Sphingosine 1-phosphate induces filopodia formation through S1PR2 activation of ERM proteins (original) (raw)
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Sphingosine 1-phosphate regulates cytoskeleton dynamics: Implications in its biological response
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2006
The bioactive sphingolipid sphingosine 1-phosphate (S1P) elicits robust cytoskeletal rearrangement in a large variety of cell systems, mainly acting through a panel of specific cell surface receptors, named S1P receptors. Recent studies have begun to delineate the molecular mechanisms involved in the complex process responsible for cytoskeletal rearrangement following S1P ligation to its receptors. Notably, changes of cell shape and/or motility induced by S1P via cytoskeletal remodelling are functional to the biological action exerted by S1P which appears to be highly cellspecific. This review focuses on the current knowledge of the regulatory mechanisms of cytoskeleton dynamics elicited by S1P, with special emphasis on the relationship between cytoskeletal remodelling and the biological effects evoked by the sphingolipid in various cell types.
The EMBO journal, 1996
Sphingosine-1-phosphate (S1P) is a bioactive lysosphingolipid implicated in mitogenesis and cytoskeletal remodelling, but its mechanism of action is poorly understood. We report here that in N1E-115 neuronal cells, S1P mimics the G protein-coupled receptor agonist lysophosphatidic acid (LPA) in rapidly inducing neurite retraction and soma rounding, a process driven by Rho-dependent contraction of the actin cytoskeleton. S1P is approximately 100-fold more potent than LPA in evoking these shape changes, with an EC50 as low as 1.5 nM. Microinjection of S1P has no effect, neither has addition of sphingosine or ceramide. As with LPA, S1P action is inhibited by suramin and subject to homologous desensitization; however, the responses to S1P and LPA do not show cross-desensitization. We conclude that S1P activates its own high affinity receptor to trigger Rho-regutated cytoskeletal events. Thus, S1P and LPA may belong to an emerging family of bioactive lysophospholipids that act through di...
The FASEB Journal, 2004
Plasminogen activators (tPA and uPA) are serine proteases that convert the circulating zymogen plasminogen to active plasmin and mediate fibrin degradation. These multifunctional proteins trigger various biological events such as extracellular matrix degradation, cell adhesion, migration, and proliferation, through not yet fully characterized mechanisms. We report that, in smooth muscle cells and ECV-304 carcinoma cells, tPA and ATF (the N-terminal catalytically inactive fragment of tPA) elicited DNA synthesis that requires activation of the sphingomyelin/ceramide/sphingosine-1-phosphate (Spm/Cer/S1P), signaling pathway and was blocked by D-erythro-2-(N-myristoylamino)-1-phenyl-propanol (D-MAPP) and N-N'-dimethyl sphingosine (DMS), two classical inhibitors of sphingosine-1-phosphate biosynthesis. Binding of tPA to its receptor uPAR triggered the coordinated activation of two key enzymes of the Spm/Cer/S1P pathway, the neutral sphingomyelinase and the sphingosine kinase-1 that was mediated by a common pertussis toxin (PTX)-sensitive mechanism. The tPA-induced sphingosine kinase-1 activation was mediated by Src, since it was inhibited by herbimycin A and in SrcK-cells (overexpressing a dominant negative kinase defective form of Src) and by ERK1/2 (early phase peaking at 15 min). Sphingosine kinase-1 activation was followed by a second phase of ERK1/2 phosphorylation (peaking at 120 min) and subsequent DNA synthesis, which were inhibited by D-MAPP and DMS, by anti-EGD-1 antibodies and in SrcK-cells (in which the mitogenic signaling was rescued by sphingosine-1-phosphate). Altogether, these data underline a pivotal role for the Spm/Cer/S1P pathway in the tPA-induced mitogenic signaling.
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 2019
Hearing loss is among the most prevalent sensory impairments in humans. Cochlear implantable devices represent the current therapies for hearing loss but have various shortcomings. ERM (ezrin-radixin-moesin) are a family of adaptor proteins that link plasma membrane with actin cytoskeleton, playing a crucial role in cell morphology and in the formation of membrane protrusions. Recently, bioactive sphingolipids have emerged as regulators of ERM proteins. Sphingosine 1-phosphate (S1P) is a pleiotropic sphingolipid which regulates fundamental cellular functions such as proliferation, survival, migration as well as processes such as development and inflammation mainly via ligation to its specific receptors S1PR (S1P 1-5). Experimental findings demonstrate a key role for S1P signaling axis in the maintenance of auditory function. Preservation of cellular junctions is a fundamental function both for S1P and ERM proteins, crucial for the maintenance of cochlear integrity. In the present work, S1P was found to activate ERM in a S1P 2-dependent manner in murine auditory epithelial progenitors US/VOT-E36. S1P-induced ERM activation potently contributed to actin cytoskeletal remodeling and to the appearance of ionic currents and membrane passive properties changes typical of more differentiated cells. Moreover, PKC and Akt activation was found to mediate S1P-induced ERM phosphorylation. The obtained findings contribute to demonstrate the role of S1P signaling pathway in inner ear biology and to disclose potential innovative therapeutical approaches in the field of hearing loss prevention and treatment.
