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Background: As an integral component of cell membrane repair machinery, MG53 (mitsugumin 53) is important for cardioprotection induced by ischemia preconditioning and postconditioning. However, it also impairs insulin signaling via its E3 ligase activity-mediated ubiquitination-dependent degradation of IR (insulin receptor) and IRS1 (insulin receptor substrate 1) and its myokine function-induced allosteric blockage of IR. Here, we sought to develop MG53 into a cardioprotection therapy by separating its detrimental metabolic effects from beneficial actions. Methods: Using immunoprecipitation-mass spectrometry, site-specific mutation, in vitro kinase assay, and in vivo animal studies, we investigated the role of MG53 phosphorylation at serine 255 (S255). In particular, utilizing recombinant proteins and gene knock-in approaches, we evaluated the potential therapeutic effect of MG53-S255A mutant in treating cardiac ischemia/reperfusion injury in diabetic mice. Results: We identified S255 phosphorylation as a prerequisite for MG53 E3 ligase activity. Furthermore, MG53 S255 phosphorylation was mediated by GSK3β (glycogen synthase kinase 3 beta) and markedly elevated in the animal models with metabolic disorders. Thus, IR-IRS1-GSK3β-MG53 formed a vicious cycle in the pathogenesis of metabolic disorders where aberrant insulin signaling led to hyper-activation of GSK3β, which in turn, phosphorylated MG53 and enhanced its E3 ligase activity, and further impaired insulin sensitivity. Importantly, S255A mutant eliminated the E3 ligase activity while retained cell protective function of MG53. Consequently, the S255A mutant, but not the wild type MG53, protected the heart against ischemia/reperfusion injury in db/db mice with advanced diabetes, although both elicited cardioprotection in normal mice. Moreover, in S255A knock-in mice, S255A mutant also mitigated ischemia/reperfusion-induced myocardial damage in the diabetic setting. Conclusions: S255 phosphorylation is a biased regulation of MG53 E3 ligase activity. The MG53-S255A mutant provides a promising approach for the treatment of acute myocardial injury, especially in patients with metabolic disorders.

MG53 is a tripartite motif (TRIM) family E3 ligase and plays important biological functions. Here we present the cryo-EM structure of human MG53, showing that MG53 is a homodimer consisting of a ‘body’ and two ‘wings’. Intermolecular interactions are mainly distributed in the ‘body’ which is relatively stable, while two ‘wings’ are more dynamic. The overall architecture of MG53 is distinct from those of TRIM20 and TRIM25, illustrating the broad structural diversity of this protein family.

The receptor-interacting protein kinase 1 (RIPK1) is an essential signaling molecule in pathways for cell survival, apoptosis, and necroptosis. We report here that RIPK1 is upregulated in human colorectal cancer and promotes cell proliferation when overexpressed in a colon cancer cell line. RIPK1 interacts with mitochondrial Ca2+ uniporter (MCU) to promote proliferation by increasing mitochondrial Ca2+ uptake and energy metabolism. The ubiquitination site of RIPK1 (RIPK1-K377) was critical for this interaction with MCU and function in promoting cell proliferation. These findings identify the RIPK1-MCU pathway as a promising target to treat colorectal cancer.Significance: RIPK1-mediated cell proliferation through MCU is a central mechanism underlying colorectal cancer progression and may prove to be an important therapeutic target for colorectal cancer treatment. Cancer Res; 78(11); 2876–85. ©2018 AACR.

Figure S1. High levels of RIPK1 Expression shows Poor Prognosis. (A) Relative levels of RIPK1 expression in CRC on different tumor stages (n = 40). (B) Relative levels of RIPK1 expression between alive (n=30) and death (n=8) in CRC.

Table S1 shows the patients information in CRC.

Background: Cardiac ischemia/reperfusion (I/R) injury has emerged as an important therapeutic target for ischemic heart disease, the leading cause of morbidity and mortality worldwide. At present, there is no effective therapy for reducing cardiac I/R injury. CaMKII (Ca 2+ /calmodulin-dependent kinase II) plays a pivotal role in the pathogenesis of severe heart conditions, including I/R injury. Pharmacological inhibition of CaMKII is an important strategy in the protection against myocardial damage and cardiac diseases. To date, there is no drug targeting CaMKII for the clinical therapy of heart disease. Furthermore, at present, there is no selective inhibitor of CaMKII-δ, the major CaMKII isoform in the heart. Methods: A small-molecule kinase inhibitor library and a high-throughput screening system for the kinase activity assay of CaMKII-δ9 (the most abundant CaMKII-δ splice variant in human heart) were used to screen for CaMKII-δ inhibitors. Using cultured neonatal rat ventricular myocytes, human embryonic stem cell–derived cardiomyocytes, and in vivo mouse models, in conjunction with myocardial injury induced by I/R (or hypoxia/reoxygenation) and CaMKII-δ9 overexpression, we sought to investigate the protection of hesperadin against cardiomyocyte death and cardiac diseases. BALB/c nude mice with xenografted tumors of human cancer cells were used to evaluate the in vivo antitumor effect of hesperadin. Results: Based on the small-molecule kinase inhibitor library and screening system, we found that hesperadin, an Aurora B kinase inhibitor with antitumor activity in vitro, directly bound to CaMKII-δ and specifically blocked its activation in an ATP-competitive manner. Hesperadin functionally ameliorated both I/R- and overexpressed CaMKII-δ9–induced cardiomyocyte death, myocardial damage, and heart failure in both rodents and human embryonic stem cell–derived cardiomyocytes. In addition, in an in vivo BALB/c nude mouse model with xenografted tumors of human cancer cells, hesperadin delayed tumor growth without inducing cardiomyocyte death or cardiac injury. Conclusions: Here, we identified hesperadin as a specific small-molecule inhibitor of CaMKII-δ with dual functions of cardioprotective and antitumor effects. These findings not only suggest that hesperadin is a promising leading compound for clinical therapy of cardiac I/R injury and heart failure, but also provide a strategy for the joint therapy of cancer and cardiovascular disease caused by anticancer treatment.

