Pancreatic duodenal homeobox 1 protein is a novel beta-cell-specific autoantigen for type I diabetes.
Pancreatic duodenal homeobox 1 (Pdx1) protein is a key transcription factor involved in the regulation of insulin gene expression that is expressed at high levels in the beta-cells of the pancreatic islets. We asked whether Pdx1 is a target of anti-islet autoimmunity in type I diabetes (T1D). Pdx1 autoantibodies (PAAs) were detected in non-obese diabetic (NOD) mice using ELISA, western blotting, and radioimmunoprecipitation of [(35)S]-labeled insulinoma cell line-derived Pdx1 protein. PAAs were detected as early as at 5 weeks of age, and generally peaked before the onset of clinically overt diabetes in diabetes-prone female NOD mice. Levels declined substantially after the onset of diabetes. PAAs were not detected in the sera of NOD-scid, C57BL/6, or BALB/c mice. The titers of PAAs in NOD mouse sera were as high as 1/93 750 by ELISA. The fine specificity of PAAs was determined by western blotting using a series of truncated recombinant Pdx1 proteins. The immunodominant epitopes were located to the C-terminus of the Pdx1 (p200-283) in NOD mice. PAAs also were detected in sera from human T1D patients, but the major epitopes were localized to amino acids 159-200 as well as the same region (p200-283) recognized by PAAs from NOD mice. Using [(3)H]thymidine incorporation, the p83 fragment of Pdx1 specifically stimulated proliferation of splenic T cells from recent-onset diabetic NOD mice. The presence of PAAs in prediabetic NOD mice and human T1D patients, and Pdx1-specific T-cell proliferation in NOD mice provide a strong rationale for further investigation of the pathogenic role of immune responses against Pdx1 in T1D.
Li
Shi-Wu
SW
Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, FL 32610-0275, USA.
Koya
Vijay
V
Li
Yi
Y
Donelan
William
W
Lin
Peng
P
Reeves
Westley H
WH
Yang
Li-Jun
LJ
D000818:Animals; D000918:Antibody Specificity; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D001324:Autoantigens / Q000097:blood / Q000276:immunology*; D015551:Autoimmunity; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000276:immunology* / Q000473:pathology; D005260:Female; D018398:Homeodomain Proteins / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D006801:Humans; D016056:Immunodominant Epitopes / Q000097:blood; D050417:Insulin-Secreting Cells / Q000276:immunology*; D007340:Insulinoma / Q000276:immunology; D051379:Mice; D020297:Mice, Congenic; D016688:Mice, Inbred NOD; D008815:Mice, Inbred Strains; D016513:Mice, SCID; D050505:Mutant Proteins / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology / Q000494:pharmacology; D011236:Prediabetic State / Q000276:immunology; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D013154:Spleen / Q000473:pathology; D013601:T-Lymphocytes / Q000473:pathology; D015534:Trans-Activators / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology
D001323:Autoantibodies; D001324:Autoantigens; D018398:Homeodomain Proteins; D016056:Immunodominant Epitopes; D050505:Mutant Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein