Cytosolic chloride ion is a key factor in lysosomal acidification and function of autophagy in human gastric cancer cell.
The purpose of the present study was to clarify roles of cytosolic chloride ion (Cl(-) ) in regulation of lysosomal acidification [intra-lysosomal pH (pHlys )] and autophagy function in human gastric cancer cell line (MKN28). The MKN28 cells cultured under a low Cl(-) condition elevated pHlys and reduced the intra-lysosomal Cl(-) concentration ([Cl(-) ]lys ) via reduction of cytosolic Cl(-) concentration ([Cl(-) ]c ), showing abnormal accumulation of LC3II and p62 participating in autophagy function (dysfunction of autophagy) accompanied by inhibition of cell proliferation via G0 /G1 arrest without induction of apoptosis. We also studied effects of direct modification of H(+) transport on lysosomal acidification and autophagy. Application of bafilomycin A1 (an inhibitor of V-type H(+) -ATPase) or ethyl isopropyl amiloride [EIPA; an inhibitor of Na(+) /H(+) exchanger (NHE)] elevated pHlys and decreased [Cl(-) ]lys associated with inhibition of cell proliferation via induction of G0 /G1 arrest similar to the culture under a low Cl(-) condition. However, unlike low Cl(-) condition, application of the compound, bafilomycin A1 or EIPA, induced apoptosis associated with increases in caspase 3 and 9 without large reduction in [Cl(-) ]c compared with low Cl(-) condition. These observations suggest that the lowered [Cl(-) ]c primarily causes dysfunction of autophagy without apoptosis via dysfunction of lysosome induced by disturbance of intra-lysosomal acidification. This is the first study showing that cytosolic Cl(-) is a key factor of lysosome acidification and autophagy.
['Hosogi|Shigekuni|S|', 'Kusuzaki|Katsuyuki|K|', 'Inui|Toshio|T|', 'Wang|Xiangdong|X|', 'Marunaka|Yoshinori|Y|']
D000143:Acids D017209:Apoptosis D051017:Apoptosis Regulatory Proteins D001343:Autophagy D015153:Blotting, Western D002453:Cell Cycle D049109:Cell Proliferation D002712:Chlorides D003600:Cytosol D006706:Homeostasis D006801:Humans D008247:Lysosomes D013274:Stomach Neoplasms D014407:Tumor Cells, Cultured
chloride ion lysosome autophagy pH apoptosis