Molecular and Cellular Biology, 2008
Sphingosine kinase 1 (SphK1) catalyzes the phosphorylation of sphingosine to produce the potent lipid mediator sphingosine-1-phosphate (S1P), which plays a critical role in cell motility via its cell surface receptors. Here, we have identified filamin A (FLNa), an actin-cross-linking protein involved in cell movement, as a bona fide SphK1interacting protein. Heregulin stimulated SphK1 activity only in FLNa-expressing A7 melanoma cells but not in FLNa-deficient cells and induced its translocation and colocalization with FLNa at lamellipodia. SphK1 was required for heregulin-induced migration, lamellipodia formation, activation of PAK1, and subsequent FLNa phosphorylation. S1P directly stimulated PAK1 kinase, suggesting that it may be a target of intracellularly generated S1P. Heregulin also induced colocalization of S1P 1 (promotility S1P receptor) but not S1P 2 , with SphK1 and FLNa at membrane ruffles. Moreover, an S1P 1 antagonist inhibited the lamellipodia formation induced by heregulin. Hence, FLNa links SphK1 and S1P 1 to locally influence the dynamics of actin cytoskeletal structures by orchestrating the concerted actions of the triumvirate of SphK1, FLNa, and PAK1, each of which requires and/or regulates the actions of the others, at lamellipodia to promote cell movement.
Intracellular localization of sphingosine kinase 120200108 33423 1rpk7az
Sphingosine-1-phosphate (S1P) has emerged as a potent bioactive lipid with established roles in essential cellular processes such as vascular maturity, cell proliferation, traffi cking of immune cells, cytoskeletal rearrangement, invasion, and angiogenesis ( 1-3 ). Key to such diversity of functions lies in the ability of S1P to act as both an intracellular effector molecule and an extracellular ligand for a family of fi ve G protein-coupled receptors, S1PR 1-5 ( 4-7 ). S1P made within the cell can be secreted from the cell where it binds S1PRs in an autocrine or paracrine fashion, triggering a wide range of cellular responses, including proliferation, enhanced extracellular matrix assembly, stimulation of adherens junctions, formation of stress fibers, and inhibition of apoptosis induced by either ceramide or growth factor withdrawal ( 8-11 ).
Intracellular localization of sphingosine kinase 120200108 95442 1y1x5sw
Journal of Lipid Research , 2010
Sphingosine-1-phosphate (S1P) has emerged as a potent bioactive lipid with established roles in essential cellular processes such as vascular maturity, cell proliferation, traf-fi cking of immune cells, cytoskeletal rearrangement, invasion , and angiogenesis (1-3). Key to such diversity of functions lies in the ability of S1P to act as both an intracel-lular effector molecule and an extracellular ligand for a family of fi ve G protein-coupled receptors, S1PR 1-5 (4-7). S1P made within the cell can be secreted from the cell where it binds S1PRs in an autocrine or paracrine fashion, triggering a wide range of cellular responses, including proliferation, enhanced extracellular matrix assembly, stimulation of adherens junctions, formation of stress fibers , and inhibition of apoptosis induced by either cer-amide or growth factor withdrawal (8-11). Like many signaling molecules, basal levels of S1P are tightly controlled by balancing synthesis with degradation. S1P is generated by the ATP-dependent phosphorylation of sphingosine catalyzed by sphingosine kinase (SK), of which there are two mammalian isoforms: SK1 and SK2. After being produced by SK, there are several possible Abstract Sphingosine kinase 1 (SK1) produces sphin-gosine-1-phosphate (S1P), a potent signaling lipid. The sub-cellular localization of SK1 can dictate its signaling function. Here, we use artifi cial targeting of SK1 to either the plasma membrane (PM) or the endoplasmic reticulum (ER) to test the effects of compartmentalization of SK1 on substrate utilization and downstream metabolism of S1P. Expression of untargeted or ER-targeted SK1, but surprisingly not PM-targeted SK1, results in a dramatic increase in the phosphor-ylation of dihydrosphingosine, a metabolic precursor in de novo ceramide synthesis. Conversely, knockdown of endog-enous SK1 diminishes both dihydrosphingosine-1-phosphate and S1P levels. We tested the effects of SK1 localization on degradation of S1P by depletion of the ER-localized S1P phosphatases and lyase. Remarkably, S1P produced at the PM was degraded to the same extent as that produced in the ER. This indicates that there is an effi cient mechanism for the transport of S1P from the PM to the ER. In acute labeling experiments, we fi nd that S1P degradation is primarily driven by lyase cleavage of S1P. Counterintuitively, when S1P-specifi c phosphatases are depleted, acute labeling of S1P is signifi cantly reduced, indicative of a phosphatase-dependent recycling process. We conclude that the local-ization of SK1 infl uences the substrate pools that it has access to and that S1P can rapidly translocate from the site where it is synthesized to other intracellular sites.-Siow, D. L., C. D. Anderson, E. V. Berdyshev, A. Skobeleva, S. M. Pitson, and B. W. Wattenberg. Intracellular localization of sphingosine kinase 1 alters access to substrate pools but does not affect the degradative fate of sphingosine-1-phosphate. Abbreviations: CIB1, calcium and integrin binding protein 1; ER, endoplasmic reticulum; Hek293, human embryonic kidney cell; HeLa, human cervical carcinoma cell; LDH, lactate dehydrogenase; PM, plasma membrane; PMA, phorbol ester; siRNA, small interfering RNA; SK, sphingosine kinase; S1P, sphingosine-1-phosphate.
