title: Proteomic Investigation on Grp94-IgG Complexes Circulating in Plasma of Type 1 Diabetic Subjects.
abstract: The glucose-regulated protein94 (Grp94) has been found in complexes with IgG in plasma of Type 1 (T1) diabetic subjects; however, the pathogenetic meaning of Grp94-IgG complexes has not yet been elucidated. To shed light on the nature and structure of these complexes in vivo, we conducted a proteomic analysis on plasma of both T1 diabetic subjects and healthy control subjects. IgG purified from plasma was submitted to 2D PAGE followed by Western blotting and mass analysis. Grp94 was detected in plasma of all diabetic but not control subjects and found linked with its N-terminus to the IgG heavy chain. Mass analysis of heavy chain of IgG that binds Grp94 also in vitro, forming stable complexes with characteristics similar to those of native ones, permitted identifying CH2 and CH3 regions as those involved in binding Grp94. At the electron microscopy, IgG from diabetic plasma appeared as fibrils of various lengthes and dimensions, suggestive of elevated aggregating tendency conferred to IgG by Grp94. The nonimmune nature of complexes turned out to be responsible for the particular stability and structure adopted by complexes in plasma of diabetic subjects. Results are of relevance to understanding the pathogenetic mechanisms underlying diabetes and its complications.
authors.affiliation: Department of Molecular Medicine, Section of Biological Chemistry, University of Padua, Via G. Colombo 3, 35131 Padua, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Roveri
authors.affiliation: Department of Molecular Medicine, Section of Biological Chemistry, University of Padua, Via G. Colombo 3, 35131 Padua, Italy.
authors.forename: Mattia
authors.initials: M
authors.lastname: Zaccarin
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Largo E. Meneghetti 2, 35131 Padua, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pagetta
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Largo E. Meneghetti 2, 35131 Padua, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Tramentozzi
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Largo E. Meneghetti 2, 35131 Padua, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Finotti
mesh_terms: D000328:Adult; D015153:Blotting, Western; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000378:metabolism / Q000648:ultrastructure; D007143:Immunoglobulin Heavy Chains / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000097:blood* / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron; D046912:Multiprotein Complexes / Q000097:blood / Q000378:metabolism / Q000648:ultrastructure; D040901:Proteomics; D055815:Young Adult
chemical_list: D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D008562:Membrane Glycoproteins; D046912:Multiprotein Complexes; C053387:endoplasmin