SynergyX: a multi-modality mutual attention network for interpretable drug synergy prediction.

Discovering effective anti-tumor drug combinations is crucial for advancing cancer therapy. Taking full account of intricate biological interactions is highly important in accurately predicting drug synergy. However, the extremely limited prior knowledge poses great challenges in developing current computational methods. To address this, we introduce SynergyX, a multi-modality mutual attention network to improve anti-tumor drug synergy prediction. It dynamically captures cross-modal interactions, allowing for the modeling of complex biological networks and drug interactions. A convolution-augmented attention structure is adopted to integrate multi-omic data in this framework effectively. Compared with other state-of-the-art models, SynergyX demonstrates superior predictive accuracy in both the General Test and Blind Test and cross-dataset validation. By exhaustively screening combinations of approved drugs, SynergyX reveals its ability to identify promising drug combination candidates for potential lung cancer treatment. Another notable advantage lies in its multidimensional interpretability. Taking Sorafenib and Vorinostat as an example, SynergyX serves as a powerful tool for uncovering drug-gene interactions and deciphering cell selectivity mechanisms. In summary, SynergyX provides an illuminating and interpretable framework, poised to catalyze the expedition of drug synergy discovery and deepen our comprehension of rational combination therapy.

G protein-coupled estrogen receptor 1 ameliorates nonalcoholic steatohepatitis through targeting AMPK-dependent signaling.

Nonalcoholic fatty liver disease (NAFLD), especially nonalcoholic steatohepatitis (NASH), has emerged as a prevalent cause of liver cirrhosis and hepatocellular carcinoma, posing severe public health challenges worldwide. The incidence of NASH is highly correlated with an increased prevalence of obesity, insulin resistance, diabetes, and other metabolic diseases. Currently, no approved drugs specifically targeted for the therapies of NASH partially due to the unclear pathophysiological mechanisms. G protein-coupled estrogen receptor 1 (GPER1) is a membrane estrogen receptor involved in the development of metabolic diseases such as obesity and diabetes. However, the function of GPER1 in NAFLD/NASH progression remains unknown. Here, we show that GPER1 exerts a beneficial role in insulin resistance, hepatic lipid accumulation, oxidative stress, or inflammation in vivo and in vitro. In particular, we observed that the lipid accumulation, inflammatory response, fibrosis, or insulin resistance in mouse NAFLD/NASH models were exacerbated by hepatocyte-specific GPER1 knockout but obviously mitigated by hepatic GPER1 activation in female and male mice. Mechanistically, hepatic GPER1 activates AMP-activated protein kinase signaling by inducing cyclic AMP release, thereby exerting its protective effect. These data suggest that GPER1 may be a promising therapeutic target for NASH.

The palmitoyltransferase ZDHHC21 regulates oxidative phosphorylation to induce differentiation block and stemness in AML.

Acute myeloid leukemia (AML) is an aggressive hematological malignancy. Nearly 50% of patients who receive the most intensive treatment inevitably experience disease relapse, likely resulting from the persistence of drug-resistant leukemia stem cells (LSCs). AML cells, especially LSCs, are highly dependent on mitochondrial oxidative phosphorylation (OXPHOS) for survival, but the mechanism involved in OXPHOS hyperactivity is unclear, and a noncytotoxic strategy to inhibit OXPHOS is lacking. To our knowledge, this study is the first to demonstrate that ZDHHC21 palmitoyltransferase serves as a key regulator of OXPHOS hyperactivity in AML cells. The depletion/inhibition of ZDHHC21 effectively induced myeloid differentiation and weakened stemness potential by inhibiting OXPHOS in AML cells. Interestingly, FMS-like tyrosine kinase-3 internal tandem duplication (FLT3-ITD)-mutated AML cells expressed significantly higher levels of ZDHHC21 and exhibited better sensitivity to ZDHHC21 inhibition. Mechanistically, ZDHHC21 specifically catalyzed the palmitoylation of mitochondrial adenylate kinase 2 (AK2) and further activated OXPHOS in leukemic blasts. Inhibition of ZDHHC21 arrested the in vivo growth of AML cells and extended the survival of mice inoculated with AML cell lines and patient derived xenograft AML blasts. Moreover, targeting ZDHHC21 to suppress OXPHOS markedly eradicated AML blasts and enhanced chemotherapy efficacy in relapsed/refractory leukemia. Together, these findings not only uncover a new biological function of palmitoyltransferase ZDHHC21 in regulating AML OXPHOS but also indicate that ZDHHC21 inhibition is a promising therapeutic regimen for patients with AML, especially relapsed/refractory leukemia.

