Negative regulation of AMPK signaling by high glucose via E3 ubiquitin ligase MG53.

As a master regulator of metabolism, AMP-activated protein kinase (AMPK) is activated upon energy and glucose shortage but suppressed upon overnutrition. Exaggerated negative regulation of AMPK signaling by nutrient overload plays a crucial role in metabolic diseases. However, the mechanism underlying the negative regulation is poorly understood. Here, we demonstrate that high glucose represses AMPK signaling via MG53 (also called TRIM72) E3-ubiquitin-ligase-mediated AMPKα degradation and deactivation. Specifically, high-glucose-stimulated reactive oxygen species (ROS) signals AKT to phosphorylate AMPKα at S485/491, which facilitates the recruitment of MG53 and the subsequent ubiquitination and degradation of AMPKα. In addition, high glucose deactivates AMPK by ROS-dependent suppression of phosphorylation of AMPKα at T172. These findings not only delineate the mechanism underlying the impairment of AMPK signaling in overnutrition-related diseases but also highlight the significance of keeping the yin-yang balance of AMPK signaling in the maintenance of metabolic homeostasis.

Correction: DPPA2/4 and SUMO E3 ligase PIAS4 opposingly regulate zygotic transcriptional program.

[This corrects the article DOI: 10.1371/journal.pbio.3000324.].

Targeting CaMKII-δ9 Ameliorates Cardiac Ischemia/Reperfusion Injury by Inhibiting Myocardial Inflammation.

BACKGROUND: CaMKII (Ca2+/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 IKKß (inhibitor of NF-κB [nuclear factor-κB] kinase subunit ß), 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.

Blocking MG53S255 Phosphorylation Protects Diabetic Heart From Ischemic Injury.

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, MG53S255 phosphorylation was mediated by GSK3ß (glycogen synthase kinase 3 beta) and markedly elevated in the animal models with metabolic disorders. Thus, IR-IRS1-GSK3ß-MG53 formed a vicious cycle in the pathogenesis of metabolic disorders where aberrant insulin signaling led to hyper-activation of GSK3ß, 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.

Comparison of the clinical and radiographic outcomes of cortical bone trajectory and traditional trajectory pedicle screw fixation in transforaminal lumbar interbody fusion: a randomized controlled trial.

PURPOSE: To compare the clinical outcomes and radiographic outcomes of cortical bone trajectory (CBT) and traditional trajectory (TT) pedicle screw fixation in patients treated with single-level transforaminal lumbar interbody fusion (TLIF). METHODS: This trial included a total of 224 patients with lumbar spine disease who required single-level TLIF surgery. Patients were randomly assigned to the CBT and TT groups at a 1:1 ratio. Demographics and clinical and radiographic data were collected to evaluate the efficacy and safety of CBT and TT screw fixation in TLIF. RESULTS: The baseline characteristic data were similar between the CBT and TT groups. Back and leg pain for both the CBT and TT groups improved significantly from baseline to 24 months postoperatively. The CBT group experienced less pain than the TT group at one week postoperatively. The postoperative radiographic results showed that the accuracy of screw placement was significantly increased in the CBT group compared with the TT group (P < 0.05). The CBT group had a significantly lower rate of FJV than the TT group (P < 0.05). In addition, the rate of fusion and the rate of screw loosening were similar between the CBT and TT groups according to screw loosening criteria. CONCLUSION: This prospective, randomized controlled analysis suggests that clinical outcomes and radiographic characteristics, including fusion rates and caudal screw loosening rates, were comparable between CBT and TT screw fixation. Compared with the TT group, the CBT group showed advantages in the accuracy of screw placement and the FJV rate. CLINICAL TRIALS REGISTRATION: This trial has been registered at the US National Institutes of Health Clinical Trials Registry: NCT03105167.

Novel CaMKII-δ Inhibitor Hesperadin Exerts Dual Functions to Ameliorate Cardiac Ischemia/Reperfusion Injury and Inhibit Tumor Growth.

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 (Ca2+/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.

Diazo-carboxyl Click Derivatization Enables Sensitive Analysis of Carboxylic Acid Metabolites in Biosamples.

