Cardiac Ischemic Preconditioning Promotes MG53 Secretion Through H ₂ O ₂ -Activated Protein Kinase C-δ Signaling

Abstract

Background: Ischemic heart disease is the leading cause of morbidity and mortality worldwide. Ischemic preconditioning (IPC) is the most powerful intrinsic protection against cardiac ischemia/reperfusion injury. Previous studies have shown that a multifunctional TRIM family protein, MG53 (mitsugumin 53; also called TRIM72), not only plays an essential role in IPC-mediated cardioprotection against ischemia/reperfusion injury but also ameliorates mechanical damage. In addition to its intracellular actions, as a myokine/cardiokine, MG53 can be secreted from the heart and skeletal muscle in response to metabolic stress. However, it is unknown whether IPC-mediated cardioprotection is causally related to MG53 secretion and, if so, what the underlying mechanism is. Methods: Using proteomic analysis in conjunction with genetic and pharmacological approaches, we examined MG53 secretion in response to IPC and explored the underlying mechanism using rodents in in vivo, isolated perfused hearts, and cultured neonatal rat ventricular cardiomyocytes. Moreover, using recombinant MG53 proteins, we investigated the potential biological function of secreted MG53 in the context of IPC and ischemia/reperfusion injury. Results: We found that IPC triggered robust MG53 secretion in rodents in vivo, perfused hearts, and cultured cardiac myocytes without causing cell membrane leakage. Mechanistically, IPC promoted MG53 secretion through H 2 O 2 -evoked activation of protein kinase-C-δ. Specifically, IPC-induced myocardial MG53 secretion was mediated by H 2 O 2 -triggered phosphorylation of protein kinase-C-δ at Y311, which is necessary and sufficient to facilitate MG53 secretion. Functionally, systemic delivery of recombinant MG53 proteins to mimic elevated circulating MG53 not only restored IPC function in MG53-deficient mice but also protected rodent hearts from ischemia/reperfusion injury even in the absence of IPC. Moreover, oxidative stress by H 2 O 2 augmented MG53 secretion, and MG53 knockdown exacerbated H 2 O 2 -induced cell injury in human embryonic stem cell–derived cardiomyocytes, despite relatively low basal expression of MG53 in human heart. Conclusions: We conclude that IPC and oxidative stress can trigger MG53 secretion from the heart via an H 2 O 2 –protein kinase-C-δ–dependent mechanism and that extracellular MG53 can participate in IPC protection against cardiac ischemia/reperfusion injury.

Serum MG53/TRIM72 Is Associated With the Presence and Severity of Coronary Artery Disease and Acute Myocardial Infarction

“…In addition, the circulating MG53 levels in mice with I/R injury correlated with the concentration of creatine kinase. More importantly, Dan et al showed that IPC and oxidative stress could promoted MG53 secretion from perfused hearts in rodent (Shan et al, 2020). This effect was mediated by H 2 O 2 -induced PKC-δ phosphorylation at Y311.…”

Cardiac effects and clinical applications of MG53

“…Interestingly, a recent study from Xiao’s group showed that MG53 is secreted from the mouse heart in response to IPC or oxidative stress, and that the released MG53 protects the heart against IR injury via increased phosphorylation of protein kinase-C-δ (PKCδ) (Fig. 1 ) [ 18 ]. Furthermore, administration of recombinant MG53 proteins to simulate increased circulating MG53 significantly restored IPC function in MG53 KO mice and protected their hearts from IR injury, even without IPC [ 18 ].…”

“…1 ) [ 18 ]. Furthermore, administration of recombinant MG53 proteins to simulate increased circulating MG53 significantly restored IPC function in MG53 KO mice and protected their hearts from IR injury, even without IPC [ 18 ].…”

“… NO Regulate KChIP2 by modulating NF-κB activity Bian et al [ 63 ] tPA-MG53 TG mice db/db mice Mice with sustained elevation of MG53 in their bloodstream show normal glucose handling and lived a healthy lifespan. NO Enhanced tissue repair and regeneration Wu et al [ 47 ] Diabetic db/db mice Neutralizing circulating MG53 with monoclonal antibodies has therapeutic effects in db/db mice YES MG53 binds to the insulin receptor inhibiting the insulin signaling pathway Wang et al [ 60 ] db/db mice Gain or loss of MG53, and administration of rhMG53 did not altered insulin signaling and glucose handling NO N/A Shan et al [ 18 ] IPC, I/R model of mice IPC induced secretion of MG53 and rhMG53 treatment are cardioprotective against I/R injury. NO Elevated activation of PKCδ Philouze et al [ 65 ] MG53 KO mice, HFD MG53 gene knock-down in muscle cells does not lead to impaired insulin response.…”

“… Activation of Akt/GSK3β pathway. Shan et al [ 18 ] I/R induced MI w/wo IPC in both mouse and rats For rats: 3 mg/kg, i.v. ; two dose: 5 min prior ischemia and post reperfusion; For mice: 6 mg/kg, i.v.…”