bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscle RING-finger proteins (MuRF) regulate protein kinase A activity via retrograde vesicular transport of PKA RI-alpha
Authors: Li N , Hammer E , Li Y , Voelker U , Fielitz J
Published: October 2024

Background

Muscle RING finger (MuRF) proteins are muscle-restricted E3 ubiquitin ligases that control protein degradation in striated muscles. MuRF proteins have coordinate functions for maintenance of striated muscle structure and function that depends on their target proteins. MuRF1 is a key enzyme in muscle atrophy. MuRF2 and MuRF3 bind to and stabilize microtubules which affects striated muscle differentiation and contraction. Although some MuRF-interaction partners have been described only few have been proven to be targeted for proteasomal degradation. To better understand the function of MuRF proteins, we set out to identify and functionally characterize novel MuRF target proteins.

Methods and Results

Stable isotope labeling of amino acids in cell culture followed by affinity purification and quantitative mass spectrometry analysis (SILAC-AP-MS) was used to identify the interactome of MuRF proteins. We identified the mammalian retromer subunit sorting nexin 5 (SNX5) that is involved in subcellular trafficking as a novel MuRF2 and MuRF3 interaction partner. Coimmunoprecipitation experiments and immunocytochemistry confirmed physical interaction and colocalization between SNX5 and MuRF2 or MuRF3. The interaction domains were mapped. MuRF2, MuRF3 and SNX5 were colocalized to early endosomes at microtubules in myocytes. MuRF2 mediated the ubiquitin proteasome system-dependent degradation of SNX5 in a RING-finger dependent manner, whereas MuRF3 stabilized SNX5. Using mass spectrometry, we identified the regulatory subunit of protein kinase A (PKA-RI-α) as a cargo of SNX5 coated early endosomes in myocytes. CRISPR-Cas9 and siRNA experiments showed that SNX5 regulates PKA activity by stabilizing PKA-RI-α in myocytes. Deletion of SNX5 resulted in PKA activation and inhibition of the HDAC5-MEF2 axis that disturbed myogenic differentiation.

Conclusion

MuRF2 and MuRF3 play opposing roles in SNX5-mediated retrograde transport of early endosomes along microtubules in myocytes. This mechanism is involved in regulation of PKA catalytic activity via stabilization of PKA-RI-α and controls differentiation of striated muscles.
Investigating the role of WT1 in Brugada syndrome pathophysiology
Authors: Marsman E M J , Bosada F M , Offerhaus J A , Beekman L , Wilde L M , Casini S , Verkerk A O , Wilde A A M , Boukens B J , Remme C A , Bezzina C R
Published: October 2024

Background

Brugada syndrome (BrS) is a heritable arrhythmic disorder presumably caused by conduction slowing in the right ventricular (RV) outflow tract (RVOT). A recent genome-wide association study found an association between common variants on chromosome 11 near WT1, tagged by the SNP rs72905083, and BrS susceptibility.

Purpose

To study whether WT1 affects cardiac conduction and could therefore represents the underlying association of the chr11 locus with BrS susceptibility.

Methods

We conducted in silico analyses of omics datasets to identify the likely causal gene at the chr11 BrS locus. Next, we conducted electrophysiological studies in heterozygous young adult (4 months old) Wt1-deficient (Wt1+/-) mice and wild-type littermates to explore the effect of Wt1 on cardiac conduction. To study the potential role of Wt1 in the setting of reduced conduction reserve, we compared aged Scn5a haploinsufficient mice (Scn5a+/-;Wt1+/+, 17 months) with littermates haploinsufficient for both Wt1 and Scn5a (Scn5a+/-;Wt1+/-). Optical mapping was performed in Langendorff-perfused hearts, where conduction was further challenged by acute ajmaline administration or by pacing at the effective refractory period (ERP). Transcriptomic analyses were conducted in Wt1+/- and wild-type mice by RNAseq of PCM1-sorted cardiomyocytes.

Results

Analysis of omics datasets uncovered WT1 as the likely causal gene since WT1 was the closest gene to, and in fact overlapped, the BrS-associated region; promoter capture Hi-C data in human tissue showed chromatin contact between the promoter of WT1 and the associated region; and H3K27ac ChIP-seq signals (i.e. enhancer activity) of putative cardiac enhancers located within the associated region were correlated with WT1 transcript abundance across multiple tissues (Z-score = 4.32, p=1.57e-05).

No differences were observed in ECG parameters or optically mapped epicardial conduction between Wt1+/- mice and wild-type littermates. However, comparison of aged Scn5a+/-;Wt1+/- and Scn5a+/-; Wt1+/+ hearts, in the setting of acute ajmaline challenge or pacing at the ERP, showed faster conduction in RV/RVOT in the presence of Wt1 haploinsufficiency (genotype effect: p=0.057 and p=0.041 for RV and RVOT epicardial conduction, respectively, during ajmaline challenge; p=0.034 for RV epicardial conduction during pacing at ERP).

RNAseq of RV/RVOT cardiomyocytes revealed higher Scn5a expression in Wt1+/- vs wild-type (p=0.006).

Conclusion

We identified WT1 as the gene that most likely underlies the effect of the chr11 BrS susceptibility locus. Functional data revealed protective effects of reduced Wt1 expression in the setting of reduced conduction reserve. Transcriptomic data suggest that this occurs through a transcriptional effect on Scn5a expression.
METTL3 drives heart failure by regulating Spp1 and Fos m6A modification in myocardial infarction
Authors: Cheng H , Li L N , Qian J Y , Zou Y Z , Ma J Y , Ge J B
Published: October 2024

Background

While m6A modification has been reported in myocardial infarction (MI), the detailed mechanism by which METTL3 regulates the progression of the disease has not yet been elucidated, and it remains unclear why m6A modification increases after MI.

