Effects of phosphalipase C on alkaline phosphatase and mineralization

Abstract

An osteoblastic cell line: MC3T3-E1, forms mineralized tissues during cell culture with increased alkaline phosphatase (ALP) activity. Addition of phosphatidylinositol-specific phospholipase C (PIPLC) to culture medium released membranebound ALP and highly increased ALP activity in the medium, compared to naturally released ALP without PIPLC. Continuous treatment with PIPLC did not affect mineralization of MC3T3-E1 cells, but treatment for only 2 hours every 3 days increased mineralizaiton at its late stage. We suspect that these results were not caused by activation of released ALP or increased ALP mRNA by the PIPLC treatment. These results suggest that embedded ALP was exposed by release of membrane-bound ALP, and that the newly exposed ALP was important for mineralization of the cells.