Sphingosine kinase-mediated calcium signaling by muscarinic acetylcholine receptors

doi:10.1016/S0024-3205(01)01049-9

Life Sciences

Volume 68, Issues 22–23, 27 April 2001, Pages 2535-2540

https://doi.org/10.1016/S0024-3205(01)01049-9 Get rights and content

Abstract

Based on the finding that G protein-coupled receptors (GPCRs) can induce Ca²+ mobilization, apparently independent of the phospholipase C (PLC)/inositol-1,4,5-trisphosphate (IP₃) pathway, we investigated whether sphingosine kinase, which generates sphingosine-1-phosphate (SPP), is involved in calcium signaling by mAChR and other GPCRs. Inhibition of sphingosine kinase by DL-threo-dihydrosphingosine and N,N-dimethylsphingosine markedly inhibited [Ca²+]_i increases elicited by M₂ and M₃ mAChRs in HEK-293 cells without affecting PLC activation. Activation of M₂ and M₃ mAChR rapidly and transiently stimulated production of SPP. Furthermore, microinjection of SPP into HEK-293 cells induced rapid and transient Ca²+ mobilization. Pretreatment of HEK-293 cells with the calcium chelator BAPTA/AM fully blocked mAChR-induced SPP production. On the other hand, incubation of HEK-293 cells with calcium ionophores activated SPP production. Similar findings were obtained for formyl peptide and P2Y₂ purinergic receptors in HL-60 cells. On the basis of these studies we propose, that following initial IP₃ production by receptor-mediated PLC activation, a local discrete increase in [Ca²+]_i induces sphingosine kinase stimulation, which ultimately leads to full calcium mobilization. Thus, sphingosine kinase activation most likely represents an amplification system for calcium signaling by mAChRs and other GPCRs.

