore, the results suggest that 1,064 bp promoter fragment can drive tissue-specific expression of the Col11a2 gene.