Inhaled TRIM72 Protein Protects Ventilation Injury to the Lung through Injury-guided Cell Repair

Alveolar Organoids in Lung Disease Modeling

Lung organoids display a tissue-specific functional phenomenon and mimic the features of the original organ. They can reflect the properties of the cells, such as morphology, polarity, proliferation rate, gene expression, and genomic profile. Alveolar type 2 (AT2) cells have a stem cell potential in the adult lung. They produce and secrete pulmonary surfactant and proliferate to restore the epithelium after damage. Therefore, AT2 cells are used to generate alveolar organoids and can recapitulate distal lung structures. Also, AT2 cells in human-induced pluripotent stem cell (iPSC)-derived alveolospheres express surfactant proteins and other factors, indicating their application as suitable models for studying cell-cell interactions. Recently, they have been utilized to define mechanisms of disease development, such as COVID-19, lung cancer, idiopathic pulmonary fibrosis, and chronic obstructive pulmonary disease. In this review, we show lung organoid applications in various pulmonary diseases, drug screening, and personalized medicine. In addition, stem cell-based therapeutics and approaches relevant to lung repair were highlighted. We also described the signaling pathways and epigenetic regulation of lung regeneration. It is critical to identify novel regulators of alveolar organoid generations to promote lung repair in pulmonary diseases.

Mechanisms of Endothelial Cell Membrane Repair: Progress and Perspectives

Endothelial cells are the crucial inner lining of blood vessels, which are pivotal in vascular homeostasis and integrity. However, these cells are perpetually subjected to a myriad of mechanical, chemical, and biological stresses that can compromise their plasma membranes. A sophisticated repair system involving key molecules, such as calcium, annexins, dysferlin, and MG53, is essential for maintaining endothelial viability. These components orchestrate complex mechanisms, including exocytosis and endocytosis, to repair membrane disruptions. Dysfunctions in this repair machinery, often exacerbated by aging, are linked to endothelial cell death, subsequently contributing to the onset of atherosclerosis and the progression of cardiovascular diseases (CVD) and stroke, major causes of mortality in the United States. Thus, identifying the core machinery for endothelial cell membrane repair is critically important for understanding the pathogenesis of CVD and stroke and developing novel therapeutic strategies for combating CVD and stroke. This review summarizes the recent advances in understanding the mechanisms of endothelial cell membrane repair. The future directions of this research area are also highlighted.

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.

Leveraging Plasma Membrane Repair Therapeutics for Treating Neurodegenerative Diseases

Plasma membrane repair is an essential cellular mechanism that reseals membrane disruptions after a variety of insults, and compromised repair capacity can contribute to the progression of many diseases. Neurodegenerative diseases are marked by membrane damage from many sources, reduced membrane integrity, elevated intracellular calcium concentrations, enhanced reactive oxygen species production, mitochondrial dysfunction, and widespread neuronal death. While the toxic intracellular effects of these changes in cellular physiology have been defined, the specific mechanism of neuronal death in certain neurodegenerative diseases remains unclear. An abundance of recent evidence indicates that neuronal membrane damage and pore formation in the membrane are key contributors to neurodegenerative disease pathogenesis. In this review, we have outlined evidence supporting the hypothesis that membrane damage is a contributor to neurodegenerative diseases and that therapeutically enhancing membrane repair can potentially combat neuronal death.

Chorionic villus-derived mesenchymal stem cells induce E3 ligase TRIM72 expression and regulate cell behaviors through ubiquitination of p53 in trophoblasts

Preeclampsia is a significant contributor for maternal or fetal morbidity and mortality, which is characterized by reduced invasion capacity of trophoblasts and is regulated by extracellular matrix (ECM). It is still under investigation whether chorionic villus-derived mesenchymal stem cells (CVMSC) could affect the functionality of trophoblasts. In this study, CVMSC-derived exosomes were isolated; their effect on trophoblasts was investigated based on the CCK8 assay, migration assay, and apoptosis detection. And the underlying mechanism of this effect was investigated using mRNA sequencing, western blot, co-immunoprecipitation, luciferase report assay, and ubiquitination assay. The results show that CVMSC-derived exosomes promote migration and proliferation of trophoblasts, and also reduce cell apoptosis. mRNA sequencing confirmed that after treatment of CVMSC-derived exosomes, Tripartite Motif Containing 72 (TRIM72) expression was upregulated and Tumor Protein P53 (P53) expression was downregulated, both significantly in trophoblasts. Subsequent study confirms that TRM72 can directly interact with P53 and promote P53 ubiquitination and proteasomal degradation, reducing apoptosis rate and elevating proliferation and migration in trophoblasts. Our study confirms that CVMSC-derived exosomes promote trophoblast migration and proliferation by upregulating TRIM72 expression, and subsequently advance P53 ubiquitination and proteasomal degradation.

Ventilator-induced lung-injury in mouse models: Is there a trap?