Purpose

To investigate the role and mechanism of METTL3 in regulating its targets through m6A methylation in MI. The research results will not only add new content to the basic mechanism of myocardial protection but also provide new ideas and new targets for the prevention and treatment of MI.

Methods

Through MeRIP-seq and extensive bioinformatics analysis, the target genes SPP1 and FOS with the most significant m6A modification and differential expression in MI were screened. We successfully constructed heart specific Mettl3 knockout mice (Mettl3CKO) to verify that METTL3 promotes the deterioration of cardiac function after MI. We performed complementary molecular methods to assess protein quantity and interactions to identify mechanisms regulating this response. We manipulated select molecular pathways using both genetic and pharmacological methods to validate these mechanisms.

Results

Here, we showed that METTL3 exerted methyltransferase activity-dependent functions in gene regulation in MI, and a significant transcription factor HuR assisted the function of METTL3. and demonstrated that METTL3 was critical for the promotion of heart failure after MI. More specifically, METTL3 directly interacted with HuR through its nuclear localization domain in the cell nucleus under normoxia condition. When hypoxia developed, METTL3 separated from HuR and deposited m6A into 5’UTR of Spp1 and Fos mRNA to maintain their stability. In contrast, HuR bound to the ARE domain of 3’UTR of Spp1 and Fos mRNA to take them to the cytosol, maintaining their stability. Moreover, HIF-1α directly interacted with the HRE domain of Mettl3 to promote its transcription, and HuR bound to the ARE domain of 3’UTR of Mettl3 mRNA to maintain its stability to promote following translation.

Conclusions

Collectively, our studies revealed previously unappreciated functions of METTL3 with the help of HuR, and a direct target of HIF-1α under normoxia condition, which together contribute to its essential function in MI, suggesting therapeutic potential for targeting the METTL3/HuR/Spp1(Fos) mRNA axis.Figure1
Fractalkine Inhibition in Acute Myocardial Infarction leads to reduced intramyocardial haemorrhage
Authors: Loh S , Ekinci Y , Bennaceur K , Ogundimu E , Bigirumurame T , Maier R , Jeyalan V , Egred M , Mcdiarmid A , Maredia N , Plein S , Olin T , Richardson G , Austin D , Spyridopoulos I
Published: October 2024

Background

The fractalkine receptor CX3CR1 has been linked to the development of microvascular obstruction (MVO) in ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI). Pre-clinical studies have demonstrated a reduction in infarct size, inflammation and intramyocardial haemorrhage (IMH) with inhibition of CX3CR1.

Purpose

The FRACTAL study is a phase IIa, pilot, randomized, 2-arm parallel group, placebo-controlled, double blinded, multi-centre trial. In addition to assessing the safety and tolerability of the fractalkine inhibitor KAND567 in STEMI patients, a subgroup exploratory analysis was performed. We investigated into the translation of MRI and blood samples characteristics between the two groups.

Methods

Patients with an anterior STEMI who had an occluded proximal to mid left anterior descending (LAD) artery were recruited. These patients had to present within 5 hours of the onset of their chest pain. They were subsequently randomised on a 1:1 basis to receive either KAND567 or placebo. Patients then underwent an MRI at day 3, and subsequently a comparator at 3 months. Additionally, throughout the period of their follow-up, patients would regularly undergo blood sampling to assess multiple parameters.

Results

Of the 71 patients recruited into the study, 29 patients in the KAND567 arm and 28 patients in the placebo arm received both MRIs. The KAND567 arm had shown a similar troponin rise at day 1 compared to placebo (4357 vs 4286). Baseline MRI demonstrated an identical infarct size between both arms. The presence and absence of IMH was then analysed defining IMH+ as presence of IMH and IMH- as IMH absence. The presence of IMH in patients showed a larger infarct size. The infarct size of IMH+ were the same between KAND567 and placebo, which was a similar finding in the IMH- arm too. However, when compared to day 90 MRI demonstrated a numerically smaller infarct size in the KAND567 group with a smaller percentage of IMH. This was consistent with a lower rate of IMH in the KAND567 arm too, when compared between the groups (35.5% vs 55.2%; p=0.15) (see table below). This seemed to be related to the smaller distribution IMH+, as the IMH+ infarcts were much larger in both arms, whilst overall infarct size in IMH subgroup were identical.

Conclusion

KAND567 appears to prevent the transition from IMH- to IMH+, while it doesn’t change infarct size in the respective subgroups of IMH+ or IMH-.MRI Comparator Table
Red blood cell distribution width to albumin ratio as novel prognostic biomarker in cardiovascular disease
Authors: Arba I F , Multazam C C Z , Widiarti W , Siahaan P P , Oktaviono Y H , Setyobudi D , Saputra P B T
Published: October 2024

Background

The red blood cell distribution width-to-albumin ratio (RAR) is a novel, cost-effective, and accessible biomarker for inflammation. Although numerous studies have investigated the relationship between RAR values and mortality in cardiovascular diseases (CVD), the generalizability and robustness of these individual studies' results remain uncertain, underscoring the necessity for a meta-analysis.

Purpose

To explore the pooled association between RAR and all-cause mortality in several CVDs.

Methods

A systematic search for eligible studies was conducted across scientific databases, including Scopus, Web of Science, PubMed, and ProQuest, up to February 1, 2024. Mortality hazard ratios (HRs) for the highest versus lowest RAR categories were pooled using the Generic Inverse Variance method. A dose-response meta-analysis was performed using generalized least-squares regression to estimate trends of HRs across dose categories. Publication bias was assessed by inspecting funnel plots and performing Egger's test. Subgroup analyses were based on the underlying CVDs. Statistical analyses were executed in RStudio software, with the significance threshold set at p < 0.05.