Carboxylic acids are central metabolites in bioenergetics, signal transduction, and post-translation protein regulation. However, the quantitative analysis of carboxylic acids as an indispensable part of metabolomics is prohibitively challenging, particularly in trace amounts of biosamples. Here we report a diazo-carboxyl/hydroxylamine-ketone double click derivatization method for the sensitive analysis of hydrophilic, low-molecular-weight carboxylic acids. In general, our method renders a 5- to 2000-fold higher response in mass spectrometry along with improved chromatographic separation. With this method, we presented the near-single-cell analysis of carboxylic acid metabolites in 10 mouse egg cells before and after fertilization. Malate, fumarate, and ß-hydroxybutyrate were found to decrease after fertilization. We also monitored the isotope labeling kinetics of carboxylic acids inside adherent cells cultured in 96-well plates during drug treatment. Finally, we applied this method to plasma or serum samples (5 µL) collected from mice and humans under pathological and physiological conditions. The double click derivatization method paves a way toward single-cell metabolomics and bedside diagnostics.

Heterodimerization With 5-HT2BR Is Indispensable for ß2AR-Mediated Cardioprotection.

RATIONALE: The ß2-adrenoceptor (ß2-AR), a prototypical GPCR (G protein-coupled receptor), couples to both Gs and Gi proteins. Stimulation of the ß2-AR is beneficial to humans and animals with heart failure presumably because it activates the downstream Gi-PI3K-Akt cell survival pathway. Cardiac ß2-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 ß2-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 ß2-ARs with another GPCR, 5-hydroxytryptamine receptors 2B (5-HT2BRs). METHODS AND RESULTS: Using pharmacological, genetic and biophysical protein-protein interaction approaches, we studied the cardioprotective effect of the ß2-agonist, MNF, and explored the underlying mechanism in both in vivo in mice and cultured rodent cardiomyocytes insulted with doxorubicin, hydrogen peroxide (H2O2) 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, H2O2 or hypoxia/reoxygenation. Mechanistically, we found that MNF or another ß2-agonist zinterol markedly promoted heterodimerization of ß2-ARs with 5-HT2BRs. Upregulation of the heterodimerized 5-HT2BRs and ß2-ARs enhanced ß2-AR-stimulated Gi-Akt signaling and cardioprotection while knockdown or pharmacological inhibition of the 5-HT2BR attenuated ß2-AR-stimulated Gi signaling and cardioprotection. CONCLUSIONS: These data demonstrate that the ß2-AR-stimulated cardioprotective Gi signaling depends on the heterodimerization of ß2-ARs and 5-HT2BRs.

Cryo-EM structure of human MG53 homodimer.

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.

Anthropogenic heat variation during the COVID-19 pandemic control measures in four Chinese megacities.

Anthropogenic heat (AH) is an important input for the urban thermal environment. While reduction in AH during the Coronavirus disease 2019 (COVID-19) pandemic may have weakened urban heat islands (UHI), quantitative assessments on this are lacking. Here, a new AH estimation method based on a remote sensing surface energy balance (RS-SEB) without hysteresis from heat storage was proposed to clarify the effects of COVID-19 control measures on AH. To weaken the impact of shadows, a simple and novel calibration method was developed to estimate the SEB in multiple regions and periods. To overcome the hysteresis of AH caused by heat storage, RS-SEB was combined with an inventory-based model and thermal stability analysis framework. The resulting AH was consistent with the latest global AH dataset and had a much higher spatial resolution, providing objective and refined features of human activities during the pandemic. Our study of four Chinese megacities (Wuhan, Shanghai, Beijing, and Guangzhou) indicated that COVID-19 control measures severely restricted human activities and notably reduced AH. The reduction was up to 50% in Wuhan during the lockdown in February 2020 and gradually decreased after the lockdown was eased in April 2020, similar to that in Shanghai during the Level 1 pandemic response. In contrast, AH was less reduced in Guangzhou during the same period and increased in Beijing owing to extended central heating use in winter. AH decreased more in urban centers and the change in AH varied in terms of urban land use between cities and periods. Although UHI changes during the COVID-19 pandemic cannot be entirely attributed to AH changes, the considerable reduction in AH is an important feature accompanying the weakening of the UHI.

Age-related changes in cervical sagittal alignment: based on 625 Chinese asymptomatic subjects.

