H. Ito et al., Molecular cloning and biological activity of a novel lysyl oxidase-relatedgene expressed in cartilage, J BIOL CHEM, 276(26), 2001, pp. 24023-24029
We cloned a cDNA encoding a novel lysyl oxidase-related protein, named LOXC
, by suppression subtractive hybridization between differentiated and calci
fied ATDC5 cells, a clonal mouse chondrogenic EC cell line. The deduced ami
no acid sequence of mouse LOXC consists of 757 amino acids and shows 50% id
entity with that of mouse lysyl oxidase. Northern blot analysis showed a di
stinct hybridization band of 5.4 kilobases, and Western blot analysis showe
d an immunoreactive band at 82 kilodaltons. Expression of LOXC mRNA was det
ected in osteoblastic MC3T3-E1 cells and embryonic fibroblast C3H10T1/2 cel
ls, whereas none of NIH3T3 fibroblasts and myoblastic C2C12 cells expressed
LOXC mRNA in vitro. Moreover, the LOXC mRNA and protein levels dramaticall
y increased throughout a process of chondrogenic differentiation in ATDC5 c
ells. In vivo, LOXC gene expression was localized in hypertrophic and calci
fied chondrocytes of growth plates in adult mice. The conditioned media of
COS-7 cells transfected with the full-length LOXC cDNA showed the lysyl oxi
dase activity in both type I and type II collagens derived from chick embry
os, and these activities of LOXC were inhibited by P-aminopropionitrile, a
specific inhibitor of lysyl oxidase. Our data indicate that LOXC is express
ed in cartilage in vivo and modulates the formation of a collagenous extrac
ellular matrix.