ISG15 blocks cardiac glycolysis and ensures sufficient mitochondrial energy production during Coxsackievirus B3 infection

Abstract

Aims Virus infection triggers inflammation and, may impose nutrient shortage to the heart. Supported by type I interferon (IFN) signaling, cardiomyocytes counteract infection by various effector processes, with the IFN-stimulated gene of 15 kDa (ISG15) system being intensively regulated and protein modification with ISG15 protecting mice Coxsackievirus B3 (CVB3) infection. The underlying molecular aspects how the ISG15 system affects the functional properties of respective protein substrates in the heart are unknown. Methods and Results Based on the protective properties due to protein ISGylation, we set out a study investigating CVB3-infected mice in depth and found cardiac atrophy with lower cardiac output in ISG15-/- mice. By mass spectrometry, we identified the protein targets of the ISG15 conjugation machinery in heart tissue and explored how ISGylation affects their function. The cardiac ISGylome showed a strong enrichment of ISGylation substrates within glycolytic metabolic processes. Two control enzymes of the glycolytic pathway, hexokinase 2 (HK2) and phosphofructokinase muscle form (PFK1), were identified as bona fide ISGylation targets during infection. In an integrative approach complemented with enzymatic functional testing and structural modeling, we demonstrate that protein ISGylation obstructs the activity of HK2 and PFK1. Seahorse-based investigation of glycolysis in cardiomyocytes revealed that, by conjugating proteins, the ISG15 system prevents the infection-/IFN-induced upregulation of glycolysis. We complemented our analysis with proteomics-based advanced computational modeling of cardiac energy metabolism. Our calculations revealed an ISG15-dependent preservation of the metabolic capacity in cardiac tissue during CVB3 infection. Functional profiling of mitochondrial respiration in cardiomyocytes and mouse heart tissue by Seahorse technology showed an enhanced oxidative activity in cells with a competent ISG15 system. Conclusions Our study demonstrates that ISG15 controls critical nodes in cardiac metabolism. ISG15 reduces the glucose demand, supports higher ATP production capacity in the heart, despite nutrient shortage in infection, and counteracts cardiac atrophy and dysfunction.

Derivation of human trophoblast stem cells from placentas at birth

“…Additionally, interferon, interferon gamma, and ISGylation signaling pathways were upregulated in hTSCs in TUA medium but not in TSCM f TUA. Notably, the ISGylation pathway is associated with lipid metabolism [17][18][19][20] . Use of lipid-rich albumin is critical to deriving hTSCs from term CTBs, as discussed in the following section, and these lipids are withdrawn when hTSCs are transitioned to TSCM from TUA medium.…”

Interferons and interferon-related pathways in heart disease

“…The authors of that article attributed the protective actions of ISG15 to the ISGylation of CVB3 2A protease, limiting CVB3-induced cleavage of host eukaryotic initiation factor 4γ (eIF4G) in cardiomyocytes, which ordinarily promotes viral infection by restricting host cell protein translation ( 26 ). A recent study, further illuminated the role of ISG15 in viral myocarditis, concluding that induction of ISG15 in myocarditis functions to counter cardiac atrophy and dysfunction by increasing the heart's metabolic capacity through downregulation of cardiac glycolysis and enhancing the respiratory activity of mitochondria ( 52 ).…”