title: Intercellular Odontoblast Communication via ATP Mediated by Pannexin-1 Channel and Phospholipase C-coupled Receptor Activation.
abstract: Extracellular ATP released via pannexin-1 channels, in response to the activation of mechanosensitive-TRP channels during odontoblast mechanical stimulation, mediates intercellular communication among odontoblasts in dental pulp slice preparation dissected from rat incisor. Recently, odontoblast cell lines, such as mouse odontoblast lineage cells, have been widely used to investigate physiological/pathological cellular functions. To clarify whether the odontoblast cell lines also communicate with each other by diffusible chemical substance(s), we investigated the chemical intercellular communication among cells from mouse odontoblast cell lines following mechanical stimulation. A single cell was stimulated using a glass pipette filled with standard extracellular solution. We measured intracellular free Ca(2+) concentration ([Ca(2+)]i) by fura-2 in stimulated cells, as well as in cells located nearby. Direct mechanical stimulation to a single odontoblast increased [Ca(2+)]i, which showed sensitivity to capsazepine. In addition, we observed increases in [Ca(2+)]i not only in the mechanically stimulated odontoblast, but also in nearby odontoblasts. We could observe mechanical stimulation-induced increase in [Ca(2+)]i in a stimulated human embryo kidney (HEK) 293 cell, but not in nearby HEK293 cells. The increase in [Ca(2+)]i in nearby odontoblasts, but not in the stimulated odontoblast, was inhibited by adenosine triphosphate (ATP) release channel (pannexin-1) inhibitor in a concentration- and spatial-dependent manner. Moreover, in the presence of phospholipase C (PLC) inhibitor, the increase in [Ca(2+)]i in nearby odontoblasts, following mechanical stimulation of a single odontoblast, was abolished. We could record some inward currents evoked from odontoblasts near the stimulated odontoblast, but the currents were observed in only 4.8% of the recorded odontoblasts. The results of this study showed that ATP is released via pannexin-1, from a mechanically stimulated odontoblast, which transmits a signal to nearby odontoblasts by predominant activation of PLC-coupled nucleotide receptors.
authors.affiliation: Department of Physiology, Tokyo Dental College Tokyo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Physiology, Tokyo Dental College Tokyo, Japan ; Department of Crown and Bridge Prosthodontics, Tokyo Dental College Tokyo, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Furuya
authors.affiliation: Department of Physiology, Tokyo Dental College Tokyo, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Department of Physiology, Tokyo Dental College Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kojima
authors.affiliation: Department of Physiology, Tokyo Dental College Tokyo, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tazaki
authors.affiliation: Department of Crown and Bridge Prosthodontics, Tokyo Dental College Tokyo, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Physiology, Tokyo Dental College Tokyo, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shibukawa
keywords: P2Y; adenosine triphosphate; odontoblast; pannexin-1; paracrine; transient receptor potential channel