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Sphingosine-1-phosphate (S1P) activates STAT3 to protect against de novo acute heart failure (AHF)
2018, Life Sciences
Citation Excerpt :
It is also highly possible that S1P may act as an intracellular agent without the necessity for receptor binding. Indeed, intracellular endogenous S1P is known to be involved in the regulation of cell survival paths, ion channels and calcium activity within the cell, independently of its specific cell binding receptors [18,23]. It is also unclear how exogenous S1P may interact the endogenous levels of S1P present within the cell.
Acute heart failure (AHF) is a burden disease, with high mortality and re-hospitalisations. Using an ex-vivo model of AHF, we have previously reported that sphingosine-1-phosphate (S1P) confers cardioprotection. However, the mechanisms remain to be elucidated. In the present study, we aimed to examine the role of the cardioprotective signal transducer and activator of transcription 3 (STAT3) in S1P mediated improved functional recovery in AHF.
Isolated hearts from male Long-Evans rats were subjected to hypotensive AHF for 35 min followed by a recovery phase of 30 min (n ≥ 4/group). S1P (10 nM) was given during either the hypotensive or the recovery phase with/without an inhibitor of STAT3, AG490. Functional parameters were recorded throughout the experiment.
Following an AHF insult, S1P, given during the recovery phase, improved the heart rate (HR) compared to the control (175.2 ± 30.7 vs. 71.6 ± 27.4 beats per minute (BPM); p < 0.05), with no changes in the left ventricular developed pressure. This effect was associated with an increase in phosphorylated STAT3 levels in the nucleus. Addition of AG490 with S1P abolished the cardioprotective effect of S1P (42.3 ± 17.1 vs. 148.8 ± 26.4 BPM for S1P; p < 0.05).
Our data suggest that S1P protects in an ex-vivo rat heart model of AHF by activation of STAT3 and provide further evidence for the usage of S1P as a potential therapy in patients suffering from AHF.
Sexual dimorphism of metabolic and vascular dysfunction in aged mice and those lacking the sphingosine 1-phosphate receptor 3
2017, Experimental Gerontology
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Another mechanism leading to vasodilation that could be impacted in a sex-dependent manner in the aged is signaling by S1P downstream of the muscarinic-3 (M3) receptor. Methacholine activates sphingosine kinase through M3 (Mulders et al., 2009; Pfaff et al., 2005; van Koppen et al., 2001) and loss of S1PR3 abolishes dilation of aortic (large conduit) arteries (Nofer et al., 2004). These results indicate that methacholine-induced vasodilation in mesenteric arteries could also depend on S1P signaling.
Elderly people often suffer adverse health because of inflammation associated with poor metabolism and cardiovascular dysfunction, but these conditions present differently in men and women. We performed experiments in aged male and female mice to understand this sexual dimorphism. We focused on sphingosine 1-phosphate (S1P) signaling, which has both protective and detrimental effects on vascular and metabolic function. We examined vascular function of mesenteric (resistance) arteries from aged male and female wild-type (WT) mice compared to littermate S1P receptor 3 (S1PR3) knockouts (KO). We also measured plasma glucose, insulin, triglycerides, adiponectin, corticosterone and inflammatory cytokines. The novel results of this study are: 1) methacholine-induced vasodilation relied completely on S1PR3 in both sexes, but was dependent on nitric oxide synthase (NOS) only in arteries from aged female mice; 2) S1P-induced vasoconstriction depended solely on S1PR3 in arteries from males, but only partly in females; 3) vasoconstriction to a thromboxane mimetic was decreased by endogenous NOS activity only in arteries from females, regardless of genotype; 4) myogenic responses were lower in arteries from aged WT males compared to females and responses in arteries from KO females were lower than WT females, while the opposite was true of arteries from male mice; 5) aged male mice showed higher fasting glucose and triglycerides with lower plasma adiponectin compared to females and 6) lack of signaling through S1PR3 in females was associated with decreased plasma adiponectin and increased inflammatory mediators. This study showed that there is considerable sexual dimorphism in the vascular and metabolic responses of aged mice and that reduced signaling through S1PR3 could be one mechanism to explain these effects. These results also emphasize that different treatments for mitigating the deleterious effects on vascular health in aged males versus females should be considered.
Sphingosine kinase: Role in regulation of bioactive sphingolipid mediators in inflammation
2010, Biochimie
Sphingolipids and their synthetic enzymes are emerging as important mediators in inflammatory responses and as regulators of immune cell functions. In particular, sphingosine kinase (SK) and its product sphingosine-1-phosphate (S1P) have been extensively implicated in these processes. SK catalyzes the phosphorylation of sphingosine to S1P and exists as two isoforms, SK1 and SK2. SK1 has been shown to be activated by cytokines including tumor necrosis factor-alpha (TNF-α) and interleukin1-β (IL1-β). The activation of SK1 in this pathway has been shown to be, at least in part, required for mediating TNF-α and IL1-β inflammatory responses in cells, including induction of cyclo-oxygenase 2 (COX2). In addition to their role in inflammatory signaling, SK and S1P have also been implicated in various immune cell functions including, mast cell degranulation, migration of neutrophils, and migration and maturation of lymphocytes. The involvement of sphingolipids and sphingolipid metabolizing enzymes in inflammatory signaling and immune cell functions has implicated these mediators in numerous inflammatory disease states as well. The contribution of these mediators, specifically SK1 and S1P, to inflammation and disease are discussed in this review.
