Open AccessCytosolic chloride ion is a key factor in lysosomal acidification and function of autophagy in human gastric cancer cell
Author(s) -
Hosogi Shigekuni,
Kusuzaki Katsuyuki,
Inui Toshio,
Wang Xiangdong,
Marunaka Yoshinori
Publication year - 2014
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/jcmm.12257
Subject(s) - autophagy , bafilomycin , lysosome , cytosol , chemistry , apoptosis , programmed cell death , microbiology and biotechnology , biochemistry , biology , enzyme
The purpose of the present study was to clarify roles of cytosolic chloride ion ( Cl − ) in regulation of lysosomal acidification [intra‐lysosomal pH (pH lys )] and autophagy function in human gastric cancer cell line ( MKN 28). The MKN 28 cells cultured under a low Cl − condition elevated pH lys and reduced the intra‐lysosomal Cl − concentration ([ Cl − ] lys ) via reduction of cytosolic Cl − concentration ([ Cl − ] c ), showing abnormal accumulation of LC 3II and p62 participating in autophagy function (dysfunction of autophagy) accompanied by inhibition of cell proliferation via G 0 /G 1 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 + ‐ ATP ase) or ethyl isopropyl amiloride [ EIPA ; an inhibitor of Na + / H + exchanger ( NHE )] elevated pH lys and decreased [ Cl − ] lys associated with inhibition of cell proliferation via induction of G 0 /G 1 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.