title: Functional Reconstitution of the Insulin-Secreting Porosome Complex in Live Cells.
abstract: Supramolecular cup-shaped lipoprotein structures called porosomes embedded in the cell plasma membrane mediate fractional release of intravesicular contents from cells during secretion. The presence of porosomes, have been documented in many cell types including neurons, acinar cells of the exocrine pancreas, GH-secreting cells of the pituitary, and insulin-secreting pancreatic β-cells. Functional reconstitution of porosomes into artificial lipid membranes, have also been accomplished. Earlier studies on mouse insulin-secreting Min6 cells report 100-nm porosome complexes composed of nearly 30 proteins. In the current study, porosomes have been functionally reconstituted for the first time in live cells. Isolated Min6 porosomes reconstituted into live Min6 cells demonstrate augmented levels of porosome proteins and a consequent increase in the potency and efficacy of glucose-stimulated insulin release. Elevated glucose-stimulated insulin secretion 48 hours after reconstitution, reflects on the remarkable stability and viability of reconstituted porosomes, documenting the functional reconstitution of native porosomes in live cells. These results, establish a new paradigm in porosome-mediated insulin secretion in β-cells.
authors.affiliation: Department of Physiology (A.R.N., S.P.K., K.T.L., B.P.J.), Wayne State University School of Medicine, Detroit, Michigan 48201; and Department of Pathology and Laboratory Medicine (D.J.T.), Microscopy Imaging Center, University of Vermont College of Medicine, Burlington, Vermont 05405.
authors.forename: Akshata R
authors.initials: AR
authors.lastname: Naik
authors.affiliation: Department of Physiology (A.R.N., S.P.K., K.T.L., B.P.J.), Wayne State University School of Medicine, Detroit, Michigan 48201; and Department of Pathology and Laboratory Medicine (D.J.T.), Microscopy Imaging Center, University of Vermont College of Medicine, Burlington, Vermont 05405.
authors.forename: Sanjana P
authors.initials: SP
authors.lastname: Kulkarni
authors.affiliation: Department of Physiology (A.R.N., S.P.K., K.T.L., B.P.J.), Wayne State University School of Medicine, Detroit, Michigan 48201; and Department of Pathology and Laboratory Medicine (D.J.T.), Microscopy Imaging Center, University of Vermont College of Medicine, Burlington, Vermont 05405.
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Lewis
authors.affiliation: Department of Physiology (A.R.N., S.P.K., K.T.L., B.P.J.), Wayne State University School of Medicine, Detroit, Michigan 48201; and Department of Pathology and Laboratory Medicine (D.J.T.), Microscopy Imaging Center, University of Vermont College of Medicine, Burlington, Vermont 05405.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Taatjes
authors.affiliation: Department of Physiology (A.R.N., S.P.K., K.T.L., B.P.J.), Wayne State University School of Medicine, Detroit, Michigan 48201; and Department of Pathology and Laboratory Medicine (D.J.T.), Microscopy Imaging Center, University of Vermont College of Medicine, Burlington, Vermont 05405.
authors.forename: Bhanu P
authors.initials: BP
authors.lastname: Jena
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D006943:Hyperglycemia / Q000097:blood / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D021962:Membrane Microdomains / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D024683:Potassium Channels, Tandem Pore Domain / Q000378:metabolism*; D055550:Protein Stability; D021381:Protein Transport; D053838:Scattering, Small Angle; D012636:Secretory Rate; D050825:Synaptosomal-Associated Protein 25 / Q000302:isolation & purification / Q000378:metabolism*; D050827:Syntaxin 1 / Q000378:metabolism*; D014961:X-Ray Diffraction
chemical_list: D007328:Insulin; D024683:Potassium Channels, Tandem Pore Domain; C494209:Snap25 protein, mouse; C494214:Stx1a protein, mouse; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; C103742:potassium channel protein TREK-1; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C417708:Gnai3 protein, mouse