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Updated: May 22, 2026
An Improved Method to Isolate Mitochondrial Contact Sites
Published on: June 16, 2023
Identification of 14-3-3γ as a Mieap-interacting protein and its role in mitochondrial quality control
Abstract:
Mieap, a p53-inducible protein, controls mitochondrial integrity by inducing the accumulation of lysosomal proteins within mitochondria. This phenomenon is designated MALM, for Mieap-induced accumulation of lysosome-like organelles within mitochondria. To identify this novel Mieap-interacting protein(s), we performed a two-dimensional image-converted analysis of liquid chromatography and mass spectrometry (2DICAL) on the proteins immunoprecipitated by an anti-Mieap antibody. We indentified 14-3-3γ as one of the proteins that was included in the Mieap-binding protein complex when MALM was induced. The interaction between Mieap and 14-3-3γ was confirmed on the exogenous and endogenous proteins. Interestingly, 14-3-3γ was localized within mitochondria when MALM occurred. A 14-3-3γ deficiency did not affect the accumulation of Mieap and lysosomal proteins within mitochondria, but dramatically inhibited the elimination of oxidized mitochondrial proteins. These results suggest that 14-3-3γ plays a critical role in eliminating oxidized mitochondrial proteins during the MALM process by interacting with Mieap within mitochondria.
Insights
Mieap protein initiates mitochondrial repair by accumulating lysosomal proteins, a process called MALM. The study identifies 14-3-3γ as crucial for clearing oxidized mitochondrial proteins during MALM.
Area of Science:
- Cell Biology
- Mitochondrial Biology
- Protein Interactions
Background:
- Mitochondrial integrity is vital for cellular health.
- Mieap (p53-inducible protein) regulates mitochondrial integrity.
- Mieap induces Mieap-induced accumulation of lysosome-like organelles within mitochondria (MALM).
Purpose of the Study:
- To identify novel Mieap-interacting proteins involved in MALM.
- To elucidate the role of identified proteins in mitochondrial protein quality control.
Main Methods:
- Two-dimensional image-converted analysis of liquid chromatography and mass spectrometry (2DICAL) was used to identify Mieap-binding proteins.
- Immunoprecipitation with anti-Mieap antibody was performed.
- Exogenous and endogenous protein interactions were confirmed.
- Mitochondrial localization studies were conducted.
- Functional assays were performed in 14-3-3γ deficient cells.
Main Results:
- 14-3-3γ was identified as a Mieap-interacting protein during MALM.
- Mieap and 14-3-3γ interaction was confirmed both exogenously and endogenously.
- 14-3-3γ localized to mitochondria during MALM.
- 14-3-3γ deficiency impaired the elimination of oxidized mitochondrial proteins but not lysosomal protein accumulation.
- Mieap and lysosomal protein accumulation within mitochondria was unaffected by 14-3-3γ deficiency.
Conclusions:
- 14-3-3γ interacts with Mieap within mitochondria.
- 14-3-3γ is essential for the clearance of oxidized mitochondrial proteins during the MALM process.
- This interaction is critical for maintaining mitochondrial quality control.
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