Reversible lysine fatty acylation of an anchoring protein mediates adipocyte adrenergic signaling.

N-myristoylation on glycine is an irreversible modification that has long been recognized to govern protein localization and function. In contrast, the biological roles of lysine myristoylation remain ill-defined. We demonstrate that the cytoplasmic scaffolding protein, gravin-α/A kinase-anchoring protein 12, is myristoylated on two lysine residues embedded in its carboxyl-terminal protein kinase A (PKA) binding domain. Histone deacetylase 11 (HDAC11) docks to an adjacent region of gravin-α and demyristoylates these sites. In brown and white adipocytes, lysine myristoylation of gravin-α is required for signaling via ß2- and ß3-adrenergic receptors (ß-ARs), which are G protein-coupled receptors (GPCRs). Lysine myristoylation of gravin-α drives ß-ARs to lipid raft membrane microdomains, which results in PKA activation and downstream signaling that culminates in protective thermogenic gene expression. These findings define reversible lysine myristoylation as a mechanism for controlling GPCR signaling and highlight the potential of inhibiting HDAC11 to manipulate adipocyte phenotypes for therapeutic purposes.

Functional genetic variants of the disulfidptosis-related INF2 gene predict survival of hepatitis B virus-related hepatocellular carcinoma.

Disulfidptosis is a novel form of programmed cell death involved in migration and invasion of cancer cells, but few studies investigated the roles of genetic variants in disulfidptosis-related genes in survival of patients with hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). We used Cox proportional hazards regression analyses, Kaplan-Meier curves and receiver operating characteristic curves to assess effects of genetic variants in 14 disulfidptosis-related genes on overall survival of 866 HBV-HCC patients. The Bayesian false discovery probability was used for multiple testing corrections. We also investigated biological mechanisms of the significant variants through expression quantitative trait loci analyses using the data from publicly available databases, luciferase reporter assays and differential expression analyses. As a result, we identified two independently functional single nucleotide polymorphisms (SNPs) (INF2 rs4072285 G > A and INF2 rs4444271 A > T) that predicted overall survival of HBV-HCC patients, with adjusted hazard ratios of 1.60 (95% CI = 1.22-2.11, P = 0.001) and 1.50 (95% CI = 1.80-1.90, P < 0.001), respectively, after multiple testing correction. Luciferase reporter assays indicated that both INF2 rs4072285 A and INF2 rs4444271 T alleles increased INF2 mRNA expression levels (P < 0.001) that were also higher in HCC tumor tissues than in adjacent normal tissues (P < 0.001); such elevated INF2 expression levels were associated with a poorer survival of HBV-HCC patients (P < 0.001) in the TCGA database. In summary, this study supported that INF2 rs4072285 and INF2 rs4444271 may be novel biomarkers for survival of HBV-HCC patients.

Topological phases and non-Hermitian topology in tunable nonreciprocal cyclic three-mode optical systems.

