title: An ATP-dependent mechanism mediates intercellular calcium signaling in bone cell network under single cell nanoindentation.
abstract: To investigate the roles of intercellular gap junctions and extracellular ATP diffusion in bone cell calcium signaling propagation in bone tissue, in vitro bone cell networks were constructed by using microcontact printing and self-assembled monolayer technologies. In the network, neighboring cells were interconnected through functional gap junctions. A single cell at the center of the network was mechanically stimulated by using an AFM nanoindenter. Intracellular calcium ([Ca2+](i)) responses of the bone cell network were recorded and analyzed. In the untreated groups, calcium propagation from the stimulated cell to neighboring cells was observed in 40% of the tests. No significant difference was observed in this percentage when the intercellular gap junctions were blocked. This number, however, decreased to 10% in the extracellular ATP-pathway-blocked group. When both the gap junction and ATP pathways were blocked, intercellular calcium waves were abolished. When the intracellular calcium store in ER was depleted, the indented cell can generate calcium transients, but no [Ca2+](i) signal can be propagated to the neighboring cells. No [Ca2+](i) response was detected in the cell network when the extracellular calcium source was removed. These findings identified the biochemical pathways involved in the calcium signaling propagation in bone cell networks.
authors.affiliation: Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Huo
authors.forename: Xin L
authors.initials: XL
authors.lastname: Lu
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Costa
authors.forename: Qiaobing
authors.initials: Q
authors.lastname: Xu
authors.forename: X Edward
authors.initials: XE
authors.lastname: Guo
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002450:Cell Communication / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D048430:Cell Shape / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D045604:Extracellular Fluid / Q000378:metabolism; D017629:Gap Junctions / Q000502:physiology*; D051379:Mice; D041681:NIH 3T3 Cells; D010011:Osteocytes / Q000166:cytology / Q000378:metabolism*; D013314:Stress, Mechanical
chemical_list: D000255:Adenosine Triphosphate; D002118:Calcium