MG53 as a Novel Therapeutic Protein to Treat Acute Lung Injury

Enhancing Membrane Repair Using Recombinant MG53/TRIM72 (rhMG53) Reduces Neurotoxicity in Alzheimer's Disease Models

Alzheimer's Disease (AD) is the most common neurodegenerative disease that involves neuronal cell death initiated by the breakdown of the plasma membrane. Amyloid beta (Aβ), a hallmark protein that contributes to AD pathogenesis, is known to interact directly with the plasma membrane and induce increased intracellular calcium levels, reactive oxygen species (ROS), and cell death. Our recent studies revealed that elevated levels of Aβ42 induce a plasma membrane repair defect in neurons that compromises this conserved cellular response that would normally repair the disruption. Here, we tested if recombinant MG53/TRIM72 protein (rhMG53), a therapeutic protein known to increase plasma membrane repair capacity, could enhance membrane repair in AD neurons. rhMG53 increased plasma membrane repair in ex vivo and in vitro tissue treated with Aβ42 or cerebrospinal fluid from AD patients, normalizing intracellular calcium levels, ROS, and cell death in treated cells. This study demonstrates that increasing plasma membrane repair can rescue neural cells from the neurotoxic effects of Aβ, indicating that elevating plasma membrane repair could be a viable therapeutic approach to reduce neuronal death in AD.

Branched-chain amino acids and L-alanine supplementation ameliorate calcium dyshomeostasis in sarcopenia: New insights for nutritional interventions

Introduction: During aging, sarcopenia and decline in physiological processes lead to partial loss of muscle strength, atrophy, and increased fatigability. Muscle changes may be related to a reduced intake of essential amino acids playing a role in proteostasis. We have recently shown that branched-chain amino acid (BCAA) supplements improve atrophy and weakness in models of muscle disuse and aging. Considering the key roles that the alteration of Ca2+-related homeostasis and store-operated calcium entry (SOCE) play in several muscle dysfunctions, this study has been aimed at gaining insight into the potential ability of BCAA-based dietary formulations in aged mice on various players of Ca2+ dyshomeostasis. Methods: Seventeen-month-old male C57BL/6J mice received a 12-week supplementation with BCAAs alone or boosted with two equivalents of L-alanine (2-Ala) or with dipeptide L-alanyl-L-alanine (Di-Ala) in drinking water. Outcomes were evaluated on ex vivo skeletal muscles indices vs. adult 3-month-old male C57BL/6J mice. Results: Ca2+ imaging confirmed a decrease in SOCE and an increase of resting Ca2+ concentration in aged vs. adult mice without alteration in the canonical components of SOCE. Aged muscles vs. adult muscles were characterized by a decrease in the expression of ryanodine receptor 1 (RyR1), the Sarco-Endoplasmic Reticulum Calcium ATPase (SERCA) pump, and sarcalumenin together with an alteration of the expression of mitsugumin 29 and mitsugumin 53, two recently recognized players in the SOCE mechanism. BCAAs, particularly the formulation BCAAs+2-Ala, were able to ameliorate all these alterations. Discussion: These results provide evidence that Ca2+ homeostasis dysfunction plays a role in the functional deficit observed in aged muscle and supports the interest of dietary BCAA supplementation in counteracting sarcopenia-related SOCE dysregulation.

Fracture haematoma proteomics

Aims

The aim of this study was to determine the fracture haematoma (fxH) proteome after multiple trauma using label-free proteomics, comparing two different fracture treatment strategies.

Methods

A porcine multiple trauma model was used in which two fracture treatment strategies were compared: early total care (ETC) and damage control orthopaedics (DCO). fxH was harvested and analyzed using liquid chromatography-tandem mass spectrometry. Per group, discriminating proteins were identified and protein interaction analyses were performed to further elucidate key biomolecular pathways in the early fracture healing phase.

