Impaired skeletal formation in mice overexpressing DMP1

Abstract

Michael Albazzaz, Karthikeyan Narayanan, Jianjun Hao, Roma Andheri, Amsaveni Ramachandran, Sriram Ravindran, Anne GeorgeBrodie Tooth Development Genetics and Regenerative Medicine Research Laboratory, University of Illinois, Chicago, IL, USAAbstract: Dentin matrix protein 1 (DMP1) is a noncollagenous protein expressed in mineralized tissues such as bone, dentin, and cartilage. To investigate the role of DMP1 during bone formation, transgenic mice overexpressing DMP1 under the control of the CMV promoter were generated. These mice displayed an increased mineralization phenotype in bone. In addition, accelerated terminal differentiation of the epiphyseal growth plate chondrocytes were also observed. To investigate the potential role of DMP1 in osteoblast differentiation, bone marrow stem cells were stimulated with DMP1 and assayed for “early” and “late” markers for osteoblast differentiation. DMP1 treatment increased the expression of CBFA1, BMP2, COL1, and OCN within two days. An in vitro mineralized nodule formation assay demonstrated that the bone marrow stem cells could differentiate and form a mineralized matrix in the presence of DMP1. Together, these results support a model whereby DMP1 functions as a key regulatory molecule that is required for normal growth and development of bone and cartilage.Keywords: dentin matrix protein 1, mineralization, osteoblast, chondrocytes, transgenic mice