scholarly journals Role of P2-purinergic receptors in rat Leydig cell steroidogenesis

1996 ◽  
Vol 320 (2) ◽  
pp. 499-504 ◽  
Author(s):  
Carlo FORESTA ◽  
Marco ROSSATO ◽  
Andrea NOGARA ◽  
Francesco GOTTARDELLO ◽  
Paola BORDON ◽  
...  
Keyword(s):  
Leydig Cells ◽  
Purinergic Receptors ◽  
External Medium ◽  
Purinergic Receptor ◽  
Extracellular Atp ◽  
Receptor Subtype ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Testosterone Secretion ◽  
P2 Purinergic Receptors

The present study investigated the effects of extracellular ATP on the intracellular calcium ion concentration ([Ca2+]i) and testosterone production in isolated adult rat Leydig cells. This nucleotide caused an increase in [Ca2+]i, with a maximal effect at a concentration of 100 µM ATP, comprising a rapid initial spike followed by a long-lasting plateau. The first rapid spike was dependent on the release of Ca2+ from internal stores, since it also occurred in Ca2+-free medium and was abolished after depletion of internal stores with thapsigargin. The second, long-lasting, phase was dependent on the influx of Ca2+ from the extracellular medium. After 3 h of incubation, extracellular ATP stimulated testosterone secretion in a dose-dependent manner, with a maximal effect at 100 µM. Activation of steroidogenesis by ATP was fully dependent on the presence of Ca2+ in the external medium. Among different nucleotides, only ATP, adenosine 5´-[γ-thio]triphosphate, UTP, benzoylbenzoic-ATP and 2-methylthio-ATP were effective in inducing both the rise in [Ca2+]i and testosterone secretion. These effects were blocked by preincubation of Leydig cells with oxidized ATP, an inhibitor of the P2Z-purinergic receptor subtype. These results show that rat Leydig cells possess P2-purinergic receptors whose activation triggers an increase in [Ca2+]i due to the release of Ca2+ from internal stores and Ca2+ influx from the external medium. The stimulatory effect of extracellular ATP on testosterone secretion seems to be coupled to the influx of Ca2+ from the external medium.

P2X7 receptor cross-talk regulates ATP-induced pannexin 1 internalization

2017 ◽  
Vol 474 (13) ◽  
pp. 2133-2144 ◽  
Author(s):  
Andrew K.J. Boyce ◽  
Leigh Anne Swayne
Keyword(s):  
Nervous System ◽  
Cross Talk ◽  
Purinergic Receptors ◽  
Atp Release ◽  
Extracellular Atp ◽  
Signalling Pathways ◽  
Physical Interaction ◽  
Cell Periphery ◽  
Dependent Manner ◽  
Pannexin 1

In the nervous system, extracellular ATP levels transiently increase in physiological and pathophysiological circumstances, effecting key signalling pathways in plasticity and inflammation through purinergic receptors. Pannexin 1 (Panx1) forms ion- and metabolite-permeable channels that mediate ATP release and are particularly enriched in the nervous system. Our recent study demonstrated that elevation of extracellular ATP triggers Panx1 internalization in a concentration- and time-dependent manner. Notably, this effect was sensitive to inhibition of ionotropic P2X7 purinergic receptors (P2X7Rs). Here, we report our novel findings from the detailed investigation of the mechanism underlying P2X7R–Panx1 cross-talk in ATP-stimulated internalization. We demonstrate that extracellular ATP triggers and is required for the clustering of P2X7Rs and Panx1 on Neuro2a cells through an extracellular physical interaction with the Panx1 first extracellular loop (EL1). Importantly, disruption of P2X7R–Panx1 clustering by mutation of tryptophan 74 within the Panx1 EL1 inhibits Panx1 internalization. Notably, P2X7R–Panx1 clustering and internalization are independent of P2X7R-associated intracellular signalling pathways (Ca2+ influx and Src activation). Further analysis revealed that cholesterol is required for ATP-stimulated P2X7R–Panx1 clustering at the cell periphery. Taken together, our data suggest that extracellular ATP induces and is required for Panx1 EL1-mediated, cholesterol-dependent P2X7R–Panx1 clustering and endocytosis. These findings have important implications for understanding the role of Panx1 in the nervous system and provide important new insights into Panx1–P2X7R cross-talk.

scholarly journals P2Y1 and P2Y13 purinergic receptors mediate Ca2+ signaling and proliferative responses in pulmonary artery vasa vasorum endothelial cells

