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Mieap, a p53-inducible protein, controls mitochondrial quality by repairing or eliminating unhealthy mitochondria.

Kitamura N, Nakamura Y, Miyamoto Y, Miyamoto T, Kabu K, Yoshida M, Futamura M, Ichinose S, Arakawa H - PLoS ONE (2011)

Bottom Line: Deficiency of NIX also completely impaired MALM.The inactivation of p53 severely impaired both MALM and MIV generation, leading to accumulation of unhealthy mitochondria.These results suggest that (1) mitochondrial ROS and NIX are essential factors for MALM, (2) MIV is a novel mechanism for lysosomal degradation of mitochondria, and (3) the p53-Mieap pathway plays a pivotal role in MQC by repairing or eliminating unhealthy mitochondria via MALM or MIV generation, respectively.

View Article: PubMed Central - PubMed

Affiliation: Cancer Medicine and Biophysics Division, National Cancer Center Research Institute, Tokyo, Japan.

ABSTRACT
Maintenance of healthy mitochondria prevents aging, cancer, and a variety of degenerative diseases that are due to the result of defective mitochondrial quality control (MQC). Recently, we discovered a novel mechanism for MQC, in which Mieap induces intramitochondrial lysosome-like organella that plays a critical role in the elimination of oxidized mitochondrial proteins (designated MALM for Mieap-induced accumulation of lysosome-like organelles within mitochondria). However, a large part of the mechanisms for MQC remains unknown. Here, we report additional mechanisms for Mieap-regulated MQC. Reactive oxygen species (ROS) scavengers completely inhibited MALM. A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap. Deficiency of NIX also completely impaired MALM. When MALM was inhibited, Mieap induced vacuole-like structures (designated as MIV for Mieap-induced vacuole), which engulfed and degraded the unhealthy mitochondria by accumulating lysosomes. The inactivation of p53 severely impaired both MALM and MIV generation, leading to accumulation of unhealthy mitochondria. These results suggest that (1) mitochondrial ROS and NIX are essential factors for MALM, (2) MIV is a novel mechanism for lysosomal degradation of mitochondria, and (3) the p53-Mieap pathway plays a pivotal role in MQC by repairing or eliminating unhealthy mitochondria via MALM or MIV generation, respectively.

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Mieap induces vacuole-like structures in order to eliminate unhealthy mitochondria.(A) Light microscopic analysis of MIV. MIVs are detected by light microscopy (LM) in A549 and U373MG cells infected with Ad-Mieap at an MOI of 60. Arrows indicate MIVs. Scale bar  = 20 µm. (B) IF analysis of MIV. Mieap (green) signal is detected around the edge of MIV. Arrows indicate MIVs. Scale bar  = 20 µm. (C) MIV eats mitochondria. Mitochondria indicated by DsRed-mito are engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. Mitochondria in A549 infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 20 µm. (D) MIV does not eat endoplasmic reticulum. Endoplasmic reticulum (ER) indicated by DsRed-ER is not engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. ER in A549 infected with Ad-LacZ at an MOI of 60 is shown as a negative control. Scale bar  = 20 µm. (E) MIV contains active lysosomal enzymes. IF analysis of A549 infected with Ad-Mieap at an MOI of 60 was carried out with anti-Mieap antibody (green) and anti-LAMP antibody (red), anti-cathepsin D antibody (red), or Lysotracker-red (red). The strong red signals of cathepsin D and Lysotracker-red were detected within MIV. Scale bar  = 20 µm. (F) Electron microscopy. MIV was examined by electron microscopy (EM). Black and large vacuole-like structures are detected in A549 infected with Ad-Mieap at an MOI of 60, which contain various sizes of vesicles. MIV directly engulfes mitochondria (indicated by arrows). Mitochondria are indicated by “M”. A549 cells infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 500 nm or 10 µm.
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pone-0016060-g005: Mieap induces vacuole-like structures in order to eliminate unhealthy mitochondria.(A) Light microscopic analysis of MIV. MIVs are detected by light microscopy (LM) in A549 and U373MG cells infected with Ad-Mieap at an MOI of 60. Arrows indicate MIVs. Scale bar  = 20 µm. (B) IF analysis of MIV. Mieap (green) signal is detected around the edge of MIV. Arrows indicate MIVs. Scale bar  = 20 µm. (C) MIV eats mitochondria. Mitochondria indicated by DsRed-mito are engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. Mitochondria in A549 infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 20 µm. (D) MIV does not eat endoplasmic reticulum. Endoplasmic reticulum (ER) indicated by DsRed-ER is not engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. ER in A549 infected with Ad-LacZ at an MOI of 60 is shown as a negative control. Scale bar  = 20 µm. (E) MIV contains active lysosomal enzymes. IF analysis of A549 infected with Ad-Mieap at an MOI of 60 was carried out with anti-Mieap antibody (green) and anti-LAMP antibody (red), anti-cathepsin D antibody (red), or Lysotracker-red (red). The strong red signals of cathepsin D and Lysotracker-red were detected within MIV. Scale bar  = 20 µm. (F) Electron microscopy. MIV was examined by electron microscopy (EM). Black and large vacuole-like structures are detected in A549 infected with Ad-Mieap at an MOI of 60, which contain various sizes of vesicles. MIV directly engulfes mitochondria (indicated by arrows). Mitochondria are indicated by “M”. A549 cells infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 500 nm or 10 µm.

