Col2a1 cre

All experiments were performed according to protocols approved by the Animal Care and Use Committee of The University of Tokyo. In each experiment, we compared the genotypes of littermates maintained in a C57BL/6J background. Col2a1-Cre (ref. 22 (link)) and Prrx1-Cre mice21 (link) were purchased from the Jackson Laboratory. Col2a1-Cre^ERT mice26 (link) and Rela^fl/flmice24 (link) were generously provided by Professor Fanxin Long (Washington University, St Louis) and Professor Roland M. Schmid (Technical University of Munich), respectively. Col10a1-Cre mice were generated by insertion of IRES-Cre-polyA cassette into the 3′-untranslated region23 (link).
To generate Prrx1-Cre; Rela^fl/fl, Col2a1-Cre; Rela^fl/fl, Col10a1-Cre; Rela^fl/fl, and Col2a1-Cre^ERT; Rela^fl/fl mice, Rela^fl/fl mice were mated with Prrx1-Cre, Col2a1-Cre, Col10a1-Cre, or Col2a1-Cre^ERT mice to obtain Prrx1-Cre;Rela^fl/+, Col2a1-Cre;Rela^fl/+, Col10a1-Cre;Rela^fl/+ and Col2a1-Cre^ERT;Rela^fl/+ mice, respectively, and then mated with Rela^fl/fl mice. Sequences of the primers used for genotyping are shown in Supplementary Table 1.

Mice carrying Utx flox (Jackson Laboratory) were mated with C57BL/6 mice carrying cartilage-specific collagen type II (Col2a1) gene promoter-driven Cre recombinase mice (Col2a1^cre/+ C57BL/6; Jackson Laboratory) to breed homozygous Utx knockout mice (Co12a1^Cre/+-Utx^fl/fl; UtxKO) and wild-type mice (Col2a1^Cre/−-Utx^−/−; WT). Genotypes were confirmed using primers for flox and Cre (Supplemental Table 1) and ABI 7900 Detection System (Applied Biosystems).