title: Neutrophil microtubules suppress polarity and enhance directional migration.
abstract: How do microtubules, which maintain and direct polarity of many eukaryotic cells, regulate polarity of blood neutrophils? In sharp contrast to most cells, disrupting a neutrophil's microtubule network with nocodazole causes it to polarize and migrate [Niggli, V. (2003) J. Cell Sci. 116, 813-822]. Nocodazole induces the same responses in differentiated HL-60 cells, a model neutrophil cell line, and reduces their chemotactic prowess by causing them to pursue abnormally circuitous paths in migrating toward a stationary point source of an attractant, f-Met-Leu-Phe (fMLP). The chemotactic defect stems from dramatic nocodazole-induced imbalance between the divergent, opposed fMLP-induced "backness" and "frontness" signals responsible for neutrophil polarity. Nocodazole (i) stimulates backness by increasing Rho- and actomyosin-dependent contractility, as reported by Niggli, and also (ii) impairs fMLP-dependent frontness: pseudopods are flatter, contain less F-actin, and show decreased membrane translocation of PH-Akt-GFP, a fluorescent marker for 3'-phosphoinositide lipids. Inhibiting backness with a pharmacologic inhibitor of a Rho-dependent kinase substantially reverses nocodazole's effects on chemotaxis, straightness of migration paths, morphology, and PH-Akt-GFP translocation. Thus, microtubules normally balance backness vs. frontness signals, preventing backness from reducing the strength of pseudopods and from impairing directional migration.
authors.affiliation: Department of Cellular and Molecular Pharmacology and Cardiovascular Research Institute, University of California, San Francisco, CA 94143-0450, USA.
authors.forename: Jingsong
authors.initials: J
authors.lastname: Xu
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Alexandra
authors.initials: A
authors.lastname: Van Keymeulen
authors.forename: Maike
authors.initials: M
authors.lastname: Rentel
authors.forename: Henry R
authors.initials: HR
authors.lastname: Bourne
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D002633:Chemotaxis; D018076:DNA, Complementary / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D008870:Microtubules / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D015739:Nocodazole / Q000494:pharmacology; D021381:Protein Transport; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
chemical_list: D000970:Antineoplastic Agents; D018076:DNA, Complementary; D049452:Green Fluorescent Proteins; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015739:Nocodazole