As an integral component of cell membrane repair machinery, MG53 (mitsugumin 53) is important for cardioprotection induced by ischemia preconditioning and postconditioning. However, it also impairs insulin signaling via its E3 ligase activity-mediated ubiquitination-dependent degradation of IR (insulin receptor) and IRS1 (insulin receptor substrate 1) and its myokine function-induced allosteric blockage of IR. Here, we sought to develop MG53 into a cardioprotection therapy by separating its detrimental metabolic effects from beneficial actions.Using immunoprecipitation-mass spectrometry, site-specific mutation, in vitro kinase assay, and in vivo animal studies, we investigated the role of MG53 phosphorylation at serine 255 (S255). In particular, utilizing recombinant proteins and gene knock-in approaches, we evaluated the potential therapeutic effect of MG53-S255A mutant in treating cardiac ischemia/reperfusion injury in diabetic mice.We identified S255 phosphorylation as a prerequisite for MG53 E3 ligase activity. Furthermore, MG53S255 phosphorylation is a biased regulation of MG53 E3 ligase activity. The MG53-S255A mutant provides a promising approach for the treatment of acute myocardial injury, especially in patients with metabolic disorders.

Angiopoietin-like protein 3 (ANGPTL3) is an important regulator of lipoproteins by inhibiting both lipoprotein and endothelial lipases. It has been intensively investigated as a drug target for the treatment of dyslipidemia. In the present study, a modified small interfering RNA (siRNA) conjugated with GalNAc

Mammals exhibit limited heart regeneration ability, which can lead to heart failure after myocardial infarction. In contrast, zebrafish exhibit remarkable cardiac regeneration capacity. Several cell types and signaling pathways have been reported to participate in this process. However, a comprehensive analysis of how different cells and signals interact and coordinate to regulate cardiac regeneration is unavailable. We collected major cardiac cell types from zebrafish and performed high-precision single-cell transcriptome analyses during both development and post-injury regeneration. We revealed the cellular heterogeneity as well as the molecular progress of cardiomyocytes during these processes, and identified a subtype of atrial cardiomyocyte exhibiting a stem-like state which may transdifferentiate into ventricular cardiomyocytes during regeneration. Furthermore, we identified a regeneration-induced cell (RIC) population in the epicardium-derived cells (EPDC), and demonstrated Angiopoietin 4 (Angpt4) as a specific regulator of heart regeneration. angpt4 expression is specifically and transiently activated in RIC, which initiates a signaling cascade from EPDC to endocardium through the Tie2-MAPK pathway, and further induces activation of cathepsin K in cardiomyocytes through RA signaling. Loss of angpt4 leads to defects in scar tissue resolution and cardiomyocyte proliferation, while overexpression of angpt4 accelerates regeneration. Furthermore, we found that ANGPT4 could enhance proliferation of neonatal rat cardiomyocytes, and promote cardiac repair in mice after myocardial infarction, indicating that the function of Angpt4 is conserved in mammals. Our study provides a mechanistic understanding of heart regeneration at single-cell precision, identifies Angpt4 as a key regulator of cardiomyocyte proliferation and regeneration, and offers a novel therapeutic target for improved recovery after human heart injuries.

Rationale: The β 2 -adrenoceptor (β 2 -AR), a prototypical GPCR (G protein-coupled receptor), couples to both G s and G i proteins. Stimulation of the β 2 -AR is beneficial to humans and animals with heart failure presumably because it activates the downstream G i -PI3K-Akt cell survival pathway. Cardiac β 2 -AR signaling can be regulated by crosstalk or heterodimerization with other GPCRs, but the physiological and pathophysiological significance of this type of regulation has not been sufficiently demonstrated. Objective: Here, we aim to investigate the potential cardioprotective effect of β 2 -adrenergic stimulation with a subtype-selective agonist, (R,R’)-4-methoxy-1-naphthylfenoterol (MNF), and to decipher the underlying mechanism with a particular emphasis on the role of heterodimerization of β 2 -ARs with another GPCR, 5-hydroxytryptamine receptors 2B (5-HT 2B Rs). Methods and Results: Using pharmacological, genetic and biophysical protein-protein interaction approaches, we studied the cardioprotective effect of the β 2 -agonist, MNF, and explored the underlying mechanism in both in vivo in mice and cultured rodent cardiomyocytes insulted with doxorubicin, hydrogen peroxide (H 2 O 2 ) or ischemia/reperfusion. In doxorubicin (Dox)-treated mice, MNF reduced mortality and body weight loss, while improving cardiac function and cardiomyocyte viability. MNF also alleviated myocardial ischemia/reperfusion injury. In cultured rodent cardiomyocytes, MNF inhibited DNA damage and cell death caused by Dox, H 2 O 2 or hypoxia/reoxygenation. Mechanistically, we found that MNF or another β 2 -agonist zinterol markedly promoted heterodimerization of β 2 -ARs with 5-HT 2B Rs. Upregulation of the heterodimerized 5-HT 2B Rs and β 2 -ARs enhanced β 2 -AR-stimulated G i -Akt signaling and cardioprotection while knockdown or pharmacological inhibition of the 5-HT 2B R attenuated β 2 -AR-stimulated G i signaling and cardioprotection. Conclusions: These data demonstrate that the β 2 -AR-stimulated cardioprotective G i signaling depends on the heterodimerization of β 2 -ARs and 5-HT 2B Rs.

