NEW YORK (Reuters Health) - A polymorphism of the gene expressing asporin, a cartilage extracellular matrix (ECM) component, increases susceptibility to osteoarthritis, Japanese researchers report in a January 2nd advance online publication of Nature Genetics.
Dr. Shiro Ikegawa of The Institute of Physical and Chemical Research, Tokyo and colleagues note that the “functional integrity of the joint is maintained through a delicate balance between degradation and synthesis of the cartilage ECM.” This is controlled by chondrocytes and a breakdown in the cartilage ECM leads to osteoarthritis.
Asporin is abundantly expressed in osteoarthritis articular cartilage, which prompted the researchers to examine its possible role in the condition.
In case-control studies in two separate populations with knee osteoarthritis, the researchers found that a polymorphism in the aspartic acid repeat of the gene encoding asporin was overexpressed relative to the common D13 allele. Its frequency was increased with disease severity. A similar pattern was seen in patients with hip osteoarthritis.
The researchers then established that asporin negatively regulates chondrogenesis in vitro by inhibiting transforming growth factor-beta.
“Taken together, these findings provide another functional link between extracellular matrix proteins, transforming growth factor-beta and disease, suggesting new therapeutic strategies for osteoarthritis,” Dr. Ikegawa’s group concludes.
Source: Nat Genet 2005. [ Google search on this article ]
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