We propose a method for simulating a 1D non-Hermitian Su-Schrieffer-Heeger model with modulated nonreciprocal hopping using a cyclic three-mode optical system. The current system exhibits different localization of topologically nontrivial phases, which can be characterized by the winding number. We find that the eigenenergies of such a system undergo a real-complex transition as the nonreciprocal hopping changes, accompanied by a non-Bloch parity-time symmetry breaking. We explain this phase transition by considering the evolution of saddle points on the complex energy plan and the ratio of complex eigenenergies. Additionally, we demonstrate that the skin states resulting from the non-Hermitian skin effect possess higher-order exceptional points under the critical point of the non-Bloch parity-time phase transition. Furthermore, we investigate the non-Hermitian skin phase transition by the directional mean inverse participation ratio and the generalized Brillouin zone. This work provides an alternative way to investigate the novel topological and non-Hermitian effects in nonreciprocal optical systems.

Comparative characteristics of early-onset vs. late-onset advanced colorectal cancer: a nationwide study in China.

BACKGROUND: The incidence of early-onset colorectal cancer (EOCRC, diagnosed in patients under the age of 50 years) has been increasing around the world. Here, we aimed to systematically identify distinctive features of EOCRC. METHODS: From 2020 to 2021, we conducted a nationwide survey in 19 hospitals, collecting data on advanced CRC patients' demographics, clinical features, disease knowledge, medical experiences, expenditures, and health-related quality of life (HRQOL). We compared these features between EOCRC and late-onset colorectal cancer (LOCRC, ≥ 50 years old) groups and analyzed the association between EOCRC and HRQOL using multivariate linear regression. FINDINGS: In total, 991 patients with EOCRC and 3581 patients with LOCRC were included. Compared to the LOCRC group, the EOCRC group had higher levels of education, were more informed about the risk factors for CRC, were more likely to have widespread metastases throughout the body, were more inclined to undergo gene testing, and were more likely to opt for targeted therapy, radiotherapy, and chemotherapy. However, HRQOL in the EOCRC group was similar to that of the LOCRC group, and no significant association was observed between EOCRC and HRQOL (beta: -0.753, P value: 0.307). INTERPRETATION: In Chinese patients, EOCRC patients had more aggressive features. Despite undergoing more intensified treatments and gene testing, they had similar HRQOL compared with LOCRC. These findings advocate for a more tailored approach to treatment, especially for young CRC patients with advanced TNM stages and metastasis.

Regioselective Thiol-yne Reaction of Thiol with ((Methyl-d3)sulfonyl)ethyne: Synthesis of (2-((Methyl-d3)sulfonyl)vinyl)sulfides.

Herein, we have developed a new method for the synthesis of ((methyl-d3)sulfonyl)ethyne, which is cost-effective and environmentally friendly and can be synthesized at the gram level. As an ideal thiol-yne reagent, it can be reacted with various types of thiols to afford (Z)- and (E)-type vinyl sulfides under different conditions with high selectivity. In addition, it can complete the conformational transition from Z- to E-type products under suitable conditions, and can also carry out further derivatization smoothly. The deuterium content of all products was greater than 99%. The preliminary mechanistic studies support the visible light-mediated radical course, and herein provide a novel and efficient synthetic strategy for the direct introduction of deuterated methyl groups, enriching the methods for the construction of C-S bond-containing compounds.

Dapagliflozin Suppresses Isoprenaline-Induced Cardiac Hypertrophy Through Inhibition of Mitochondrial Fission.