Background: CaMKII (Ca 2+ /calmodulin-dependent kinase II) plays a central role in cardiac ischemia/reperfusion (I/R) injury—an important therapeutic target for ischemic heart disease. In the heart, CaMKII-δ is the predominant isoform and further alternatively spliced into 11 variants. In humans, CaMKII-δ9 and CaMKII-δ3, the major cardiac splice variants, inversely regulate cardiomyocyte viability with the former pro-death and the latter pro-survival. However, it is unknown whether specific inhibition of the detrimental CaMKII-δ9 prevents cardiac I/R injury and, if so, what is the underlying mechanism. Here, we aim to investigate the cardioprotective effect of specific CaMKII-δ9 inhibition against myocardial I/R damage and determine the underlying mechanisms. Methods: The role and mechanism of CaMKII-δ9 in cardiac I/R injury were investigated in mice in vivo, neonatal rat ventricular myocytes, and human embryonic stem cell–derived cardiomyocytes. Results: We demonstrate that CaMKII-δ9 inhibition with knockdown or knockout of its feature exon, exon 16, protects the heart against I/R-elicited injury and subsequent heart failure. I/R-induced cardiac inflammation was also ameliorated by CaMKII-δ9 inhibition, and compared with the previously well-studied CaMKII-δ2, CaMKII-δ9 overexpression caused more profound cardiac inflammation. Mechanistically, in addition to IKKβ (inhibitor of NF-κB [nuclear factor-κB] kinase subunit β), CaMKII-δ9, but not δ2, directly interacted with IκBα (NF-κB inhibitor α) with its feature exon 13-16-17 combination and increased IκBα phosphorylation and consequently elicited more pronounced activation of NF-κB signaling and inflammatory response. Furthermore, the essential role of CaMKII-δ9 in myocardial inflammation and damage was confirmed in human cardiomyocytes. Conclusions: We not only identified CaMKII-δ9-IKK/IκB-NF-κB signaling as a new regulator of human cardiomyocyte inflammation but also demonstrated that specifically targeting CaMKII-δ9, the most abundant CaMKII-δ splice variant in human heart, markedly suppresses I/R-induced cardiac NF-κB activation, inflammation, and injury and subsequently ameliorates myocardial remodeling and heart failure, providing a novel therapeutic strategy for various ischemic heart diseases.

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.

Several recent clinical studies have shown that serum homocysteine (Hcy) levels are positively correlated, while vitamin BWe examined the effects of HHcy on NASH progression, metabolism, and autophagy in dietary and genetic mouse models, patients, and primates. We employed vitamin BSerum Hcy correlated with hepatic inflammation and fibrosis in NASH. Elevated hepatic Hcy induced and exacerbated NASH. Gene expression of hepatic Hcy-metabolizing enzymes was downregulated in NASH. Surprisingly, we found increased homocysteinylation (Hcy-lation) and ubiquitination of multiple hepatic proteins in NASH including the key autophagosome/lysosome fusion protein, Syntaxin 17 (Stx17). This protein was Hcy-lated and ubiquitinated, and its degradation led to a block in autophagy. Genetic manipulation of Stx17 revealed its critical role in regulating autophagy, inflammation and fibrosis during HHcy. Remarkably, dietary BHHcy plays a key role in the pathogenesis of NASH via Stx17 homocysteinylation. BThe incidence of non-alcoholic steatohepatitis, for which there are no approved pharmacological therapies, is increasing, posing a significant healthcare challenge. Herein, based on studies in mice, primates and humans, we found that dietary supplementation with vitamin B

Summary The AMP-activated protein kinase (AMPK) is a principal nutrient sensor and a master regulator of cellular energy homeostasis. Once activated, AMPK induces glucose uptake, which leads to a transient decrease in blood glucose level and can be used as an indicator of AMPK activity. Here, we present a protocol accessing AMPK activity in mice by measuring glucose uptake induced by AMPK activators, MK8722 and A769662. This protocol can be used to evaluate AMPK signaling in vivo under various pathophysiological conditions. For complete details on the use and execution of this protocol, please refer to Jiang et al. (2021)., Graphical Abstract, Highlights • Measurement of blood glucose level in mice using glucometer • Inducing glucose uptake in mice by administration of AMPK activators • Evaluation of AMPK activity in vivo via measuring AMPK activator-induced glucose, The AMP-activated protein kinase (AMPK) is a principal nutrient sensor and a master regulator of cellular energy homeostasis. Once activated, AMPK induces glucose uptake, which leads to a transient decrease in blood glucose level and can be used as an indicator of AMPK activity. Here, we present a protocol accessing AMPK activity in mice by measuring glucose uptake induced by AMPK activators, MK8722 and A769662. This protocol can be used to evaluate AMPK signaling in vivo under various pathophysiological conditions.

