A 182 bp fragment of the mouse pro alpha 1(II) collagen gene is sufficient to direct chondrocyte expression in transgenic mice.
Type II collagen is a major chondrocyte-specific component of the cartilage extracellular matrix and it represents a typical differentiation marker of mature chondrocytes. In order to delineate cis-acting elements of the mouse pro alpha 1(II) collagen gene that control chondrocyte-specific expression in intact mouse embryos, we generated transgenic mice harboring chimeric constructions in which varying lengths of the promoter and intron 1 sequences were linked to a beta-galactosidase reporter gene. A construction containing a 3,000 bp promoter and a 3,020 bp intron 1 fragment directed high levels of beta-galactosidase expression specifically to chondrocytes. Expression of the transgene coincided with the temporal expression of the endogenous gene at all stages of embryonic development. Successive deletions of intron 1 delineated a 182 bp fragment which targeted beta-galactosidase expression to chondrocytes with the same specificity as the larger intron 1 fragment. Transgenic mice harboring a 309 bp Col2a1 promoter lacking intron 1 tester sequences showed no beta-galactosidase expression in chondrocytes. Reduction of the 182 bp fragment to a 73 bp subfragment surrounding a decamer sequence previously reported to be involved in chondrocyte specificity, resulted in loss of transgene expression in chondrocytes. When the Col2a1 promoter was replaced with a minimal beta-globin promoter, the 182 bp intron 1 sequence was still able to target expression of the transgene to chondrocytes. We conclude that a 182 bp intron 1 DNA segment of the mouse Col2a1 gene contains the necessary information to confer high-level, temporally correct, chondrocyte expression on a reporter gene in intact mouse embryos and that Col2a1 promoter sequences are dispensable for chondrocyte expression.
Zhou
G
G
Department of Molecular Genetics, University of Texas, M. D. Anderson Cancer Center, Houston 77030, USA.
Garofalo
S
S
Mukhopadhyay
K
K
Lefebvre
V
V
Smith
C N
CN
Eberspaecher
H
H
de Crombrugghe
B
B
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D015415:Biomarkers / Q000737:chemistry; D002356:Cartilage / Q000166:cytology / Q000378:metabolism*; D002872:Chromosome Deletion; D003094:Collagen / Q000235:genetics*; D005786:Gene Expression Regulation / Q000502:physiology*; D005914:Globins / Q000235:genetics; D007438:Introns; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D011498:Protein Precursors / Q000235:genetics*; D001616:beta-Galactosidase / Q000235:genetics
D015415:Biomarkers; D011498:Protein Precursors; D005914:Globins; D003094:Collagen; D001616:beta-Galactosidase