Neuropeptide Y mobilizes intracellular Ca2+ and increases inositol phosphate production in Human Erythroleukemia Cells

doi:10.1016/0006-291X(89)92721-6

Biochemical and Biophysical Research Communications

Volume 165, Issue 3, 30 December 1989, Pages 1138-1144

https://doi.org/10.1016/0006-291X(89)92721-6 Get rights and content

Abstract

The intracellular concentration of free Ca²⁺ was monitored by measuring the fluorescence of fura-2 loaded Human Erythroleukemia Cells. Neuropeptide Y (NPY) increased intracellular Ca²⁺ in a dose-dependent manner and the 50% effective concentration was 2 nM. Chelation of extracellular Ca²⁺ by EGTA did not reduce the NPY-mediated increase in cytoplasmic Ca²⁺, indicating that the increase in fluorescence was due to the release of intracellular Ca²⁺. A second dose of NPY, after intracellular Ca²⁺ had returned to basal levels, failed to elicit a response, indicating that the NPY receptor had undergone desensitization. In similar experiments, NPY increased the formation of inositol phosphates, suggesting that the mobilization of Ca²⁺ from intracellular stores in HEL cells was secondary to the generation of inositol phosphates and stimulation of phospholipase C.

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Cited by (42)

Neuropeptide Y rapidly enhances [Ca <sup>2+</sup>] <inf>i</inf> transients and Ca <sup>2+</sup> sparks in adult rat ventricular myocytes through Y <inf>1</inf> receptor and PLC activation
2005, Journal of Molecular and Cellular Cardiology
Citation Excerpt :
So, Ca2+ release increased by NPY without modification in the transmembrane Ca2+ influx through ICa in adult rat cardiac myocytes. This finding is in agreement with the reported increased Ca2+ mobilization from intracellular stores, independent of extracellular Ca2+, in other cell types [36,37]. Moreover, the fact of increase SR Ca2+ release without increasing ICa could explain why the NPY positive inotropic effect is transient.
Neuropeptide Y (NPY) is the most abundant peptide in the mammalian heart, but its cardiac actions are not fully understood. Here we investigate the effect of NPY in intracellular Ca²⁺ release, using isolated rat cardiac myocytes and confocal microscopy. Cardiac myocytes were field-stimulated at 1 Hz. The evoked [Ca²⁺]_i transient was of higher amplitude and of faster decay in the presence of 100 nM NPY. Cell contraction was also increased by NPY. We analyzed the occurrence of Ca²⁺ sparks and their characteristics after NPY application. NPY significantly increased Ca²⁺ sparks frequency in quiescent cells. The Ca²⁺ spark amplitude was enhanced by NPY but the other characteristics of Ca²⁺ sparks were not significantly altered. Because cardiac myocytes express both Y₁ and Y₂ NPY receptors, we repeated the experiments in the presence of the receptor blockers, BIBP3226 and BIIE0246. We found that Y₁ NPY receptor blockade completely inhibited NPY effects on [Ca²⁺]_i transient. PTX-sensitive G-proteins and/or phospholypase C (PLC) have been invoked to mediate NPY effects in other cell types. We tested these two hypotheses. In PTX-treated myocytes NPY was still effective, which suggests that the observed NPY actions are not mediated by PTX-sensitive G-proteins. In contrast, the increase in [Ca²⁺]_i transient by NPY was completely inhibited by the PLC inhibitor U73122. In conclusion, we find that NPY has a positive inotropic effect in isolated rat cardiac myocytes, which involves increase in Ca²⁺ release after activation of Y₁ NPY receptor and subsequent stimulation of PLC.
Changes with aging in the modulation by neuropeptide Y of murine peritoneal macrophage functions
2001, Journal of Neuroimmunology
Some age-related changes in immune function may be due, at least in part, to a disturbance in the communication between the nervous and immune systems. In the present work, the effects in vitro of neuropeptide Y (NPY) (10⁻¹³ to 10⁻⁷ M) on different peritoneal macrophage functions (adherence to substrate, chemotaxis, phagocytosis, superoxide anion production, and the release of TNFα and IL-1β) have been studied on cells from young (12±2 weeks), adult (24±2 weeks), mature (50±2 weeks) and old (72±2 weeks) BALB/c mice. The specificity of these actions was confirmed using two C-terminal fragments of NPY, and the intracellular messengers (protein kinase C and cAMP) involved in the action of the neuropeptide were also analyzed. The results show that the functions studied change with aging and that the effects of NPY on each function, which are carried out through specific receptors, as well as on intracellular pathway, differ depending on age, maintaining the immune functions at physiologically adequate levels in old animals.
Neuropeptide Y Y2 receptor signalling mechanisms in the human glioblastoma cell line LN319
2001, Peptides
