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Mitophagy of damaged mitochondria occurs locally in distal neuronal axons and requires PINK1 and Parkin.

Ashrafi G, Schlehe JS, LaVoie MJ, Schwarz TL - J. Cell Biol. (2014)

Bottom Line: In PINK1(-/-) axons, damaged mitochondria did not accumulate Parkin and failed to be engulfed in autophagosomes.Similarly, initiation of mitophagy was blocked in Parkin(-/-) axons.Local mitophagy likely provides rapid neuroprotection against oxidative stress without a requirement for retrograde transport to the soma.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138 F.M. Kirby Neurobiology Center, Children's Hospital Boston, Boston, MA 02115.

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Parkin is recruited to axonal mitochondria damaged with mt-KR. (A) YFP-Parkin accumulates on a fraction of axonal mitochondria in the outlined area of mt-KR activation. (B) Line scan of the axon in A with cyan arrowheads marking two YFP-Parkin–positive mitochondria. (C and D) YFP-Parkin remained diffuse despite irradiation in the outlined area when mt-DsRed replaced mt-KR. Mitochondria with YFP-Parkin levels more than twice the background were scored as Parkin-positive here and in subsequent figures. Orange and brown arrowheads denote corresponding points in images and line scans. (E) Frequency of YFP-Parkin recruitment to irradiated mitochondria. n = 131–140 mitochondria from 12 transfections. **, P < 0.001. Error bars represent means ± SEM. AU, arbitrary unit. Bars, 5 µm.
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fig5: Parkin is recruited to axonal mitochondria damaged with mt-KR. (A) YFP-Parkin accumulates on a fraction of axonal mitochondria in the outlined area of mt-KR activation. (B) Line scan of the axon in A with cyan arrowheads marking two YFP-Parkin–positive mitochondria. (C and D) YFP-Parkin remained diffuse despite irradiation in the outlined area when mt-DsRed replaced mt-KR. Mitochondria with YFP-Parkin levels more than twice the background were scored as Parkin-positive here and in subsequent figures. Orange and brown arrowheads denote corresponding points in images and line scans. (E) Frequency of YFP-Parkin recruitment to irradiated mitochondria. n = 131–140 mitochondria from 12 transfections. **, P < 0.001. Error bars represent means ± SEM. AU, arbitrary unit. Bars, 5 µm.

Mentions: In nonneuronal cells, mitochondrial depolarization causes recruitment of Parkin from the cytoplasm to the mitochondrial outer membrane where it promotes the onset of mitophagy (Narendra et al., 2008; Geisler et al., 2010). In neurons, Parkin translocation has been reported in the cell bodies of neurons treated with CCCP or valinomycin (Seibler et al., 2011; Cai et al., 2012) but was not observed in axons treated with CCCP (Van Laar et al., 2011; Cai et al., 2012). We, in contrast, had observed accumulation of Parkin on axonal mitochondria in response to global depolarization with Antimycin A (Wang et al., 2011). Because axonal Parkin recruitment might be obscured by either overexpression of YFP-Parkin in the cytosol, excessively toxic exposure to CCCP, or failure to observe the recruitment before rapid mitophagy, we reexamined the question with locally restricted and near-physiological levels of mitochondrial damage 20 min after irradiation of mitochondria expressing mt-KR and mt-BFP with 555 nm of light. When expressed at high levels, YFP-Parkin localizes to mitochondria and arrests their motility even in the absence of mitochondrial damage (Wang et al., 2011). At low levels, however, YFP-Parkin was diffuse in the axonal cytoplasm with only minor enrichment on a few mitochondria (Fig. 5, A and B). After activation of mt-KR, YFP-Parkin accumulated on 10% of the targeted mitochondria that were previously Parkin negative (Fig. 5, A, B, and E). This recruitment was caused by ROS production by mt-KR; only 3% of mitochondria were Parkin positive after equivalent irradiation of mt-DsRed (P < 0.01; Fig. 5, C–E). Thus, local damage to a small subset of axonal mitochondria is sufficient to recruit Parkin selectively to the affected population.


