title: Nucleocytoplasmic shuttling of STK16 (PKL12), a Golgi-resident serine/threonine kinase involved in VEGF expression regulation.
abstract: PKL12/STK16 protein is the first identified mammalian member of a ser/thr kinase subfamily that is conserved across several kingdoms, with a broad expression pattern in murine tissues and cell types. Endogenous STK16 subcellular localization was evaluated by indirect immunofluorescence in NIH/3T3 and NRK cells, demonstrating a Golgi-associated pattern that appears to be independent of signals provided by integrin pathways. When cells were treated with brefeldin A (BFA) or nocodazole, drugs that promote Golgi disorganization, we observed STK16 translocation to the nuclear compartment. Constitutive overexpression of this protein by retroviral vectors also promotes accumulation of STK16 in the nuclear compartment, as shown by subfractionation studies. A kinase-dead STK16 mutant (E202A) was used to demonstrate that both the Golgi association and the nuclear translocation capabilities seem to be independent of the STK16 kinase activity. In addition, we show that STK16 overexpression in several cell lines enhances their capacity to produce and secrete VEGF. To confirm these data in vivo, we injected tumor cells overexpressing STK16 into immunodeficient BALBc/SCID mice. HT1080-derived tumors overexpressing STK16 showed increased volume and number of blood vessels compared to controls. Altogether, these data concur with previous reports suggesting a potential role for STK16 as a transcriptional co-activator.
authors.affiliation: Departamento de Inmunología y Oncología, Centro Nacional de Biotecnología/CSIC, Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid, Spain.
authors.forename: Bárbara
authors.initials: B
authors.lastname: Guinea
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Ligos
authors.forename: Teresa
authors.initials: T
authors.lastname: Laín de Lera
authors.forename: Juan
authors.initials: J
authors.lastname: Martín-Caballero
authors.forename: Juana
authors.initials: J
authors.lastname: Flores
authors.forename: Manuel
authors.initials: M
authors.lastname: Gonzalez de la Peña
authors.forename: Javier
authors.initials: J
authors.lastname: García-Castro
authors.forename: Antonio
authors.initials: A
authors.lastname: Bernad
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D005786:Gene Expression Regulation; D006056:Golgi Apparatus / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; C486000:Stk16 protein, mouse; C486001:Stk16 protein, rat; D017346:Protein Serine-Threonine Kinases; C418980:STK16 protein, human