Bone morphogenetic protein-2-induced alpha 2 (I) collagen expression in odontoblastic MDPC-23 cells mediated by Smad proteins

Objective: To characterize the role of Smads proteins in alpha 2 (I) collagen (COL1A2) gene expression induced by bone morphogenetic protein-2 (BMP-2) in odontoblast cell line MDPC-23.

Methods: Endogenous Smad protein expression was determined by immunocytochemistry. Smads function and their role in COL1A2 gene expression were investigated in cotransfection experiments using promoter-luciferase reporter gene construct.

Results: MDPC-23 cells expressed Smad1, Smad5 and Smad6. BMP-2 promoted the activation of COL1A2 promoter reporter construct. Transient overexpression of Smad1 or Smad5 was enhanced, while overexpression of Smad6 inhibited BMP-2-induced COL1A2 promoter activity. BMP-2 inducibility could be blocked by overexpression of Smad1 or Smad5 dominant negative mutant.

Conclusions: Smad signaling is functioning and appears to be involved in BMP-2-induced COL1A2 collagen transcription in MDPC-23. Smad signaling may play an important role in odontoblast differentiation and dentin extracellular matrix formation mediated by BMP-2.