ABSTRACT: Dapagliflozin (DAPA) is a novel oral hypoglycemic agent, and there is increasing evidence that DAPA has a protective effect against cardiovascular disease. The study aimed to investigate how DAPA inhibits cardiac hypertrophy and explore its potential mechanisms. By continuously infusing isoprenaline (ISO) for 2 weeks using a subcutaneous osmotic pump, a cardiac hypertrophic model was established in male C57BL/6 mice. On day 14 after surgery, echocardiography showed that left ventricle mass (LV mass), interventricular septum, left ventricle posterior wall diastole, and left ventricular posterior wall systole were significantly increased, and ejection fraction was decreased compared with control mice. Masson and Wheat Germ Agglutinin staining indicated enhanced myocardial fibrosis and cell morphology compared with control mice. Importantly, these effects were inhibited by DAPA treatment in ISO-induced mice. In H9c2 cells and neonatal rat cardiomyocytes, we found that mitochondrial fragmentation and mitochondrial oxidative stress were significantly augmented in the ISO-induced group. However, DAPA rescued the cardiac hypertrophy in ISO-induced H9c2 cells and neonatal rat cardiomyocytes. Mechanistically, we found that DAPA restored the PIM1 activity in ISO-induced H9c2 cells and subsequent increase in dynamin-associated protein 1 (Drp1) phosphorylation at S616 and decrease in Drp1 phosphorylation at S637 in ISO-induced cells. We found that DAPA mitigated ISO-induced cardiac hypertrophy by suppressing Drp1-mediated mitochondrial fission in a PIM1-dependent fashion.

zDHHC20-driven S-palmitoylation of CD80 is required for its costimulatory function.

CD80 is a transmembrane glycoprotein belonging to the B7 family, which has emerged as a crucial molecule in T cell modulation via the CD28 or CTLA4 axes. CD80-involved regulation of immune balance is a finely tuned process and it is important to elucidate the underlying mechanism for regulating CD80 function. In this study we investigated the post-translational modification of CD80 and its biological relevance. By using a metabolic labeling strategy, we found that CD80 was S-palmitoylated on multiple cysteine residues (Cys261/262/266/271) in both the transmembrane and the cytoplasmic regions. We further identified zDHHC20 as a bona fide palmitoyl-transferase determining the S-palmitoylation level of CD80. We demonstrated that S-palmitoylation protected CD80 protein from ubiquitination degradation, regulating the protein stability, and ensured its accurate plasma membrane localization. The palmitoylation-deficient mutant (4CS) CD80 disrupted these functions, ultimately resulting in the loss of its costimulatory function upon T cell activation. Taken together, our results describe a new post-translational modification of CD80 by S-palmitoylation as a novel mechanism for the regulation of CD80 upon T cell activation.

[Zuogui Pills improve testicular development of offspring rats exposed to prenatal stress via Cx43].

This study aims to reveal the mechanism of prenatal stress in affecting the testicular development of offspring rats and the intervention effects of Zuogui Pills via connexin 43(Cx43). Forty pregnant SD rats were randomized into a blank control group, a mo-del group, a high-dose(18.9 g·kg~(-1)) Zuogui Pills group, a low-dose(9.45 g·kg~(-1)) Zuogui Pills group, and a vitamin E(1.44 mg·kg~(-1)) group. The other groups except the blank control group was subjected to chronic unpredictable mild stress for the modeling of prenatal stress. The model was evaluated by sucrose preference test, open field test, and enzyme-linked immunosorbent assay(ELISA) of the glucocorticoid level. ELISA was employed to measure the thyroxine 4(T4), testosterone(T), and follicle-stimulating hormone(FSH) levels to assess kidney deficiency. Hematoxylin-eosin(HE) staining was employed to evaluate the status of testicular germ cells. An automatic sperm analyzer was used to measure the sperm quality. Immunofluorescence double staining was employed to detect the expression of Cx43 and follicle-stimulating hormone receptor(FSHR) in the testes of offspring rats. The mRNA and protein levels of Cx43, FSHR, phosphatidylinositol 3-kinase(PI3K), and protein kinase B(Akt) were determined by real-time fluorescence quantitative polymerase chain reaction and Western blot, respectively. Prenatal stress induced testicular development disorders in offspring rats. The HE staining results showed that on the day of birth, the model group had reduced seminiferous tubules in the testes, elevated FSH level in the serum, and lowered Cx43 level in the testicular tissue. Male offspring rats of 60 days old had reduced testicular spermatogenic function, decreased sperm quality, elevated FSH level and lowered T level in the serum, and down-regulated protein and mRNA levels of Cx43, FSHR, PI3K, and Akt in the testicular tissue. Zuogui Pills alleviated the abnormal development and dysfunction of testicles in the offspring rats caused by prenatal stress. In summary, Zuogui Pills may weaken the effects of prenatal stress on testicular development and spermatogenic function of offspring rats by activating the PI3K/Akt pathway to regulate Cx43 expression in the testicular tissue.