Results

This systematic review and meta-analysis reviewed 16 high-quality studies published between 2021 and 2024 with 30,933 participants. The underlying diseases in the included studies were Acute Myocardial Infarction (AMI), Heart Failure (HF), Atrial Fibrillation (AF), aortic valvular disease, stroke and pulmonary embolism. The lowest quartile range for RAR was 0.80–1.20 ml/g, while the highest quartile ranged from 6.09 to 15.45 ml/g. Pooled results with a random-effect model showed that patients with higher RAR had significantly increased risk of all-cause mortality (HR 1.88, 95%CI 1.59–2.23, p<0.0001, I² = 91%). Non-linearity was observed in the dose-response relationship; thus, it was primarily illustrated using the restricted cubic spline model, with the linear model provided for comparison. A 1 ml/g increase in RAR corresponded to a 27% rise in the predicted HR for all-cause mortality (HR 1.27, 95%CI 1.16–1.39; p < 0.0001). Subgroup analyses based on the primary CVD diagnoses in the included studies confirmed a significant association between RAR values and all-cause mortality across all subgroups (AMI: HR 2.43, 95%CI 1.52–3.87, I² = 45%; HF: HR 1.78, 95%CI 1.13–2.81, I² = 94%; Stroke: HR 1.58, 95%CI 0.94–2.67, I² = 90%; Other CVD: HR 1.97, 95%CI 1.34–2.89, I² = 57%; p for interaction 0.24).

Conclusion

This is the first meta-analysis demonstrating the positive dose-response association between RAR values and all-cause mortality in CVD. Thus, RAR may be considered as a simple and practical prognostic biomarker in CVD.Forest plot based on CVD diagnosisDose-response RAR value to HR
LCZ696 (sacubitril/valsartan) alleviates residual cardiac remodeling of large ventricular aneurysms after surgical ventricular reconstruction by mediating circMap4k2/LIN28A/PDK1 pathway
Authors: Yan J , Tan N
Published: October 2024

Introduction

The treatment of refractory heart failure (HF) with large ventricular aneurysms (LVA) faces difficulties and requires effective therapy. Surgical ventricular reconstruction (SVR) is used to reverse cardiac remodeling for these patients, however, residual remodeling and dysfunction after SVR limits the improvement of HF. Recently, we reported that circMap4k2 promoted cardiac regeneration in the plication zone and attenuated residual remodeling after SVR. LCZ696 (sacubitril/valsartan) can reduce cardiac remodeling in early HF, while efficacy is poor in refractory HF with severe remodeling. It is unclear whether LCZ696 could improve residual remodeling and regulate circMap4k2 after SVR attenuates partial cardiac remodeling.

Purpose

We aimed to explore whether LCZ696 would reverse residual remodeling after SVR and related mechanisms.

Methods

Adult Male C57BL/6 mice were subjected to myocardial infarction (MI) or sham surgery. Four weeks later, MI mice with a LVA underwent SVR or a second open-chest operation and were randomized to LCZ696 or vehicle for four-week. Echocardiography and histological analysis were used to evaluate heart function, cardiac remodeling, and myocardial regeneration. Bioinformatics analysis, molecular docking analysis, RNA immunoprecipitation (RIP) and RNA pulldown were used to explore the underlying mechanisms.

Results

Compared with vehicle-treated SVR and LCZ696-treated non-SVR mice, LCZ696-treated SVR mice had significantly smaller left ventricular volume, better ejection fraction, lower heart-to-body weight ratio, less myocardial fibrosis and more positive staining of Ki-67, phospho-histone H3, and Aurora B in the plication zone. LCZ696 up-regulated the cardiac expression of circMap4k2 in SVR mice. Silencing of circMap4k2 markedly blocked the curative effects of LCZ696 on SVR mice, while overexpression of circMap4k2 enhanced these effects. We predicted 22 proteins that may bind to circMap4k2, among which lin-28 homolog A (LIN28A) had the highest binding potential, and confirmed the combination between circMap4k2 and LIN28A. Mechanistically, LCZ696-induced circMap4k2 bound to LIN28A, increased downstream pyruvate dehydrogenase kinase 1 (PDK1) expression, which activated glycolysis in injured myocardium and ultimately promoted cardiomyocyte proliferation.

Conclusions

LCZ696 improves cardiac metabolism and increases cardiac regeneration in the plication zone by mediating circMap4k2/LIN28A/PDK1 pathway, thereby attenuating residual remodeling and restoring heart function after SVR.
RBM20 promotes doxorubicin-induced cardiotoxicity by Atp6v0a1 alternative splicing
Authors: Qiu Z , Sun Z , Wang Z , Wu Y , Li Z , Fan Y , Yang W , Chen Y , Hua S , Jin W
Published: October 2024

Background & Objective: Doxorubicin (dox), an effective chemotherapy drug, is extremely limited in clinical practice by its lethal cardiotoxicity. Whereas dysregulation of splice-regulatory networks has been reported in cardiomyopathies, the role of RNA binding motif protein 20 (RBM20), an adaptive splice regulator, in doxorubicin-induced cardiotoxicity (DIC) remained to be elucidated.

Purpose

Here we aimed to show the role of RBM20 in DIC and elucidate the relationship between alternative splicing and lysosome acidification impairment.

