title: Serine protease HtrA1 associates with microtubules and inhibits cell migration.
abstract: HtrA1 belongs to a family of serine proteases found in organisms ranging from bacteria to humans. Bacterial HtrA1 (DegP) is a heat shock-induced protein that behaves as a chaperone at low temperature and as a protease at high temperature to help remove unfolded proteins during heat shock. In contrast to bacterial HtrA1, little is known about the function of human HtrA1. Here, we report the first evidence that human HtrA1 is a microtubule-associated protein and modulates microtubule stability and cell motility. Intracellular HtrA1 is localized to microtubules in a PDZ (PSD95, Dlg, ZO1) domain-dependent, nocodazole-sensitive manner. During microtubule assembly, intracellular HtrA associates with centrosomes and newly polymerized microtubules. In vitro, purified HtrA1 promotes microtubule assembly. Moreover, HtrA1 cosediments and copurifies with microtubules. Purified HtrA1 associates with purified alpha- and beta-tubulins, and immunoprecipitation of endogenous HtrA1 results in coprecipitation of alpha-, beta-, and gamma-tubulins. Finally, downregulation of HtrA1 promotes cell motility, whereas enhanced expression of HtrA1 attenuates cell motility. These results offer an original identification of HtrA1 as a microtubule-associated protein and provide initial mechanistic insights into the role of HtrA1 in the regulation of cell motility by modulating microtubule stability.
authors.affiliation: Experimental Pathology, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Chien
authors.forename: Takayo
authors.initials: T
authors.lastname: Ota
authors.forename: Giovanni
authors.initials: G
authors.lastname: Aletti
authors.forename: Ravi
authors.initials: R
authors.lastname: Shridhar
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Boccellino
authors.forename: Lucio
authors.initials: L
authors.lastname: Quagliuolo
authors.forename: Alfonso
authors.initials: A
authors.lastname: Baldi
authors.forename: Viji
authors.initials: V
authors.lastname: Shridhar
mesh_terms: D001665:Binding Sites; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D000074289:High-Temperature Requirement A Serine Peptidase 1; D000074923:High-Temperature Requirement A Serine Peptidase 2; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D011108:Polymers / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism
chemical_list: D024101:Mitochondrial Proteins; D011108:Polymers; D014404:Tubulin; D049452:Green Fluorescent Proteins; C474013:HTRA3 protein, human; D000074289:High-Temperature Requirement A Serine Peptidase 1; C474012:HTRA1 protein, human; D012697:Serine Endopeptidases; D000074923:High-Temperature Requirement A Serine Peptidase 2