title: Membrane Supply and Demand Regulates F-Actin in a Cell Surface Reservoir.
abstract: Cells store membrane in surface reservoirs of pits and protrusions. These membrane reservoirs facilitate cell shape change and buffer mechanical stress, but we do not know how reservoir dynamics are regulated. During cellularization, the first cytokinesis in Drosophila embryos, a reservoir of microvilli unfolds to fuel cleavage furrow ingression. We find that regulated exocytosis adds membrane to the reservoir before and during unfolding. Dynamic F-actin deforms exocytosed membrane into microvilli. Single microvilli extend and retract in ∼20 s, while the overall reservoir is depleted in sync with furrow ingression over 60-70 min. Using pharmacological and genetic perturbations, we show that exocytosis promotes microvillar F-actin assembly, while furrow ingression controls microvillar F-actin disassembly. Thus, reservoir F-actin and, consequently, reservoir dynamics are regulated by membrane supply from exocytosis and membrane demand from furrow ingression.
authors.affiliation: Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Figard
authors.affiliation: Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Mengyu
authors.initials: M
authors.lastname: Wang
authors.affiliation: Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA.
authors.forename: Liuliu
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA.
authors.forename: Ido
authors.initials: I
authors.lastname: Golding
authors.affiliation: Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA. Electronic address: sokac@bcm.edu.
authors.forename: Anna Marie
authors.initials: AM
authors.lastname: Sokac
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D005089:Exocytosis; D008871:Microvilli / Q000378:metabolism
chemical_list: D000199:Actins