title: Identification of a functional nuclear export sequence in diacylglycerol kinase-zeta.
abstract: Diacylglycerol kinases (DGKs) are key regulators of diacylglycerol-dependent signaling pathways. Among the 10 DGK isoforms, DGK-zeta is the only nuclear form that contains a nuclear localization signal. Here, by site-directed mutagenesis, we showed that DGK-zeta also displays a functional independent nuclear export signal (NES) sequence between the amino acid residues 362-370. Indeed, the NES mutant forms of DGK-zeta accumulated in the nucleus to a much greater extent than wildtype DGK-zeta. Moreover, treatment with leptomycin B, an inhibitor of leucine-rich type NES, resulted in accumulation of both endogenous and ectopically expressed DGK-zeta in the nucleus, demonstrating that nuclear export of DGK-zeta is chromosome regional maintenance protein 1 (CRM1)-dependent. Previously, we reported that nuclear DGK-zeta is a negative regulator of cell cycle progression in C2C12 mouse myoblasts. In this paper, we documented that enhancement of DGK-zeta nuclear localization by NES sequence mutation, increases G(0)/G(1) block in C2C12 cells. Overall, our data demonstrate that DGK-zeta export from nucleus to cytoplasm is regulated by a leucine-rich NES through the exportin CRM1 and suggest that the nuclear localization of DGK-zeta could finely tune its function as a regulator of G(1)/S cell cycle transition.
authors.affiliation: Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell'Apparato Locomotore, Cell Signaling Laboratory, Università di Bologna, Bologna, Italy.
authors.forename: Camilla
authors.initials: C
authors.lastname: Evangelisti
authors.forename: Gian Carlo
authors.initials: GC
authors.lastname: Gaboardi
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Billi
authors.forename: Andrea
authors.initials: A
authors.lastname: Ognibene
authors.forename: Kaoru
authors.initials: K
authors.lastname: Goto
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Tazzari
authors.forename: James A
authors.initials: JA
authors.lastname: McCubrey
authors.forename: Alberto M
authors.initials: AM
authors.lastname: Martelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D002467:Cell Nucleus / Q000201:enzymology*; D019852:Diacylglycerol Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D016193:G1 Phase; D028884:Karyopherins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D049790:Nuclear Export Signals / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016192:Resting Phase, Cell Cycle; D015398:Signal Transduction; D000097606:Exportin 1 Protein
chemical_list: D000903:Antibiotics, Antineoplastic; D019852:Diacylglycerol Kinase; D005231:Fatty Acids, Unsaturated; D028884:Karyopherins; D049790:Nuclear Export Signals; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D000097606:Exportin 1 Protein; C512480:diacylglycerol kinase zeta, mouse; C038753:leptomycin B