title: PASK (proline-alanine-rich Ste20-related kinase) binds to tubulin and microtubules and is involved in microtubule stabilization.
abstract: Proline-alanine-rich Ste20-related kinase (PASK, also referred to as SPAK) has been linked to ion transport regulation. Here, we report two novel activities of PASK: binding to tubulin and microtubules and the promotion of microtubule assembly. Tubulin binding assay showed that full-length PASK and its kinase domain bound to purified tubulin whereas the N-terminal or C-terminal non-catalytic domains of PASK did not. The full-length PASK and its kinase domain were sedimented with paclitaxel-stabilized microtubules by ultracentrifugation. These results indicate that the kinase domain of PASK can interact directly with both microtubules and soluble tubulin in vitro. Truncated PASK lacking the N-terminal non-catalytic domain promoted microtubule assembly at a subcritical concentration of purified tubulin. FLAG-PASK expressed in COS-7 cells translocated to the cytoskeleton when the cells were stimulated with hypertonic sodium chloride, and stabilized microtubules against depolymerization by nocodazole. Our findings suggest that PASK may regulate the cytoskeleton by modulating microtubule stability.
authors.affiliation: Department of Neural Regeneration and Cell Communication, Mie University Graduate School of Medicine, Tsu, Mie 514-8507, Japan.
authors.forename: Tomonari
authors.initials: T
authors.lastname: Tsutsumi
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Kosaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ushiro
authors.forename: Kazushi
authors.initials: K
authors.lastname: Kimura
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Honda
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Kayahara
authors.forename: Akira
authors.initials: A
authors.lastname: Mizoguchi
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism*; D013552:Swine; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D014404:Tubulin; C116037:PAS domain kinases; D017346:Protein Serine-Threonine Kinases