tbuckley/cabot-search huggingface dataset:
Abstract We137: PGC-1α-dependent transcriptional regulatory mechanisms for tricarboxylic acid cycle genes in the heart.
Authors: Samta Veera, Junichi Sadoshima, Shinichi Oka
Journal: Circulation Research (2024)

Many metabolic genes, including tricarboxylic acid (TCA) cycle genes, are downregulated in heart failure, which may promote the pathology due to insufficient energy production. To clarify how TCA cycle genes are downregulated in the failing heart, it is a prerequisite to clarify how these genes are transcribed in the normal heart. PGC-1α is a transcriptional co-activator that broadly induces metabolic genes through activation of transcription factors, such as ERR, Nrf1, Gabpa and YY1. Here we show that PGC-1α transcribes 13 among 14 TCA cycle genes partly through ERR, Nrf1, Gabpa and YY1. Thirteen TCA cycle genes, except for Suclg2, were downregulated in cardiac specific PGC-1α knockout (KO) mice (Relative mRNA levels in KO mice compared to wild type (WT) were CS 0.66*, Aco2 0.64*, Idh3a 0.62*, Idh3b 0.54*, Idh3g 0.54*, Ogdh 0.64*, Suclg1 0.45*, Suclg2: 1.1, Sdha 0.57*, Sdhb 0.53*, Sdhc 0.72*, Sdhd 0.57*, Fh1 0.32* and Mdh2 0.54*,p&lt;0.05 vs. WT). ChIP-sequencing with PGC-1α antibody demonstrated that PGC-1α is localized at the promoter of thirteen TCA cycle genes, besides Suclg2. Bioinformatics analyses identified consensus binding sequences of ERR, Nrf1, Gabpa and YY1 in these promoters. Gene expression analyses with knockdown of these transcription factors demonstrated that a transcription factor whose binding sequence is found proximal to the PGC-1α localization peak transcribes the downstream genes in general. These transcription factor binding sequences were well conserved between mice and humans. ERR-, Nrf1- and Gabpa-dependent PGC-1α recruitment was verified with in vitro DNA binding assays using endogenous promoter sequences of Idh3a, Idh3g and Sdha. Taken together, this study clarifies a precise transcriptional mechanism for TCA cycle genes in the normal heart, which could be useful for understanding how those genes are dysregulated in the failing heart.
Abstract Mo087: A shared gene regulatory network underlies atrial pathophysiology in atrial fibrillation and heart failure mouse models
Authors: Sonja Lazarevic, Carlos Perez-Cerventes, Zhezhen Wang, Kaitlyn Shen, Margaret Gadek, Douglas Chapski, Timothy McKinsey, Thomas Vondriska, Alexander Ruthenburg, David Park, Ivan Moskowitz
Journal: Circulation Research (2024)

Atrial fibrillation and heart failure have a strong epidemiologic link, however the mechanisms underlying their mutual risk remain unresolved. We revealed a remarkable correlation of both gene expression and genomic features in the atria of atrial fibrillation (AF, Tbx5 deletion) and heart failure (HF, TAC banding) mouse models. Tbx5 - and TAC-dependent gene expression in the left atria demonstrated a correlation coefficient of 0.8. Remarkably, 118 transcription factors were dysregulated in both models and 109 shared directionality in both cases, suggesting a shared transcriptional response. Differential non-coding transcriptional profiling to identify altered cis -regulatory regions demonstrated a correlation coefficient of 0.81 between the models, including ~1,800 shared differentially expressed ncRNAs, of which ~400 emanated from accessible candidate regulatory elements. Integration with chromatin architecture allowed identification of lineage-specific shared AF and HF gene regulatory networks. A TBX5-driven ncRNA-defined regulatory element drives expression of Klf15, an inhibitor of cardiac hypertrophy, in the wild-type cardiomyocytes that is downregulated in both mouse and human heart failure. Whereas in mouse HF and AF a disease-specific ncRNA-defined regulatory element is upregulated with Sox9 , an important transcriptional regulator of fibroblast activation. This work indicates that AF and HF initiate a shared atrial pathological genomic response, including downregulation of a wild-type GRN that normally prevents injury-based disease signaling and upregulation of a disease GRN that promotes atrial remodeling, uncovering a common genomic underpinning of atrial disease.
Abstract We122: Suppression of defender against cell death 1 (Dad1) induces cardiomyocyte death by regulating cell adhesion proteins.
Authors: Shota Mori, Shota Tanaka, Yoshiaki Okada, Masanori Obana, Yasushi Fujio
Journal: Circulation Research (2024)