Method

Mice were treated with intraperitoneal injection of cumulative 20mg/kg doxorubicin with four equal injections over a period of 2 weeks to induce DIC. The contribution of RBM20 in cardiotoxicity was evaluated in conditional cardiomyocyte-specific RBM20 overexpression (RBM20tg/+/Myh6-CreERT) mice. The regulatory factor of RBM20 was determined through luciferase assay and chromatin immunoprecipitation in vitro. Autophagic flux was evaluated by transmission electron microscope in RBM20tg/+/Myh6-CreERT mice and by lysotracker and a tandem fluorescence RFP-GFP-LC3 reporter system in RBM20 overexpressed or knockdown cardiomyocyte. RBM20-dependent splicing events were identified by rMATS 3.2.5 on the RNA-sequencing data.

Results

In the DIC human myocardium and murine model, we observed significant elevation of RBM20 in cardiomyocytes. Cardiomyocyte-specific RBM20 overexpression resulted in severe cardiac dysfunction reflected by dilated ventricles, declined left ventricular ejection fraction, increased chamber stiffness and lower survival rate. After screening for potential upstream transcription factors, c-Jun was identified to bind and upregulate RBM20 directly. The inhibition of c-Jun by SR 11302 could partially mitigate DIC in vitro. Mechanistically, RBM20 was positively related with autophagic flux blockade and impaired lysosome acidification by shifting Atp6v0a1, the a1-subunit of the V0 domain of vacuolar H+-ATPases, toward an exon 6-7 exclusion isoform without altering total transcript levels. By restoring exon 6-7-containing ATP6V0a1 level, we were able to reduce DIC by restoring normal autophagic flux.

Conclusion

Overall, our study reveals that elevation of RBM20 disturbed lysosome acidification in doxorubicin induced cardiotoxicity via the alternative splicing of Atp6v0a1, leading to heart failure.JUN-Rbm20 upregulattion promoted DICRBM20 alternative spliced atp6v0a1
The contribution of iron metabolism to heart failure: a haematological and biochemical perspective
Authors: Menezes Falcao L , Matias A , Santos M , Aguiar L , Barbosa M , Melicio A , Faustino P , Bicho M , Inacio A
Published: October 2024

Introduction

Heart failure (HF) can be influenced by diverse modulators, such as genes involved in iron metabolism - HFE, SLC40A1 and TMPRSS6, and haematological and biochemical parameters - serum iron, ferritin, transferrin saturation, mean corpuscular volume (MCV) and Red Cell Distribution Width (RDW).

Objectives

To investigate the association of genetic variants in the HFE gene [C282Y (rs1800562) and H63D (rs1799945)], SLC40A1 (rs1439816 and rs2304704) and TMPRSS6 (rs855791) with haematological parameters and biochemical biomarkers of iron metabolism in HF and in its various forms of presentation [preserved Ejection Fraction-HFpEF and non-preserved Ejection Fraction-HFnpEF (middly reduced + reduced)], in each sex.

Methods

301 individuals with HF were studied (141 men and 160 women), with a median age of 80 years (min=31 and max=99) and a median body mass index (BMI) of 25.90 kg/m2 (min=16.50 and max=47.30). Multiplex PCR-ARMS technique was used to analyze the HFE gene variants (C282Y and H63D) and Endpoint Genotyping was used for the remaining variants. Statistical analysis was carried out using SPSS software, version 28.0, with a statistical significance level of p<0.05.

Results

The presence of indicators of iron deficiency anaemia was verified in the haematological and biochemical parameters in our population of HF. Significant differences were found in serum iron values in the presence of the mutant allele for the three genes studied: 1)in the H63D (p=0.006) for females, and more particularly in females with HFnpEF (p=0.020); 2) in the rs1439816 for males (p=0.035) and more particularly in males with HFpEF (p=0.036); and 3) in the rs855791 for males (p=0.018). As for ferritin, significant differences were found in the presence of the mutant allele for the rs2304704 (p=0.001) in females. For transferrin saturation, significant differences were found in the presence of the mutant allele for the three genes studied: 1) in the H63D (p=0.013) for females, more specifically in females with HFpEF (p=0.043); 2) in the rs1439816 in males (p=0.037); and 3) in the rs855791 in females (p=0.034), particularly in females with HFpEF (p=0.023), and in males (p=0.032), particularly in males with HFpEF (p=0.037). Analyzing the MCV, there were statistically significant differences in the presence of the mutant allele for the rs2304704 (p=0.012) in females, particularly in those with HFpEF (p<0.001). Regarding RDW, significant differences were found in the presence of the mutant allele of the C282Y polymorphism in females with HFpEF (p=0.048).

Conclusion

Ferropenic anaemia highly prevalent in this population with HF. All the genes analyzed contribute to the modulation of the analyzed parameters/biomarkers, however, the SLC40A1 gene showed greater modulating capacity. Genetic modulation was more relevant in HFpEF women, suggesting that this sex is the most susceptible to genetic modulation.
Stress memory of heart failure in hematopoietic niche promotes recurrence via adipocytic skewing of mesenchymal stromal cells
Authors: Goto K , Nakayama Y , Manabe I , Komuro I , Fujiu K , Takeda N
Published: October 2024

Background

Heart failure (HF) is marked by recurrent acute decompensations, which poses significant treatment challenges in advanced stages. Our preceding work demonstrated that hematopoietic stem cells (HSCs) from HF-experienced mice induce cardiac fibrosis and dysfunction when transplanted, as a result of epigenetic alterations favoring myeloid hematopoiesis and impeding the differentiation of monocytes into cardiac mature macrophages. These findings hint at epigenetic modifications in HSCs as potential drivers of HF recurrence, suggesting their manipulation as a novel therapeutic strategy. However, the exact mechanisms by which HF-associated stress leads to these epigenetic changes remain unclear. Given the crucial role of bone marrow mesenchymal stromal cells (MSCs) in maintaining HSC stemness, this study explores the impact of cardiac stress on MSC function and its subsequent effect on HSCs.