Sphingosine kinase 1 is essential for proteinase-activated receptor-1 signalling in epithelial and endothelial cells
2009, International Journal of Biochemistry and Cell Biology
There is accumulating evidence that activation of sphingosine kinase 1 (SPHK1) is an important element in intracellular signalling cascades initiated by stimulation of multiple receptors, including certain growth factor, cytokine, and also G-protein coupled receptors. We here report that stimulation of the lung epithelial cell line A549 by thrombin leads to transient increase of SPHK1 activity and elevation of intracellular sphingosine-1-phosphate (S1P); abrogation of this stimulation by SPHK1-specific siRNA, pharmacological inhibition, or expression of a dominant-negative SPHK1 mutant blocks the response to thrombin, as measured by secretion of MCP-1, IL-6, IL-8, and PGE₂. Using selective stimulation of proteinase-activated receptors (PARs) a specific involvement of SPHK1 in the PAR-1 induced responses in A549 cell, including activation of NFκB, was evident, while PAR-2 and PAR-4 responses were independent of SPHK1. Moreover, PAR-1 or thrombin-induced cytokine production and adhesion factor expression of human umbilical vein endothelial cells was also seen to depend on SPHK1. Using dermal microvascular endothelial cells from SPHK1-deficient mice, we showed that absence of the enzyme abrogates MCP-1 production induced in these cells upon treatment with thrombin or PAR-1 activating peptide. We propose SPHK1 inhibition as a novel way to block PAR-1 mediated signalling, which could be useful in treatment of a number of diseases, in particular in atherosclerosis.
Sphingosine kinase/sphingosine 1-phosphate signalling in central nervous system
2009, Cellular Signalling
Sphingolipids were once regarded as inert structural components of cell membranes. Now these metabolites are generally believed to be important bioactive molecules that control a wide repertoire of cellular processes such as proliferation and survival of cells. Along with these ubiquitous cell functions observed in many peripheral tissues sphingolipid metabolites, especially sphingosine 1-phosphate, exert important neuron-specific functions such as regulation of neurotransmitter release. This review summarizes physiological and pathological roles of sphingolipid metabolites emphasizing the role of sphingosine 1-phosphate in the central nervous system.
K6PC-5, a direct activator of sphingosine kinase 1, promotes epidermal differentiation through intracellular CA<sup>2+</sup> signaling
2008, Journal of Investigative Dermatology
Sphingosine-1-phosphate (S1P), a bioactive sphingolipid metabolite, regulates multiple cellular responses such as Ca²⁺ signaling, growth, survival, and differentiation. Because sphingosine kinase (SphK) is the enzyme directly responsible for production of S1P, many factors have been identified that regulate its activity and subsequent S1P levels. Here we synthesized a previously unidentified SphK activator, K6PC-5, and have studied its effects on intracellular Ca²⁺ signaling in HaCaT cells and epidermal differentiation in murine skin. K6PC-5, a hydrophobic compound chemically named N-(1,3-dihydroxyisopropyl)-2-hexyl-3-oxo-decanamide, activated SphK (obtained from C57BL/6 murine blood and F9-12 cell lysates) in a dose-dependent manner. K6PC-5 induced both intracellular Ca²⁺ concentration ([Ca²⁺]_i) oscillations in HaCaT cells and Ca²⁺ mobilization in hairless mouse epidermis. Both dimethylsphingosine (DMS) and dihydroxysphingosine (DHS), SphK inhibitors, and transfection of SphK1-siRNA blocked K6PC-5-induced increases in [Ca²⁺]_i. The K6PC-5-induced [Ca²⁺]_i oscillations were dependent on thapsigargin-sensitive Ca²⁺ stores and Ca²⁺ entry, but independent of the classical phospholipase C-mediated pathway. In addition, K6PC-5 enhanced the expression of involucrin and filaggrin, specific differentiation-associated marker proteins in HaCaT cells, whereas transfection of SphK1-siRNA blocked the increase of involucrin. Topical K6PC-5 also enhanced the expression of involucrin, loricrin, filaggrin, and keratin 5 in intact murine epidermis. Finally, topical K6PC-5 inhibited epidermal hyperplasia by exerting antiproliferative effects on keratinocytes in murine epidermis. These results suggest that K6PC-5 acts to regulate both differentiation and proliferation of keratinocytes via [Ca²⁺]_i responses through S1P production. Thus, regulation of S1P levels may represent a novel approach for treatment of skin disorders characterized by abnormal differentiation and proliferation, such as atopic dermatitis and psoriasis.

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Properties, regulation and function of muscarinic receptorSphingosine kinase-mediated calcium signaling by muscarinic acetylcholine receptors

Abstract

Properties, regulation and function of muscarinic receptor
Sphingosine kinase-mediated calcium signaling by muscarinic acetylcholine receptors