title: Proteome of the insulin-secreting Min6 cell porosome complex: involvement of Hsp90 in its assembly and function.
abstract: Porosomes are secretory portals located at the cell plasma membrane involved in the regulated release of intravesicular contents from cells. Porosomes have been immunoisolated from a number of cells including the exocrine pancreas and neurons, biochemically characterized, and functionally reconstituted into an artificial lipid membrane. In the current study, the proteome of the porosome complex in mouse insulinoma Min6 cells was determined, demonstrating among other proteins, the presence of 30 core proteins including the heat shock protein Hsp90. Half maximal inhibition of Hsp90 using the specific inhibitor 17-demethoxy-17-(2-prophenylamino) geldanamycin, results in the loss of proteins, including the calcium-transporting ATPase type 2C and the potassium channel subfamily K member 2 from the Min6 porosome. This loss of porosome proteins is reflected in the observed inhibition of glucose stimulated insulin release from Min6 cells exposed to the Hsp90 specific inhibitor. Results from the study implicate Hsp90 in the assembly and function of the porosome complex.
  
  
  CONCLUSIONS
  In the present study, the porosome proteome in the insulin-secreting mouse β-cell line Min6 has been determined. Nearly 30 core proteins including the heat shock protein Hsp90 are found to compose the Min6 porosome complex. Results from the study implicate Hsp90 in the assembly of the Min6 porosome. These new findings will facilitate understanding of the porosome assembly and its function in insulin secretion.
authors.affiliation: Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA.
authors.forename: Amulya
authors.initials: A
authors.lastname: Rajagopal
authors.affiliation: Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA.
authors.forename: Sanjana
authors.initials: S
authors.lastname: Kulkarni
authors.affiliation: Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA.
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Lewis
authors.affiliation: Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA.
authors.forename: Xuequn
authors.initials: X
authors.lastname: Chen
authors.affiliation: Wayne State University, Department of Physics and Astronomy, Detroit, MI, USA.
authors.forename: Abir
authors.initials: A
authors.lastname: Maarouf
authors.affiliation: Wayne State University, Department of Physics and Astronomy, Detroit, MI, USA.
authors.forename: Christopher V
authors.initials: CV
authors.lastname: Kelly
authors.affiliation: Department of Pathology and Laboratory Medicine, Microscopy Imaging Center, University of Vermont College of Medicine, Burlington, VT 05405, USA.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Taatjes
authors.affiliation: Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA; Wayne State University, Department of Physics and Astronomy, Detroit, MI, USA. Electronic address: bjena@med.wayne.edu.
authors.forename: Bhanu P
authors.initials: BP
authors.lastname: Jena
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D018841:HSP90 Heat-Shock Proteins / Q000502:physiology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D013058:Mass Spectrometry; D051379:Mice; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D020543:Proteome / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D022142:Secretory Vesicles / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
chemical_list: D018841:HSP90 Heat-Shock Proteins; D007328:Insulin; D020543:Proteome; D005947:Glucose
keywords: Hsp90; Insulin secretion; Mass spectrometry; Min6 cell porosome proteome