Translocation of lysosomal cathepsin D caused by oxidative stress or proteasome inhibition in primary cultured neurons and astrocytes.
We reported previously that N-linked glycoproteins were accumulated in the cytosol of the normal aging rat brain, and that one protein had been identified as cathepsin D (Mech. Ageing Dev., 127, 771-778 (2006)). In this study, to elucidate the mechanism of cathepsin D accumulation in the cytosol, we examined the effects of oxidative stress and proteasome inhibition on the apoptosis and subcellular localization of cathepsin D in primary cultured neurons and astrocytes. Using 4'-6-diamidino-2-phenylindole (DAPI)- or Hoechst 33342-staining and annexin V detection, we found that oxidative stress caused by tert-butyl hydroperoxide and proteasome inhibition by lactacystin induced apoptosis in neurons and astrocytes. Furthermore, after cell fractionation, it was demonstrated that cathepsin D was translocated from lysosomes to cytosol under apoptosis-inducing conditions in both cells. These results suggested that oxidative stress and the suppression of proteasome activity triggered the translocation of cathepsin D from lysosomes to cytosol. The possible mechanism of age-related accumulation of cathepsin D in the cytosol of the normal rat brain will be discussed.
Miura
Yuri
Y
Research Team for Functional Genomics, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan. miura@tmig.or.jp
Sakurai
Yoko
Y
Hayakawa
Masato
M
Shimada
Yukiko
Y
Zempel
Hans
H
Sato
Yuji
Y
Hisanaga
Shin-ichi
S
Endo
Tamao
T
D000111:Acetylcysteine / Q000031:analogs & derivatives; D000375:Aging / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001253:Astrocytes / Q000378:metabolism*; D001692:Biological Transport; D002402:Cathepsin D / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D061988:Proteasome Inhibitors; D051381:Rats; D017208:Rats, Wistar; D020122:tert-Butylhydroperoxide
D061988:Proteasome Inhibitors; C067713:lactacystin; D020122:tert-Butylhydroperoxide; D002402:Cathepsin D; D000111:Acetylcysteine