Pancreatic hormone and glutamic acid decarboxylase expression in the mousethymus: A real-time PCR study

We devised a real-time RT-PCR method for the quantification of preproinsuli n 1 and 2, proglucagon, prosomatostatin, and GAD 65 and 67 mRNAs in the thy mus, using specific primers and internal probes. Corresponding standard cRN A synthesis and normalization to 18S ribosomal RNA allowed direct quantific ation. Then, during the first month of life, the expression of each substan ce of interest was measured in the thymus of NOD mice (a spontaneous model of type 1 diabetes), C57BL/6, BALB/c and lymphocyte-deficient mice (NODscid , NODrag, BALBlcscid and C57BL/6rag). In all mouse thymuses, preproinsulin 1 and GAD 65 were undetectable, preproinsulin 2 and proglucagon showed low expression, whereas that of GAD 67 and somatostatin were high. In 7-day-old mice, GAD 67 and prosomatostatin thymic expressions were lower in NOD than in C57BL/6, and at the same age, the scid mutation but not the rag mutatio n induced higher expression of all investigated genes compared to control m ice. In conclusion, our data allowed the quantification of the expression o f pancreatic factors in the mouse thymus. Investigations are underway to qu antify, at the cellular level, i.e., in thymic dendritic/macrophage cells, the RNA expression of potential autoantigens, such as preproinsulin 2 and G AD 67. (C) 2001 Academic Press.