Anales RANF

P.105 P2X7R INDIRECTLY REGULATES THE JAM-A PROTEIN CONTENT VIA MODULATION OF THE GSK-3 β AND PKC- β1 K. Barth, K-P. Wesslau, A. Stein, M. Kasper Institute of Anatomy, Medical Faculty “Carl Gustav Carus, Dresden, Germany The alveolar epithelial cells represent an important part of the alveolar barrier, which is maintained by tight junction proteins, particularly JAM-A, occludin and claudin-18 that regulate paracellular permeability. Precision-cut lung slices of wildtype and knockout lungs and immortal epithelial lung E10 cells were treated with bleomycin, the P2X7R inhibitor oxATP and the agonist BzATP, respectively, to evaluate early changes in JAM-A expression. Immunohistochemical and biochemical methods were used. In order to examine the role of GSK- 3β and PKC- β 1 in the expression of JAM-A in alveolar epithelial cells, we used LiCl for GSK- 3β and an specific inhibitor for PKC- β1 inhibiting experiments, respectively. In this study, we report in the P2X7R knockout mice a strong increase in epithelial JAM-A expression as compared to the wildtype. Data showed evidence for a P2X7R dependent JAM-A expression in vitro . Inhibition of the P2X7R using oxATP increased JAM-A, whereas activation of the receptor decreased JAM-A protein level. Inhibiting experiments with LiCl showed a modulating effect on BLM-induced alterations in JAM-A levels. PKC- β 1 inhibition normalized the BLM-induced increase in protein level of JAM-A. In addition, BLM treated precision-cut lung slices from P2rx7 -/- mice responded with a lower increase in mRNA expression of JAM-A than BLM-treated precision-cut lung slices from WT mice. Our data suggest that increased constitutive JAM-A protein level in P2rx7 -/- mice may have a protective effect against BLM-induced lung injury.