Involvment of voltaged gated proton channel (hv) inhibition, in leukemic Jurkat T cells apoptosis

ASUAJE, A; MARTÍN, P; ORLOWSKI, A; SMALDINI, P; AIELLO, EA; GONZÁLES LEÓN, C; DOCENA, G; MILESI, V

Buenos Aires

Congreso; Argentinean Society for Immunology and French Society for Immunoloy; 2015

Background The human voltage gated proton channel (hHv) is a highly selective ion channel present in almost every immune system cell responsible of fast H+ions extrusion. Its activity is markedly regulated by voltage and the pHo/pHi ratio, and it is blocked by Zn2+ ions. In leukemic Jurkat T cells (as in many others) intracellular acidification was described as an early key stepfor several apoptosis mechanisms, so, hHv inhibition could trigger cell cidification and apoptosis. Methods: hHv currents were recorded by patch-clamp. pHi was measured by BECEF fluorometry in cells suspension and apoptosis analysed by flow cytometry using propidium iodide(PI)/Annexin V-FITC (AnnexinV+/PI- were considered as cells undergoing early apoptosis). Cells were incubated during 9 hs with or without Zn+2 (1mM) in: resting, acidified with propionic acid and in presence of NAC (a ROS scavenger). Results: The presence of H+ currents was electrophysiologically-confirmed and completely blocked by 250 µM of free Zn2+. Then, extracellular Zn2+ (1mM) induced intracellular acidification in Jurkat T cells in restingconditions (control: -0.04 ± 0.03, n=6 vs with Zn2+: -0.21 ± 0.02, n=7) and prevents pHi recovery after acid load with propionic acid (Vi, [ΔpH/s], cont: 0.027±0.003, n=6 vs. Zn+2: 0.007±0.001, n=7). Finally, the presence of Zn+2, induced a significant increase in the frequency of AnnexinV+ cells (40.7% ± 10.3 Zn+2 vs 13.2% ± 2.7 control conditions), which was not reverted by NAC. Conclusions Our findings suggest that hHv channels might be an important but unexplored player in apoptosis control mechanisms of the leukemic Jurkat T cells.