SummaryDiabetic heart disease is highly prevalent and characterized by diastolic dysfunction. The mechanisms of diabetic heart disease are poorly understood and no targeted therapies are available. Here we show that the diabetic myocardium (type 1 and type 2) is characterized by marked glycogen elevation and ectopic cellular localization - a paradoxical metabolic pathology given suppressed cardiomyocyte glucose uptake in diabetes. We demonstrate involvement of a glycogen-selective autophagy pathway (‘glycophagy’) defect in mediating this pathology. Genetically manipulated deficiency of Gabarapl1, an Atg8 autophagy homologue, induces cardiac glycogen accumulation and diastolic dysfunction. Stbd1, the Gabarapl1 cognate autophagosome partner is identified as a unique component of the early glycoproteome response to hyperglycemia in cardiac, but not skeletal muscle. Cardiac-targeted in vivo Gabarapl1 gene delivery normalizes glycogen levels, diastolic function and cardiomyocyte mechanics. These findings reveal that cardiac glycophagy is a key metabolic homeostatic process perturbed in diabetes that can be remediated by Gabarapl1 intervention.

Rationale: βARs (β-adrenergic receptors) are prototypical GPCRs (G protein–coupled receptors) that play a pivotal role in sympathetic regulation. In heart cells, β 1 AR signaling mediates a global response, including both l -type Ca 2+ channels in the sarcolemma/T tubules and RyRs (ryanodine receptors) in the SR (sarcoplasmic reticulum). In contrast, β 2 AR mediates local signaling with little effect on the function of SR proteins. Objective: To investigate the signaling relationship between β 1 ARs and β 2 ARs. Method and Results: Using whole-cell patch-clamp analyses combined with confocal Ca 2+ imaging, we found that the activation of compartmentalized β 2 AR signaling was able to convert the β 1 AR signaling from global to local mode, preventing β 1 ARs from phosphorylating RyRs that were only nanometers away from sarcolemma/T tubules. This offside compartmentalization was eliminated by selective inhibition of β 2 AR, GRK2 (GPCR kinase-2), βarr1 (β-arrestin-1), and phosphodiesterase-4. A knockin rat model harboring mutations of the last 3 serine residues of the β 1 AR C terminus, a component of the putative βarr1 binding site and GRK2 phosphorylation site, eliminated the offside compartmentalization conferred by β 2 AR activation. Conclusions: β 2 AR stimulation compartmentalizes β 1 AR signaling into nanoscale local domains in a phosphodiesterase-4–dependent manner by targeting the C terminus of β 1 ARs. This finding reveals a fundamental negative feed-forward mechanism that serves to avoid the cytotoxicity of circulating catecholamine and to sharpen the transient β 1 AR response of sympathetic excitation.

Background and Purpose— Emergency medical services (EMSs) are critical for early treatment of patients with ischemic stroke, yet data on EMS utilization and its association with timely treatment in China are still limited. Methods— We examined data from the Chinese Stroke Center Alliance for patients with ischemic stroke from June 2015 to June 2018. Absolute standardized difference was used for covariates’ balance assessments. We used multivariable logistic models with the generalized estimating equations to account for intrahospital clustering in identifying demographic and clinical factors associated with EMS use as well as in evaluating the association of EMS use with timely treatment. Results— Of the 560 447 patients with ischemic stroke analyzed, only 69 841 (12.5%) were transported by EMS. Multivariable-adjusted results indicated that those with younger age, lower levels of education, less insurance coverage, lower income, lower stroke severity, hypertension, diabetes mellitus, and peripheral vascular disease were less likely to use EMS. However, a history of cardiovascular diseases was associated with increased EMS usage. Compared with self-transport, EMS transport was associated with significantly shorter onset-to-door time, door-to-needle time (if prenotification was sent), earlier arrival (adjusted odds ratio [95% CIs] were 2.07 [1.95–2.20] for onset-to-door time ≤2 hours, 2.32 [2.18–2.47] for onset-to-door time ≤3.5 hours), and more rapid treatment (2.96 [2.88–3.05] for IV-tPA [intravenous recombinant tissue-type plasminogen activator] in eligible patients, 1.70 [1.62–1.77] for treatment with IV-tPA by 3 hours if onset-to-door time ≤2 hours, and 1.76 [1.70–1.83] for treatment with IV-tPA by 4.5 hours if onset-to-door time ≤3.5 hours). Conclusions— Although EMS transportation is associated with substantial reductions in prehospital delay and improved likelihood of early arrival and timely treatment, rate of utilization is currently low among Chinese patients with ischemic stroke. Developing an efficient EMS system and promoting culture-adapted education efforts are necessary for improving EMS activation.

