An experimental mouse model of spontaneous generation of HodgkinDisease by introduction of GANP RNA-primase gene

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We investigated the molecule that induces lymphomas in mouse. Beta RNA primase GANP was found in germinal center B cells that are rapidly proliferating and maturating upon stimulation with T cell-dependent antigen immunization in vivo. Loss of GANP mice displayed no apparent abnormalities but showed a lack of generation of high-affinity antibody production with reduced somatic hypermutation of immunogolobulin. V-region genes with respect to the antigen stimulation. The mice lacked the high-affinity type mutations. The effect of GANP was further confirmed by the over expression of GANP using transgenic strategy, that clearly indicated the augmented somatic hypermutation rates and the high-affinity type mutations in antigen driven B cells. To prove this further, we studied the affinity of the antibodies by measuring the affinity of the specific antibodies at the monoclonal level. More than 6000 monoclonal antibodies were generated after immunization with nitrophenyl-chicken g-globulin an … More d establishment of the hybridomas secreting anti-NP specific antibodies. GANP-trangenic (GANP-Tg) mice generated the monoclonal antibodies with higher affinity to the hapten NP as KD×109M in comparison with the lower affinities from the wild-type littermate controls. Interestingly, the high affinitymonoclonal antibodies were generated by the V-regions with more somatic hypermutations and using the non-canonical V-region gene in a system of O57BL/6 mice system. These results indicated that GANP is involved in generation of high-affinity B cells upon immunization with antigen by regulating the induction of V-region mutations and/or the repair of the DNA damage during B cell clonal expansion and the selection in germinal center regions.The expression of GANP was detected extremely high in the lymphoma specimens by histochemical analysis with anti-GANP specific and the phosphorylated GANP-specific monoclonal antibodies. Human Hodgkin lymphoma, Read-Sternberg cells displayed the higher expression. The monoclonal antibodies were useful for detection of the malignant cells in the mixed population of the lymphomas often observed in human HD clinical samples. We examined whether the increased expression of GANP could be a causative factor of lymphomas in mice. GANP-Tg generated lymphomas of non-B/non-T cell type as quite similar to the human HD lymphomas spontaneously in aged group. These results indicated that the augmented and abnormal expression of GANP is a causative factor of lymphomas of HD-like lymphomas in mice. We speculated that the additional factors are involved in the generation of lymphomas, presumably associated with the infections with various viruses and the stresses of the immune system in peripheral lymphoid organs. Less