Purpose

This study aims to elucidate the mechanisms behind the phenotypic changes in HSCs and to identify novel therapeutic targets to mitigate HF recurrence by investigating the role of MSCs in the hematopoietic niche under cardiac stress.

Methods & Results

Initially, we examined MSC phenotypic changes during HF using bulk and single-cell RNA sequencing. Results from transverse aortic constriction (TAC) model mice revealed a shift towards adipocyte differentiation under cardiac stress. Histological analyses confirmed an increase in adipocytes in TAC mice compared to controls, suggesting a stress-induced predisposition of MSCs towards adipocytic lineage commitment. This trend was further supported by ex vivo models using MSCs isolated from TAC mice. Notably, the proportion of adipocyte lineage-specific MSCs correlated with cardiac dysfunction severity.

Subsequently, we assessed the impact of HF-conditioned MSCs on HF development by transplanting healthy HSCs with MSCs from control or TAC mice. Mice receiving HF-conditioned MSCs developed HF, evidenced by reduced ejection fraction and cardiac fibrosis. In these mice, a notable increase in HSC proliferation and a relative increase of myeloid cells within the peripheral blood were observed, along with an increase in proinflammatory cardiac macrophages. These findings suggest HF induces a "stress memory" in bone marrow MSCs.

To test the potential of inhibiting adipocyte differentiation of MSCs in erasing this stress memory, we administered MSC phenotype-modulating agents to TAC mice, resulting in improved cardiac function and the disappearance of adipocytes from the bone marrow.

Conclusions

This study sheds light on how cardiac stress affects the bone marrow niche, leading to adipocytic skewing of MSCs and subsequent alterations in HSCs, thereby exacerbating cardiac dysfunction. The potential of targeting bone marrow niche components in HF treatment is highlighted.
Deletion of nephrocystin 4 exacerbates cardiac function and survival rate in a mouse model of cardio-renal syndrome
Authors: Sato J , Otaki Y , Watanabe T , Ono H , Yamaguchi R , Tachibana S , Kobayashi Y , Aono T , Goto J , Takahashi H , Arimoto T , Ochi H , Konta T , Watanabe M
Published: October 2024

Background

Cardiorenal syndrome (CRS), characterized by cardiac and renal dysfunction, is an increasing health problem associated with high mortality rate. Nephrocystin 4 (NPHP4) gene is the major cause of end-stage renal disease in children. We have reported NPHP4 single nucleotide polymorphism is the genetic risk for CRS and subsequent cardiovascular events in general population. However, the functional role of Nphp4 in the development of CRS has never been examined yet.

Methods and Results

We generated systemic Nphp4 knockout (KO) mice deleting exon 3 to 8 using CRISPR-Cas9 system. RNA sequence analysis of heart and kidney tissues demonstrated that gene-sets related to mitochondrial function were significantly downregulated in Nphp4 KO mice compared to their wild-type (WT) littermates. Nphp4 KO mice showed less cardiac hypertrophy, however, exacerbated cardiac function and survival compared to WT mice in a CRS model induced by thoracic transverse aortic constriction. Nphp4 located in endosome and cell membrane in H9C2 cardiomyocytes. Immunoprecipitation confirmed protein interaction between Nphp4 and HECT-type E3 ligase Itch. Furthermore, we found that Itch targeted Lats2 and insulin-like growth factor-1 receptor in cardiomyocytes. Knockdown of Nphp4 activated Hippo signaling and worsened mitochondrial function in H9C2 cardiomyocytes through the inhibition of Itch-dependent Lats2 degradation. Knockdown of Nphp4 inhibited insulin-like growth factor-1 signaling through the disturbance of Itch-mediated endosome function.

Conclusions

Deletion of Nphp4 impaired compensatory cardiac hypertrophy and exacerbated cardiac function and survival in a mouse CRS model through mitochondrial dysfunction. Nphp4 mediated Hippo signaling and insulin-like growth factor-1 signaling through the interaction with Itch. NPHP4 could be the novel therapeutic target in CRS.figure1figure2
Intact DNA repair in differentiated cardiomyocytes is essential for maintaining cardiac function in response to pressure overload in mice
Authors: De Boer M , Hoeijmakers J H J , Duncker D J
Published: October 2024

Introduction

DNA in every cell is continuously damaged and DNA repair mechanisms are essential for protection against DNA damage-induced aging-related diseases. For example, deficient repair of endogenously generated DNA damage in mice with cardiomyocyte-restricted inactivation of Xpg, is associated with progressive heart failure.

Purpose

Here we tested the hypothesis that unrepaired DNA damage in differentiated cardiomyocytes increases cardiac vulnerability in response to hemodynamic overload.

Methods

To increase the burden of spontaneous DNA damage, we generated mice with cardiomyocyte-restricted inactivation of DNA repair endonuclease XPG. At 8 weeks of age, αMHC-Xpgc/- and control (Ctrl) mice were subjected to pressure overload by transverse aortic constriction (TAC). Eight weeks after TAC, left ventricular (LV) function was assessed using echocardiography and hemodynamic measurements, followed by molecular and histological analyses.