PURPOSE: This work aimed to provide a comprehensive description of cervical alignment including cranial arch and caudal arch according to age, thus offering a reference database for cervical deformity treatment. METHODS: Total 150 males and 475 females aged at 48-88 were enrolled from August 2021 to May 2022. Radiographic parameters were measured, including Occipito-C2 angle (O-C2), C2-7 angle (C2-7), cranial arch, caudal arch, T1-slope (T1s), and C2-7 sagittal vertical axis (C2-7 SVA). Pearson correlation coefficient was employed in analyzing associations among sagittal parameters and between age and each parameter. Five groups were set according to different age stages, namely group with age 40-59 (N = 77), group with age 60-64 (N = 189), group with age 65-69 (N = 214), group with age 70-74 (N = 97), and group with age exceeding 75 (N = 48). An analysis of variance (ANOVA) test was applied to compare multi-sets of cervical sagittal parameters (CSPs). Chi-square test or Fisher's exact test was used in assessing the relationships of various cervical alignment patterns with age groups. RESULTS: T1s exhibited the strongest correlation with C2-7 (r = 0.655) and caudal arch (r = 0.561), and moderately correlated with cranial arch (r = 0.355). The positive correlations between age and C2-7 angle (r = 0.189, P < 0.001), cranial arch (r = 0.150, P < 0.001), caudal arch (r = 0.112, P = 0.005), T1s (r = 0.250, P < 0.001), as well as C2-7 SVA (r = 0.090, P = 0.024) were observed. Moreover, two progressive growths of C2-7 were shown after 60-64 and 70-74 years old, respectively. Thereof, cranial arch increased greatly after the age of 60-64, followed by a relative stability in the degeneration. The notable growth of caudal arch was observed after the age of 70-74, and the growth remained stable when exceeding the age of 75. The difference between cervical alignment patterns and age groups was obvious (Fisher's exact test P < 0.001). CONCLUSION: This work explored in detail the normal reference values of cervical sagittal alignment including cranial arch and caudal arch under different age groups. Age-related changes in cervical alignment depended on the increase in the cranial and caudal arches in different proportions with age.

Description of age-related changes in cervical sagittal alignment based on pelvic incidence classification in asymptomatic Chinese population.

PURPOSE: To investigate the pelvic incidence (PI)- and age-related cervical alignment changes of Chinese healthy population. METHODS: Six hundred and twenty-five asymptomatic adult subjects, who underwent the standing whole spinal radiograph, were recruited in this work. The sagittal parameters were measured, including Occipito-C2 angle (O-C2), C2-7 angle (C2-7), cranial arch, caudal arch, T1-slope (T1S), C2-7 sagittal vertical axis (C2-7 SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), PI, and sagittal vertical axis (SVA). All subjects were stratified into 5 age groups, namely 40-59 years, 60-64 years, 65-69 years, 70-74 years, and 75 years and above, with each age group further divided into 2 subgroups based on PI (deeming PI < 50° as low PI, and PI ≥ 50° as high PI). The correlations between PI or age, and other sagittal parameters were assessed. The age-related changes of sagittal parameters in each PI subgroup were also assessed, followed by one-way analysis of variance analysis for change comparison between age groups. RESULTS: The average cervical sagittal parameters were as below: 18.2 ± 6.8° for O-C2, 10.4 ± 10.2° for C2-7, 3.9 ± 7.5° for cranial arch, 6.5 ± 7.1° for caudal arch, 23.6 ± 7.3° for T1S, and 21.0 ± 9.7 mm for C2-7 SVA. There was no obvious difference observed between PI and cervical sagittal parameters, excepting for caudal arch. While, C2-7, cranial arch, caudal arch, T1S, and C2-7 SVA increased remarkably with the age. Thereof, C2-7 exhibited great increases at the age of 60-64 years and 70-74 years, respectively, cranial arch increased notably at 60-64 years of age, and caudal arch developed obviously at 70-74 years of age, regardless of PI. CONCLUSION: This study showed the PI- and age-related cervical alignment changes of Chinese healthy population. Based on the classification in our study, high or low PI apparently did not correlate with the occurrence of cervical degenerative disease.

Functional and Adaptive Significance of Promoter Mutations That Affect Divergent Myocardial Expressions of TRIM72 in Primates.

