Prognostic Value of Circulating MG53 Levels in Acute Myocardial Infarction

MG53: A new protagonist in the precise treatment of cardiomyopathies

Cardiomyopathies (CMs) are highly heterogeneous progressive heart diseases characterised by structural and functional abnormalities of the heart, whose intricate pathogenesis has resulted in a lack of effective treatment options. Mitsugumin 53 (MG53), also known as Tripartite motif protein 72 (TRIM72), is a tripartite motif family protein from the immuno-proteomic library expressed primarily in the heart and skeletal muscle. Recent studies have identified MG53 as a potential cardioprotective protein that may play a crucial role in CMs. Therefore, the objective of this review is to comprehensively examine the underlying mechanisms mediated by MG53 responsible for myocardial protection, elucidate the potential role of MG53 in various CMs as well as its dominant status in the diagnosis and prognosis of human myocardial injury, and evaluate the potential therapeutic value of recombinant human MG53 (rhMG53) in CMs. It is expected to yield novel perspectives regarding the clinical diagnosis and therapeutic treatment of CMs.

MG53 alleviates hypoxia/reoxygenation-induced cardiomyocyte injury by succinylation and ubiquitination modification

BACKGROUND

Mitsugumin 53 (MG53) is a membrane repair factor that is associated with acute myocardial infarction. This study aimed to investigate the effects of MG53 on cardiomyocyte injury and the posttranslational modification of MG53.

METHODS

Cardiomyocyte injury was evaluated by enzyme-linked immunosorbent assay and flow cytometry. The succinylation and ubiquitination levels of MG53 were examined by immunoprecipitation (IP) and western blot. The relationship between MG53 and KAT3B or SIRT7 was assessed by co-IP and immunofluorescence.

RESULTS

The results showed that overexpression of MG53 inhibited inflammation response and apoptosis of cardiomyocytes induced by hypoxia/reoxygenation (H/R). Succinylation and protein levels of MG53 were downregulated in H/R-induced cells, which was inhibited by SIRT7 and promoted by KAT3B. SIRT7 aggravated and KAT3B alleviated MG53-mediated cardiomyocyte injury. Moreover, MG53 was succinylated and ubiquitinated at K130.

CONCLUSION

SIRT7 inhibited/KAT3B promoted succinylation of MG53 at K130 sites, which suppressed ubiquitination of MG53 and upregulated its protein levels, thereby alleviating H/R-induced cardiomyocyte injury. The findings suggested that MG53 may be a potential therapy for myocardial infarction.

Association of MG53 with presence of type 2 diabetes mellitus, glycemic control, and diabetic complications

OBJECTIVES

Mitsugumin 53 (MG53) is a myokine that acts as a membrane repair protein in tissues. Data on the effect of MG53 on insulin signaling and type 2 diabetes mellitus (T2 DM) are still unknown; most are from preclinical studies. Nevertheless, some researchers have argued that it may be a new pathogenic factor, and therapies targeting MG53 may be a new avenue for T2 DM. Our study aims to evaluate the relationship of circulating MG53 levels with the presence of diabetes, diabetic complications, and glycemic control.

METHODS

We conducted a case-control study with 107 patients with T2 DM and 105 subjects without insulin resistance-related disease. Concurrent blood samples were used for serum MG53 levels and other biochemical laboratory data. MG53 concentration was measured using Human-MG53, an enzyme-linked immunosorbent assay kit (Cat# CSB-EL024511HU).

RESULTS

We found no difference in MG53 levels between the diabetic and control groups (p = 0.914). Furthermore, when the subjects were divided into tertiles according to their MG53 levels, we did not find any difference between the groups in terms of the presence of diabetes (p = 0.981). Additionally, no correlation was observed between weight, BMI, waist circumference, systolic and diastolic blood pressure, fasting blood glucose, HbA1c, albumin excretion in the urine, e-GFR levels, and MG53. Finally, MG53 levels were similar between the groups with and without microvascular and macrovascular complications of diabetes.

