Asporin Polymorphism Tied to Osteoarthritis

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Asporin Polymorphism Tied to Osteoarthritis

Reuters Health Information 2005. © 2005 Reuters Ltd.

NEW YORK (Reuters Health) Jan 10 - 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.

Nat Genet 2005.

http://www.medscape.com/viewarticle/497182