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A Flow Cytometry-based Assay for Measuring Mitochondrial Membrane Potential in Cardiac Myocytes After Hypoxia/Reoxygenation
Published on: July 13, 2018
MG53 preserves mitochondrial integrity of cardiomyocytes during ischemia reperfusion-induced oxidative stress
Kristyn Gumpper-Fedus1, Ki Ho Park1, Hanley Ma1
1The Ohio State University Wexner Medical Center, Department of Surgery, Columbus, OH, 43210, USA.
Abstract:
Ischemic injury to the heart induces mitochondrial dysfunction due to increasing oxidative stress. MG53, also known as TRIM72, is highly expressed in striated muscle, is secreted as a myokine after exercise, and is essential for repairing damaged plasma membrane of many tissues by interacting with the membrane lipid phosphatidylserine (PS). We hypothesized MG53 could preserve mitochondrial integrity after an ischemic event by binding to the mitochondrial-specific lipid, cardiolipin (CL), for mitochondria protection to prevent mitophagy. Fluorescent imaging and Western blotting experiments showed recombinant human MG53 (rhMG53) translocated to the mitochondria after ischemic injury in vivo and in vitro. Fluorescent imaging indicated rhMG53 treatment reduced superoxide generation in ex vivo and in vitro models. Lipid-binding assay indicated MG53 binds to CL. Transfecting cardiomyocytes with the mitochondria-targeted mt-mKeima showed inhibition of mitophagy after MG53 treatment. Overall, we show that rhMG53 treatment may preserve cardiac function by preserving mitochondria in cardiomyocytes. These findings suggest MG53's interactions with mitochondria could be an attractive avenue for developing MG53 as a targeted protein therapy for cardioprotection.
Insights
MG53 protein protects heart mitochondria from oxidative stress after ischemic injury. This novel cardioprotective mechanism involves MG53 binding to cardiolipin, preventing mitophagy and preserving cardiac function, suggesting potential for protein therapy.
Area of Science:
- Cardiovascular Biology
- Mitochondrial Medicine
- Protein Therapeutics
Background:
- Ischemic heart injury causes mitochondrial dysfunction and oxidative stress.
- MG53 (TRIM72) is a muscle protein involved in membrane repair.
- MG53's role in mitochondrial protection after ischemia is unexplored.
Purpose of the Study:
- To investigate if MG53 protects mitochondria from ischemic injury.
- To determine if MG53 binds to mitochondrial cardiolipin (CL).
- To assess MG53's effect on mitophagy and cardiac function.
Main Methods:
- In vivo and in vitro fluorescent imaging and Western blotting.
- Lipid-binding assays to confirm MG53-CL interaction.
- Mitochondria-targeted fluorescent reporters to assess mitophagy.
Main Results:
- Recombinant human MG53 (rhMG53) localized to mitochondria post-ischemia.
- rhMG53 treatment reduced mitochondrial superoxide generation.
- MG53 demonstrated binding to cardiolipin and inhibited mitophagy.
- rhMG53 treatment preserved cardiac function in models.
Conclusions:
- MG53 preserves mitochondrial integrity and cardiac function following ischemic injury.
- MG53's interaction with cardiolipin is key to its cardioprotective effects.
- MG53 represents a promising therapeutic target for protein therapy in cardioprotection.