Dopant-Free Polymer Hole Transport Materials for Highly Stable and Efficient CsPbI3 Perovskite Solar Cells.

All-inorganic perovskite CsPbI3 contains no volatile organic components and is a thermally stable photoactive material for wide-bandgap perovskite solar cells (PSCs); however, CsPbI3 readily undergoes undesirable phase transitions due to the hygroscopic nature of the ionic dopants used in commonly used hole transport materials. In the current study, the popular donor material PM6 in organic solar cells is used as a hole transport layer (HTL). The benzodithiophene-based backbone-conjugated polymer requires no dopant and leads to a higher power conversion efficiency (PCE) than 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD). Moreover, PM6 also shows priorities in hole mobility, hydrophobicity, cascade energy level alignment, and even defect passivation of perovskite films. With PM6 as the dopant-free HTL, the PSCs achieve a champion PCE of 18.27% with a competitive fill factor of 82.8%. Notably, the present PCE is based on the dopant-free HTL in CsPbI3 PSCs reported thus far. The PSCs with PM6 as the HTL retain over 90% of the initial PCE stored in a glovebox filled with N2 for 3000 h. In contrast, the PSCs with Spiro-OMeTAD as the HTL maintain ≈80% of the initial PCE under the same conditions.

TGSA: protein-protein association-based twin graph neural networks for drug response prediction with similarity augmentation.

MOTIVATION: Drug response prediction (DRP) plays an important role in precision medicine (e.g. for cancer analysis and treatment). Recent advances in deep learning algorithms make it possible to predict drug responses accurately based on genetic profiles. However, existing methods ignore the potential relationships among genes. In addition, similarity among cell lines/drugs was rarely considered explicitly. RESULTS: We propose a novel DRP framework, called TGSA, to make better use of prior domain knowledge. TGSA consists of Twin Graph neural networks for Drug Response Prediction (TGDRP) and a Similarity Augmentation (SA) module to fuse fine-grained and coarse-grained information. Specifically, TGDRP abstracts cell lines as graphs based on STRING protein-protein association networks and uses Graph Neural Networks (GNNs) for representation learning. SA views DRP as an edge regression problem on a heterogeneous graph and utilizes GNNs to smooth the representations of similar cell lines/drugs. Besides, we introduce an auxiliary pre-training strategy to remedy the identified limitations of scarce data and poor out-of-distribution generalization. Extensive experiments on the GDSC2 dataset demonstrate that our TGSA consistently outperforms all the state-of-the-art baselines under various experimental settings. We further evaluate the effectiveness and contributions of each component of TGSA via ablation experiments. The promising performance of TGSA shows enormous potential for clinical applications in precision medicine. AVAILABILITY AND IMPLEMENTATION: The source code is available at https://github.com/violet-sto/TGSA. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Role of OAS gene family in COVID-19 induced heart failure.

