Matrix Gla protein is differentially expressed during the deposition of a calcified matrix by vascular pericytes

PCR-based subtractive hybridisation was used to identify genes up-regulated when pericytes undergo osteogenic differentiation and deposit a calcified matrix, cDNA pools mere generated from confluent pericytes and from pericyt e cultures containing calcified nodules, A pericyte cDNA library was screen ed with the product of the subtraction procedure (calcified minus confluent cDNA) and the majority of the positive clones mere identified as matrix Gl a protein (MGP). Northern analysis and immunohistochemistry demonstrated th at MGP was only expressed by pericytes in calcified nodules, Antibodies to MGP inhibited the deposition of a calcified matrix by pericytes, suggesting that MGP regulates both cell differentiation and calcification. (C) 2000 F ederation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.