Two subtypes of G protein‐coupled nucleotide receptors, P2Y₁ and P2Y₂ are involved in calcium signalling in glioma C6 cells

Abstract

] i . 6 ADP inhibited isoproterenol-induced cyclic AMP accumulation. PTX blocked this eect, but PPADS did not. 7 RT ± PCR analysis revealed the molecular identity of P2Y receptors expressed by glioma C6 cells to be both P2Y 1 and P2Y 2 . 8 It is concluded that both P2Y 1 and P2Y 2 receptors co-exist in glioma C6 cells. ADP acts as agonist of the ®rst, and ATP and UTP of the second one. Both receptors are linked to phospholipase C (PLC).

2′, 3′-O-(4-benzoylbenzoyl)–ATP-mediated calcium signaling in rat glioma C6 cells: role of the P2Y2 nucleotide receptor

“…In the presence of EGTA, UTP caused a transient increase in [Ca 2+ ] i to 2.38± AU; following the return to the baseline the addition of CaCl 2 led to an increase of [Ca 2+ ] i to 1.83±0.11 AU (n=97). The same kinetics of the biphasic Ca 2+ response induced by 100 μM ATP or 10 μM ADP in glioma C6 cells was shown previously [14,15,20]. Thus, BzATP, similar to ATP, UTP, and ADP, generates the depletion of the ER stores that gives a signal to voltage-independent Ca 2+ channels and gives rise to Ca 2+ influx across plasma membrane.…”

“…The biphasic process that involves PLC stimulation and inositol-1,4,5-trisphosphate (IP 3 ) formation causes release of Ca 2+ from the ER store via IP 3 receptors (the first phase of the response) and is followed by capacitative Ca 2+ entry via voltage-independent Ca 2+ channels in the plasma membrane, as a consequence of the depletion of the ER store (the second phase of the response) [6,7]. Such process is ubiquitous in all nonexcitable cells and has been previously described by us in glioma C6 as the result of ATP and UTP-evoked P2Y 2 receptor activation [8,14,15,20]. Similarly, we have demonstrated that in C6 cells, thapsigargin, acting without IP 3 production as a specific inhibitor of the ER Ca 2+ -ATPase, initiated Ca 2+ response consistent with the capacitative model of Ca 2+ entry, in which the depletion of intracellular stores provides a signal for the transmembrane Ca 2+ influx [8,20].…”

“…In each case, the agonist was added in the initial absence of extracellular Ca 2+ (arrow), then the medium was exchanged for the standard buffer containing 2 mM CaCl 2 (arrow). BBG was added either 3 min prior to the addition of BzATP (b); after termination of the first phase of the response, 3 min prior to the exchange of the medium (c); or was present during all experiment (d Their activation by 100 μM ATP and 100 μM UTP led to a biphasic intracellular Ca 2+ mobilization [14]. The present study showed that BzATP-induced Ca 2+ elevation started with an initial peak followed by a long sustained phase in the manner typical for the P2Y metabotropic receptors.…”

“…We have previously shown that both the ADP-or 2MeSADP-induced stimulation of P2Y 1 , and the ATP-or UTP-induced stimulation of P2Y 2 , initiate typical biphasic Ca 2+ responses [8,10,[13][14][15]. In contrast, the presence and activity of P2X receptors in glioma C6 cells is weakly documented [14]. Recently, Wei et al [16] suggested functional expression of the P2X 7 receptor in this type of cells, as activation by BzATP led to an increase in [Ca 2+ ] i .…”

Pannexin1 Drives Multicellular Aggregate Compaction via a Signaling Cascade That Remodels the Actin Cytoskeleton

“…Given that extracellular ATP can bind to P 2 X 7 cationic channel (27) and P 2 Y 1 /P 2 Y 2 G-protein coupled (28) purinergic receptors, both shown to be expressed in C6 glioma cells (29,30), we then determined which receptor pathway is dominant in aggregate compaction. Wild-type and Panx1 rods were first treated with suramin (100 M), a nonspecific purinergic antagonist.…”