Neuropeptide Y (NPY) regulates neurotransmitter release through activation of the Y2 receptor subtype. We have recently characterized a human glioblastoma cell line, LN319, that expresses exclusively NPY Y2 receptors and have demonstrated that NPY triggers transient decreases in cAMP and increases in intracellular calcium responses. The present study was designed to further characterize calcium signalling by NPY and bradykinin (BK) in LN319 cells. Both agonists elevated free intracellular calcium ([Ca²⁺]_i) without soliciting calcium influx. NPY appeared to activate two distinct signalling cascades that liberate calcium from thapsigargin- and ryanodine-insensitive compartments. One pathway proceeded through phospholipase C (PLC)-dependent phosphatidylinositol turnover, while the other triggered calcium release through a so far unidentified mediator. Part of the response was sensitive to pertussis toxin (PTX) under conditions where the toxin totally abolished the NPY-mediated effects on cAMP. The calcium release induced by BK on the other hand was largely PTX-insensitive, PLC-dependent, and from both thapsigargin- and ryanodine-sensitive stores. Following stimulation with NPY, subsequent [Ca²⁺]_i responses to NPY were strongly depressed. Partial heterologous desensitization occurred, when BK was used as the first agonist, whereas NPY had no effect on a subsequent stimulation with BK. These data suggest that NPY-induced calcium mobilization in LN319 cells involves two different G proteins and signalling mediators, and a hitherto unidentified calcium compartment. Homologous desensitization of NPY signalling might be explained by receptor-G protein uncoupling, while heterologous desensitization by BK could be the result of either transient depletion or inhibition of a mediator in the calcium signalling cascades activated by NPY.
Limited signal transduction repertoire of human Y<inf>5</inf> neuropeptide Y receptors expressed in HEC-1B cells
2001, Peptides
In HEC-1B cells transfected with human Y₅ neuropeptide Y (NPY) receptors (but not in non-transfected cells) NPY inhibited forskolin-stimulated cAMP accumulation in a pertussis toxin-sensitive manner (−log EC₅₀ 8.88 ± 0.25). Elevations of intracellular Ca²⁺ were largely restricted to very high NPY concentrations and similar in transfected and nontransfected cells. NPY did not increase inositol phosphate accumulation and did not activate a variety of isoforms of protein kinase C or mitogen-activated protein kinases. We conclude that at least upon expression in HEC-1B cells the signal transduction of Y₅ NPY receptors is limited to inhibition of cAMP accumulation.
Characterization of Y<inf>1</inf>, Y<inf>2</inf> and Y<inf>5</inf> subtypes of the neuropeptide Y (NPY) receptor in rabbit kidney: Sensitivity of ligand binding to guanine nucleotides and phospholipase C inhibitors
1998, Regulatory Peptides
The binding of two peptide YY/neuropeptide Y analogues selective for major subtypes of neuropeptide Y (NPY) receptors was compared in particulates from rabbit kidney cortex employing modulators of activity of G-proteins, phospholipase enzymes, and ion channels. The binding of (Leu³¹,Pro³⁴)human peptide YY resembled the patterns observed previously for the brain tissue Y₁ receptor, exhibiting a high sensitivity to monovalent cations, disulfide disruptors, guanosine polyphosphates and phospholipase C inhibitors. However, this binding was bimodal in response to human pancreatic polypeptide and to peptides selective for the Y₂ subtype of the NPY receptor, displaying a large component pharmacologically similar to the brain Y₅ receptor. This kidney Y₅-like binding largely shared the sensitivity to monovalent cations, guanine nucleotides and phospholipase C inhibitors found for either the kidney or the brain Y₁ receptor, and also was activated by Ca²⁺ ion. Both Y₁- and Y₅-like binding in the kidney displayed a uniformly low reactivity to a nonpeptidic Y₁ antagonist, BIBP-3226, and to a receptor peptide mimetic, mastoparan analogue MAS-7. The kidney Y₂ binding shared the low sensitivity to ionic environment observed for the brain Y₂ subtype, and was only partially sensitive to guanine nucleotides or to MAS-7. The Y₂ liganding had a sensitivity to phospholipase C inhibitors similar to the Y₁/Y₅ binding. This reactivity was retained in the fraction of the Y₂ receptor persisting detergent solubilization in a high-affinity form, which, however, was activated rather than inhibited by G-protein agonists.
Neuropeptide Y receptor subtypes
1995, Life Sciences
Neuropeptide Y (NPY) is an amidated 36-amino acid peptide with a wide distribution in the central and peripheral nervous system. It can evoke numerous physiological responses by activating specific receptors. Studies using NPY analogs in various model systems and cell types demonstrate different orders of ligand potency and receptor binding affinity. These studies suggest the existence of multiple subtypes of NPY receptors. NPY has been described to bind to at least three different receptors, Y₁, Y₂ and Y₃. NPY has also been shown to interact with sigma receptor in vivo and in vitro. There are indications that more subtypes might exist. Ligand binding studies reveal that Y₁, Y₂ and Y₃ receptors are all G-protein coupled. It is not yet confirmed whether the sigma receptor that interacts with NPY is G-protein coupled. Some studies show that NPY receptors may interact with other classical receptors, including α- and β-adrenoceptors and cholinergic receptors. In the case of α- and β-adrenoceptors, the receptor-receptor interaction is possibly via a pertussis toxin-sensitive G-protein. NPY receptors are coupled to various signal transduction mechanisms including inhibition of adenylate cyclase, and stimulation or inhibition of increases in intracellular Ca²⁺. Specific links between individual NPY receptor subtype and a particular signal transduction pathway are not established.

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Neuropeptide Y mobilizes intracellular Ca2+ and increases inositol phosphate production in Human Erythroleukemia Cells

Abstract

Nature

Nature

J. Neurosci

Life Sci

Regul. Peptides

Neurosci. Lett

Neurosci. Lett

Neurosci. Lett

Neuropeptide Y mobilizes intracellular Ca²⁺ and increases inositol phosphate production in Human Erythroleukemia Cells