| 1. |
- Stroikin, Yuri, et al.
(author)
-
Increased resistance of lipofuscin-loaded prematurely senescent fibroblasts to starvation-induced programmed cell death
- 2007
-
In: Biogerontology (Dordrecht). - : Springer Science and Business Media LLC. - 1389-5729 .- 1573-6768. ; 8:1, s. 43-53
-
Journal article (peer-reviewed)abstract
- Alterations of cellular structures often found in ageing cells is mainly the result of production of reactive oxygen species and a consequence of aerobic life. Both oxidative stress and decreased degradative capacity of lysosomal system cause accumulation of intralysosomal age-related pigment called lipofuscin. To investigate the influence of lipofuscin on cell function, we compared survival of lipofuscin-loaded and control human fibroblasts following complete starvation induced by exposure to phosphate-buffered saline (PBS). Starving of control fibroblasts resulted in lysosomal alkalinisation, relocation of cathepsin D to the cytosol, caspase-3 activation and, finally, cell death, which became evident 72 h after the start of exposure to PBS. Increase of lysosomal pH was significantly less prominent in lipofuscin-loaded cells than in controls and was accompanied neither by leakage of cathepsin D nor by caspase-3 activation even 96 h after the initiation of starvation. Suppression of autophagy by 3-methyladenine (3-MA) accelerated cell death, while inhibition of cathepsin D delayed it, implying an important role of autophagy in cell survival during starvation and showing the involvement of lysosomes in starvation-induced cell death. Disturbed apoptotic response found in lipofuscin-loaded cells can be interpreted as an example of hormesis—an adaptation to low doses of otherwise harmful agents, in this case of lipofuscin, which has a protective effect at moderate amounts but becomes toxic at large quantities.
|
|
| 2. |
- Stroikin, Yuri, et al.
(author)
-
Lysosome-targeted stress reveals increased stability of lipofuscin-containing lysosomes
- 2008
-
In: Age (Omaha). - : Springer. - 0161-9152 .- 1574-4647. ; 30:1, s. 31-42
-
Journal article (peer-reviewed)abstract
- 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.
|
|
