Purinergic and Store‐Operated Ca²⁺ Signaling Mechanisms in Mesenchymal Stem Cells and Their Roles in ATP‐Induced Stimulation of Cell Migration

ATP is an extrinsic signal that can induce an increase in the cytosolic Ca2+ level ([Ca2+]c) in mesenchymal stem cells (MSCs). However, the cognate intrinsic mechanisms underlying ATP-induced Ca2+ signaling in MSCs is still contentious, and their importance in MSC migration remains unknown. In this study, we investigated the molecular mechanisms underlying ATP-induced Ca2+ signaling and their roles in the regulation of cell migration in human dental pulp MSCs (hDP-MSCs). RT-PCR analysis of mRNA transcripts and interrogation of agonist-induced increases in the [Ca2+]c support that P2X7, P2Y1, and P2Y11 receptors participate in ATP-induced Ca2+ signaling. In addition, following P2Y receptor activation, Ca2+ release-activated Ca2+ Orai1/Stim1 channel as a downstream mechanism also plays a significant role in ATP-induced Ca2+ signaling. ATP concentration-dependently stimulates hDP-MSC migration. Pharmacological and genetic interventions of the expression or function of the P2X7, P2Y1 and P2Y11 receptors, and Orai1/Stim1 channel support critical involvement of these Ca2+ signaling mechanisms in ATP-induced stimulation of hDP-MSC migration. Taken together, this study provide evidence to show that purinergic P2X7, P2Y1, and P2Y11 receptors and store-operated Orai1/Stim1 channel represent important molecular mechanisms responsible for ATP-induced Ca2+ signaling in hDP-MSCs and activation of these mechanisms stimulates hDP-MSC migration. Such information is useful in building a mechanistic understanding of MSC homing in tissue homeostasis and developing more efficient MSC-based therapeutic applications.