Background: Mitsugumin 53 (MG53 or TRIM72), a striated muscle-specific E3 ligase, promotes ubiquitin-dependent degradation of the insulin receptor and insulin receptor substrate-1 and subsequently induces insulin resistance, resulting in metabolic syndrome and type 2 diabetes mellitus (T2DM). However, it is unknown how MG53 from muscle regulates systemic insulin response and energy metabolism. Increasing evidence demonstrates that muscle secretes proteins as myokines or cardiokines that regulate systemic metabolic processes. We hypothesize that MG53 may act as a myokine/cardiokine, contributing to interorgan regulation of insulin sensitivity and metabolic homeostasis. Methods: Using perfused rodent hearts or skeletal muscle, we investigated whether high glucose, high insulin, or their combination (conditions mimicking metabolic syndrome or T2DM) alters MG53 protein concentration in the perfusate. We also measured serum MG53 levels in rodents and humans in the presence or absence of metabolic diseases, particularly T2DM. The effects of circulating MG53 on multiorgan insulin response were evaluated by systemic delivery of recombinant MG53 protein to mice. Furthermore, the potential involvement of circulating MG53 in the pathogenesis of T2DM was assessed by neutralizing blood MG53 with monoclonal antibodies in diabetic db/db mice. Finally, to delineate the mechanism underlying the action of extracellular MG53 on insulin signaling, we analyzed the potential interaction of MG53 with extracellular domain of insulin receptor using coimmunoprecipitation and surface plasmon resonance assays. Results: Here, we demonstrate that MG53 is a glucose-sensitive myokine/cardiokine that governs the interorgan regulation of insulin sensitivity. First, high glucose or high insulin induces MG53 secretion from isolated rodent hearts and skeletal muscle. Second, hyperglycemia is accompanied by increased circulating MG53 in humans and rodents with diabetes mellitus. Third, systemic delivery of recombinant MG53 or cardiac-specific overexpression of MG53 causes systemic insulin resistance and metabolic syndrome in mice, whereas neutralizing circulating MG53 with monoclonal antibodies has therapeutic effects in T2DM db/db mice. Mechanistically, MG53 binds to the extracellular domain of the insulin receptor and acts as an allosteric blocker. Conclusions: Thus, MG53 has dual actions as a myokine/cardiokine and an E3 ligase, synergistically inhibiting the insulin signaling pathway. Targeting circulating MG53 opens a new therapeutic avenue for T2DM and its complications.

Although conventional genetic modification approaches for protein knockdown work very successfully due to the increasing use of CRISPR/Cas9, effective techniques for achieving protein depletion in adult animals, especially in large animals such as non-human primates, are lacking. Here, we report a chemical approach based on PROTACs technology that efficiently and quickly knocks down FKBP12 (12-kDa FK506-binding) protein globally in vivo. Both intraperitoneal and oral administration led to rapid, robust, and reversible FKBP12 degradation in mice. The efficiency and practicality of this method were successfully demonstrated in both large and small animals (mice, rats, Bama pigs, and rhesus monkeys). Furthermore, we showed this approach can also be applied to effectively knockdown other target proteins such as Bruton's tyrosine kinase (BTK). This chemical protein knockdown strategy provides a powerful research tool for gene function studies in animals, particularly in large animals, for which gene-targeted knockout strategies may remain unfeasible.

β-Arrestins are a small family of proteins important for signal transduction at G protein-coupled receptors (GPCRs). β-Arrestins are involved in the desensitization of GPCRs. Recently, biased ligands possessing different efficacies in activating the G protein- versus the β-arrestin-dependent signals downstream of a single GPCR have emerged, which can be used to selectively modulate GPCR signal transduction in such a way that desirable signals are enhanced to produce therapeutic effects while undesirable signals of the same GPCR are suppressed to avoid side effects. In the present study, we evaluated agonist bias for compounds developed along a drug discovery project of β(2)-adrenoceptor agonists. About 150 compounds, including derivatives of fenoterol, 2-amino-1-phenylethanol and 2-amino-2-phenylethanol, were obtained or synthesized, and initially screened for their β-adrenoceptor-mediated activities in the guinea pig tracheal smooth muscle relaxation assay or the cardiomyocyte contractility assay. Nineteen bioactive compounds were further assessed using both the HTRF cAMP assay and the PathHunter β-arrestin assay. Their concentration-response data in stimulating cAMP synthesis and β-arrestin recruitment were applied to the Black–Leff operational model for ligand bias quantitation. As a result, three compounds (L-2, L-4, and L-12) with the core structure of 5-(1-amino-2-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one were identified as a new series of β-arrestin-biased β(2)-adrenoceptor agonists, whereas salmeterol was found to be G(s)-biased. These findings would facilitate the development of novel drugs for the treatment of both heart failure and asthma.

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by destructive polyarthritis and systemic complications. It increases cardiovascular morbidity and mortality. However, the mechanism underlying RA-related cardiac damage remains largely unknown. Here, we found and characterized a non-human primate (NHP) model with spontaneous RA similar to the human conditions. Compared with the control group, the cardiac function in RA monkeys showed progressively deterioration; histologically, we found significantly increased inflammatory cell infiltration, cell death, and fibrosis in RA monkey heart tissue. Mechanistically, the upregulated receptor-interacting protein kinase 1 (RIPK1) in RA monkey heart tissue bound to voltage-dependent anion-selective channel 1 (VDAC1), increased VDAC1 oligomerization, and subsequently induced cardiac cell death and functional impairment. These findings identified that RIPK1-VDAC1 pathway is a promising target to treat cardiac impairment in RA. This unique model of RA will provide a valuable tool for mechanistic and translational studies.