Results

Cardiomyocyte-restricted inactivation of Xpg resulted in systolic as well as diastolic LV dysfunction (Table). TAC-induced LV hypertrophy is similar in both groups (Ctrl 38%; αMHC-Xpgc/- 34%). In Ctrl mice, LV hypertrophy was accompanied by minimal LV dilation and modest changes in systolic and diastolic LV function. Conversely, TAC in αMHC-Xpgc/- produced severe LV dysfunction and resulted in overt congestive heart failure, demonstrated by aggravation of LV dilation, and marked increases in LV end-diastolic pressure, left atrial weight and lung fluid weight, which was accompanied by further increases in the expression levels of the hypertrophic marker genes atrial natriuretic peptide and beta-myosin heavy chain (Table). Moreover, lectin staining revealed a decrease in capillary density and TUNEL staining revealed further elevated levels of myocardial apoptosis. In addition, a significant increase of myocardial collagen content was observed.

Conclusion

Cardiomyocyte-restricted loss of DNA repair protein XPG increases cardiac vulnerability to develop heart failure in response to pressure overload. These findings underscore the importance of genomic stability for maintenance of cardiac function, not only during basal conditions, but also in response to a pathological stimulus.
MRPL44 haploinsufficient mouse spontaneously develops hypertrophic cardiomyopathy and shows systolic dysfunction after aldosterone treatment
Authors: Okamoto R , Ye Z , Ito R , Moriwaki K , Ito H , Kimena L , Ichikawa M , Dohi K
Published: October 2024

Introduction

It has been recently reported there are big differences in pathophysiological and molecular phenotypes in mouse and human hypertrophic cardiomyopathy. These differences are observed all in terms of myocyte redox, mitochondrial number and respiration, mitochondrial reactive oxygen species generation and Ca2+ handling. Therefore we should search for molecules to be able to induce similar phenotype and molecular signaling both in mice and human. Mitochondrial ribosomal large subunit 44 (MRPL44) knockout mice were embryonic lethal, for which mutations are known to cause mitochondrial infantile cardiomyopathy and hypertrophic cardiomyopathy.

Purpose

Our purpose is to investigate the effect of MRPL44 haploinsufficiency in mice.

Methods

MRPL44 haploinsufficient (MRPL44+/-) mice were generated. Mineralocorticoid receptor-associated hypertension mice were induced in MRPL44+/- and wild-type (WT, MRPL44+/+) mice with subcutaneous infusion of aldosterone(Aldo) and 8% NaCl food for 4 weeks after uninephrectomy. Systolic blood pressure was measured by tail cuffs every week. WB, qPCR, cardiac echo, and histological examinations were performed. RNA sequencing analysis, electron microscopy examinations and mitochondrial activity assay were performed to find differences between MRPL44+/- and MRPL44+/+ mice.

Results

MRPL44 haploinsufficient mice spontaneously developed left ventricular hypertrophy in 6 weeks old. Heart rate, blood pressure, and cardiac systolic function were normal in MRPL44 haploinsufficient mice. MRPL44 was decreased about to 70% in MRPL44 haploinsufficient mice and mitochondrial arrangement were impaired in electron microscopic analysis. After Aldo treatment, blood pressure elevation were similar, however, MRPL44 haploinsufficient mice developed left ventricular systolic dysfunction and dilation compared with MRPL44+/+ mice. WB showed mitochondrial electron transport chain protein complex IV expression was significantly decreased. Furthermore, mitochondrial activity assay showed MRPL44 haploinsufficient mice had a significant reduction in complex IV activity, whereas complex I and II activity were similar to MRPL44+/+ mice. RNA sequencing analysis showed the significant changes in the expression of ribosomal subunits coded by nucleus in addition to mitochondrial ribosomal subunits. These results indicate MRPL44 plays an important role in the cardiac function of mitochondrial electron transport chain protein complexes via the expression of ribosomal protein subunits coded by both nucleus and mitochondria.

Conclusions

MRPL44 haploinsufficient mice spontaneously develop left ventricular hypertrophy and shows systolic dysfunction after aldosterone treatment accompanied with oxidative phosphorylation enzyme dysfunction.
Assessing boundary conditions in CFD for transvalvular pressure gradient calculation in cardiac hemodynamics
Authors: Wu F , Feng S , Wang H , He X , Wang S , He G , Pan X
Published: October 2024

Background

Computational fluid dynamics (CFD), which has the advantages of providing detailed pressure distribution, has been widely used for cardiac function assessment and heart disease diagnosis. However, the results are usually influenced by the boundary conditions. Particularly, the transvalvular pressure gradient, which serves as a crucial indicator for mitral stenosis and the efficacy of mitral valve surgery, can easily be miscalculated. Here, we assess the effects of widely used boundary conditions on the transvalvular pressure gradient computed based on the Bernoulli equation and the line probe, respectively.

Purpose

This study aims to determine the effects of boundary conditions on the transvalvular pressure gradient in CFD.

Methods

We constructed cardiac models including left atrium, left ventricle, aorta from CT and mitral valve from transesophageal echocardiography data (Figure 1). The intraventricular flow fields were computed using CFD tool with four different boundary conditions (BC) at the same cardiac output. BC1 involved specifying the total flow rate of the aorta, with zero pressure at the entrance of the pulmonary veins. BC2 maintained equal flow rates at the entrances of the pulmonary veins. BC3 followed Murray's law, where the flow rate ratio in the pulmonary veins is proportional to the 1.5 power of the area ratio. BC4 followed Poiseuille's law, where the flow rate ratio is proportional to the square of the area ratio. The results encompassed the mean transvalvular pressure gradient and peak transvalvular pressure gradient obtained through the Bernoulli equation and the line probe methods, respectively.