Cis-regulatory elements play important roles in tissue-specific gene expression and in the evolution of various phenotypes, and mutations in promoters and enhancers may be responsible for adaptations of species to environments. TRIM72 is a highly conserved protein that is involved in energy metabolism. Its expression in the heart varies considerably in primates, with high levels of expression in Old World monkeys and near absence in hominids. Here, we combine phylogenetic hypothesis testing and experimentation to demonstrate that mutations in promoter are responsible for the differences among primate species in the heart-specific expression of TRIM72. Maximum likelihood estimates of lineage-specific substitution rates under local-clock models show that relative to the evolutionary rate of introns, the rate of promoter was accelerated by 78% in the common ancestor of Old World monkeys, suggesting a role for positive selection in the evolution of the TRIM72 promoter, possibly driven by selective pressure due to changes in cardiac physiology after species divergence. We demonstrate that mutations in the TRIM72 promoter account for the differential myocardial TRIM72 expression of the human and the rhesus macaque. Furthermore, changes in TRIM72 expression alter the expression of genes involved in oxidative phosphorylation, which in turn affects mitochondrial respiration and cardiac energy capacity. On a broader timescale, phylogenetic regression analyses of data from 29 mammalian species show that mammals with high cardiac expression of TRIM72 have high heart rate, suggesting that the expression changes of TRIM72 may be related to differences in the heart physiology of those species.

Emerging role of STING signalling in CNS injury: inflammation, autophagy, necroptosis, ferroptosis and pyroptosis.

Stimulator of interferons genes (STING), which is crucial for the secretion of type I interferons and proinflammatory cytokines in response to cytosolic nucleic acids, plays a key role in the innate immune system. Studies have revealed the participation of the STING pathway in unregulated inflammatory processes, traumatic brain injury (TBI), spinal cord injury (SCI), subarachnoid haemorrhage (SAH) and hypoxic-ischaemic encephalopathy (HIE). STING signalling is markedly increased in CNS injury, and STING agonists might facilitate the pathogenesis of CNS injury. However, the effects of STING-regulated signalling activation in CNS injury are not well understood. Aberrant activation of STING increases inflammatory events, type I interferon responses, and cell death. cGAS is the primary pathway that induces STING activation. Herein, we provide a comprehensive review of the latest findings related to STING signalling and the cGAS-STING pathway and highlight the control mechanisms and their functions in CNS injury. Furthermore, we summarize and explore the most recent advances toward obtaining an understanding of the involvement of STING signalling in programmed cell death (autophagy, necroptosis, ferroptosis and pyroptosis) during CNS injury. We also review potential therapeutic agents that are capable of regulating the cGAS-STING signalling pathway, which facilitates our understanding of cGAS-STING signalling functions in CNS injury and the potential value of this signalling pathway as a treatment target.

DPPA2/4 and SUMO E3 ligase PIAS4 opposingly regulate zygotic transcriptional program.

The molecular mechanism controlling the zygotic genome activation (ZGA) in mammals remains poorly understood. The 2-cell (2C)-like cells spontaneously emerging from cultures of mouse embryonic stem cells (ESCs) share some key transcriptional and epigenetic programs with 2C-stage embryos. By studying the transition of ESCs into 2C-like cells, we identified developmental pluripotency associated 2 and 4 (Dppa2/4) as important regulators controlling zygotic transcriptional program through directly up-regulating the expression of double homeobox (Dux). In addition, we found that DPPA2 protein is sumoylated and its activity is negatively regulated by small ubiquitin-like modifier (Sumo) E3 ligase protein inhibitor of activated STAT 4 (PIAS4). PIAS4 is down-regulated during ZGA process and during transitioning of ESCs into 2C-like cells. Depleting Pias4 or overexpressing Dppa2/4 is sufficient to activate 2C-like transcriptional program, whereas depleting Dppa2/4 or forced expression of Pias4 or Sumo2-Dppa2 inhibits 2C-like transcriptional program. Furthermore, ectopic expression of Pias4 or Sumo2-Dppa2 impairs early mouse embryo development. In summary, our study identifies key molecular rivals consisting of transcription factors and a Sumo2 E3 ligase that regulate zygotic transcriptional program upstream of Dux.

Maslinic acid prevents IL-1ß-induced inflammatory response in osteoarthritis via PI3K/AKT/NF-κB pathways.

Osteoarthritis (OA) is a degenerative joint disease characterized by destruction of articular cartilage. The inflammatory response is the most important factor affecting the disease process. As interleukin-1ß (IL-1ß) stimulates several key mediators in the inflammatory response, it plays a major role in the pathogenesis of OA. Maslinic acid (MA) is a natural compound distributed in olive fruit. Previous studies have found that maslinic acid has an inhibitory effect on inflammation, but its specific role in the progression of OA disease has not been studied so far. In this study, we aim to assess the protective effect of MA on OA progression by in vitro and in vivo experiments. Our results indicate that, in IL-1ß-induced inflammatory response, MA is effective in attenuating some major inflammatory mediators such as nitric oxide (NO) and prostaglandin E2, and inhibits the expression of IL-6, inducible nitric oxide synthase, cyclooxygenase-2, and tumor necrosis factor-α (TNF-α) in a concentration-dependent manner. Also, MA downregulated the expression levels of thrombospondin motif 5 (ADAMTS5) and matrix metalloproteinase 13 in chondrocytes, resulting in reduced degradation of its extracellular matrix. Mechanistically, MA exhibits an anti-inflammatory effect by inactivating the PI3K/AKT/NF-κB pathway. In vivo, the protective effect of MA on OA development can be detected in a surgically induced mouse OA model. In summary, these findings suggest that MA can be used as a safe and effective potential OA therapeutic strategy.

