Oxidative stress impairs autophagic flux in prion protein-deficient hippocampal cells.
We previously reported that autophagy is upregulated in Prnp-deficient (Prnp ( 0/0) ) hippocampal neuronal cells in comparison to cellular prion protein (PrP (C) )-expressing (Prnp (+/+) ) control cells under conditions of serum deprivation. In this study, we determined whether a protective mechanism of PrP (C)  is associated with autophagy using Prnp ( 0/0)  hippocampal neuronal cells under hydrogen peroxide (H 2O 2)-induced oxidative stress. We found that Prnp ( 0/0)  cells were more susceptible to oxidative stress than Prnp (+/+)  cells in a dose- and time-dependent manner. In addition, we observed enhanced autophagy by immunoblotting, which detected the conversion of microtubule-associated protein 1 light chain 3 β (LC3B)-I to LC3B-II, and we observed increased punctate LC3B immunostaining in H 2O 2-treated Prnp ( 0/0)  cells compared with H 2O 2-treated control cells. Interestingly, this enhanced autophagy was due to impaired autophagic flux in the H 2O 2-treated Prnp ( 0/0)  cells, while the H 2O 2-treated Prnp (+/+)  cells showed enhanced autophagic flux. Furthermore, caspase-dependent and independent apoptosis was observed when both cell lines were exposed to H 2O 2. Moreover, the inhibition of autophagosome formation by Atg7 siRNA revealed that increased autophagic flux in Prnp (+/+)  cells contributes to the prosurvival effect of autophagy against H 2O 2 cytotoxicity. Taken together, our results provide the first experimental evidence that the deficiency of PrP (C)  may impair autophagic flux via H 2O 2-induced oxidative stress.
Ilsong Institute of Life Science, Hallym University, Anyang, Korea.
Jae-Min
JM
Oh
Eun-Kyoung
EK
Choi
Richard I
RI
Carp
Yong-Sun
YS
Kim
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D008954:Models, Biological; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects; D011328:Prions / Q000378:metabolism*; D020011:Protective Agents / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D013997:Time Factors; D014199:Trehalose / Q000494:pharmacology
D011328:Prions; D020011:Protective Agents; C025946:3-methyladenine; D014199:Trehalose; D006861:Hydrogen Peroxide; D020169:Caspases; D000225:Adenine; D020123:Sirolimus