期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
卷 1788, 期 2, 页码 470-476出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbamem.2008.11.018
关键词
Lysosome; Cholesterol; Ion permeability; Membrane fluidity; Methyl-beta-cyclodextrin (M beta CD)
资金
- National Natural Science Foundation of China [30470446]
Cholesterol is an essential component of lysosomal membranes. In this study, we investigated the effects of membrane cholesterol on the permeability of rat liver lysosomes to K+ and H+, and the organelle stability. Through the measurements of lysosomal beta-hexosaminidase free activity, membrane potential, membrane fluidity, intra-lysosomal pH, and lysosomal proton leakage, we established that methyl-beta-cyclodextrin (M beta CD)-produced loss of membrane cholesterol could increase the lysosomal permeability to both potassium ions and protons, and fluidize the lysosomal membranes. As a result, potassium ions entered the lysosomes through K+/H+ exchange, which produced osmotic imbalance across the membranes and osmotically destabilized the lysosomes. In addition, treatment of the lysosomes with M beta CD caused leakage of the lysosomal protons and raised the intra-lysosomal pH. The results indicate that membrane cholesterol plays important roles in the maintenance of the lysosomal limited permeability to K+ and H+. Loss of this membrane sterol is critical for the organelle acidification and stability. (c) 2008 Elsevier B.V. All rights reserved.
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