Results

Figures 2(A-D) present the contours of transvalvular pressure under peak flow velocity conditions and the isosurfaces of vorticity within the ventricle. The results show that the pressure within the atrium is notably lower in the BC2, leading to a 63% underestimation in the mean transvalvular pressure gradient and a 22.9% deviation in the peak transvalvular pressure gradient (Figure 2 F). The transvalvular pressure gradient for BC1, BC3, and BC4 do not exceed 10%. The results reveal that the pressure distribution and vorticity within the ventricle are consistent, primarily due to the influence of the mitral valve.

Conclusion

When evaluating transvalvular pressure gradient using CFD, it is crucial to specify appropriate boundary conditions. Using inappropriate boundary conditions may lead to underestimation of the transvalvular pressure gradient, thereby affecting further diagnostic decisions. In research studies, it is recommended to allocate flow in different branch vessels according to Murray's law, where the flow in different branch vessels is proportional to the 1.5 power of the vessel cross-sectional area.Modelling flow chartTransvalvular pressure gradient
Cancer ameliorates cardiac dysfunction and suppresses fibrosis in a mouse model for Duchenne muscular dystrophy
Authors: Achlaug L , Awwad L , Langier-Goncalves I , Goldenberg T , Aronheim A
Published: October 2024

The interplay between heart failure and cancer represents a double-edged sword. Whereas cardiac remodeling promotes cancer progression, tumor growth suppresses cardiac hypertrophy and reduces fibrosis deposition. Whether these two opposing interactions are connected awaits to be determined. In addition, it is not known whether cancer affects solely the heart, or if other organs are affected as well. To explore the dual interaction between heart failure and cancer, we studied the human genetic disease Duchenne Muscular Dystrophy (DMD) using the MDX mouse model. We analyzed fibrosis and cardiac function as well as molecular parameters by multiple methods in the heart, diaphragm, lungs, skeletal muscles, and tumors derived from MDX and control mice. Surprisingly, cardiac dysfunction in MDX mice failed to promote murine cancer cell growth. In contrast, tumor-bearing MDX mice displayed reduced fibrosis in the heart , skeletal and diaphragm muscles, resulting in improved cardiac function. The latter is at least partially mediated via M2 macrophage recruitment to the heart and diaphragm muscles. Remarkably, an analysis of of cytokines in the blood of tumor-bearing and non-tumor-bearing MDX mice initially revealed several potential factors. These factors hold promise in significantly reducing fibrosis within our model. Administering these factors simultaneously to MDX mice led to decreased fibrosis in the heart, diaphragm, and skeletal muscles, along with an improvement in cardiac function. Collectively, our data support the notion that the effect of heart failure on tumor promotion is independent of the improved cardiac function in tumor-bearing mice. Reduced fibrosis in tumor-bearing MDX mice stems from the suppression of new fibrosis synthesis and the removal of existing fibrosis. These findings offer potential therapeutic strategies for DMD patients, fibrotic diseases, and cardiac dysfunction.Tumor growth suppresses fibrosisGraphical representation
Genome-wide association study of CMR image-based aortic stiffness in 45,789 individuals identifies loci linked with cardiovascular diseases
Authors: Paliwal N , Henry A , Finan C , Davies R , Hughes A , Williams B , Malarstig A , Lumbers R T , Hingorani A D
Published: October 2024

Background

The use of artificial intelligence on large-scale cardiac magnetic resonance (CMR) imaging data has enabled detailed characterisation of cardiac shape and function for use in genome-wide association studies (GWAS), leading to improved understanding of genetic aetiology of cardiovascular diseases (CVDs). Aortic stiffness is associated with increased risk of cardiovascular events in observational studies. Here, we present a novel CMR-based pressure-independent measure of aortic stiffness, identify genetic associations and explore links with CVDs.

Purpose

Identify genetic contributions to pressure-independent aortic stiffness and links to CVDs using large-scale GWAS analysis on the UK Biobank cohort.

Methods

A pre-trained neural network was used to segment CMR images of participants in the UK Biobank to quantify ascending aorta diameter, which together with contemporaneous systolic and diastolic blood pressure measurements (SBP, DBP, respectively) were used to calculate a pressure-independent measure of aortic stiffness (β0). The measurement assumes an exponential relationship between pressure and aortic diameter. We then performed a GWAS on β0 in 45,789 participants of European ancestry without CVDs. A multi-trait-based conditional & joint analysis (mtCOJO) was performed to estimate genetic effects independent of SBP, DBP and aortic area. We mapped the independent lead variants associated with aortic stiffness at P < 5x10-8 to nearest gene, and characterised shared genetic association across CVDs using Open Targets Platform database.

Results

The GWAS identified 17 independent lead variants, including 6 that remained significant in the conditional analysis. Four of these lead variants, not previously reported in GWAS of other aortic traits, were located near CTD-2203A3.1, MCF2L, CFDP1 and CDH13 genes (red annotations in the Figure). MCF2L, CFDP1 and CDH13 have been associated with coronary artery disease, and CFDP1 with myocardial infarction and coronary atherosclerosis in previous studies.

Conclusion

A GWAS of CMR-derived aortic stiffness identified 4 loci distinct from other aortic traits that also associate with other CVDs, suggesting genetic links between aortic stiffness and CVDs. Further analyses are required to explore biological mechanisms underlying these genetic associations.Aortic Stiffness Manhattan Plot
Human epicardial adipose tissue secretome alters metabolomic profile and induces endothelial-to-mesenchymal transition in human lymphatic endothelial cells
Authors: Abe I , Takahashi M , Yamasaki H , Harada T , Takano M , Kondo H , Teshima Y , Takahashi N
Published: October 2024

Background

Cardiac lymphatic systems play an important role in maintaining myocardial fluid homeostasis during inflammation. We have recently reported the epicardial adipose tissue (EAT)-derived factor induces inflammation and fibrosis in atrial myocardium, which lead to atrial fibrillation (AF). However, the direct effect of EAT on the cardiac lymphatic endothelial cells (LECs) remains unknown.

