Cr. Flannery et al., EXPRESSION AND ACTIVITY OF ARTICULAR-CARTILAGE HYALURONIDASES, Biochemical and biophysical research communications (Print), 251(3), 1998, pp. 824-829
The glycosaminoglycan hyaluronan is an important component of the extr
acellular matrix of articular cartilage, contributing to both the stru
ctural and functional integrity of this highly specialized tissue. Hya
luronan is known to be synthesized and turned over by the resident cho
ndrocytes, although the mechanisms involved in hyaluronan degradation
are not precisely defined. Recently, the cDNA sequences of extracellul
ar hyaluronidases present on spermatazoa and in human serum have been
reported, and we have utilized these data to investigate the expressio
n and activity of these and/or related enzymes by articular cartilage
chondrocytes. By using ''gene-homology'' RT-PCR techniques, three hyal
uronidase isozymes were found to be expressed by chondrocytes, and hya
luronidase activity was detected in cell membrane extracts and conditi
oned media from chondrocyte monolayer cultures following acidification
to pH 4.5 or pH 3.7. In addition, the levels of mRNA for two of the c
hondrocyte hyaluronidases were upregulated by IL-1 and TNF stimulation
, thereby implicating cartilage-derived hyaluronidase activity as a fa
ctor contributing to cytokine-induced extracellular matrix degradation
during synovial joint disease. (C) 1998 Academic Press.