2011 ◽  
Vol 300 (2) ◽  
pp. C266-C275 ◽  
Author(s):  
Taras Lyubchenko ◽  
Heather Woodward ◽  
Kristopher D. Veo ◽  
Nana Burns ◽  
Hala Nijmeh ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Artery ◽  
Purinergic Receptors ◽  
Purinergic Receptor ◽  
Extracellular Atp ◽  
Vasa Vasorum ◽  
Receptor Subtypes ◽  
Extracellular Nucleotide ◽  
Selective Antagonist ◽  
Intracellular Ca

Extracellular ATP and ADP have been shown to exhibit potent angiogenic effects on pulmonary artery adventitial vasa vasorum endothelial cells (VVEC). However, the molecular signaling mechanisms of extracellular nucleotide-mediated angiogenesis remain not fully elucidated. Since elevation of intracellular Ca2+ concentration ([Ca2+]i) is required for cell proliferation and occurs in response to extracellular nucleotides, this study was undertaken to delineate the purinergic receptor subtypes involved in Ca2+ signaling and extracellular nucleotide-mediated mitogenic responses in VVEC. Our data indicate that stimulation of VVEC with extracellular ATP resulted in the elevation of [Ca2+]i via Ca2+ influx through plasma membrane channels as well as Ca2+ mobilization from intracellular stores. Moreover, extracellular ATP induced simultaneous Ca2+ responses in both cytosolic and nuclear compartments. An increase in [Ca2+]i was observed in response to a wide range of purinergic receptor agonists, including ATP, ADP, ATPγS, ADPβS, UTP, UDP, 2-methylthio-ATP (MeSATP), 2-methylthio-ADP (MeSADP), and BzATP, but not adenosine, AMP, diadenosine tetraphosphate, αβMeATP, and βγMeATP. Using RT-PCR, we identified mRNA for the P2Y1, P2Y2, P2Y4, P2Y13, P2Y14, P2X2, P2X5, P2X7, A1, A2b, and A3 purinergic receptors in VVEC. Preincubation of VVEC with the P2Y1 selective antagonist MRS2179 and the P2Y13 selective antagonist MRS2211, as well as with pertussis toxin, attenuated at varying degrees agonist-induced intracellular Ca2+ responses and activation of ERK1/2, Akt, and S6 ribosomal protein, indicating that P2Y1 and P2Y13 receptors play a major role in VVEC growth responses. Considering the broad physiological implications of purinergic signaling in the regulation of angiogenesis and vascular homeostasis, our findings suggest that P2Y1 and P2Y13 receptors may represent novel and specific targets for treatment of pathological vascular remodeling involving vasa vasorum expansion.

Effects of extracellular ATP on ICa, [Ca2+]i, and contraction in isolated ferret ventricular myocytes

1993 ◽  
Vol 264 (3) ◽  
pp. C702-C708 ◽  
Author(s):  
Y. Qu ◽  
H. M. Himmel ◽  
D. L. Campbell ◽  
H. C. Strauss
Keyword(s):  
Action Potential ◽  
Ventricular Myocytes ◽  
Ventricular Myocardium ◽  
Inhibitory Effect ◽  
Extracellular Atp ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
The Right

The effects of extracellular ATP on the voltage-activated "L-type" Ca current (ICa), action potential, resting and transient intracellular Ca2+ levels, and cell contraction were examined in enzymatically isolated myocytes from the right ventricles of ferrets. With the use of the whole cell patch-clamp technique, extracellular ATP (10(-7) to 10(-3) M) inhibited ICa in a time- and concentration-dependent manner. ATP decreased the peak amplitude of ICa without altering the residual current at the end of 500-ms clamp steps. The concentration-response relationship for ATP inhibition of ICa was well described by a conventional Michaelis-Menten relationship with a half-maximal inhibitory concentration of 1 microM and a maximal effect of 50%. Consistent with its inhibitory effect on ICa, ATP hyperpolarized the plateau phase and shortened the action potential duration. In fura-2-loaded myocytes, extracellular ATP did not change the resting myoplasmic Ca2+ levels; however, when current was elicited under voltage-clamp conditions, ATP both decreased the myoplasmic intracellular Ca2+ transient and inhibited the degree of cell shortening. Our results suggest that ATP could be a genuine and potent extracellular modulator of cardiac function in ferret ventricular myocardium.

scholarly journals Purinergic signaling, DAMPs, and inflammation

2020 ◽  
Vol 318 (5) ◽  
pp. C832-C835 ◽  
Author(s):  
Francesco Di Virgilio ◽  
Alba Clara Sarti ◽  
Robson Coutinho-Silva
Keyword(s):  
Plasma Membrane ◽  
Purinergic Receptors ◽  
Purinergic Signaling ◽  
Extracellular Atp ◽  
Main Metabolite ◽  
P2 Purinergic Receptors ◽  
Evolutionary Features ◽  
Multicellular Organisms ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

