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Eukaryotic elongation factor 1A interacts with sphingosine kinase and directly enhances its catalytic activity

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dc.contributor.authorLeclercq, T.
dc.contributor.authorMoretti, P.
dc.contributor.authorVadas, M.
dc.contributor.authorPitson, S.
dc.date.issued2008
dc.description.abstractSphingosine 1-phosphate (S1P) has many important roles in mammalian cells, including contributing to the control of cell survival and proliferation. S1P is generated by sphingosine kinases (SKs), of which two mammalian isoforms have been identified (SK1 and SK2). To gain a better understanding of SK regulation, we have used a yeast two-hybrid screen to identify SK1-interacting proteins and established elongation factor 1A (eEF1A) as one such protein that associates with both SK1 and SK2. We show the direct interaction of eEF1A with the SKs in vitro, whereas the physiological relevance of this association was demonstrated by co-immunoprecipitation of the endogenous proteins from cell lysates. Although the canonical role of eEF1A resides in protein synthesis, it has also been implicated in other roles, including regulating the activity of some signaling enzymes. Thus, we examined the potential role of eEF1A in regulation of the SKs and show that eEF1A is able to directly increase the activity of SK1 and SK2 3-fold in vitro. Substrate kinetics demonstrated that eEF1A increased the catalytic rate of both SKs, while having no observable effect on substrate affinities of these enzymes for either ATP or sphingosine. Overexpression of eEF1A in quiescent Chinese hamster ovary cells increased cellular SK activity, whereas a small interfering RNAmediated decrease in eEF1A levels in MCF7 cells substantially reduced cellular SK activity and S1P levels, supporting the in vivo physiological relevance of this interaction. Thus, this study has established a novel mechanism of regulation of both SK1 and SK2 that is mediated by their interaction with eEF1A.
dc.description.statementofresponsibilityTamara M. Leclercq, Paul A. B. Moretti, Mathew A. Vadas, and Stuart M. Pitson
dc.identifier.citationJournal of Biological Chemistry, 2008; 283(15):9606-9614
dc.identifier.doi10.1074/jbc.M708782200
dc.identifier.issn0021-9258
dc.identifier.issn1083-351X
dc.identifier.orcidPitson, S. [0000-0002-9527-2740]
dc.identifier.urihttp://hdl.handle.net/2440/52304
dc.language.isoen
dc.publisherAmer Soc Biochemistry Molecular Biology Inc
dc.rightsCopyright 2008 by The American Society for Biochemistry and Molecular Biology
dc.source.urihttps://doi.org/10.1074/jbc.M708782200
dc.subjectCHO Cells
dc.subjectAnimals
dc.subjectHumans
dc.subjectCricetulus
dc.subjectSphingosine
dc.subjectPeptide Elongation Factor 1
dc.subjectIsoenzymes
dc.subjectPhosphotransferases (Alcohol Group Acceptor)
dc.subjectLysophospholipids
dc.subjectRNA, Small Interfering
dc.subjectSignal Transduction
dc.subjectCell Proliferation
dc.subjectCell Survival
dc.subjectEnzyme Activation
dc.subjectProtein Binding
dc.subjectCatalysis
dc.subjectCricetinae
dc.titleEukaryotic elongation factor 1A interacts with sphingosine kinase and directly enhances its catalytic activity
dc.typeJournal article
pubs.publication-statusPublished

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