CONCLUSION

Our research finding provides insightful clinical evidence of lack of association between the levels of MG53 and T2 DM or glycemic control, at least in the studied population of Turkeys ethnicity. However, further clinical studies are warranted to establish solid evidence of the link between MG53, insulin resistance and glycemic control in a wider population elsewhere in the world.

Protective role of MG53 against ischemia/reperfusion injury on multiple organs: A narrative review

Ischemia/reperfusion (I/R) injury is a common clinical problem after coronary angioplasty, cardiopulmonary resuscitation, and organ transplantation, which can lead to cell damage and death. Mitsugumin 53 (MG53), also known as Trim72, is a conservative member of the TRIM family and is highly expressed in mouse skeletal and cardiac muscle, with minimal amounts in humans. MG53 has been proven to be involved in repairing cell membrane damage. It has a protective effect on I/R injury in multiple oxygen-dependent organs, such as the heart, brain, lung, kidney, and liver. Recombinant human MG53 also plays a unique role in I/R, sepsis, and other aspects, which is expected to provide new ideas for related treatment. This article briefly reviews the pathophysiology of I/R injury and how MG53 mitigates multi-organ I/R injury.

MG53 marks poor beta cell performance and predicts onset of type 2 diabetes in subjects with different degrees of glucose tolerance

AIM

- MG53 is a myokine modulating insulin signalling in several tissues; its relationship to glucose tolerance or risk of developing type 2 diabetes mellitus (T2DM) is unknown. This observational, prospective study aimed at evaluating the relationship between MG53 and glucose tolerance, testing whether its circulating levels may be associated with disease progression in a cohort at high risk of T2DM.

METHODS

- Five hundred and fifteen subjects who underwent a deep characterization of their glucose tolerance in the years 2003-2005 participated in this study. MG53 levels were measured at baseline. Glucose tolerance status was available over a follow-up of 15±2 years for 283 of them; their vital status as of December 2020 was also retrieved.

RESULTS

- MG53 levels were significantly lower in subjects with normal glucose tolerance than in subjects with impaired glucose regulation (IGR) or T2DM. Individuals in the highest MG53 levels quartile had more frequently 1h-post load glucose ≥155 mg/dL (54% vs 39%; p=0.015), worse proportional control of β-cell function (p<0.05-0.01), as determined by mathematical modelling, and worse Disposition Index (DI) (0.0155±0.0081 vs 0.0277±0.0030; p<0.0001). At follow-up, baseline MG53 levels were higher in progressors than in non-progressors (120.1±76.7 vs 72.7±63.2 pg/ml; p=0.001; ROC curve area for incident diabetes of 0.704). In a multivariable regression with classic risk factors for T2DM and DI, MG53 remained independently associated with progression with T2DM.

CONCLUSION

- MG53 may be a novel biomarker of glucose dysregulation associated with β-cell dysfunction, likely improving our ability to identify, among high-risk subjects, those more likely to develop T2DM.

Diagnostic and Prognostic Biomarkers for Myocardial Infarction

The incidence of myocardial infarction (MI) increases every year worldwide. Better diagnostic and prognostic biomarkers for clinical applications are the consistent pursuit of MI research. In addition to electrocardiogram, echocardiography, coronary angiography, etc., circulating biomarkers are essential for the diagnosis, prognosis, and treatment effect monitoring of MI patients. In this review, we assessed both strength and weakness of MI circulating biomarkers including: (1) originated from damaged myocardial tissues including current golden standard cardiac troponin, (2) released from non-myocardial tissues due to MI-induced systems reactions, and (3) preexisted in blood circulation before the occurrence of MI event. We also summarized newly reported MI biomarkers. We proposed that the biomarkers preexisting in blood circulation before MI incidents should be emphasized in research and development for MI prevention in near future.