Mechanosensitivity and intercellular communication in HOBIT osteoblastic cells: a possible role for gap junction hemichannels.
Mechanically induced intercellular Ca2+ signalling was investigated in differentiated HOBIT osteoblastic cells. HOBIT cells express connexin43 clustered at the cell-to-cell boundary and display functional intercellular coupling assessed by intercellular transfer of Lucifer yellow. Mechanical stimulation of single cells, besides leading to an intracellular Ca2+ rise, induced a wave of increased Ca2+ that was radially propagated to surrounding cells. Treatment of cells with thapsigargin blocked mechanically induced signal propagation. Intercellular Ca2+ spreading was inhibited by 18alpha-glycyrrhetinic acid, demonstrating the involvement of gap junctions in signal propagation. Suramin and apyrase decreased the extent of wave propagation, suggesting that ATP-mediated paracrine stimulation contribute to cell-to-cell signalling. The functional expression of gap-junctional hemichannels was evidenced in experiments of Mn2+ quenching, extracellular dye uptake and intracellular Ca2+ release, activated by uptake of inositol 1,4,5-trisphosphate from the external medium. Gap-junctional hemichannels were activated by low extracellular Ca2+ concentrations and inhibited by 18alpha-glycyrrhetinic acid.
Romanello
Milena
M
Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, Università di Trieste, via Licio Giorgieri 1, I-34127 Trieste, Italy. dandrea@bbcm.univ.trieste.it
Veronesi
Valentina
V
D'Andrea
Paola
P
D000328:Adult; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D017629:Gap Junctions / Q000502:physiology*; D006801:Humans; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D010006:Osteoblasts / Q000502:physiology*; D019899:Paracrine Communication / Q000502:physiology; D010812:Physical Stimulation
D002118:Calcium