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Updated: Aug 5, 2026
LAD-Ligation: A Murine Model of Myocardial Infarction
Published on: October 14, 2009
Facilitation of Autophagosome-Lysosome Fusion by LAPTM4A: A Novel Strategy for Attenuating Myocardial
Siyi Zhou1,2, Jiayi Liu3,4, Manli Hu1
1State Key Laboratory of New Targets Discovery and Drug Development for Major Diseases, Gannan Innovation and Translational Medicine Research Institute, School of Pharmacy, First Affiliated Hospital, Gannan Medical University, Ganzhou, China (S.Z., M.H., S.T., J.Z., H.C., S.W., X. Zhou, X.C., Y.H., Z.S., L.B., H.Y., H. Liu, J. Wan, X.-J.Z., J.C., Z.-G.S., X. Zhang, H. Li).
Background:
Myocardial ischemia-reperfusion (MIR) injury compromises therapeutic effects of revascularization and leads to functional impairment and exacerbation of structural damage in the heart. Limiting the damage caused by MIR is crucial but is still an unmet clinical need because of the complexity of the underlying mechanisms. Increasing evidence suggests that lysosomal autophagy plays a significant regulatory role in MIR injury. The specific mechanisms involved remain to be fully understood.
Methods:
We here systematically analyzed the murine MIR model database to screen the potentially protective lysosome-localized proteins against MIR injury. The positive hits were further functionally screened and validated for their capability on autophagy and hypoxia/reoxygenation insults of cardiomyocytes. After exploring the detailed molecular mechanism underlying the protective effects of the target protein, we generated target gene cardiac-specific knockout mice and overexpression mice to verify its function in mouse MIR injury models.
Results:
LAPTM4A (lysosome-associated protein transmembrane 4 alpha) stood out as a significant protective lysosome-localized protein from the screening. LAPTM4A deficiency significantly heightened the inflammatory response and cell death both in primary cardiomyocytes and in a MIR-induced mouse model. Conversely, LAPTM4A overexpression exerted protective effects on cell viability and myocardial damage. Mechanistically, LAPTM4A interacts with Rubicon (Run domain Beclin1-interacting and cysteine-rich domain-containing protein), hindering its engagement within the Beclin1 complex, resulting in a robust augmentation of autophagic flux and thereby mitigating cardiac damage during reperfusion. It is important to note that Rubicon knockdown markedly reversed the aggravated injury induced by LAPTM4A knockdown, further verifying the effects of LAPTM4A depend on Rubicon.
Conclusions:
Our findings screened out and validated that LAPTM4A is a lysosome-localized protein exerting protective effects against MIR injury by facilitating autophagic flux. Targeting LAPTM4A represents a promising therapeutic strategy for mitigating MIR injury.
Insights
Lysosome-associated protein transmembrane 4 alpha (LAPTM4A) protects the heart from injury after reperfusion. This protein enhances autophagy, reducing cell death and damage, offering a potential therapeutic target for myocardial ischemia-reperfusion injury.
Area of Science:
- Cardiovascular Biology
- Cellular Autophagy
- Molecular Mechanisms of Disease
Background:
- Myocardial ischemia-reperfusion (MIR) injury impairs heart function and limits revascularization success.
- Understanding MIR injury mechanisms is critical for developing effective treatments.
- Lysosomal autophagy is increasingly recognized as a key regulator in MIR injury.
Purpose of the Study:
- To identify lysosome-localized proteins that protect against MIR injury.
- To elucidate the molecular mechanisms by which these proteins exert protective effects.
- To validate the therapeutic potential of identified proteins in preclinical models.
Main Methods:
- Systematic screening of a murine MIR model database for protective lysosome-localized proteins.
- Functional validation of candidate proteins in cardiomyocyte and MIR models.
- Investigation of molecular interactions and generation of cardiac-specific knockout/overexpression mice.
Main Results:
- LAPTM4A (lysosome-associated protein transmembrane 4 alpha) was identified as a protective protein.
- LAPTM4A deficiency exacerbated inflammation and cell death; overexpression improved viability.
- LAPTM4A interacts with Rubicon, enhancing autophagic flux and mitigating cardiac damage.
Conclusions:
- LAPTM4A is a lysosome-localized protein that protects against MIR injury by promoting autophagic flux.
- Targeting LAPTM4A presents a promising therapeutic strategy for mitigating cardiac damage during reperfusion.
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