Regulation and functional roles of sphingosine kinases
Naunyn-Schmiedeberg's Archives of Pharmacology, 2007
Sphingosine kinases (SphKs) catalyze the phosphorylation of sphingosine to sphingosine-1-phosphate (S1P). Together with other sphingolipid metabolizing enzymes, SphKs regulate the balance of the lipid mediators, ceramide, sphingosine, and S1P. The ubiquitous mediator S1P regulates cellular functions such as proliferation and survival, cytoskeleton architecture and Ca 2+ homoeostasis, migration, and adhesion by activating specific high-affinity G-protein-coupled receptors or by acting intracellularly. In mammals, two isoforms of SphK have been identified. They are activated by G-protein-coupled receptors, receptor tyrosine kinases, immunoglobulin receptors, cytokines, and other stimuli. The molecular mechanisms by which SphK1 and SphK2 are specifically regulated are complex and only partially understood. Although SphK1 and SphK2 appear to have opposing roles, promoting cell growth and apoptosis, respectively, they can obviously also substitute for each other, as mice deficient in either SphK1 or SphK2 had no obvious abnormalities, whereas double-knockout animals were embryonic lethal. In this review, our understanding of structure, regulation, and functional roles of SphKs is updated and discussed with regard to their implication in pathophysiological and disease states.
Biochemical Journal, 2004
Sphingosine (Sph) has been implicated as a modulator of membrane signal transduction systems and as a regulatory element of cardiac and skeletal muscle physiology, but little information is presently available on its precise mechanism of action. Recent studies have shown that sphingosine 1-phosphate (S1P), generated by the action of sphingosine kinase (SphK) on Sph, also possesses biological activity, acting as an intracellular messenger, as well as an extracellular ligand for specific membrane receptors. At present, however, it is not clear whether the biological effects elicited by Sph are attributable to its conversion into S1P. In the present study, we show that Sph significantly stimulated phospholipase D (PLD) activity in mouse C2C12 myoblasts via a previously unrecognized mechanism that requires the conversion of Sph into S1P and its subsequent action as extracellular ligand. Indeed, Sph-induced activation of PLD was inhibited by N,Ndimethyl-D-erythro-sphingosine (DMS), at concentrations cap-able of specifically inhibiting SphK. Moreover, the crucial role of SphK-derived S1P in the activation of PLD by Sph was confirmed by the observed potentiated effect of Sph in myoblasts where SphK1 was overexpressed, and the attenuated response in cells transfected with the dominant negative form of SphK1. Notably, the measurement of S1P formation in vivo by employing labelled ATP revealed that cell-associated SphK activity in the extracellular compartment largely contributed to the transformation of Sph into S1P, with the amount of SphK released into the medium being negligible. It will be important to establish whether the mechanism of action identified in the present study is implicated in the multiple biological effects elicited by Sph in muscle cells.
PLOS ONE, 2019
Sphingolipids regulate several aspects of cell behavior and it has been demonstrated that cells adjust their sphingolipid metabolism in response to metabolic needs. Particularly, sphingosine-1-phosphate (S1P), a final product of sphingolipid metabolism, is a potent bioactive lipid involved in the regulation of various cellular processes, including cell proliferation, cell migration, actin cytoskeletal reorganization and cell adhesion. In previous work in rat renal papillae, we showed that sphingosine kinase (SK) expression and S1P levels are developmentally regulated and control de novo sphingolipid synthesis. The aim of the present study was to evaluate the participation of SK/S1P pathway in the triggering of cell differentiation by external hypertonicity. We found that hypertonicity evoked a sharp decrease in SK expression, thus activating the de novo sphingolipid synthesis pathway. Furthermore, the inhibition of SK activity evoked a relaxation of cell-cell adherens junction (AJ) with accumulation of the AJ complex (E-cadherin/β-catenin/α-catenin) in the Golgi complex, preventing the acquisition of the differentiated cell phenotype. This phenotype alteration was a consequence of a sphingolipid misbalance with an increase in ceramide levels. Moreover, we found that SNAI1 and SNAI2 were located in the cell nucleus with impairment of cell differentiation induced by SK inhibition, a fact that is considered a biochemical marker of epithelial to mesenchymal transition. So, we suggest that the expression and activity of SK1, but not SK2, act as a control system, allowing epithelial cells to synchronize the various branches of sphingolipid metabolism for an adequate cell differentiation program.