The βHere, we aim to investigate the potential cardioprotective effect of βUsing pharmacological, genetic and biophysical protein-protein interaction approaches, we studied the cardioprotective effect of the βThese data demonstrate that the β

Introduction: MG53, essential for cardiac ischemic protection, negatively regulates insulin receptor (IR) to trigger globular metabolic dysfunction, which makes up a big obstacle for its clinical use. In vitro evidence shows that C14A site of MG53 might be a promising target both to abolish MG53 regulation on IR and to keep as much protective function. However, in vivo effect on C14A mutation of MG53 is urgent to be explored. Results: Here, we found C14A knock-in mice exerted relieved insulin resistance, blood glucose, and metabolic phenotype in high fat diet-induced pre-diabetic model. C14A mutation did NOT lessen the protective effect of MG53 by either intracellular knock-in or extracellular addition of mutant protein against ischemia/reperfusion(I/R) injury in db/+ mice. Consistent with our previous study, we found that administration of MG53 on diabetic mice showed aggravated blood glucose, insulin resistance, and unstable cardiac function to induce a higher risk under I/R attack. C14A mutation reduced the affinity between IR ECD and MG53 to block recombinant human (rh) MG53-WT-triggered acute hyperglycemia, increased heart infarct area and death rate on db/db mice during I/R injury. Post-conditioning of rhMG53-C14A stabilized intra-operative blood glucose and showed stronger anti-I/R ability than MG53-WT protein on db/db mice. Conclusions: C14A mutation is a potential target for MG53 treatment on diabetic heart. This potential therapeutic approach for the treatment of patients within type 2 diabetes provides a strategy of gene engineering optimizing well-known target to draw on advantages and avoid pitfalls.

Introduction: 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 (I/R) injury. Previous studies have shown that a multifunctional TRIM family protein, MG53 (or TRIM72), not only plays an essential role in IPC-mediated cardioprotection, but also as a myokine/cardiokine, can be secreted from the heart and skeletal muscle in response to metabolic stress in addition to its intracellular actions. Hypothesis: We hypothesized that IPC-mediated cardioprotection is causally related to MG53 secretion and figured out the underlying mechanism. Methods and Results: 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. IPC profoundly increased perfusate MG53 levels in mouse hearts by 5.50 ± 0.32 and 4.26 ± 0.40 folds from baseline over 0-60 and 60-120 min of reperfusion, respectively. Mechanistically, IPC-induced MG53 secretion is dependent on H 2 O 2 -evoked, Src-mediated phosphorylation of PKC-δ-Y311. Functionally, systemic delivery of recombinant human MG53 proteins (rhMG53) to mimic elevated circulating MG53 not only restored IPC function in MG53-deficient mice, but also protected rodent hearts from I/R injury even in the absence of IPC. Treatment of rhMG53 overtly decreased the infarct size (IF/AAR) induced by I/R compared to the BSA-treated control group (11.9 ± 1.8% vs 27.3 ± 2.0%, P 2 O 2 augmented MG53 secretion, and MG53 knockdown exacerbated H 2 O 2 -induced cell injury in human embryonic stem cell-derived cardiomyocytes. Conclusions: In conclusion, IPC and oxidative stress can trigger MG53 secretion from the heart via an H 2 O 2 -PKC-δ-dependent mechanism, and secreted MG53 acts as an essential factor conveying IPC-induced cardioprotection against ischemia/reperfusion injury. Recombinant MG53 proteins can be developed into a novel treatment for various diseases of human heart in which the endogenous MG53 is low.

The receptor-interacting protein kinase 1 (RIPK1) is an essential signaling molecule in pathways for cell survival, apoptosis, and necroptosis. We report here that RIPK1 is upregulated in human colorectal cancer and promotes cell proliferation when overexpressed in a colon cancer cell line. RIPK1 interacts with mitochondrial Ca2+ uniporter (MCU) to promote proliferation by increasing mitochondrial Ca2+ uptake and energy metabolism. The ubiquitination site of RIPK1 (RIPK1-K377) was critical for this interaction with MCU and function in promoting cell proliferation. These findings identify the RIPK1-MCU pathway as a promising target to treat colorectal cancer. Significance: RIPK1-mediated cell proliferation through MCU is a central mechanism underlying colorectal cancer progression and may prove to be an important therapeutic target for colorectal cancer treatment. Cancer Res; 78(11); 2876–85. ©2018 AACR.

MG53 is a member of tripartite motif family (TRIM) that expressed most abundantly in striated muscle. Using rodent models, many studies have demonstrated the MG53 not only facilitates membrane repair after ischemia reperfusion injury, but also contributes to the protective effects of both pre- and post-conditioning. Recently, however, it has been shown that MG53 participates in the regulation of many metabolic processes, especially insulin signaling pathway. Thus, sustained overexpression of MG53 may contribute to the development of various metabolic disorders in striated muscle. In this review, using cardiac muscle as an example, we will discuss muscle metabolic disturbances associated with diabetes and the current understanding of the underlying molecular mechanisms; in particular, the pathogenesis of diabetic cardiomyopathy. We will focus on the pathways that MG53 regulates and how the dysregulation of MG53 leads to metabolic disorders, thereby establishing a causal relationship between sustained upregulation of MG53 and the development of muscle insulin resistance and metabolic disorders. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.

Summary Exogenous overexpression of target genes in both general and specific cell types is important for mechanistic studies of gene function. Here, we provide a step-by-step protocol for cell culture, plasmid transfection in HEK293T, and adenoviral infection in C2C12 cells for gene overexpression in vitro, using MG53 as an example. This protocol enables sufficient and efficient gene expression for the downstream functional analysis. For complete details on the use and execution of this protocol, please refer to Jiang et al. (2021)., Graphical abstract, Highlights • Efficient gene expression in HEK293T by plasmid transfection with Lipofectamine 3000 • Robust gene expression in C2C12 myotubes by adenoviral infection • Differentiation of C2C12 myoblasts into myotubes, Exogenous overexpression of target genes in both general and specific cell types is important for mechanistic studies of gene function. Here, we provide a step-by-step protocol for cell culture, plasmid transfection in HEK293T, and adenoviral infection in C2C12 cells for gene overexpression in vitro, using MG53 as an example. This protocol enables sufficient and efficient gene expression for the downstream functional analysis.