Results

The early fxH proteome was characterized by immunomodulatory and osteogenic proteins, and proteins involved in the coagulation cascade. Treatment-specific proteome alterations were observed. The fxH proteome of the ETC group showed increased expression of pro-inflammatory proteins related to, among others, activation of the complement system, neutrophil functioning, and macrophage activation, while showing decreased expression of proteins related to osteogenesis and tissue remodelling. Conversely, the fxH proteome of the DCO group contained various upregulated or exclusively detected proteins related to tissue regeneration and remodelling, and proteins related to anti-inflammatory and osteogenic processes.

Conclusion

The early fxH proteome of the ETC group was characterized by the expression of immunomodulatory, mainly pro-inflammatory, proteins, whereas the early fxH proteome of the DCO group was more regenerative and osteogenic in nature. These findings match clinical observations, in which enhanced surgical trauma after multiple trauma causes dysbalanced inflammation, potentially leading to reduced tissue regeneration, and gained insights into regulatory mechanisms of fracture healing after severe trauma.

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.

Is MG53 a potential therapeutic target for cancer?

Cancer treatment still encounters challenges, such as side effects and drug resistance. The tripartite-motif (TRIM) protein family is widely involved in regulation of the occurrence, development, and drug resistance of tumors. MG53, a member of the TRIM protein family, shows strong potential in cancer therapy, primarily due to its E3 ubiquitin ligase properties. The classic membrane repair function and anti-inflammatory capacity of MG53 may also be beneficial for cancer prevention and treatment. However, MG53 appears to be a key regulatory factor in impaired glucose metabolism and a negative regulatory mechanism in muscle regeneration that may have a negative effect on cancer treatment. Developing MG53 mutants that balance the pros and cons may be the key to solving the problem. This article aims to summarize the role and mechanism of MG53 in the occurrence, progression, and invasion of cancer, focusing on the potential impact of the biological function of MG53 on cancer therapy.

Activation of MG53 Enhances Cell Survival and Engraftment of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes in Injured Hearts

BACKGROUND AND OBJECTIVE

Our previous studies demonstrated that MG53 protein can protect the myocardium, but its use as a therapeutic is challenging due to its short half-life in blood circulation. This study aimed to investigate the cardioprotective role of MG53 on human induced pluripotent stem cell-derived cardiomyocytes (HiPSC-CMs) in the context of myocardial ischemia/reperfusion (I/R).

METHODS

In vitro: HiPSC-CMs were transfected with adenoviral MG53 (HiPSC-CMsMG53), in which the expression of MG53 can be controlled by doxycycline (Dox), and the cells were then exposed to H2O2 to mimic ischemia/reperfusion injury. In vivo: HiPSC-CMsMG53 were transplanted into the peri-infarct region in NSG™ mice after I/R. After surgery, mice were treated with Dox (+ Dox) to activate MG53 expression (sucrose as a control of -Dox) and then assessed by echocardiography and immunohistochemistry.

RESULTS

MG53 can be expressed in HiPSC-CMMG53 and released into the culture medium after adding Dox. The cell survival rate of HiPSC-CMMG53 was improved by Dox under the H2O2 condition. After 14 and 28 days of ischemia/reperfusion (I/R), transplanted HiPSC-CMsMG53 + Dox significantly improved heart function, including ejection fraction (EF) and fractional shortening (FS) in mice, compared to HiPSC-CMsMG53-Dox, and reduced the size of the infarction. Additionally, HiPSC-CMMG53 + Dox mice demonstrated significant engraftment in the myocardium as shown by staining human nuclei-positive cells. In addition, the cell survival-related AKT signaling was found to be more active in HiPSC-CMMG53 + Dox transplanted mice's myocardium compared to the HiPSC-CMMG53-Dox group. Notably, the Dox treatment did not cause harm to other organs.

CONCLUSION

Inducible MG53 expression is a promising approach to enhance cell survival and engraftment of HiPSC-CMs for cardiac repair.