Ventilator-induced lung injury (VILI) is a serious acute injury to the lung tissue that can develop during mechanical ventilation of patients. Due to the mechanical strain of ventilation, damage can occur in the bronchiolar and alveolar epithelium resulting in a cascade of events that may be fatal to the patients. Patients requiring mechanical ventilation are often critically ill, which limits the possibility of obtaining patient samples, making VILI research challenging. In vitro models are very important for VILI research, but the complexity of the cellular interactions in multi-organ animals, necessitates in vivo studies where the mouse model is a common choice. However, the settings and duration of ventilation used to create VILI in mice vary greatly, causing uncertainty in interpretation and comparison of results. This review examines approaches to induce VILI in mouse models for the last 10 years, to our best knowledge, summarizing methods and key parameters presented across the studies. The results imply that a more standardized approach is warranted.

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.

MG53 inhibits angiogenesis through regulating focal adhesion kinase signalling

Mitsugumin 53 (MG53), which is expressed predominantly in striated muscle, has been demonstrated to be a myokine/cardiokine secreted from striated muscle under specific conditions. The important roles of MG53 in non-striated muscle tissues have also been examined in multiple disease models. However, no previous study has implicated MG53 in the control of endothelial cell function. In order to explore the effects of MG53 on endothelial cells, human umbilical vein endothelial cells (HUVECs) were stimulated with recombinant human MG53 (rhMG53). Then, rhMG53 uptake, focal adhesion kinase (FAK)/Src/Akt/ERK1/2 signalling pathway activation, cell migration and tube formation were determined in vitro. The efficacy of rhMG53 in regulating angiogenesis was also detected in postnatal mouse retinas. The results demonstrated that rhMG53 directly entered into endothelial cells in a cholesterol-dependent manner. The uptake of rhMG53 directly bound to FAK in endothelial cells, which resulted in a significant decrease in FAK phosphorylation at Y397. Accompanied by the dephosphorylation of FAK, rhMG53 uncoupled FAK-Src interaction and reduced the phosphorylation of Src at Y416. Consequently, the activation of FAK/Src downstream signalling pathways, such as Akt and ERK1/2, was also significantly inhibited by rhMG53. Furthermore, rhMG53 remarkably decreased HUVEC migration and tube formation in vitro and postnatal mouse retinal angiogenesis in vivo. Taken together, these data indicate that rhMG53 inhibits angiogenesis through regulating FAK/Src/Akt/ERK1/2 signalling pathways. This may provide a novel molecular mechanism for the impaired angiogenesis in ischaemic diseases.

MG53, A Tissue Repair Protein with Broad Applications in Regenerative Medicine

Under natural conditions, injured cells can be repaired rapidly through inherent biological processes. However, in the case of diabetes, cardiovascular disease, muscular dystrophy, and other degenerative conditions, the natural repair process is impaired. Repair of injury to the cell membrane is an important aspect of physiology. Inadequate membrane repair function is implicated in the pathophysiology of many human disorders. Recent studies show that Mitsugumin 53 (MG53), a TRIM family protein, plays a key role in repairing cell membrane damage and facilitating tissue regeneration. Clarifying the role of MG53 and its molecular mechanism are important for the application of MG53 in regenerative medicine. In this review, we analyze current research dissecting MG53′s function in cell membrane repair and tissue regeneration, and highlight the development of recombinant human MG53 protein as a potential therapeutic agent to repair multiple-organ injuries.

TRIM72 promotes alveolar epithelial cell membrane repair and ameliorates lung fibrosis

Background

Chronic tissue injury was shown to induce progressive scarring in fibrotic diseases such as idiopathic pulmonary fibrosis (IPF), while an array of repair/regeneration and stress responses come to equilibrium to determine the outcome of injury at the organ level. In the lung, type I alveolar epithelial (ATI) cells constitute the epithelial barrier, while type II alveolar epithelial (ATII) cells play a pivotal role in regenerating the injured distal lungs. It had been demonstrated that eukaryotic cells possess repair machinery that can quickly patch the damaged plasma membrane after injury, and our previous studies discovered the membrane-mending role of Tripartite motif containing 72 (TRIM72) that expresses in a limited number of tissues including the lung. Nevertheless, the role of alveolar epithelial cell (AEC) repair in the pathogenesis of IPF has not been examined yet.

Method

In this study, we tested the specific roles of TRIM72 in the repair of ATII cells and the development of lung fibrosis. The role of membrane repair was accessed by saponin assay on isolated primary ATII cells and rat ATII cell line. The anti-fibrotic potential of TRIM72 was tested with bleomycin-treated transgenic mice.

Results

We showed that TRIM72 was upregulated following various injuries and in human IPF lungs. However, TRIM72 expression in ATII cells of the IPF lungs had aberrant subcellular localization. In vitro studies showed that TRIM72 repairs membrane injury of immortalized and primary ATIIs, leading to inhibition of stress-induced p53 activation and reduction in cell apoptosis. In vivo studies demonstrated that TRIM72 protects the integrity of the alveolar epithelial layer and reduces lung fibrosis.

