Lysosome-targeted stress reveals increased stability of lipofuscin-containing lysosomes.
Cellular ageing is associated with accumulation of undegradable intralysosomal material, called lipofuscin. In order to accelerate the lipofuscin accumulation, confluent, growth-arrested human fibroblasts were cultured under hyperoxic conditions. To provide a better insight into the effects of lipofuscin on cellular functions, we compared lysosomal stability in control and lipofuscin-loaded human fibroblasts under conditions of lysosome-targeted stress induced by exposure to either the lysosomotropic detergent MSDH or the redox-cycling quinone naphthazarin. We show that lysosomal damage, assessed by acridine-orange relocation, translocation of cathepsin D to the cytosol, and alkalinization of lysosomes, is more pronounced in control than in lipofuscin-loaded fibroblasts. Finding that lysosomal integrity was less affected or even preserved in case of lipofuscin-loaded cells enables us to suggest that lipofuscin exerts lysosome-stabilizing properties.
Division of Experimental Pathology, Department of Neuroscience and Locomotion, Faculty of Health Sciences, Linköping University, 581 85, Linköping, Sweden. yuri.stroikin@inr.liu.se
Yuri
Y
Stroikin
Hanna
H
Mild
Uno
U
Johansson
Karin
K
Roberg
Karin
K
Ollinger