Loss of membrane cholesterol affects lysosomal osmotic stability.

Lysosomal destabilization is critical for the organelle and living cells. Using methyl-beta-cyclodextrin (M beta CD) to selectively deplete lysosomal membrane cholesterol, we investigated the effect of cholesterol on the organelle osmotic stability. The results show that loss of membrane cholesterol caused changes in the lysosomal osmotic properties. The lysosomes lost the ability to resist osmotic shock and became more sensitive to osmotic stress. As a result, the lysosomes lost membrane integrity rapidly. Microscope observation showed that the lysosomes were liable to swell in the hypotonic sucrose medium. It is presumably due to an enhancement of the lysosomal permeability to water caused by the loss of membrane cholesterol. The results indicate an important role of cholesterol in the maintenance of lysosomal stability.