Axonal Lesion-Induced Dpysl3 mRNA Expression in Immature Neurons is Unaffected by Myelin-Specific T Cells

Knowing the effect of autoimmune CNS-targeting T cells on the expression of neurogenesis-associated genes is essential to understand their putative effect on hippocampal functioning. Here, we used RNA microarray analysis to study the effect of myelin-specific T cells on the gene profile in the dentate gyrus 2 days after a perforant pathway transection, when neural precursor cells are highly proliferating. By the use of Gene Ontology analysis, the MANGO database and the Allan Mouse Brain Atlas, we identified dihydropyrimidinase-like 3 (Dpysl3), due to its expression in the subgranular zone of the dentate gyrus. In situ hybridizations and quantification of Dpysl3 mRNA+ grains in the subgranular zone and granular cell layer showed a significant increase in Dpysl3 mRNA in axonal lesioned compared to control mice, and no effect of the myelin-specific T cells. Dpysl3 mRNA was not expressed in Ki-67 mRNA+ proliferating cells and NeuN mRNA+ mature neurons, but it was expressed in Nestin mRNA+ neural precursor cells and even more so in Dcx mRNA+ migrating neuroblasts. These results suggest that the regulation of Dpysl3 mRNA expression in immature granular neurons is refractory to inflammatory mediators secreted by the myelin-specific T cells, while being highly responsive to neuronal stimuli. Comparable mechanisms may support normal hippocampal functioning in diseases characterized by infiltration of autoimmune CNS-targeting T cells, such as multiple sclerosis. To allow the identification of T cell up- and downregulated transcripts involved in axonal lesion-induced neurogenesis, we compared the gene expression values in hippocampi of AxL (n=5) to TPlp+AxL (n=5) mice by the use of RNA microarray analysis.