Danger sensing is one of the most fundamental evolutionary features enabling multicellular organisms to perceive potential threats, escape from risky situations, fight actual intruders, and repair damage. Several endogenous molecules are used to “signal damage,” currently referred to as “alarmins” or “damage-associated molecular patterns” (DAMPs), most being already present within all cells (preformed DAMPs), and thus ready to be released, and others neosynthesized following injury. Over recent years it has become overwhelmingly clear that adenosine 5′-triphosphate (ATP) is a ubiquitous and extremely efficient DAMP (thus promoting inflammation), and its main metabolite, adenosine, is a strong immunosuppressant (thus dampening inflammation). Extracellular ATP ligates and activates the P2 purinergic receptors (P2Rs) and is then degraded by soluble and plasma membrane ecto-nucleotidases to generate adenosine acting at P1 purinergic receptors (P1Rs). Extracellular ATP, P2Rs, ecto-nucleotidases, adenosine, and P1Rs are basic elements of the purinergic signaling network and fundamental pillars of inflammation.

Extracellular ATP induces a nonspecific permeability of thymocyte plasma membranes

1989 ◽  
Vol 67 (9) ◽  
pp. 495-502 ◽  
Author(s):  
Chakib El-Moatassim ◽  
Nicole Bernad ◽  
Jean-Claude Mani ◽  
Jacques Dornand
Keyword(s):  
Purinergic Receptors ◽  
Plasma Membranes ◽  
Divalent Cations ◽  
Extracellular Atp ◽  
Active Species ◽  
Extracellular Nucleotides ◽  
Dependent Manner ◽  
Specific Receptors ◽  
Atp Analogs ◽  
Dose Dependent

We have previously demonstrated that extracellular ATP can give medullary thymocytes the calcium message required for the induction of their blastogenesis, without mobilization of intracellular calcium. We describe here the effects of extracellular nucleotides on membrane permeability to monovalent and divalent cations in mouse thymocytes. Among all nucleotides tested, under physiological conditions, only ATP and, to a lesser extent, 2-methylthio-ATP, adenosine 5′-O-(3-thio-triphosphate), and ADP were able to depolarize thymocyte plasma membranes and to induce Na+ and Ca2+ influxes into thymocytes; other nonhydrolysable ATP analogs were only effective in the absence of Mg2+. The ATP-induced effects were inhibited in a dose-dependent manner by Mg2+ and greatly potentiated in its absence, which suggests that the tetrabasic ATP4− is probably the active species and that a phosphotransferase activity is not involved in its effects. These ATP-mediated changes in ion fluxes result from an increase in nonspecific permeability of thymocyte membranes, probably by pore formation. These ion flux changes might be responsible for the mitogenic induction of phorbol 12-myristate 13-acetate treated medullary thymocytes. The potency order for the adenine derivatives to affect these fluxes (ATP>ADP> >AMP>adenosine) suggests the presence of ATP specific receptors (P2 purinergic receptors) on thymocyte plasma membranes.Key words: purinergic receptors, extracellular ATP, membrane potential, cation fluxes, thymocytes.

Signal transduction via P2-purinergic receptors for extracellular ATP and other nucleotides

1993 ◽  
Vol 265 (3) ◽  
pp. C577-C606 ◽  
Author(s):  
G. R. Dubyak ◽  
C. el-Moatassim
Keyword(s):  
Purinergic Receptors ◽  
Plasma Membranes ◽  
Surface Membrane ◽  
Cell Types ◽  
Extracellular Atp ◽  
Secretory Cells ◽  
Atp Receptors ◽  
Immune Effector ◽  
Functional Changes ◽  
P2 Purinergic Receptors

Extracellular ATP, at micromolar concentrations, induces significant functional changes in a wide variety of cells and tissues. ATP can be released from the cytosol of damaged cells or from exocytotic vesicles and/or granules contained in many types of secretory cells. There are also efficient extracellular mechanisms for the rapid metabolism of released nucleotides by ecto-ATPases and 5'-nucleotidases. The diverse biological responses to ATP are mediated by a variety of cell surface receptors that are activated when ATP or other nucleotides are bound. The functionally identified nucleotide or P2-purinergic receptors include 1) ATP receptors that stimulate G protein-coupled effector enzymes and signaling cascades, including inositol phospholipid hydrolysis and the mobilization of intracellular Ca2+ stores; 2) ATP receptors that directly activate ligand-gated cation channels in the plasma membranes of many excitable cell types; 3) ATP receptors that, via the rapid induction of surface membrane channels and/or pores permeable to ions and endogenous metabolites, produce cytotoxic or activation responses in macrophages and other immune effector cells; and 4) ADP receptors that trigger rapid ion fluxes and aggregation responses in platelets. Current research in this area is directed toward the identification and structural characterization of these receptors by biochemical and molecular biological approaches.

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