title: A dominant negative mutant of protein kinase CK2 exhibits altered auxin responses in Arabidopsis.
abstract: Protein kinase CK2 is a pleiotropic Ser/Thr kinase, evolutionary conserved in eukaryotes. Studies performed in different organisms, from yeast to humans, have highlighted the importance of CK2 in cell growth and cell-cycle control. However, the signalling pathways in which CK2 is involved have not been fully identified. In plants, the phytohormone auxin is a major regulator of cell growth. Recent discoveries have demonstrated that differential distribution of within auxin plant tissues is essential for developmental processes, and that this distribution is dependent on polar auxin transport. We report here that a dominant-negative mutant of CK2 (CK2mut) in Arabidopsis thaliana shows phenotypic traits that are typically linked to alterations in auxin-dependent processes. However, CK2mut plants exhibit normal responses to exogenous indole-3-acetic acid (IAA) indicating that they are not affected in the perception of the hormone but upstream in the pathway. We demonstrate that mutant plants are not deficient in IAA but are impaired in its transport. Using genetic and pharmacological tools we show that CK2 activity depletion hinders correct formation of auxin gradients and leads to widespread changes in the expression of auxin-related genes. In particular, members of the auxin efflux carrier family (PINs), and the protein kinase PINOID, both key regulators of auxin fluxes, were misexpressed. PIN4 and PIN7 were also found mislocalized, with accumulation in endosomal bodies. We propose that CK2 functions in the regulation of auxin-signalling pathways, particularly in auxin transport.
authors: Departament de Bioquímica i Biologia Molecular, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain.
authors: Maria Mar
authors: MM
authors: Marquès-Bueno
authors: Jordi
authors: J
authors: Moreno-Romero
authors: Lindy
authors: L
authors: Abas
authors: Roberto
authors: R
authors: De Michele
authors: M Carmen
authors: MC
authors: Martínez
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism* / Q000494:pharmacology; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C451260:PIN4 protein, Arabidopsis; C479554:PIN7 protein, Arabidopsis; D010937:Plant Growth Regulators; D018749:RNA, Plant; C030737:indoleacetic acid; C405165:PINOID protein, Arabidopsis; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases