Mechanical Strain Regulates Osteoblast Proliferation Through Ca-CaMK-CREB Signal Pathway / 中国医学科学杂志(英文版)

ABSTRACT

Objective To investigate the effects of mechanical strain on Ca-calmodulin dependent kinase (CaMK)-cAMP response element binding protein (CREB) signal pathway and proliferation of osteoblasts.Methods Using a four-point bending device, MC3T3-E1 cells were exposed to mechanical tensile strains of 2500 µs and 5000 µs at 0.5 Hz respectively. The intracellular free Ca([Ca]i) concentration and calmodulin activity were assayed by fluorospectrophotometry, CaMK II β, CREB, and phosphorylated (activated) CREB (p-CREB) were assessed by Western blot, and cells proliferation was assayed with MTT. Pretreatment with verapamil was carried out to block Cachannel, and inhibitor U73122 was used to inhibit phospholipase C (PLC).Results Mechanical strains of 2500 µs and 5000 µs for 1 to 10 minutes both increased [Ca]i level of the cells. The 2500 µs strain, a periodicity of 1 h/d for 3 days, activated calmodulin, elevated protein levels of CaMK II β and p-CREB, and promoted cells proliferation, which were attenuated by pretreatment of verapamil or U73122. The effects of 5000 µs strain on calmodulin, CaMK II β, p-CREB and proliferation were contrary to 2500 µs strain.Conclusion The mechanical strain regulates osteoblasts proliferation through Ca-CaMK-CREB signal pathway via Cachannel and PLC/IPtransduction cascades.