Limits...
Autophagy pathways activated in response to PDT contribute to cell resistance against ROS damage.

Dewaele M, Martinet W, Rubio N, Verfaillie T, de Witte PA, Piette J, Agostinis P - J. Cell. Mol. Med. (2010)

Bottom Line: Paradoxically, genetic loss of MA improved clearance of oxidized proteins and reduced photokilling.We found that up-regulation of chaperone-mediated autophagy (CMA) in unstressed Atg(-/-) cells compensated for MA loss and increased cellular resistance to PDT.These results disclose a stress-specific recruitment of autophagy pathways with cytoprotective function and unravel CMA as the dominant defence mechanism against PDT.

View Article: PubMed Central - PubMed

Affiliation: Cell Death Research and Therapy Laboratory, Department of Molecular Cell Biology, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium.

Show MeSH

Related in: MedlinePlus

MA deficiency reduces PDT-mediated oxidative damage to intracellular proteins without affecting the Akt-mTOR signalling. (A) Left: Total cell lysates were analysed for the presence of carbonylated protein side chains after PDT in MEF and Atg5−/− MEF, a representative OxyBlot carried out as described in Figure 3, is shown. Actin was used as a loading control (n= 3). Right: The graph represents the densitometric values of the OxyBlot normalized to actin and expressed as fold increase to controls. (B) Representative Western blot and densitometric analysis (C) of the Akt-mTOR pathway activation-status in MEF and Atg5−/− MEF after PDT (as shown in Fig. 2).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4373339&req=5

fig05: MA deficiency reduces PDT-mediated oxidative damage to intracellular proteins without affecting the Akt-mTOR signalling. (A) Left: Total cell lysates were analysed for the presence of carbonylated protein side chains after PDT in MEF and Atg5−/− MEF, a representative OxyBlot carried out as described in Figure 3, is shown. Actin was used as a loading control (n= 3). Right: The graph represents the densitometric values of the OxyBlot normalized to actin and expressed as fold increase to controls. (B) Representative Western blot and densitometric analysis (C) of the Akt-mTOR pathway activation-status in MEF and Atg5−/− MEF after PDT (as shown in Fig. 2).

Mentions: Whereas MA attenuation by siRNA-Atg5 knockdown or 3MA increased photokilling, MA-deficiency surprisingly prevented mitochondrial cytochrome c release, caspase 3 processing, PARP cleavage and apoptosis (Fig. 4A and B) as well as overall cell death (Fig. S3A, right panel). Evaluation of phosphatidylserine exposure through annexinV-FITC labelling and cell survival within a wide range of PDT doses, confirmed that Atg5−/− MEFs survived better following PDT (Fig. 4C and D). Furthermore, the cytoprotective effect of MA-deficiency against photokilling was substantiated by examining the response of RasV12 transformed WT and Atg5-KO MEFs after PDT (Fig. S4A and B), thus indicating that protection against ROS-induced apoptosis by MA loss occurs both in normal and transformed cells. Remarkably, along with the decreased apoptotic signalling, photosensitized Atg5−/− cells demonstrated an enhanced clearance of oxidized proteins as compared to their WT counterparts (Fig. 5A).


Autophagy pathways activated in response to PDT contribute to cell resistance against ROS damage.

Dewaele M, Martinet W, Rubio N, Verfaillie T, de Witte PA, Piette J, Agostinis P - J. Cell. Mol. Med. (2010)

MA deficiency reduces PDT-mediated oxidative damage to intracellular proteins without affecting the Akt-mTOR signalling. (A) Left: Total cell lysates were analysed for the presence of carbonylated protein side chains after PDT in MEF and Atg5−/− MEF, a representative OxyBlot carried out as described in Figure 3, is shown. Actin was used as a loading control (n= 3). Right: The graph represents the densitometric values of the OxyBlot normalized to actin and expressed as fold increase to controls. (B) Representative Western blot and densitometric analysis (C) of the Akt-mTOR pathway activation-status in MEF and Atg5−/− MEF after PDT (as shown in Fig. 2).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4373339&req=5

fig05: MA deficiency reduces PDT-mediated oxidative damage to intracellular proteins without affecting the Akt-mTOR signalling. (A) Left: Total cell lysates were analysed for the presence of carbonylated protein side chains after PDT in MEF and Atg5−/− MEF, a representative OxyBlot carried out as described in Figure 3, is shown. Actin was used as a loading control (n= 3). Right: The graph represents the densitometric values of the OxyBlot normalized to actin and expressed as fold increase to controls. (B) Representative Western blot and densitometric analysis (C) of the Akt-mTOR pathway activation-status in MEF and Atg5−/− MEF after PDT (as shown in Fig. 2).
Mentions: Whereas MA attenuation by siRNA-Atg5 knockdown or 3MA increased photokilling, MA-deficiency surprisingly prevented mitochondrial cytochrome c release, caspase 3 processing, PARP cleavage and apoptosis (Fig. 4A and B) as well as overall cell death (Fig. S3A, right panel). Evaluation of phosphatidylserine exposure through annexinV-FITC labelling and cell survival within a wide range of PDT doses, confirmed that Atg5−/− MEFs survived better following PDT (Fig. 4C and D). Furthermore, the cytoprotective effect of MA-deficiency against photokilling was substantiated by examining the response of RasV12 transformed WT and Atg5-KO MEFs after PDT (Fig. S4A and B), thus indicating that protection against ROS-induced apoptosis by MA loss occurs both in normal and transformed cells. Remarkably, along with the decreased apoptotic signalling, photosensitized Atg5−/− cells demonstrated an enhanced clearance of oxidized proteins as compared to their WT counterparts (Fig. 5A).

Bottom Line: Paradoxically, genetic loss of MA improved clearance of oxidized proteins and reduced photokilling.We found that up-regulation of chaperone-mediated autophagy (CMA) in unstressed Atg(-/-) cells compensated for MA loss and increased cellular resistance to PDT.These results disclose a stress-specific recruitment of autophagy pathways with cytoprotective function and unravel CMA as the dominant defence mechanism against PDT.

View Article: PubMed Central - PubMed

Affiliation: Cell Death Research and Therapy Laboratory, Department of Molecular Cell Biology, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium.

Show MeSH
Related in: MedlinePlus