Mitophagy of damaged mitochondria occurs locally in distal neuronal axons and requires PINK1 and Parkin.

Ashrafi G, Schlehe JS, LaVoie MJ, Schwarz TL - J. Cell Biol. (2014)

Parkin is recruited to axonal mitochondria damaged with mt-KR. (A) YFP-Parkin accumulates on a fraction of axonal mitochondria in the outlined area of mt-KR activation. (B) Line scan of the axon in A with cyan arrowheads marking two YFP-Parkin–positive mitochondria. (C and D) YFP-Parkin remained diffuse despite irradiation in the outlined area when mt-DsRed replaced mt-KR. Mitochondria with YFP-Parkin levels more than twice the background were scored as Parkin-positive here and in subsequent figures. Orange and brown arrowheads denote corresponding points in images and line scans. (E) Frequency of YFP-Parkin recruitment to irradiated mitochondria. n = 131–140 mitochondria from 12 transfections. **, P < 0.001. Error bars represent means ± SEM. AU, arbitrary unit. Bars, 5 µm.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4151150&req=5

fig5: Parkin is recruited to axonal mitochondria damaged with mt-KR. (A) YFP-Parkin accumulates on a fraction of axonal mitochondria in the outlined area of mt-KR activation. (B) Line scan of the axon in A with cyan arrowheads marking two YFP-Parkin–positive mitochondria. (C and D) YFP-Parkin remained diffuse despite irradiation in the outlined area when mt-DsRed replaced mt-KR. Mitochondria with YFP-Parkin levels more than twice the background were scored as Parkin-positive here and in subsequent figures. Orange and brown arrowheads denote corresponding points in images and line scans. (E) Frequency of YFP-Parkin recruitment to irradiated mitochondria. n = 131–140 mitochondria from 12 transfections. **, P < 0.001. Error bars represent means ± SEM. AU, arbitrary unit. Bars, 5 µm.
Mentions: In nonneuronal cells, mitochondrial depolarization causes recruitment of Parkin from the cytoplasm to the mitochondrial outer membrane where it promotes the onset of mitophagy (Narendra et al., 2008; Geisler et al., 2010). In neurons, Parkin translocation has been reported in the cell bodies of neurons treated with CCCP or valinomycin (Seibler et al., 2011; Cai et al., 2012) but was not observed in axons treated with CCCP (Van Laar et al., 2011; Cai et al., 2012). We, in contrast, had observed accumulation of Parkin on axonal mitochondria in response to global depolarization with Antimycin A (Wang et al., 2011). Because axonal Parkin recruitment might be obscured by either overexpression of YFP-Parkin in the cytosol, excessively toxic exposure to CCCP, or failure to observe the recruitment before rapid mitophagy, we reexamined the question with locally restricted and near-physiological levels of mitochondrial damage 20 min after irradiation of mitochondria expressing mt-KR and mt-BFP with 555 nm of light. When expressed at high levels, YFP-Parkin localizes to mitochondria and arrests their motility even in the absence of mitochondrial damage (Wang et al., 2011). At low levels, however, YFP-Parkin was diffuse in the axonal cytoplasm with only minor enrichment on a few mitochondria (Fig. 5, A and B). After activation of mt-KR, YFP-Parkin accumulated on 10% of the targeted mitochondria that were previously Parkin negative (Fig. 5, A, B, and E). This recruitment was caused by ROS production by mt-KR; only 3% of mitochondria were Parkin positive after equivalent irradiation of mt-DsRed (P < 0.01; Fig. 5, C–E). Thus, local damage to a small subset of axonal mitochondria is sufficient to recruit Parkin selectively to the affected population.

Bottom Line: In PINK1(-/-) axons, damaged mitochondria did not accumulate Parkin and failed to be engulfed in autophagosomes.Similarly, initiation of mitophagy was blocked in Parkin(-/-) axons.Local mitophagy likely provides rapid neuroprotection against oxidative stress without a requirement for retrograde transport to the soma.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138 F.M. Kirby Neurobiology Center, Children's Hospital Boston, Boston, MA 02115.

Show MeSH
Related in: MedlinePlus