BACKGROUND: COVID-19, the current global pandemic caused by SARS-CoV-2 infection, can damage the heart and lead to heart failure (HF) and even cardiac death. The 2',5'-oligoadenylate synthetase (OAS) gene family encode interferon (IFN)-induced antiviral proteins which is associated with the antiviral immune responses of COVID-19. While the potential association of OAS gene family with cardiac injury and failure in COVID-19 has not been determined. METHODS: The expression levels and biological functions of OAS gene family in SARS-CoV-2 infected cardiomyocytes dataset (GSE150392) and HF dataset (GSE120852) were determined by comprehensive bioinformatic analysis and experimental validation. The associated microRNAs (miRNAs) were explored from Targetscan and GSE104150. The potential OAS gene family-regulatory chemicals or ingredients were predicted using Comparative Toxicogenomics Database (CTD) and SymMap database. RESULTS: The OAS genes were highly expressed in both SARS-CoV-2 infected cardiomyocytes and failing hearts. The differentially expressed genes (DEGs) in the two datasets were enriched in both cardiovascular disease and COVID-19 related pathways. The miRNAs-target analysis indicated that 10 miRNAs could increase the expression of OAS genes. A variety of chemicals or ingredients were predicted regulating the expression of OAS gene family especially estradiol. CONCLUSION: OAS gene family is an important mediator of HF in COVID-19 and may serve as a potential therapeutic target for cardiac injury and HF in COVID-19.

Arctigenin impairs UBC12 enzyme activity and cullin neddylation to attenuate cancer cells.

Neddylation is a type of posttranslational protein modification that has been observed to be overactivated in various cancers. UBC12 is one of two key E2 enzymes in the neddylation pathway. Reports indicate that UBC12 deficiency may suppress lung cancer cells, such that UBC12 could play an important role in tumor progression. However, systematic studies regarding the expression profile of UBC12 in cancers and its relationship to cancer prognosis are lacking. In this study, we comprehensively analyzed UBC12 expression in diverse cancer types and found that UBC12 is markedly overexpressed in most cancers (17/21), a symptom that negatively correlates with the survival rates of cancer patients, including gastric cancer. These results demonstrate the suitability of UBC12 as a potential target for cancer treatment. Currently, no effective inhibitor targeting UBC12 has been discovered. We screened a natural product library and found, for the first time, that arctigenin has been shown to significantly inhibit UBC12 enzyme activity and cullin neddylation. The inhibition of UBC12 enzyme activity was newly found to contribute to the effects of arctigenin on suppressing the malignant phenotypes of cancer cells. Furthermore, we performed proteomics analysis and found that arctigenin intervened with cullin downstream signaling pathways and substrates, such as the tumor suppressor PDCD4. In summary, these results demonstrate the importance of UBC12 as a potential therapeutic target for cancer treatment, and, for the first time, the suitability of arctigenin as a potential compound targeting UBC12 enzyme activity. Thus, these findings provide a new strategy for inhibiting neddylation-overactivated cancers.

Diagnostic value of peripheral TiM-3, NT proBNP, and Sestrin2 testing in left-to-right shunt congenital heart disease with heart failure.

BACKGROUND: Left-to-right shunt congenital heart disease is more likely to induce recurrent respiratory infections in the patients which exacerbate pulmonary hypertension and thereby impairs cardiac function. It is urgent to explore a non-invasive and accurate diagnostic method that can show the cardiac anatomy and associated malformations in clinical research. OBJECTIVE: To determine the diagnostic value of peripheral mucin domain protein-3 (Tim-3), N-terminal pro-brain natriuretic peptide (NT proBNP), sestrin2 testing in patients with the left-to-right shunt congenital heart disease and heart failure. METHODS: Fifty-two neonates with with left to right shunt congenital heart disease and 30 healthy neonates were enrolled. Blood samples were collected within 24 h of admission from newborns for determining the content of TiM-3, NT proBNP, and Sestrin2. Analyzing the ROC curve provided insight into the diagnostic accuracy. Both a Spearman's rank correlation test and a logistic regression analysis were carried out. RESULTS: TiM-3, NT proBNP, and Sestrin2 levels in peripheral blood were statistically different in the three groups (P < 0.05). There were significant differences in LVEF and LVFS among the three groups (P < 0.05). When used to diagnose heart failure in conjunction with left-to-right shunt congenital heart disease, TiM-3, NT proBNP, and Sestrin2 exhibited sensitivity of 58.3, 58.3, and 83.3%, respectively, and specificity of 85.0, 72.5, and 70.0%. ROC curve analysis showed that the AUCs of Tim-3, NT proBNP, and sestrin2 in predicting the outcome of left-to-right shunted congenital heart disease combined with heart failure were 0.744 (95% CI, 0.580 to 0.908), 0.608 (95% CI, 0.359 to 0.857), respectively 0.744 (95% CI 0.592 to 0.896). CONCLUSION: Tim-3, NT proBNP, and sestrin2 can accurately differentiate heart failure from non-combined heart failure from left-to-right shunt congenital heart disease.