Objective

To elucidate the effect of EAT on cardiac LECs, as one of the potential causes of AF.

Methods

Human EAT samples were collected from 18 consecutive patients with or without AF patients during cardiovascular surgery. They were categorized into the sinus rhythm (SR) group (n=9, 72.7±8.6 years) and the AF group (n=9, 73.3±7.4 years). Preadipocytes were extracted from EAT by homogenization and collagenase treatment, and cultured to confluence. After differentiation to mature adipocytes, cell culture supernatant was collected, and cultured with human LECs. Cell permeability was measured by using FITC-dextran assay. Tube forming ability was analyzed by seeding LECs on the extracellular matrix gels. Metabolomic profiling of LECs was performed by GC-MS system.

Results

RT-PCR analysis revealed that cell culture supernatant from mature adipocytes of AF patients significantly increased mRNA expression of mesenchymal marker, TAGLN/SM22a (p<0.01) in human LECs, whereas mRNA expression of lymphatic endothelial markers, LYVE1 (p=0.0552) and PROX1 (p=0.0231) were decreased in human LECs, compared to those from mature adipocytes of SR patients. These data suggest cell culture supernatant from mature adipocytes of AF patients highly induce endothelial-to-mesenchymal transition (EndMT) of LECs. When assessing the endothelial barrier function by using FITC-dextran, cell culture supernatant from mature adipocytes of AF patients significantly decreased cell barrier function (p<0.01) compared to those from mature adipocytes of SR patients. Furthermore, cell culture supernatant from mature adipocytes of AF patients significantly decreased the tube forming ability of LECs (p<0.01) compared to those from mature adipocytes of SR patients. To assess the metabolomic changes in human LECs by EAT-secretome, we conducted the GC/MS analysis. Cell culture supernatant from mature adipocytes of AF patients significantly decreased several amino acids including branched-chain amino acid (BCAA; valine, leucine and isoleucine), compared to those from mature adipocytes of SR patients.

Conclusion

Our study with human EAT and LECs demonstrated that EAT-secretome from AF patients altered metabolomic profile in LECs, and highly caused EndMT in LECs, leading to impaired barrier function and the tube forming ability. Defects of lymphangiogenesis could be a therapeutic target for atrial cardiomyopathy.
Targeting the histone methyltransferase SETD7 rescues diabetes-induced impairment of angiogenic response by transcriptional repression of semaphorin 3G
Authors: Mohammed S A , Gorica E , Karsay G , Albiero M , Mengozzi A , Spinetti G , Fadini G P , Ruschitzka F , Costantino S , Paneni F
Published: October 2024

Background

Peripheral artery disease (PAD) is highly prevalent in patients with diabetes (DM) and associates with a high rate of limb amputation and poor prognosis. Surgical and catheter-based revascularization have failed to improve outcome in DM patients with PAD. Hence, a need exists to develop new treatment strategies able to promote blood vessel growth in this setting. Mono-methylation of histone 3 at lysine 4 (H3K4me1) - a specific epigenetic signature induced by the histone methyltransferase SETD7 - favours an open chromatin thus enabling gene transcription.

Purpose

To investigate whether SETD7-dependent epigenetic changes modulate angiogenic response in diabetes.

Methodology

Primary human aortic endothelial cells (HAECs) were exposed to normal glucose (NG, 5 mM) or high glucose (HG, 25 mM) concentrations for 48 hours. Unbiased gene expression profiling was performed by RNA sequencing (RNA-seq) followed by Ingenuity Pathway Analysis (IPA). In vitro assays, namely cell migration and tube formation were employed to study angiogenic properties in HAECs. SETD7 and H3K4me1 levels were investigated by Western blot and Chromatin immunoprecipitation (ChIP). Pharmacological blockade of SETD7 was achieved by using the highly selective inhibitor (R)-PFI-2. Mice with streptozotocin-induced diabetes were orally treated with (R)-PFI-2 or vehicle and underwent hindlimb ischemia by femoral artery ligation for 14 days. Blood flow recovery was analysed at 30 minutes, 7 and 14 days by laser Doppler imaging. Our experimental findings were also translated in gastrocnemius muscle samples from patients with and without diabetes.

Results

RNA-seq in HG-treated HAECs revealed a profound upregulation of the methyltransferase SETD7, an enzyme involved in mono-methylation of lysine 4 at histone 3 (H3K4me1). SETD7 upregulation in HG-treated HAECs was associated with increased H3K4me1 levels as well as with impaired endothelial cell migration and tube formation. Both SETD7 gene silencing and pharmacological inhibition by (R)PFI-2 rescued hyperglycemia-induced impairment of HAECs migration and tube formation, while SETD7 overexpression blunted the angiogenic response. RNA-seq and ChIP assays showed that SETD7-dependent H3K4me1 regulates the transcription of the angiogenesis inhibitor semaphorin-3G (SEMA-3G). Moreover, SEMA-3G overexpression blunted migration and tube formation in SETD7-depleted HAECs. In diabetic mice with hindlimb ischemia, treatment with (R)-PFI-2 improved limb vascularization and perfusion as compared to vehicle. Finally, SETD7/SEMA3G axis was upregulated in muscle specimens from T2D patients as compared to controls.

Conclusion

Targeting SETD7 represents a novel epigenetic-based therapy to boost neovascularization in diabetic patients with PAD.