title: T-cell epitope analysis on the autoantigen phogrin (IA-2beta) in the nonobese diabetic mouse.
abstract: The protein tyrosine phosphatases (PTPs) IA-2 and phogrin (IA-2beta) are major autoantigens in type 1 diabetes that possess common serological epitopes in their COOH termini. The epitopes recognized by the T-cells that cause the disease, however, remain to be defined. Eight phogrin-specific T-cell clones were generated from NOD mice, and their epitopes were mapped. The mapping was performed initially with recombinant gluthathione S-transferase-phogrin COOH deletion constructs and ultimately with overlapping synthetic peptides. Two dominant epitopes were identified: one (aa 629-649) immediately adjacent to the transmembrane domain (aa 604-628) and the second (aa 755-777) lying in the NH(2)-terminal region of the conserved PTP domain. T-cells that are specific to either of these peptides and that could destroy islet tissue in vivo though spontaneous T-cell proliferative responses were observed in prediabetic female NOD splenocytes only to the aa 755-777 epitope. In NOD female mice immunized with the epitope peptide, intramolecular determinant spreading occurred from the aa 629-649 epitope to the aa 755-777 epitope but not in the opposite direction. We concluded that the initial T-cell response to phogrin is restricted to a small number of dominant peptides and that it subsequently spreads to other regions of the molecule, including those containing the major humoral epitopes that are highly conserved between IA-2 and phogrin.
authors.affiliation: Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kelemen
authors.forename: D R
authors.initials: DR
authors.lastname: Wegmann
authors.forename: J C
authors.initials: JC
authors.lastname: Hutton
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000276:immunology*; D017635:Clonal Anergy / Q000276:immunology; D003001:Cloning, Molecular; D000939:Epitopes / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D016688:Mice, Inbred NOD / Q000276:immunology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D051381:Rats; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D011994:Recombinant Proteins / Q000276:immunology / Q000494:pharmacology; D017384:Sequence Deletion; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D001324:Autoantigens; D000939:Epitopes; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010455:Peptides; D011994:Recombinant Proteins; C102889:PTPRN2 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8