TiPARP forms nuclear condensates to degrade HIF-1α and suppress tumorigenesis.

Precisely controlling the activation of transcription factors is crucial for physiology. After a transcription factor is activated and carries out its transcriptional activity, it also needs to be properly deactivated. Here, we report a deactivation mechanism of HIF-1 and several other oncogenic transcription factors. HIF-1 promotes the transcription of an ADP ribosyltransferase, TiPARP, which serves to deactivate HIF-1. Mechanistically, TiPARP forms distinct nuclear condensates or nuclear bodies in an ADP ribosylation-dependent manner. The TiPARP nuclear bodies recruit both HIF-1α and an E3 ubiquitin ligase HUWE1, which promotes the ubiquitination and degradation of HIF-1α. Similarly, TiPARP promotes the degradation of c-Myc and estrogen receptor. By suppressing HIF-1α and other oncogenic transcription factors, TiPARP exerts strong antitumor effects both in cell culture and in mouse xenograft models. Our work reveals TiPARP as a negative-feedback regulator for multiple oncogenic transcription factors, provides insights into the functions of protein ADP-ribosylation, and suggests activating TiPARP as an anticancer strategy.

The Regulatory Effect of Receptor-Interacting Protein Kinase 3 on CaMKIIδ in TAC-Induced Myocardial Hypertrophy.

Necroptosis is a newly discovered mechanism of cell death, and its key regulatory role is attributed to the interaction of receptor-interacting protein kinases (RIPKs) RIPK1 and RIPK3. Ca2+/calmodulin-dependent protein kinase (CaMKII) is a newly discovered RIPK3 substrate, and its alternative splicing plays a fundamental role in cardiovascular diseases. In the present study, we aimed to explore the role and mechanism of necroptosis and alternative splicing of CaMKIIδ in myocardial hypertrophy. Transverse aortic constriction (TAC) was performed on wild-type and knockout mice to establish the model of myocardial hypertrophy. After 3 weeks, echocardiography, cardiac index, cross-sectional area of myocardial cells, hypertrophic gene expression, myocardial damage, and fibers were assessed. Moreover, we detected the levels of inflammatory factors (IL-6 and TNF-α) and examined the expressions of necroptosis-related proteins RIPK3, RIPK1, and phosphorylated MLKL. Meanwhile, we tested the expression levels of splicing factors ASF/SF2 and SC-35 in an attempt to explore CaMKII δ. The relationship between variable splicing disorder and the expression levels of splicing factors ASF/SF2 and SC-35. Further, we also investigated CaMKII activation, oxidative stress, and mitochondrial ultrastructure. In addition, wild-type mice were administered with a recombinant adeno-associated virus (AAV) carrying RIPK3, followed by TAC surgery to construct a model of myocardial hypertrophy, and the above-mentioned indicators were tested after 3 weeks. The results showed that RIPK3 deficiency could alleviate cardiac dysfunction, myocardial injury, aggravation of necrosis, and CaMKII activation induced by TAC surgery in mice with myocardial hypertrophy. Tail vein injection of AAV could reverse cardiac dysfunction, myocardial damage, aggravation of necrosis, and CaMKII activation in mice with myocardial hypertrophy. These results proved that RIPK3 could be used as a molecular intervention target for the prevention and treatment of myocardial hypertrophy.

