Identity of mouse IA-2 and PTP35 genes of the tyrosine phosphatase family,and their expression in neuroendocrine tissues

Recently, IA-2, one of Ihs major diabetic autoantigens, and PTP35 cDNA were independently isolated by subtraction cloning using insulinoma cells and a polymerase chain reaction (PCR)-based search for conserved sequences using NIH3T3 fibroblast cell line, respectively. By Southern blot analysis and n ucleotide sequence determination of reverse transcription PCR products, we showed that IA-2 and PTP35 are identical and exist as a single gene in a mo use genome. The expression of IA-2/PTP35 messages was detected by northern blot analysis in MIN6N8 cells, an insulinoma cell line derived from non-obe se diabetic mice, but its expression level was not affected by the ambient glucose level, phorbol-12-myristate 13-acetate or tumour necrosis factor-al pha. We also generated polyclonal antibodies to murine IA-2/PTP35 by immuni zation with recombinant proteins. Subsequent immunohistochemical analysis u sing those polyclonal antibodies disclosed that IA-2/PTP35 is strongly expr essed in mouse neuroendocrine tissues such as pancreatic islets and the hyp othalamus-pituitary gland. These results suggest that IA-2/PTP35 functions primarily in neuroendocrine tissues. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.