Pleiotrophin and chondromodulin are proteins of <30 kDa that can be isolated from fetal cartilage at levels indicating a tissue concentration in excess of 5 uM. Neither protein can be isolated in significant amounts from adult tissue. The roles of these molecules are postulated to be in the growth and development of the cartilage matrix. Pleiotrophin and chondromodulin abundance were investigated using northern blotting and RT-PCR for mRNA and western blotting of cell extracts from fetal, newborn and adult bovine cartilage for protein. In parallel, cartilage markers (collagen type II, link protein, chondroadherin) as well as actin and basic fibroblast growth factor levels (as controls) were investigated. Chondrocytes cultured in a variety of conditions (high serum, low serum, with and without retinoic acid) were also analyzed. Pleiotrophin mRNA was found to be regulated in a similar fashion to the protein; the mRNA was found in fetal and newborn tissue, but not adult tissue. Interestingly, adult chondrocytes cultured in 10% fetal calf serum expressed pleiotrophin mRNA, in contrast to cells cultured in 0.3% fetal calf serum. Chondromodulin mRNA (RT-PCR), could be detected in cells cultured from adult tissue. The anti-chondromodulin antibodies also recognized the higher molecular weight precursor of this glycoprotein in cultured chondrocytes. While these proteins do not appear to directly affect cell proliferation, they do appear to have effects on chondrocyte phenotype and are regulated differently from each other.
|Publication status||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology