Limits...
ATM mediates spermidine-induced mitophagy via PINK1 and Parkin regulation in human fibroblasts.

Qi Y, Qiu Q, Gu X, Tian Y, Zhang Y - Sci Rep (2016)

Bottom Line: Our results indicate that spermidine induces mitophagy by eliciting mitochondrial depolarization, which triggers the formation of mitophagosomes and mitolysosomes, thereby promoting the accumulation of PINK1 and translocation of Parkin to damaged mitochondria, finally leading to the decreased mitochondrial mass in GM00637 cells.These results suggest that ATM drives the initiation of the mitophagic cascade.These findings underscore the importance of a mitophagy regulatory network of ATM and PINK1/Parkin and elucidate a novel mechanism by which ATM influences spermidine-induced mitophagy.

View Article: PubMed Central - PubMed

Affiliation: Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.

ABSTRACT
The ATM (ataxia telangiectasia mutated) protein has recently been proposed to play critical roles in the response to mitochondrial dysfunction by initiating mitophagy. Here, we have used ATM-proficient GM00637 cells and ATM-deficient GM05849 cells to investigate the mitophagic effect of spermidine and to elucidate the role of ATM in spermdine-induced mitophagy. Our results indicate that spermidine induces mitophagy by eliciting mitochondrial depolarization, which triggers the formation of mitophagosomes and mitolysosomes, thereby promoting the accumulation of PINK1 and translocation of Parkin to damaged mitochondria, finally leading to the decreased mitochondrial mass in GM00637 cells. However, in GM05849 cells or GM00637 cells pretreated with the ATM kinase inhibitor KU55933, the expression of full-length PINK1 and the translocation of Parkin are blocked, and the colocalization of Parkin with either LC3 or PINK1 is disrupted. These results suggest that ATM drives the initiation of the mitophagic cascade. Our study demonstrates that spermidine induces mitophagy through ATM-dependent activation of the PINK1/Parkin pathway. These findings underscore the importance of a mitophagy regulatory network of ATM and PINK1/Parkin and elucidate a novel mechanism by which ATM influences spermidine-induced mitophagy.

No MeSH data available.


Related in: MedlinePlus

Spermidine induced ATM-dependent formation of mitophagosomes and mitolysosomes and decreased mitochondrial mass.Transmission electron micrographs of GM00637 and GM05849 cells are shown. M: mitochondrion; N: nucleus; MP: mitophagosome; ML:mitolysosome (a). Mitochondrial translocation into lysosomes in GM00637 cells (b), GM05849 cells (c) and KU55933-pretreated GM00637 cells (d) are shown. Arrows identify superimposition of green-fluorescing mitochondria with red-fluorescing lysosomes (orange-yellow in color overlay) denoting the formation of mitolysosomes. The scale bar is 10 μm. In (e), the number of LTR-labeled lysosomes containing MTG fluorescence is plotted from 20–45 cells/condition. Values are mean ± SD, *p < 0.05 vs. control. Besides, the lysates of GM00637 cells with or without KU55933 pretreatment were immunoblotted using the indicated antibodies (f). β-actin was used a loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835770&req=5

f2: Spermidine induced ATM-dependent formation of mitophagosomes and mitolysosomes and decreased mitochondrial mass.Transmission electron micrographs of GM00637 and GM05849 cells are shown. M: mitochondrion; N: nucleus; MP: mitophagosome; ML:mitolysosome (a). Mitochondrial translocation into lysosomes in GM00637 cells (b), GM05849 cells (c) and KU55933-pretreated GM00637 cells (d) are shown. Arrows identify superimposition of green-fluorescing mitochondria with red-fluorescing lysosomes (orange-yellow in color overlay) denoting the formation of mitolysosomes. The scale bar is 10 μm. In (e), the number of LTR-labeled lysosomes containing MTG fluorescence is plotted from 20–45 cells/condition. Values are mean ± SD, *p < 0.05 vs. control. Besides, the lysates of GM00637 cells with or without KU55933 pretreatment were immunoblotted using the indicated antibodies (f). β-actin was used a loading control.

Mentions: We next examined the effect of spermidine on mitophagy by direct observation using electron microscopy. GM00637 cells cultured in the presence of 50 μM spermidine for 8 h resulted in a pronounced accumulation of swollen and malformed mitochondria, along with a package of autophagosomes, that formed mitophagosomes. We also observed the monolayer membrane lysosomes engulf the mitophagosomes to become mitolysosomes. Nevertheless, spermidine had no such dramatic effects on the mitochondrial structure in GM05849 cells as indicated by the intact mitochondria (Fig. 2a).


ATM mediates spermidine-induced mitophagy via PINK1 and Parkin regulation in human fibroblasts.

Qi Y, Qiu Q, Gu X, Tian Y, Zhang Y - Sci Rep (2016)

Spermidine induced ATM-dependent formation of mitophagosomes and mitolysosomes and decreased mitochondrial mass.Transmission electron micrographs of GM00637 and GM05849 cells are shown. M: mitochondrion; N: nucleus; MP: mitophagosome; ML:mitolysosome (a). Mitochondrial translocation into lysosomes in GM00637 cells (b), GM05849 cells (c) and KU55933-pretreated GM00637 cells (d) are shown. Arrows identify superimposition of green-fluorescing mitochondria with red-fluorescing lysosomes (orange-yellow in color overlay) denoting the formation of mitolysosomes. The scale bar is 10 μm. In (e), the number of LTR-labeled lysosomes containing MTG fluorescence is plotted from 20–45 cells/condition. Values are mean ± SD, *p < 0.05 vs. control. Besides, the lysates of GM00637 cells with or without KU55933 pretreatment were immunoblotted using the indicated antibodies (f). β-actin was used a loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835770&req=5

f2: Spermidine induced ATM-dependent formation of mitophagosomes and mitolysosomes and decreased mitochondrial mass.Transmission electron micrographs of GM00637 and GM05849 cells are shown. M: mitochondrion; N: nucleus; MP: mitophagosome; ML:mitolysosome (a). Mitochondrial translocation into lysosomes in GM00637 cells (b), GM05849 cells (c) and KU55933-pretreated GM00637 cells (d) are shown. Arrows identify superimposition of green-fluorescing mitochondria with red-fluorescing lysosomes (orange-yellow in color overlay) denoting the formation of mitolysosomes. The scale bar is 10 μm. In (e), the number of LTR-labeled lysosomes containing MTG fluorescence is plotted from 20–45 cells/condition. Values are mean ± SD, *p < 0.05 vs. control. Besides, the lysates of GM00637 cells with or without KU55933 pretreatment were immunoblotted using the indicated antibodies (f). β-actin was used a loading control.
Mentions: We next examined the effect of spermidine on mitophagy by direct observation using electron microscopy. GM00637 cells cultured in the presence of 50 μM spermidine for 8 h resulted in a pronounced accumulation of swollen and malformed mitochondria, along with a package of autophagosomes, that formed mitophagosomes. We also observed the monolayer membrane lysosomes engulf the mitophagosomes to become mitolysosomes. Nevertheless, spermidine had no such dramatic effects on the mitochondrial structure in GM05849 cells as indicated by the intact mitochondria (Fig. 2a).

Bottom Line: Our results indicate that spermidine induces mitophagy by eliciting mitochondrial depolarization, which triggers the formation of mitophagosomes and mitolysosomes, thereby promoting the accumulation of PINK1 and translocation of Parkin to damaged mitochondria, finally leading to the decreased mitochondrial mass in GM00637 cells.These results suggest that ATM drives the initiation of the mitophagic cascade.These findings underscore the importance of a mitophagy regulatory network of ATM and PINK1/Parkin and elucidate a novel mechanism by which ATM influences spermidine-induced mitophagy.

View Article: PubMed Central - PubMed

Affiliation: Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.

ABSTRACT
The ATM (ataxia telangiectasia mutated) protein has recently been proposed to play critical roles in the response to mitochondrial dysfunction by initiating mitophagy. Here, we have used ATM-proficient GM00637 cells and ATM-deficient GM05849 cells to investigate the mitophagic effect of spermidine and to elucidate the role of ATM in spermdine-induced mitophagy. Our results indicate that spermidine induces mitophagy by eliciting mitochondrial depolarization, which triggers the formation of mitophagosomes and mitolysosomes, thereby promoting the accumulation of PINK1 and translocation of Parkin to damaged mitochondria, finally leading to the decreased mitochondrial mass in GM00637 cells. However, in GM05849 cells or GM00637 cells pretreated with the ATM kinase inhibitor KU55933, the expression of full-length PINK1 and the translocation of Parkin are blocked, and the colocalization of Parkin with either LC3 or PINK1 is disrupted. These results suggest that ATM drives the initiation of the mitophagic cascade. Our study demonstrates that spermidine induces mitophagy through ATM-dependent activation of the PINK1/Parkin pathway. These findings underscore the importance of a mitophagy regulatory network of ATM and PINK1/Parkin and elucidate a novel mechanism by which ATM influences spermidine-induced mitophagy.

No MeSH data available.


Related in: MedlinePlus