title: Cytoskeletal dependence of insulin granule movement dynamics in INS-1 beta-cells in response to glucose.
abstract: For pancreatic β-cells to secrete insulin in response to elevated blood glucose, insulin granules retained within the subplasmalemmal space must be transported to sites of secretion on the plasma membrane. Using a combination of super-resolution STORM imaging and live cell TIRF microscopy we investigate how the organization and dynamics of the actin and microtubule cytoskeletons in INS-1 β-cells contribute to this process. GFP-labeled insulin granules display 3 different modes of motion (stationary, diffusive-like, and directed). Diffusive-like motion dominates in basal, low glucose conditions. Upon glucose stimulation no gross rearrangement of the actin cytoskeleton is observed but there are increases in the 1) rate of microtubule polymerization; 2) rate of diffusive-like motion; and 3) proportion of granules undergoing microtubule-based directed motion. By pharmacologically perturbing the actin and microtubule cytoskeletons, we determine that microtubule-dependent granule transport occurs within the subplasmalemmal space and that the actin cytoskeleton limits this transport in basal conditions, when insulin secretion needs to be inhibited.
authors.affiliation: University of Vermont, Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, Burlington, Vermont, United States of America.
authors.forename: Aoife T
authors.initials: AT
authors.lastname: Heaslip
authors.affiliation: University of Vermont, Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, Burlington, Vermont, United States of America.
authors.forename: Shane R
authors.initials: SR
authors.lastname: Nelson
authors.affiliation: University of Vermont, Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, Burlington, Vermont, United States of America.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Lombardo
authors.affiliation: University of Vermont, Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, Burlington, Vermont, United States of America.
authors.forename: Samantha
authors.initials: S
authors.lastname: Beck Previs
authors.affiliation: University of Vermont, Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, Burlington, Vermont, United States of America.
authors.forename: Jessica
authors.initials: J
authors.lastname: Armstrong
authors.affiliation: University of Vermont, Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, Burlington, Vermont, United States of America.
authors.forename: David M
authors.initials: DM
authors.lastname: Warshaw
mesh_terms: D000818:Animals; D002460:Cell Line; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism*; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D051381:Rats; D022142:Secretory Vesicles / Q000187:drug effects / Q000378:metabolism*
chemical_list: D007328:Insulin; D005947:Glucose