Involvment of voltage gated proton channel (Hv) inhibition, in leukemic jurkat T-cells apoptosis

ASUAJE, AGUSTIN; MARTIN, PEDRO; ORLOWSKI, ALEJANDRO; SMALDINI, PAOLA; AIELLO, ALEJANDRO; GONZÁLEZ, CARLOS; DOCENA, GUILLERMO; MILESI, MARIA VERÓNICA

Ciudad Autonoma de Buenos Aires

Congreso; IV Latin American Society for Immunodeficiencies (LASID), LXIII Reunión Anual de la Sociedad Argentina de Inmunología (SAI), II French-Argentinean Immunology Meeting; 2015

LASID - SAI - FAIC

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 step for several apoptosis mechanisms, so, hHv inhibition could trigger cell acidification 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 resting conditions (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.