Dlx3 Transcriptional Regulation of Osteoblast Differentiation: Temporal Recruitment of Msx2, Dlx3, and Dlx5 Homeodomain Proteins to Chromatin of the Osteocalcin Gene

• DOI: 10.1128/mcb.24.20.9248-9261.2004
• Publication Date: 2004-09-29T02:17:34Z
• Authors: Mohammad Q. Hassan; Amjad Javed; Maria I. Morasso; Jeremy Karlin; Martin Montecino; Andre J. van Wijnen; Gary S. Stein; Janet L. Stein; Jane B. Lian
• Keywords: DLX5; RUNX2; Chromatin immunoprecipitation

Genetic studies show that Msx2 and Dlx5 homeodomain (HD) proteins support skeletal development, but null mutation of the closely related Dlx3 gene results in early embryonic lethality. Here we find expression mouse embryo is associated with new bone formation regulation osteoblast differentiation. expressed osteoblasts, overexpression osteoprogenitor cells promotes, while specific knock-down by RNA interference inhibits, induction osteogenic markers. We characterized relation to during Chromatin immunoprecipitation assays revealed a molecular switch HD protein association bone-specific osteocalcin (OC) gene. The transcriptionally repressed OC was occupied proliferating Dlx3, Dlx5, Runx2 were recruited postproliferatively initiate transcription. occupancy increased over mature osteoblasts at mineralization stage differentiation, coincident polymerase II occupancy. protein-DNA interactions stimulated promoter activity, Dlx3-Runx2 protein-protein interaction reduced Runx2-mediated Deletion analysis showed interacting domain from amino acids 376 432, which also include active subnuclear targeting sequence (376 432). Thus, provide cellular evidence for regulating cell differentiation both positive negative propose multiple constitute regulatory network mediates development phenotype through sequential distinct elements.