INVOLVMENT OF VOLTAGE GATED PROTON CHANNEL (Hv) INHIBITION, IN LEUKEMIC JURKAT T CELLS APOPTOSIS

ASUAJE, AGUSTIN; PEDRO, MARTIN; ORLOWSKI, ALEJANDRO; SMALDINI PAOLA L; AIELLO, ALEJANDRO; GONZALEZ, CARLOS; DOCENA, GUILLERMO H; MILESI, VERONICA

Congreso; I meeting LASID-FAIC-SAI; 2015

Background: The human voltage gated proton channel (hHv) is a highly selective ionchannel present in almost every immune system cell responsible of fast H+ ions extrusion. Its activity ismarkedly regulated by voltage and the pHo/pHi ratio, and it is blocked by Zn2+ ions. In leukemic JurkatT cells 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 bypatch-clamp. pHi was measured by BECEF fluorometry in cells suspension and apoptosis analysed byflow cytometry using propidium iodide(PI)/Annexin V-FITC (AnnexinV+/PI- were considered as cellsundergoing 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 ÂμM 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 withpropionic acid (Vi, [Î?pH/s], cont: 0.027±0.003, n=6 vs. Zn+2: 0.007±0.001, n=7). Finally, the presenceof Zn+2, induced a significant increase in the frequency of AnnexinV+ cells (40.7% ± 10.3 Zn+2 vs13.2% ± 2.7 control conditions), which was not reverted by NAC. Conclusions: Our findings suggestthat hHv channels might be an important but unexplored player in apoptosis control mechanisms ofJurkat T cells.