AARS2-mediated lactylation of SDHA drives mitochondrial dysfunction in viral myocarditis
W He, D WangAbstract
Background
Viral myocarditis (VMC) is a life-threatening disease with limited therapeutic targets. Elevated plasma lactate is an independent risk factor for mortality in fulminant myocarditis, yet the underlying molecular mechanisms remain unclear. Lactate can drive protein lactylation, a novel post-translational modification, but its role in VMC pathogenesis is unknown.
Purpose
To investigate the role of lactate and protein lactylation in the progression of viral myocarditis and to identify potential therapeutic targets.
Methods
Plasma and myocardial lactate levels were measured in a human cohort of fulminant myocarditis patients and in a Coxsackievirus B3 (CVB3)-induced murine VMC model. Lactylomic profiling was performed on myocardial tissue from VMC mice to identify key lactylated proteins. The functional role of the identified lactylation site (SDHA-K250la) was investigated using site-directed mutagenesis (K250R), site-specific antibodies, and functional assays for mitochondrial respiration, SDH complex assembly, and enzymatic activity. A proximity-dependent biotinylation (BioID) assay and mass spectrometry were used to screen for the responsible lactyltransferase. The therapeutic potential of targeting this pathway was evaluated using lactate-lowering agents (OXA+AZD3965) and an AARS2-specific inhibitor (SD146) in the CVB3 mouse model.
Results
Lactate levels were significantly elevated in the plasma and myocardium of both human fulminant myocarditis patients and CVB3-infected mice. Exogenous lactate exacerbated cardiac dysfunction and inflammatory infiltration in VMC mice. Lactylomic profiling revealed a marked increase in lactylation at lysine 250 of succinate dehydrogenase complex subunit A (SDHA-K250la) during VMC. Mechanistically, SDHA-K250la disrupted the assembly of the SDH complex (complex II) by attenuating its interaction with SDHB and the assembly factor SDHAF2. This led to reduced SDH enzymatic activity, impaired mitochondrial respiration, decreased ATP production, and increased cardiomyocyte pyroptosis. A SDHA-K250R mutation rescued these mitochondrial defects. We identified mitochondrial alanyl-tRNA synthetase 2 (AARS2) as the key lactyltransferase catalyzing SDHA-K250la. The AARS2-specific inhibitor SD146 significantly reduced SDHA-K250la, restored SDH activity, and ameliorated cardiac dysfunction in the CVB3-induced VMC model. Combined lactate-lowering therapy also showed significant therapeutic benefits.
Conclusions
Our study identifies a novel pathological mechanism in viral myocarditis whereby accumulated lactate drives AARS2-mediated lactylation of SDHA at K250. This modification impairs SDH complex integrity and activity, leading to mitochondrial dysfunction and cardiomyocyte injury. Targeting lactate metabolism or specifically inhibiting AARS2-mediated SDHA-K250la represents a promising therapeutic strategy for viral myocarditis.Graphical abstract