Cellular and molecular mechanisms underlying plasma membrane functionality and integrity

The plasma membrane not only protects the cell from the extracellular environment, acting as a selective barrier, but also regulates cellular events that originate at the cell surface, playing a key role in various biological processes that are essential for the preservation of cell homeostasis. Therefore, elucidation of the mechanisms involved in the maintenance of plasma membrane integrity and functionality is of utmost importance. Cells have developed mechanisms to ensure the quality of proteins that inhabit the cell surface, as well as strategies to cope with injuries inflicted to the plasma membrane. Defects in these mechanisms can lead to the development or onset of several diseases. Despite the importance of these processes, a comprehensive and holistic perspective of plasma membrane quality control is still lacking. To tackle this gap, in this Review, we provide a thorough overview of the mechanisms underlying the identification and targeting of membrane proteins that are to be removed from the cell surface, as well as the membrane repair mechanisms triggered in both physiological and pathological conditions. A better understanding of the mechanisms underlying protein quality control at the plasma membrane can reveal promising and unanticipated targets for the development of innovative therapeutic approaches.

TRIM72 exerts antitumor effects in breast cancer and modulates lactate production and MCT4 promoter activity by interacting with PPP3CA

A hypoxic tumor microenvironment (TME) promotes cancer progression, yet its value as a therapeutic target remains underexploited. Tripartite motif-containing 72 (TRIM72) may protect cells against various stresses including hypoxia. Recently, low TRIM72 expression has been implicated in cancer progression. However, the biological role and molecular mechanism of TRIM72 in breast cancer (BC) remain unclear. Herein, we analyzed the TRIM72 expression in BC tissue and cell lines by western blot (WB) and quantitative reverse transcription-PCR. We established the overexpression of TRIM72 using plasmids and lentiviral-mediated upregulation, as well as downregulation of protein phosphatase 3 catalytic subunit alpha (PPP3CA) by siRNA. The tumor-suppressive roles of TRIM72 were assessed on BT549 and MDA-MB-231 cells by MTS, Transwell, and flow cytometry assays in vitro and in xenografted tumors in vivo. The molecular mechanism of TRIM72 was investigated by luciferase reporter and co-immunoprecipitation (Co-IP) assay. Lactate production was measured by ELISA under hypoxic environments induced by CoCl2. Moreover, the expression of PI3K/Akt/mTOR pathway-associated proteins was detected by WB in BC cells. Results showed that TRIM72 was downregulated in BC. Overexpression of TRIM72 inhibited tumor proliferation and invasion in vitro and in a xenograft tumor model. Mechanistically, PPP3CA altered the inhibitory effects of TRIM72 on hypoxia-induced lactate production and monocarboxylate transporter 4-promoter activity, as well as the effect of the PI3K/Akt/mTOR signaling pathway. Our study suggests that TRIM72 modulates the TME and plays tumor-suppressive roles in BC progression. Therefore, TRIM72 may serve as a potential therapeutic target in BC.

MG53 attenuates nitrogen mustard-induced acute lung injury

Nitrogen mustard (NM) is an alkylating vesicant that causes severe pulmonary injury. Currently, there are no effective means to counteract vesicant‐induced lung injury. MG53 is a vital component of cell membrane repair and lung protection. Here, we show that mice with ablation of MG53 are more susceptible to NM‐induced lung injury than the wild‐type mice. Treatment of wild‐type mice with exogenous recombinant human MG53 (rhMG53) protein ameliorates NM‐induced lung injury by restoring arterial blood oxygen level, by improving dynamic lung compliance and by reducing airway resistance. Exposure of lung epithelial and endothelial cells to NM leads to intracellular oxidative stress that compromises the intrinsic cell membrane repair function of MG53. Exogenous rhMG53 protein applied to the culture medium protects lung epithelial and endothelial cells from NM‐induced membrane injury and oxidative stress, and enhances survival of the cells. Additionally, we show that loss of MG53 leads to increased vulnerability of macrophages to vesicant‐induced cell death. Overall, these findings support the therapeutic potential of rhMG53 to counteract vesicant‐induced lung injury.

