Anales RANF

P.32 COMPARISON OF P2X7 PROTEIN EXPRESSION IN TWO BAC- TRANSGENIC REPORTER MOUSE MODELS A. Ramírez-Fernández 1 *, N. Scalbert 1 *, R. Kopp 1 , T. Engel 2 , A. Nicke 1 1 . Ludwig-Maximilians-Universität München, Munich, Germany; 2 . Royal College of Surgeons in Ireland, Dublin, Ireland; *. These authors contributed equally. High concentrations of extracellular ATP are sensed as a danger signal by the P2X7 receptor, a non-specific cation channel which is highly expressed in immune cells. Activation of this receptor in microglia or macrophages mediates the release of pro- inflammatory cytokine IL-1 β and its blockade or deletion has shown ameliorating effects in numerous inflammatory diseases. In addition, P2X7 plays a role in diverse brain diseases such as depression, Alzheimer’s disease and epilepsy. Here, its pathophysiological role is less clear but P2X7-mediated effects on neurotransmitter release, neuronal excitability, and cell death have been shown. However, P2X7 expression and function in neurons and astrocytes have been challenging to demonstrate due to the poor specificity of the available antibodies and a complex pharmacology. In recent years, two BAC-transgenic reporter mouse models have been generated. In one line (Tg(P2rx7 EGFP)FY174Gsat), a sequence encoding a soluble EGFP has been inserted into Exon 1 of the P2rx7 gene while in the other line (Tg(RP24- 114E20P2X7 451P -StrepHis-EGFP)Ani) the EGFP sequence has been fused into the last exon of the P2rx7 gene and a P2X7-EGFP fusion protein is expressed. Although both EGFP constructs are expected to be expressed under the control of the P2rx7 promoter, preliminary data indicate substantial differences in their specific cell-type expression. Thus, the P2X7-EGFP fusion protein is dominantly expressed in microglia and oligodendrocytes but was not detected in neurons. In contrast, the soluble EGFP shows an expression pattern that can be reconciled with neuronal expression. In this study, we perform immunofluorescence staining and co-labelling for cell type-specific marker proteins to provide a detailed comparative analysis of the EGFP expression in the CNS of both mouse models. In addition, characterization of P2X7 expression during mouse development is ongoing. Preliminary data will be presented.