Functional Involvement Of NMDAR And Pathways In The Process Of Mechanotransduction In Osteoblastic Cell

Objective: To identify the transcription of particular subunits of ionotropic NMDA glutamate receptors in mouse bone marrow stromal precursor cell line D1, osteoblastic cell MC3T3-E1 and MC3T3-E1 subclone 14, investigate the involved functional pathways underlying the potential mechanisms of mechanotransduction.Methods: immunofiuorescence and western blotting were employed to identify the NMDAR subunit 1 in above three cell lines, RT-PCR was applied to discern the NMDAR subunits 2 and discriminate the pattern of AP-1 components and Cbfal/Runx2 response to cyclic strain under different conditions. The signaling inhibitors, MK801,EGTA,Cytochalasin D were used to investigate the function of NMDAR in the process of mechanotransduction and involved mechanical signaling pathway.Results: the NMDAR subunit 1 and different types of subunit 2 were identified in these cell lines, AP-1 components and bone specific transcription factor CBFA1/RUNX2 were involved in the process of mechanotransduction; the single employ of the signalling blocker MK801,EGTA,Cytochalasin D partially inhibited the cyclic strain induced activation of ERK1/2 pathway respectively, but the combination of the blocker inhibited the same pathway to the base line.Conclusion the NMDAR is expressed in bone marrow stromal precursor cell line D1, osteoblastic cell MC3T3-E1 and MC3T3-E1 subclone 14, and may be functional in these cells , and NMDAR is involved in the precess underlying the potential mechanism of mechanotransduction; NMDAR,extracellular Ca²⁺ influx and cell skeleton were involved in the process of mechanotransduction, and in a synergistic way to increase activation of ERK1/2 pathway.