Pancreatic duodenal homeobox 1 protein is a novel beta-cell-specific autoantigen for type I diabetes.

Abstract

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.

• Authors: Shi-Wu Li, Vijay Koya, Yi Li, William Donelan, Peng Lin, Westley H Reeves, Li-Jun Yang
• Journal: Laboratory investigation; a journal of technical methods and pathology (Lab Invest) Vol. 90 Issue 1 Pg. 31-9 (Jan 2010) ISSN: 1530-0307 [Electronic] United States
• PMID: 19901909 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Autoantibodies
• Autoantigens
• Homeodomain Proteins
• Immunodominant Epitopes
• Mutant Proteins
• Peptide Fragments
• Recombinant Proteins
• Trans-Activators
• pancreatic and duodenal homeobox 1 protein

Topics

• Animals
• Antibody Specificity
• Autoantibodies (blood, immunology)
• Autoantigens (blood, immunology)
• Autoimmunity
• Cell Line, Tumor
• Cell Proliferation
• Diabetes Mellitus, Type 1 (blood, immunology, pathology)
• Female
• Homeodomain Proteins (genetics, immunology, pharmacology)
• Humans
• Immunodominant Epitopes (blood)
• Insulin-Secreting Cells (immunology)
• Insulinoma (immunology)
• Mice
• Mice, Congenic
• Mice, Inbred NOD
• Mice, Inbred Strains
• Mice, SCID
• Mutant Proteins (pharmacology)
• Pancreatic Neoplasms (immunology)
• Peptide Fragments (immunology, pharmacology)
• Prediabetic State (immunology)
• Rats
• Recombinant Proteins (pharmacology)
• Spleen (pathology)
• T-Lymphocytes (pathology)
• Trans-Activators (genetics, immunology, pharmacology)