Mentions: During our studies examining the function of Mieap, we noticed another unique phenomenon induced by Mieap. When Mieap protein was overexpressed in cancer cells by infection with Ad-Mieap at an MOI of 60, a few large, vacuole-like structures appeared in the cytoplasm of the infected cells (Figure 5A). The phenomenon was confirmed in all the examined cancer cell lines. We designated this vacuole-like structure as MIV (Mieap-induced vacuole). Interestingly, Mieap was localized around the edge of the MIV (Figure 5B).


Mieap, a p53-inducible protein, controls mitochondrial quality by repairing or eliminating unhealthy mitochondria.

Kitamura N, Nakamura Y, Miyamoto Y, Miyamoto T, Kabu K, Yoshida M, Futamura M, Ichinose S, Arakawa H - PLoS ONE (2011)

Mieap induces vacuole-like structures in order to eliminate unhealthy mitochondria.(A) Light microscopic analysis of MIV. MIVs are detected by light microscopy (LM) in A549 and U373MG cells infected with Ad-Mieap at an MOI of 60. Arrows indicate MIVs. Scale bar  = 20 µm. (B) IF analysis of MIV. Mieap (green) signal is detected around the edge of MIV. Arrows indicate MIVs. Scale bar  = 20 µm. (C) MIV eats mitochondria. Mitochondria indicated by DsRed-mito are engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. Mitochondria in A549 infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 20 µm. (D) MIV does not eat endoplasmic reticulum. Endoplasmic reticulum (ER) indicated by DsRed-ER is not engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. ER in A549 infected with Ad-LacZ at an MOI of 60 is shown as a negative control. Scale bar  = 20 µm. (E) MIV contains active lysosomal enzymes. IF analysis of A549 infected with Ad-Mieap at an MOI of 60 was carried out with anti-Mieap antibody (green) and anti-LAMP antibody (red), anti-cathepsin D antibody (red), or Lysotracker-red (red). The strong red signals of cathepsin D and Lysotracker-red were detected within MIV. Scale bar  = 20 µm. (F) Electron microscopy. MIV was examined by electron microscopy (EM). Black and large vacuole-like structures are detected in A549 infected with Ad-Mieap at an MOI of 60, which contain various sizes of vesicles. MIV directly engulfes mitochondria (indicated by arrows). Mitochondria are indicated by “M”. A549 cells infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 500 nm or 10 µm.
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Related In: Results  -  Collection

