Gap junctions and fluid flow response in MC3T3-E1 cells

In the current study, we examined the role of gap junctions in oscillatory fluid flow-induced changes in intracellular Ca2+ concentration and prostagl andin release in osteoblastic cells. This work was completed in MC3T3-E1 ce lls with intact gap junctional communication as well as in MC3T3-E1 cells r endered communication deficient through expression of a dominant-negative c onnexin. Our results demonstrate that MC3T3-E1 cells with intact gap juncti ons respond to oscillatory fluid flow with significant increases in prostag landin E-2 (PGE(2)) release, whereas cells with diminished gap junctional c ommunication do not. Furthermore, we found that cytosolic Ca2+ (Ca-i(2+)) r esponse was unaltered by the disruption in gap junctional communication and was not significantly different among the cell lines. Thus our results sug gest that gap junctions contribute to the PGE(2) but not to the Ca-i(2+) re sponse to oscillatory fluid flow. These findings implicate gap junctional i ntercellular communication (GJIC) in bone cell ensemble responsiveness to o scillatory fluid flow and suggest that gap junctions and GJIC play a pivota l role in mechanotransduction mechanisms in bone.