Erythropoietin promotes myocardial infarction repair in mice by improving the function of Sca-1+ stem cells.

Myocardial infarction (MI) is one of the leading causes of death in the world. With the improvement of clinical therapy, the mortality of acute MI has been significantly reduced. However, as for the long-term impact of MI on cardiac remodeling and cardiac function, there is no effective prevention and treatment measures. Erythropoietin (EPO), a glycoprotein cytokine essential to hematopoiesis, has anti-apoptotic and pro-angiogenetic effects. Studies have shown that EPO plays a protective role in cardiomyocytes in cardiovascular diseases, such as cardiac ischemia injury and heart failure. EPO has been demonstrated to protect ischemic myocardium and improve MI repair by promoting the activation of cardiac progenitor cells (CPCs). This study aimed to investigate whether EPO can promote MI repair by enhancing the activity of stem cell antigen 1 positive stem cells (Sca-1+ SCs). Darbepoetin alpha (a long-acting EPO analog, EPOanlg) was injected into the border zone of MI in adult mice. Infarct size, cardiac remodeling and performance, cardiomyocyte apoptosis and microvessel density were measured. Lin- Sca-1+ SCs were isolated from neonatal and adult mouse hearts by magnetic sorting technology, and were used to identify the colony forming ability and the effect of EPO, respectively. The results showed that, compared to MI alone, EPOanlg reduced the infarct percentage, cardiomyocyte apoptosis ratio and left ventricular (LV) chamber dilatation, improved cardiac performance, and increased the numbers of coronary microvessels in vivo. In vitro, EPO increased the proliferation, migration and clone formation of Lin- Sca-1+ SCs likely via the EPO receptor and downstream STAT-5/p38 MAPK signaling pathways. These results suggest that EPO participates in the repair process of MI by activating Sca-1+ SCs.

The Regulatory Mechanism and Effect of Receptor-Interacting Protein Kinase 3 on Phenylephrine-Induced Cardiomyocyte Hypertrophy.

ABSTRACT: As a critical regulatory molecule, receptor-interacting protein kinase 3 (RIPK3) can mediate the signaling pathway of programmed necrosis. Calcium/calmodulin-dependent protein kinase II (CaMKII) has been proved as a new substrate for RIPK3-induced necroptosis. In this study, we aimed to investigate the regulatory mechanism of RIPK3 on phenylephrine (PE)-induced cardiomyocyte hypertrophy. Cardiomyocyte hypertrophy was induced by exposure to PE (100 µM) for 48 hours. Primary cardiomyocytes were pretreated with RIPK3 inhibitor GSK'872 (10 µM), and RIPK3 siRNA was used to deplete the intracellular expression of RIPK3. The indexes related to myocardial hypertrophy, cell injury, necroptosis, CaMKII activation, gene expression, oxidative stress, and mitochondrial membrane potential were measured. We found that after cardiomyocytes were stimulated by PE, the expressions of hypertrophy markers, atrial and brain natriuretic peptides (ANP and BNP), were increased, the release of lactate dehydrogenase was increased, the level of adenosine triphosphate (ATP) was decreased, the oxidation and phosphorylation levels of CaMKII were increased, and CaMKIIδ alternative splicing was disturbed. However, both GSK'872 and depletion of RIPK3 could reduce myocardial dysfunction, inhibit CaMKII activation and necroptosis, and finally alleviate myocardial hypertrophy. In addition, the pretreatment of RIPK3 could also lessen the accumulation of reactive oxygen species (ROS) induced by PE and stabilize the membrane potential of mitochondria. These results indicated that targeted inhibition of RIPK3 could suppress the activation of CaMKII and reduce necroptosis and oxidative stress, leading to alleviated myocardial hypertrophy. Collectively, our findings provided valuable insights into the clinical treatment of hypertrophic cardiomyopathy.