Multicentric osteolysis with nodulosis, arthritis, and cardiac defect syndrome: loss of MMP2 leads to increased apoptosis with alteration of apoptotic regulators and caspases and embryonic lethality

摘要

Abstract: Inactivating mutations of matrix metalloproteinase 2 (MMP2) cause multicentric osteolysis with nodulosis and arthritis, one of a group of inherited osteolytic and arthritic disorders. We have previously shown that mice lacking Mmp2 share similar syndromic features with the human disorder, and at the cellular level, Mmp2-/- mouse osteoblasts and osteoclasts have reduced numbers and proliferation rates at critical developmental time points. While previously hypothesized, the effect of MMP2 loss on apoptosis has not been examined in this system. We therefore sought to clarify its role in mediating the developmental defects in Mmp2-/- mice using immunohistochemistry, immunoblot analysis, and quantitative reverse transcription polymerase chain reaction analysis. We also explored the effects of MMP2 inhibition in the osteogenic sarcoma cell line SaOS2. Loss of MMP2 resulted in increased apoptosis and caspase activation both in vitro and in vivo. MMP2-deficient cells had increased Fas expression and reduced levels of the key survival signals p-FAK, p-ERK, cFLIP, and Bcl-2. Notably, and in marked contrast to their original characterization, there was a significant increase in the in utero demise of homozygous Mmp2-/- embryos. Specifically, litters from heterozygous crosses consistently yielded nearly 85% fewer than expected homozygous Mmp2-/- pups. Taken together, our findings highlight a new role for MMP2 in preventing apoptosis during development and growth.