title: 14-3-3-regulated Ca(2+)-dependent protein kinase CPK3 is required for sphingolipid-induced cell death in Arabidopsis.
abstract: In eukaryotic cells, sphingoid long chain bases (LCBs) such as sphingosine or phytosphingosine (PHS) behave as second messengers involved in various processes including programmed cell death (PCD). In plants, induction of PCD by LCBs has now been described, but the signalling pathway is still enigmatic. Using Arabidopsis, we identify new key steps in this pathway. We demonstrate that PHS induces activation of the calcium-dependent kinase CPK3, which phosphorylates its binding partners, the 14-3-3 proteins. This phosphorylation leads to the disruption of the complex and to CPK3 degradation. Using cpk3 knockout lines, we demonstrate that CPK3 is a positive regulator of LCB-mediated PCD. These findings establish 14-3-3-regulated CPK3 as a key component of the LCB pathway leading to PCD in plants.
authors.affiliation: Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, UPS, UMR 5546, BP 42617, F-31326, Castanet-Tolosan, France.
authors.forename: C
authors.initials: C
authors.lastname: Lachaud
authors.forename: E
authors.initials: E
authors.lastname: Prigent
authors.forename: P
authors.initials: P
authors.lastname: Thuleau
authors.forename: S
authors.initials: S
authors.lastname: Grat
authors.forename: D
authors.initials: D
authors.lastname: Da Silva
authors.forename: C
authors.initials: C
authors.lastname: Brière
authors.forename: C
authors.initials: C
authors.lastname: Mazars
authors.forename: V
authors.initials: V
authors.lastname: Cotelle
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D055786:Gene Knockout Techniques; D007811:Lanthanum / Q000494:pharmacology; D010766:Phosphorylation; D030821:Plants, Genetically Modified / Q000378:metabolism; D011485:Protein Binding; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D048948:14-3-3 Proteins; D029681:Arabidopsis Proteins; C028521:lanthanum chloride; D007811:Lanthanum; C516786:CPK3 protein, Arabidopsis; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C012491:phytosphingosine; D013110:Sphingosine; D002118:Calcium