MG53 (also known as tripartite motif, TRIM72) is a cardiac and skeletal muscle-specific TRIM-family protein that exhibits multiple biologic functions. First, MG53 participates in plasma membrane repair of the heart, skeletal muscle, and, other tissues. Second, MG53 is essentially involved in the cardioprotection of cardiac ischemic, preconditioning, and postconditioning by activating the PI3K-Akt-GSK3β and ERK1/2 survival signaling pathways. Moreover, systemic delivery of recombinant MG53 protein ameliorates the impact of a range of injury insults on the heart, skeletal muscle, lung, kidney, skin, and brain. It is noteworthy that chronic upregulation of MG53 induces insulin resistance and metabolic diseases, such as type 2 diabetes and its cardiovascular complications, by acting as an E3 ligase to mediate the degradation of insulin receptor and insulin receptor substrate-1. In addition, MG53 negatively regulates myogenesis. In summary, MG53 is a multifunctional protein involved in the vital physiologic and pathologic processes of multiple organs and is a promising therapeutic target for various human diseases. In this review, we comprehensively summarize current research progress on the biologic functions and therapeutic potential of MG53.

Article, see p 1056 Dilated cardiomyopathy (DCM) is a myocardial disease characterized by ventricular dilation and reduced pumping power. Numerous factors, including infections, congenital defects, genetic mutations, and exposure to chemotherapeutic agents or alcohol, can damage the myocardium and predispose the heart to DCM. Familial DCM accounts for 20% to 50% of all cases, with mutations affecting genes encoding cytoskeletal proteins (eg, titin, troponin, α-tropomyosin) or proteins required for contraction (eg, phospholamban).1 DCM is 1 of the leading causes of chronic heart failure (CHF). Conventional treatments for DCM and CHF have much in common. Mainstays include medications that block the renin-angiotensin and sympathetic nervous systems. Use of ACE inhibitors, angiotensin receptor blockers, and β-blockers in CHF is associated with reduction in both mortality and morbidity. Blocking the respective G protein-coupled receptors (GPCRs) protects the myocardium from further damage because exaggerated activation of these neurohormonal stimuli is maladaptive, leading to cardiomyocyte death, ventricular remodeling, and further deterioration of cardiac function. On the contrary, the use of inotropic agents in the treatment of heart failure has experienced ups and downs over the past 200 years. For >100 years, cardiac glycosides (digitalis) were the only effective therapy for CHF. Inotropes, including sympathomimetics, phosphodiesterase inhibitors, and calcium sensitizers developed in the late 20th century, improve short-term cardiac performance but in some cases increase mortality in the long run.2 Their use is restricted to acute decompensation in CHF. Despite these challenges, the quest for safe therapeutic agents to improve contractile performance of the failing heart has not ceased.3 In this issue of Circulation , Ryba and colleagues4 report the effect of long-term administration of TRV067, a novel ligand of the angiotensin II type 1 receptor (AT1R), on the structure and function of failing hearts in a genetic mouse model …

Obesity is characterized by aberrant fat accumulation. However, the intracellular signaling pathway that senses dietary fat and leads to fat storage remains elusive. Here, we have observed that the levels of histone deacetylase 6 (HDAC6) and the related family member HDAC10 are markedly reduced in adipose tissues of obese animals and humans. Mice with adipocyte-specific depletion of Hdac6 exhibited increased fat accumulation and reduced insulin sensitivity. In normal adipocytes, we found that reversal of P300/CBP-associated factor-induced (PCAF-induced) acetylation at K56 on cell death-inducing DFFA-like effector C (CIDEC, also known as FSP27) critically regulated lipid droplet fusion and lipid storage. Importantly, HDAC6 deacetylates CIDEC, leading to destabilization and reduced lipid droplet fusion. Accordingly, we observed elevated levels of CIDEC and its acetylated form in HDAC-deficient adipocytes as well as the adipose tissue of obese animals and humans. Fatty acids (FAs) prevented CIDEC deacetylation by promoting the dissociation of CIDEC from HDAC6, which resulted in increased association of CIDEC with PCAF on the endoplasmic reticulum. Control of CIDEC acetylation required the conversion of FAs to triacylglycerols. Thus, we have revealed a signaling axis that is involved in the coordination of nutrient availability, protein acetylation, and cellular lipid metabolic responses.

Background The impact of estimated glomerular filtration rate ( eGFR ) on clinical short‐term outcomes after stroke thrombolysis with tissue plasminogen activator remains controversial. Methods and Results We analyzed 18 320 ischemic stroke patients who received intravenous tissue plasminogen activator at participating hospitals in the Chinese Stroke Center Alliance between June 2015 and November 2017. Multivariate logistic regression models were used to evaluate associations between eGFR (2 ) and in‐hospital mortality and symptomatic intracerebral hemorrhage, adjusting for patient and hospital characteristics and the hospital clustering effect. Of the 18 320 patients receiving tissue plasminogen activator, 601 (3.3%) had an eGFR eGFR 45 to 59, 3679 (20.1%) had an eGFR 60 to 89, and 13 415 (73.2%) had an eGFR ≥90. As compared with eGFR ≥90, eGFR values CI , 2.18–5.91), 45 to 59 (4.0% versus 0.9%, adjusted odds ratio, 2.00; 95% CI , 1.18–3.38), and 60 to 89 (2.5% versus 0.9%, adjusted odds ratio, 1.67; 95% CI , 1.20–2.34) were independently associated with increased odds of in‐hospital mortality. However, there was no statistically significant association between eGFR and symptomatic intracerebral hemorrhage. Conclusions eGFR was associated with an increased risk of in‐hospital mortality in acute ischemic stroke patients after treatment with tissue plasminogen activator. eGFR is an important predictor of poststroke short‐term death but not of symptomatic intracerebral hemorrhage.

