Effects of phospholipase A2 on the lysosomal ion permeability and osmotic sensitivity.
In this study, we investigated the mechanism of PLA(2)-induced lysosomal destabilization. Through the measurements of lysosomal beta-hexosaminidase free activity, their membrane potential, the intra-lysosomal pH and the lysosomal latency loss in hypotonic sucrose medium, we established that PLA(2) could increase the lysosomal membrane permeability to both potassium ions and protons. The enzyme could also enhance the organelle osmotic sensitivity. The increases in the lysosomal ion permeability promoted influx of potassium ions into the lysosomes via K(+)/H(+) exchange. The resulted osmotic imbalance across the lysosomal membranes osmotically destabilized the lysosomes. In addition, the enhancement of the lysosomal osmotic sensitivity caused the lysosomes to become more liable to destabilization in the osmotic stress. The results explain how PLA(2) destabilized the lysosomes.
Wang
Jiong-Wei
JW
Institute of Cell Biology, Beijing Normal University, Beijing 100875, PR China.
Sun
Lin
L
Hu
Jin-Shan
JS
Li
Ying-Bin
YB
Zhang
Guo-Jiang
GJ
D000818:Animals; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000201:enzymology* / Q000378:metabolism*; D017136:Ion Transport; D008247:Lysosomes / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials; D009995:Osmosis; D010539:Permeability; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D011188:Potassium / Q000378:metabolism; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity
D011522:Protons; D010741:Phospholipases A; D054467:Phospholipases A2; D011188:Potassium