DISRUPTED EXPRESSION OF MATRIX GENES IN THE GROWTH-PLATE OF THE MOUSECARTILAGE MATRIX DEFICIENCY (CMD) MUTANT

Chondrodysplasia in the autosomal recessive cartilage matrix deficienc y (cmd) mutant is caused by lock of the proteoglycan aggrecan arising from a mutation in the gene. Homozygous cmd/cmd mice are characterized by disorganisation of chondrocytes in the growth plate, disproportion ate dwarfism, late, and perinatal lethality. We have studied the impac t of the aggrecan deficiency on the expression of other matrix genes d uring the differentiation of chondrocytes in the growth plate of cmd/c md 18.5 day fetuses. Compared with the wild-type, there are significan t differences in the growth plates of cmd mutants in the combinations of co-expression of genes encoding the glycoprotein link protein, prot eoglycan syndecan 3, collagens alpha 1 (X) [Col10a1], alpha 2 (XI) [Co l11a2], and the alternative transcripts of alpha 1 (II) [Col2a1 type I IA form], and alpha 1 (IX) [Col9a1 long and short forms]. The discorda nce of gene expression in cmd chondrocytes may be additional factors c ontributing io the disrupted cellular architecture of the growth plate resulting from the primary absence of aggrecan. (C) 1998 Wiley-Liss, Inc.