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pone-0016060-g005: Mieap induces vacuole-like structures in order to eliminate unhealthy mitochondria.(A) Light microscopic analysis of MIV. MIVs are detected by light microscopy (LM) in A549 and U373MG cells infected with Ad-Mieap at an MOI of 60. Arrows indicate MIVs. Scale bar  = 20 µm. (B) IF analysis of MIV. Mieap (green) signal is detected around the edge of MIV. Arrows indicate MIVs. Scale bar  = 20 µm. (C) MIV eats mitochondria. Mitochondria indicated by DsRed-mito are engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. Mitochondria in A549 infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 20 µm. (D) MIV does not eat endoplasmic reticulum. Endoplasmic reticulum (ER) indicated by DsRed-ER is not engulfed by MIV in A549 cells infected with Ad-Mieap at an MOI of 60. ER in A549 infected with Ad-LacZ at an MOI of 60 is shown as a negative control. Scale bar  = 20 µm. (E) MIV contains active lysosomal enzymes. IF analysis of A549 infected with Ad-Mieap at an MOI of 60 was carried out with anti-Mieap antibody (green) and anti-LAMP antibody (red), anti-cathepsin D antibody (red), or Lysotracker-red (red). The strong red signals of cathepsin D and Lysotracker-red were detected within MIV. Scale bar  = 20 µm. (F) Electron microscopy. MIV was examined by electron microscopy (EM). Black and large vacuole-like structures are detected in A549 infected with Ad-Mieap at an MOI of 60, which contain various sizes of vesicles. MIV directly engulfes mitochondria (indicated by arrows). Mitochondria are indicated by “M”. A549 cells infected with Ad-LacZ at an MOI of 60 are shown as a negative control. Scale bar  = 500 nm or 10 µm.
Mentions: During our studies examining the function of Mieap, we noticed another unique phenomenon induced by Mieap. When Mieap protein was overexpressed in cancer cells by infection with Ad-Mieap at an MOI of 60, a few large, vacuole-like structures appeared in the cytoplasm of the infected cells (Figure 5A). The phenomenon was confirmed in all the examined cancer cell lines. We designated this vacuole-like structure as MIV (Mieap-induced vacuole). Interestingly, Mieap was localized around the edge of the MIV (Figure 5B).

Bottom Line: Deficiency of NIX also completely impaired MALM.The inactivation of p53 severely impaired both MALM and MIV generation, leading to accumulation of unhealthy mitochondria.These results suggest that (1) mitochondrial ROS and NIX are essential factors for MALM, (2) MIV is a novel mechanism for lysosomal degradation of mitochondria, and (3) the p53-Mieap pathway plays a pivotal role in MQC by repairing or eliminating unhealthy mitochondria via MALM or MIV generation, respectively.

View Article: PubMed Central - PubMed

Affiliation: Cancer Medicine and Biophysics Division, National Cancer Center Research Institute, Tokyo, Japan.

ABSTRACT
Maintenance of healthy mitochondria prevents aging, cancer, and a variety of degenerative diseases that are due to the result of defective mitochondrial quality control (MQC). Recently, we discovered a novel mechanism for MQC, in which Mieap induces intramitochondrial lysosome-like organella that plays a critical role in the elimination of oxidized mitochondrial proteins (designated MALM for Mieap-induced accumulation of lysosome-like organelles within mitochondria). However, a large part of the mechanisms for MQC remains unknown. Here, we report additional mechanisms for Mieap-regulated MQC. Reactive oxygen species (ROS) scavengers completely inhibited MALM. A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap. Deficiency of NIX also completely impaired MALM. When MALM was inhibited, Mieap induced vacuole-like structures (designated as MIV for Mieap-induced vacuole), which engulfed and degraded the unhealthy mitochondria by accumulating lysosomes. The inactivation of p53 severely impaired both MALM and MIV generation, leading to accumulation of unhealthy mitochondria. These results suggest that (1) mitochondrial ROS and NIX are essential factors for MALM, (2) MIV is a novel mechanism for lysosomal degradation of mitochondria, and (3) the p53-Mieap pathway plays a pivotal role in MQC by repairing or eliminating unhealthy mitochondria via MALM or MIV generation, respectively.

Show MeSH
Related in: MedlinePlus