Cardiac Ischemic Preconditioning Promotes MG53 Secretion Through H2O2-Activated Protein Kinase C-δ Signaling.

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 H2O2-evoked activation of protein kinase-C-δ. Specifically, IPC-induced myocardial MG53 secretion was mediated by H2O2-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 H2O2 augmented MG53 secretion, and MG53 knockdown exacerbated H2O2-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 H2O2-protein kinase-C-δ-dependent mechanism and that extracellular MG53 can participate in IPC protection against cardiac ischemia/reperfusion injury.

Single-Cell Transcriptomics Reveals Chemotaxis-Mediated Intraorgan Crosstalk During Cardiogenesis.

RATIONALE: We hypothesized that the differentiation processes of cardiac progenitor cell (CP) from first and second heart fields (FHF and SHF) may undergo the unique instructive gene regulatory networks or signaling pathways, and the precise SHF progression is contingent on the FHF signaling developmental cues. OBJECTIVE: We investigated how the intraorgan communications control sequential building of discrete anatomic regions of the heart at single-cell resolution. METHODS AND RESULTS: By single-cell transcriptomic analysis of Nkx2-5 (NK2 homeobox 5) and Isl1 (ISL LIM homeobox 1) lineages at embryonic day 7.75, embryonic day 8.25, embryonic day 8.75, and embryonic day 9.25, we present a panoramic view of distinct CP differentiation hierarchies. Computational identifications of FHF- and SHF-CP descendants revealed that SHF differentiation toward cardiomyocytes underwent numerous step-like transitions, whereas earlier FHF progressed toward cardiomyocytes in a wave-like manner. Importantly, single-cell pairing analysis demonstrated that SHF-CPs were attracted to and expanded FHF-populated heart tube region through interlineage communications mediated by the chemotactic guidance (MIF [macrophage migration inhibitory factor]-CXCR2 [C-X-C motif chemokine receptor 2]). This finding was verified by pharmacological blockade of this chemotaxis in embryos manifesting limited SHF cell migration and contribution to the growth of the outflow tract and right ventricle but undetectable effects on the left ventricle or heart tube initiation. Genetic loss-of-function assay of Cxcr2 showed that the expression domain of CXCR4 was expanded predominantly at SHF. Furthermore, double knockout of Cxcr2/Cxcr4 exhibited defective SHF development, corroborating the redundant function. Mechanistically, NKX2-5 directly bound the Cxcr2 and Cxcr4 genomic loci and activated their transcription in SHF. CONCLUSIONS: Collectively, we propose a model in which the chemotaxis-mediated intraorgan crosstalk spatiotemporally guides the successive process of positioning SHF-CP and promoting primary heart expansion and patterning upon FHF-derived heart tube initiation.

Glucose-Sensitive Myokine/Cardiokine MG53 Regulates Systemic Insulin Response and Metabolic Homeostasis.

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.

Thermal Infrared Imagery Integrated with Multi-Field Information for Characterization of Pile-Reinforced Landslide Deformation.

Physical model testing can replicate the deformation process of landslide stabilizing piles and analyze the pile-landslide interaction with multiple field information, thoroughly demonstrating its deformation and failure mechanism. In this paper, an integrated monitoring system was introduced. The instrumentation used included soil pressure cells, thermal infrared (TIR) imagery, 3D laser scanner, and digital photography. In order to precisely perform field information analysis, an index was proposed to analyze thermal infrared temperature captured by infrared thermography; the qualitative relationship among stress state and deformation as well as thermal infrared temperature is analyzed. The results indicate that the integrated monitoring system is expected to be useful for characterizing the deformation process of a pile-reinforced landslide. Difference value of TIR temperature (TIRm) is a useful indicator for landslide detection, and its anomalies can be selected as a precursor to landslide deformation.