The Bulletín of Kanagawa Dental College

Vol. 36 No. 2       September- 2008

ISSN: 0385-1443      UBIC: 65

ABSTRACT

We have reponed that mutations of the gene encoding MMP-2, an extracellular matrix (ECM) degrading gelatinase, decrease bone mineral density (BMD) in long bones, but increase bone volume in calvaria. In the long bones, the osteocytic networks were disrupted and the bone density kept decreasing throughout life, while osteoblast and osteoclast functions appeared normal. To evaluate the mechanical factors in different responses of long bones and calvaria, we isolated MMP2 -/- osteoblast and osteocytes from 16-week mice and analyzed mRNAs by quantitative PCR. in the expression of certain genes, MMP2-/- long bone osteocytes responded to stretching in an entirely different manner compared to the wild type counterparts. Our results suggested that a significantly increased level of inhibitory sclerostin gene expressed in MMP2-/- long bone osteocytes reduced the activity of osteoblasts resulting in the loss of bone mass. Key words: MMP2 / Osteocyte / Osteoblasts / Mechaniical response / BMD.

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