The Emerging Roles of Tripartite Motif Proteins (TRIMs) in Acute Lung Injury

Acute lung injury (ALI) is an inflammatory disorder of the lung that causes high mortality and lacks any pharmacological intervention. Ubiquitination plays a critical role in the pathogenesis of ALI as it regulates the alveolocapillary barrier and the inflammatory response. Tripartite motif (TRIM) proteins are one of the subfamilies of the RING-type E3 ubiquitin ligases, which contains more than 80 distinct members in humans involved in a broad range of biological processes including antivirus innate immunity, development, and tumorigenesis. Recently, some studies have shown that several members of TRIM family proteins play important regulatory roles in inflammation and ALI. Herein, we integrate emerging evidence regarding the roles of TRIMs in ALI. Articles were selected from the searches of PubMed database that had the terms "acute lung injury," "ubiquitin ligases," "tripartite motif protein," "inflammation," and "ubiquitination" using both MeSH terms and keywords. Better understanding of these mechanisms may ultimately lead to novel therapeutic approaches by targeting TRIMs for ALI treatment.

MG53 suppresses tumor progression and stress granule formation by modulating G3BP2 activity in non-small cell lung cancer

Background

Cancer cells develop resistance to chemotherapeutic intervention by excessive formation of stress granules (SGs), which are modulated by an oncogenic protein G3BP2. Selective control of G3BP2/SG signaling is a potential means to treat non-small cell lung cancer (NSCLC).

Methods

Co-immunoprecipitation was conducted to identify the interaction of MG53 and G3BP2. Immunohistochemistry and live cell imaging were performed to visualize the subcellular expression or co-localization. We used shRNA to knock-down the expression MG53 or G3BP2 to test the cell migration and colony formation. The expression level of MG53 and G3BP2 in human NSCLC tissues was tested by western blot analysis. The ATO-induced oxidative stress model was used to examine the effect of rhMG53 on SG formation. Moue NSCLC allograft experiments were performed on wild type and transgenic mice with either knockout of MG53, or overexpression of MG53. Human NSCLC xenograft model in mice was used to evaluate the effect of MG53 overexpression on tumorigenesis.

Results

We show that MG53, a member of the TRIM protein family (TRIM72), modulates G3BP2 activity to control lung cancer progression. Loss of MG53 results in the progressive development of lung cancer in mg53^-/- mice. Transgenic mice with sustained elevation of MG53 in the bloodstream demonstrate reduced tumor growth following allograft transplantation of mouse NSCLC cells. Biochemical assay reveals physical interaction between G3BP2 and MG53 through the TRIM domain of MG53. Knockdown of MG53 enhances proliferation and migration of NSCLC cells, whereas reduced tumorigenicity is seen in NSCLC cells with knockdown of G3BP2 expression. The recombinant human MG53 (rhMG53) protein can enter the NSCLC cells to induce nuclear translation of G3BP2 and block arsenic trioxide-induced SG formation. The anti-proliferative effect of rhMG53 on NSCLC cells was abolished with knockout of G3BP2. rhMG53 can enhance sensitivity of NSCLC cells to undergo cell death upon treatment with cisplatin. Tailored induction of MG53 expression in NSCLC cells suppresses lung cancer growth via reduced SG formation in a xenograft model.

Conclusion

Overall, these findings support the notion that MG53 functions as a tumor suppressor by targeting G3BP2/SG activity in NSCLCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-021-01418-3.

Muscle multiorgan crosstalk with MG53 as a myokine for tissue repair and regeneration

Through stress and injury to tissues, the cell membrane is damaged and can lead to cell death and a cascade of inflammatory events. Soluble factors that mitigate and repair membrane injury are important to normal homeostasis and are a potential therapeutic intervention for regenerative medicine. A myokine is a type of naturally occurring factors that come from muscle and have impact on remote organs. MG53, a tripartite motif-containing family protein, is such a myokine which has protective effects on lungs, kidneys, liver, heart, eye, and brain. Three mechanisms of action for the beneficial regenerative medicine potential of MG53 have been identified and consist of 1) repair of acute injury to the cellular membrane, 2) anti-inflammatory effects associated with chronic injuries, and 3) rejuvenation of stem cells for tissue regeneration. As such, MG53 has the potential to be a novel and effective regeneration medicine therapeutic.