Conclusion

Our results suggest that TRIM72 protects injured lungs and ameliorates fibrosis through promoting post-injury repair of AECs.

TRIM14 Is a Key Regulator of the Type I IFN Response during Mycobacterium tuberculosis Infection

Tripartite motif-containing proteins (TRIMs) play a variety of recently described roles in innate immunity. Although many TRIMs regulate type I IFN expression following cytosolic nucleic acid sensing of viruses, their contribution to innate immune signaling and gene expression during bacterial infection remains largely unknown. Because Mycobacterium tuberculosis is an activator of cGAS-dependent cytosolic DNA sensing, we set out to investigate a role for TRIM proteins in regulating macrophage responses to M. tuberculosis In this study, we demonstrate that TRIM14, a noncanonical TRIM that lacks an E3 ubiquitin ligase RING domain, is a critical negative regulator of the type I IFN response in Mus musculus macrophages. We show that TRIM14 interacts with both cGAS and TBK1 and that macrophages lacking TRIM14 dramatically hyperinduce IFN stimulated gene (ISG) expression following M. tuberculosis infection, cytosolic nucleic acid transfection, and IFN-β treatment. Consistent with a defect in resolution of the type I IFN response, Trim14 knockout macrophages have more phospho-Ser754 STAT3 relative to phospho-Ser727 and fail to upregulate the STAT3 target Socs3, which is required to turn off IFNAR signaling. These data support a model whereby TRIM14 acts as a scaffold between TBK1 and STAT3 to promote phosphorylation of STAT3 at Ser727 and resolve ISG expression. Remarkably, Trim14 knockout macrophages hyperinduce expression of antimicrobial genes like Nos2 and are significantly better than control cells at limiting M. tuberculosis replication. Collectively, these data reveal an unappreciated role for TRIM14 in resolving type I IFN responses and controlling M. tuberculosis infection.

Enhancing membrane repair increases regeneration in a sciatic injury model

Various injuries to the neural tissues can cause irreversible damage to multiple functions of the nervous system ranging from motor control to cognitive function. The limited treatment options available for patients have led to extensive interest in studying the mechanisms of neuronal regeneration and recovery from injury. Since many neurons are terminally differentiated, by increasing cell survival following injury it may be possible to minimize the impact of these injuries and provide translational potential for treatment of neuronal diseases. While several cell types are known to survive injury through plasma membrane repair mechanisms, there has been little investigation of membrane repair in neurons and even fewer efforts to target membrane repair as a therapy in neurons. Studies from our laboratory group and others demonstrated that mitsugumin 53 (MG53), a muscle-enriched tripartite motif (TRIM) family protein also known as TRIM72, is an essential component of the cell membrane repair machinery in skeletal muscle. Interestingly, recombinant human MG53 (rhMG53) can be applied exogenously to increase membrane repair capacity both in vitro and in vivo. Increasing the membrane repair capacity of neurons could potentially minimize the death of these cells and affect the progression of various neuronal diseases. In this study we assess the therapeutic potential of rhMG53 to increase membrane repair in cultured neurons and in an in vivo mouse model of neurotrauma. We found that a robust repair response exists in various neuronal cells and that rhMG53 can increase neuronal membrane repair both in vitro and in vivo. These findings provide direct evidence of conserved membrane repair responses in neurons and that these repair mechanisms can be targeted as a potential therapeutic approach for neuronal injury.

TRIM21 Mitigates Human Lung Microvascular Endothelial Cells' Inflammatory Responses to LPS

Endothelial cell (EC) inflammation is regarded as an important pathogenic feature of many inflammatory diseases, including acute lung injury and sepsis. An increase in EC inflammation results in neutrophil infiltration from the blood to the site of inflammation, further promoting EC permeability. The ubiquitin E3 ligase TRIM21 has been implicated in human disorders; however, the roles of TRIM21 in endothelial dysfunction and acute lung injury have not been reported. Here, we reveal an antiinflammatory property of TRIM21 in a mouse model of acute lung injury and human lung microvascular ECs. Overexpression of TRIM21 by lentiviral vector infection effectively dampened LPS-induced neutrophil infiltration, cytokine release, and edema in mice. TRIM21 inhibited human lung microvascular endothelial cell inflammatory responses as evidenced by attenuation of the NF-κB pathway, release of IL-8, expression of intercellular adhesion molecules, and adhesion of monocytes to ECs. Furthermore, we demonstrated that TRIM21 was predominantly degraded by an increase in its monoubiquitination and lysosomal degradation after inflammatory stimuli. Thus, inhibition of vascular endothelial inflammation by TRIM21 provides a novel therapeutic target to lessen pulmonary inflammation.