title: Multiple roles of filopodial dynamics in particle capture and phagocytosis and phenotypes of Cdc42 and Myo10 deletion.
abstract: Macrophage filopodia, finger-like membrane protrusions, were first implicated in phagocytosis more than 100 years ago, but little is still known about the involvement of these actin-dependent structures in particle clearance. Using spinning disk confocal microscopy to image filopodial dynamics in mouse resident Lifeact-EGFP macrophages, we show that filopodia, or filopodia-like structures, support pathogen clearance by multiple means. Filopodia supported the phagocytic uptake of bacterial (Escherichia coli) particles by (i) capturing along the filopodial shaft and surfing toward the cell body, the most common mode of capture; (ii) capturing via the tip followed by retraction; (iii) combinations of surfing and retraction; or (iv) sweeping actions. In addition, filopodia supported the uptake of zymosan (Saccharomyces cerevisiae) particles by (i) providing fixation, (ii) capturing at the tip and filopodia-guided actin anterograde flow with phagocytic cup formation, and (iii) the rapid growth of new protrusions. To explore the role of filopodia-inducing Cdc42, we generated myeloid-restricted Cdc42 knock-out mice. Cdc42-deficient macrophages exhibited rapid phagocytic cup kinetics, but reduced particle clearance, which could be explained by the marked rounded-up morphology of these cells. Macrophages lacking Myo10, thought to act downstream of Cdc42, had normal morphology, motility, and phagocytic cup formation, but displayed markedly reduced filopodia formation. In conclusion, live-cell imaging revealed multiple mechanisms involving macrophage filopodia in particle capture and engulfment. Cdc42 is not critical for filopodia or phagocytic cup formation, but plays a key role in driving macrophage lamellipodial spreading.
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Horsthemke
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Anne C
authors.initials: AC
authors.lastname: Bachg
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Groll
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Moyzio
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Müther
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Hemkemeyer
authors.affiliation: the Institut für Zelldynamik und Bildgebung, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Wedlich-Söldner
authors.affiliation: the Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria, and.
authors.forename: Michael
authors.initials: M
authors.lastname: Sixt
authors.affiliation: the Institut für Medizinische Physik und Biophysik, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Tacke
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bähler
authors.affiliation: From the Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany, hanley@uni-muenster.de.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hanley
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000502:physiology*; D002633:Chemotaxis; D017353:Gene Deletion; D005838:Genotype; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D017737:Macrophages, Peritoneal / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D009154:Mutation; D009218:Myosins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010587:Phagocytosis; D010641:Phenotype; D011554:Pseudopodia / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: C581598:Cdc42 protein, mouse; C409064:Myo10 protein, mouse; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D049452:Green Fluorescent Proteins; D016203:CDC2 Protein Kinase; D009218:Myosins; D020764:cdc42 GTP-Binding Protein
keywords: CDC42; Myo10; Toll-like receptor 4 (TLR4); actin; filopodia; macrophage; phagocytosis