title: Actin-based motility during endocytosis in budding yeast.
abstract: Actin assembly nucleated by Arp2/3 complex has been implicated in the formation and movement of endocytic vesicles. The dendritic nucleation model has been proposed to account for Arp2/3-mediated actin assembly and movement. Here, we explored the model by examining the role of capping protein in vivo, with quantitative tracking analysis of fluorescence markers for different stages of endocytosis in yeast. Capping protein was most important for the initial movement of endocytic vesicles away from the plasma membrane, which presumably corresponds to vesicle scission and release. The next phase of endosome movement away from the plasma membrane was also affected, but less so. The results are consistent with the dendritic nucleation model's prediction of capping protein as important for efficient actin assembly and force production. In contrast, the movement of late-stage endocytic vesicles, traveling through the cytoplasm en route to the vacuole, did not depend on capping protein. The movement of these vesicles was found previously to depend on Lsb6, a WASp interactor, whereas Lsb6 was found here to be dispensable for early endosome movement. Thus, the molecular requirements for Arp2/3-based actin assembly differ in early versus later stages of endocytosis. Finally, acute loss of actin cables led to increased patch motility.
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Kyoungtae
authors.initials: K
authors.lastname: Kim
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Galletta
authors.forename: Kevin O
authors.initials: KO
authors.lastname: Schmidt
authors.forename: Fanny S
authors.initials: FS
authors.lastname: Chang
authors.forename: Kendall J
authors.initials: KJ
authors.lastname: Blumer
authors.forename: John A
authors.initials: JA
authors.lastname: Cooper
mesh_terms: D051344:Actin Capping Proteins / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D015415:Biomarkers; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D004705:Endocytosis / Q000502:physiology*; D005656:Fungal Proteins / Q000378:metabolism; D011108:Polymers; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D004718:Saccharomycetales / Q000166:cytology* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D051344:Actin Capping Proteins; D000199:Actins; D015415:Biomarkers; C092350:FM 4-64; D005656:Fungal Proteins; D011108:Polymers; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D011993:Recombinant Fusion Proteins