EXTRACELLULAR REGULATED KINASES 1/2 (ERK1/2) INVOLVE IN EARLY STAGES OF MICE CRANIAL SUTURES OSTEOGENESIS

Introduction: A normal pattern of calvarial sutures morphogenesis is related to equilibrium between proliferation of osteogenic precursors within the sutural mesenchymal cells and differentiation of these cells to osteoblasts. In a variety of cell types, processes such as proliferation, differentiation and apoptosis require mitogen activated protein kinases (MAPK) family members such as extracellular regulated kinases1/2(ERK1/2). In this study, we focused on immunoexpression pattern of ERK1/2 in osteogenesis of mouse calvarial sutures during different prenatal and postnatal stages.
Methods and Materials: Upper part of mice skull were fixed in 10% formalin and decalcified. The paraffin -embedded blocks from 12,15,18 days of embryonic(E12, E15, E18) and 1 and 7 days neonatal (N1, N7) samples of mice were prepared. Five μm thickness sections were stained with monoclonal antibody against ERK1/2 by using standard immunohistochemitry (IHC) ABC staining procedure. ERK1/2 expression pattern was scaled and analyzed.
Results: Immunoreactivity of ERK1/2 in both sutures in E12 was strong. After E12, expression pattern of ERK1/2 clearly decreased. Both sutures in late embryonic (E18), early (N1) and one week (N7) neonate showed significant down regulation of ERK1/2.
Conclusions: ERK1/2 involve in proliferation and differentiation of sutural mesenchymal cells to osteoblasts in early embryonic stages. It appears that normal closure of skull sutures during postnatal period promotes in the absence of ERK1/2.