title: Armadillo repeat-containing kinesins and a NIMA-related kinase are required for epidermal-cell morphogenesis in Arabidopsis.
abstract: The involvement of kinesin motor proteins in both cell-tip growth and cell-shape determination has been well characterized in various organisms. However, the functions of kinesins during cell morphogenesis in higher plants remain largely unknown. In the current study, we demonstrate that an armadillo repeat-containing kinesin-related protein, ARMADILLO REPEAT KINESIN1 (ARK1), is involved in root-hair morphogenesis. Microtubule polymers are more abundant in ark1 null allele root hairs, but analysis shows that these extra microtubules are concentrated in the endoplasm, and not in the cortical array, suggesting that ARK1 regulates tip growth by limiting the assembly and distribution of endoplasmic microtubules. The ARK1 gene has two homologues in the Arabidopsis genome, ARK2 and ARK3, and our results show that ARK2 is involved in root-cell morphogenesis. We further reveal that a NIMA-related protein kinase, NEK6, binds to the ARK family proteins and has pleiotropic effects on epidermal-cell morphogenesis, suggesting that NEK6 is involved in cell morphogenesis in Arabidopsis via microtubule functions associated with these armadillo repeat-containing kinesins. We discuss the function of NIMA-related protein kinases and armadillo repeat-containing kinesins in the cell morphogenesis of eukaryotes.
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sakai
authors.forename: Hannie van der
authors.initials: Hv
authors.lastname: Honing
authors.forename: Miki
authors.initials: M
authors.lastname: Nishioka
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Uehara
authors.forename: Mihoko
authors.initials: M
authors.lastname: Takahashi
authors.forename: Noriko
authors.initials: N
authors.lastname: Fujisawa
authors.forename: Kensuke
authors.initials: K
authors.lastname: Saji
authors.forename: Motoaki
authors.initials: M
authors.lastname: Seki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shinozaki
authors.forename: Mark A
authors.initials: MA
authors.lastname: Jones
authors.forename: Nicholas
authors.initials: N
authors.lastname: Smirnoff
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Okada
authors.forename: Geoffrey O
authors.initials: GO
authors.lastname: Wasteneys
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D051186:Armadillo Domain Proteins / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000502:physiology*; D002454:Cell Differentiation; D017343:Genes, Plant; D016547:Kinesins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D009024:Morphogenesis / Q000502:physiology*; D000072380:NIMA-Related Kinase 1; D018517:Plant Roots / Q000254:growth & development; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*
chemical_list: D051186:Armadillo Domain Proteins; D018797:Cell Cycle Proteins; D000072380:NIMA-Related Kinase 1; D017346:Protein Serine-Threonine Kinases; D016547:Kinesins