Background and Purpose— We aim to compare the risk of 1-year ischemic stroke recurrence and death for atrial fibrillation diagnosed after stroke (AFDAS), atrial fibrillation known before stroke (KAF), and sinus rhythm (SR). Methods— From June 2012 to January 2013, 19 604 patients with acute ischemic stroke were admitted to 219 urban hospitals in the China National Stroke Registry II. Based on heart rhythm assessed during admission, we classified patients as AFDAS, KAF, or SR. We explored the relationship between heart rhythm groups and 1-year ischemic stroke recurrence or death by using Cox regression adjusted for multiple covariates. Considering that death is a competing risk for stroke recurrence, we used the competing risks analysis of Fine and Gray and subdistribution Cox proportional hazards to test the association between heart rhythm and 1-year outcomes. Results— Among 19 604 ischemic stroke patients, 17 727 had SR, 495 AFDAS, and 1382 KAF. At 1 year, 54 (10.9%) patients with AFDAS, 182 (13.2%) with KAF, and 1008 (5.7%) with SR had recurrent ischemic strokes ( P P Conclusions— This study showed that AFDAS had similar risk of 1-year ischemic stroke recurrence and mortality when compared with KAF and higher risk when compared with SR. The potential risk of AFDAS should be given more emphasis, and appropriate treatment is needed to achieve reduction in the incidence of stroke recurrence and mortality.

Background and Purpose- Emergency medical services (EMSs) are critical for early treatment of patients with ischemic stroke, yet data on EMS utilization and its association with timely treatment in China are still limited. Methods- We examined data from the Chinese Stroke Center Alliance for patients with ischemic stroke from June 2015 to June 2018. Absolute standardized difference was used for covariates' balance assessments. We used multivariable logistic models with the generalized estimating equations to account for intrahospital clustering in identifying demographic and clinical factors associated with EMS use as well as in evaluating the association of EMS use with timely treatment. Results- Of the 560 447 patients with ischemic stroke analyzed, only 69 841 (12.5%) were transported by EMS. Multivariable-adjusted results indicated that those with younger age, lower levels of education, less insurance coverage, lower income, lower stroke severity, hypertension, diabetes mellitus, and peripheral vascular disease were less likely to use EMS. However, a history of cardiovascular diseases was associated with increased EMS usage. Compared with self-transport, EMS transport was associated with significantly shorter onset-to-door time, door-to-needle time (if prenotification was sent), earlier arrival (adjusted odds ratio [95% CIs] were 2.07 [1.95-2.20] for onset-to-door time ≤2 hours, 2.32 [2.18-2.47] for onset-to-door time ≤3.5 hours), and more rapid treatment (2.96 [2.88-3.05] for IV-tPA [intravenous recombinant tissue-type plasminogen activator] in eligible patients, 1.70 [1.62-1.77] for treatment with IV-tPA by 3 hours if onset-to-door time ≤2 hours, and 1.76 [1.70-1.83] for treatment with IV-tPA by 4.5 hours if onset-to-door time ≤3.5 hours). Conclusions- Although EMS transportation is associated with substantial reductions in prehospital delay and improved likelihood of early arrival and timely treatment, rate of utilization is currently low among Chinese patients with ischemic stroke. Developing an efficient EMS system and promoting culture-adapted education efforts are necessary for improving EMS activation.

βARs (β-adrenergic receptors) are prototypical GPCRs (G protein-coupled receptors) that play a pivotal role in sympathetic regulation. In heart cells, βTo investigate the signaling relationship between βUsing whole-cell patch-clamp analyses combined with confocal Caβ

Ca2+/calmodulin-dependent kinase II (CaMKII) is a multifunctional serine/threonine kinase family, and its δ isoform is predominant in the heart. Excessive CaMKII activation plays a pivotal role in the pathogenesis of severe heart conditions, including myocardial infarction, cardiomyopathy and heart failure. However, the identity of CaMKII splice variants and the mechanism(s) underlying CaMKII-mediated cardiac pathology remain elusive. Here, we show that CaMKII-δ9, the most abundant CaMKII-δ splice variant in human heart, potently promotes cardiomyocyte death, cardiomyopathy and heart failure by disrupting cardiomyocyte genome stability. Mechanistically, CaMKII-δ9, but not the previously well-studied CaMKII-δ2 and CaMKII-δ3, targets the ubiquitin-conjugating enzyme E2T (UBE2T) for phosphorylation and degradation, disrupting UBE2T-dependent DNA repair and leading to the accumulation of DNA damage and genome instability. These findings not only reveal a crucial role of CaMKII in the regulation of DNA repair, but also mark the CaMKII-δ9-UBE2T-DNA damage pathway as an important therapeutic target for cardiomyopathy and heart failure.