Introduction: Suppression of cardiomyocyte loss is considered a promising strategy for the prevention of the onset of heart failure (HF). Previously, defender against cell death 1 ( Dad1 ) was identified as a cytoprotective gene. Dad1 forms a complex with staurosporine and temperature sensitive 3A (Stt3A), a catalytic subunit of oligosaccharyltransferase (OST) complex which is responsible for N-glycosylation. However, the function of Dad1 in cardiomyocytes remains unknown. Hypothesis: The disruption of cell-extracellular matrix interactions results in cell death, known as anoikis. Because various cell adhesion proteins are N-glycosylated, we hypothesized that Dad1 suppressed anoikis by regulating N-glycosylation of cell adhesion proteins in cardiomyocytes. Methods: Neonatal rat cardiomyocytes were cultured and the expression of Dad1 or Stt3A was knocked down using siRNA. The protein expression was assessed with immunoblot analysis, and cell viability was evaluated using a CellTiter-Blue assay kit. Results: The suppression of Dad1 using siRNAs reduced cardiomyocyte viability ( p &lt;0.01, n=4). Interestingly, suppression of Dad1 impaired the N-glycosylation of integrin β1 and decreased the expression of mature integrin β1 ( p &lt;0.01, n=3). These changes inactivated integrin-mediated signal transduction through dephosphorylation of focal adhesion kinase ( p &lt;0.01, n=5). In addition, enhanced cell-extracellular matrix interactions by using adhesamine rescued the cardiomyocyte death by Dad1 knockdown ( p &lt;0.01, n=4). Next, we pursued the relationship between Dad1 and Stt3A. Dad1 knockdown decreased the expression of Stt3A ( p &lt;0.01, n=6). Suppression of Stt3A induced cardiomyocyte death accompanied by the changes of cell adhesion proteins ( p &lt;0.01, n=4). Finally, double knockdown of Dad1 and Stt3A did not induce a further reduction in cell viability compared with the knockdown of only Dad1 ( p &lt;0.05, n=4), suggesting that cardiomyocyte death by Dad1 knockdown was dependent on Stt3A. Conclusion: Dad1 is required for the stabilization of Stt3A and suppresses cardiomyocyte anoikis by regulating N-glycosylation of cell adhesion proteins in an OST-dependent manner. Dad1-mediated cardiomyocyte survival could be a therapeutic target against HF.
Abstract We008: Hallmark Maturation of the Human Pluripotent Stem Cells-derived Cardiovascular Progenitors in Myocardial Infarcted Large Animal Model
Authors: Swarnaseetha Adusumalli, Samantha Lim, Lei Ye, Eric lim, Shuxun Ren, Yibin Wang, Enrico Petretto, Karl Tryggvason, Lynn Yap
Journal: Circulation Research (2024)

For the goal of regenerative cardiology, cellular therapy may be used to restore injured heart muscle. The molecular mechanisms behind the engraftment and maturation of these transplanted cells, however, remain poorly understood. Thus, to obtain a comprehensive understanding of the complex transcriptional landscapes within their transplanted spatial context, we utilized spatial transcriptomics in this study. We have previously demonstrated the safety and effectiveness of transplanting our cardiovascular progenitors (CVPs) produced from laminin-221 into pig hearts that had suffered myocardial infarction (MI). Here, we undertake 10x spatial transcriptomics in chronic MI pig models at 1-, 4-, and 12 weeks post-transplantation to further our understanding of these cells in vivo. With confidence, we can distinguish between the transcripts from the pigs and the humans in the infarcted region. By using human-specific anti-Ku80 antibodies for immunohistochemical labeling of the pig tissue samples, this in silico prediction was verified. The CVPs' engraftment and longevity in the infracted region were shown by the long-term identification and staining of human cells at various time points. It is interesting to note that after 12 weeks, ribosomal and mitochondrial activity were higher than at 1 and 2 weeks. These results are consistent with the hallmarks of cardiac maturation, in which cells transit from immature fetal-like cells to mature cardiomyocytes (CMs) by switching their metabolic energy source from glucose to fatty acids. Also, by comparing the heart-specific genes, including MYH6 and MYH7, we were able to quantify the myosin isoform switches in the xenograft over time. Furthermore, to delineate the fate of the transplanted cells, we performed a ligand-receptor interaction analysis. Intriguing, we identified the midkine protein as a possible secreted human paracrine factor that enhances angiogenesis in the graft. In conclusion, we have shown the successful engraftment and maturation of human CVPs toward CMs using spatial transcriptomic technology. These data will be used to understand other aspects of regenerative cardiology such as the mechanism of VTs and in vivo cellular repair mechanisms. A shiny app atlas has been generated to share our transcriptomics data for all to explore gene expression of human transplanted cells in myocardial infarcted pig hearts.
Abstract We130: Novel Role of RBFox1 in Myocardial Infarction Induced Heart Failure
Authors: Mengying He, Cansheng Zhu, Nkechi Onubogu, Caitlin Keezer, Xingyu He, Yigang Wang, Xinyang Hu, Shuyuan Sheng, Yibin Wang, chen gao
Journal: Circulation Research (2024)

Introduction: Alternative mRNA splicing affects a broad spectrum of cardiac genes during pathological manifestation of heart diseases. Earlier studies from our lab have identified a muscle-specific isoform of RBFox1 to be a key RNA splicing regulator in pressure overload induced heart failure through regulating cardiac transcription factor alternative splicing. However, the physiological impact of RBFox1 in myocardial infarction (MI), and the RBFox1 downstream mRNA alternative splicing events during MI induced cardiac remodeling remains unknown. Goals: To investigate the functional impact of RBFox1 in MI induced cardiac remodeling. Method and Results: At both mRNA and protein levels, we found RBFox1 to be significantly decreased in Sprague-Dawley Rat hearts post MI. To investigate the functional impact of RBFox1 in myocardial infarction, we utilized AAV9 to achieve cardiac specific expression of RBFox1 in rats. Interestingly, expression of RBFox1 prevented cardiac dysfunction post MI characterized by improved cardiac function based on echocardiography. Expression of RBFox1 further reduced hypertrophy, cell death and fibrotic remodeling at both molecular and histological levels post MI. In vitro, expression of RBFox1 is sufficient to prevent hypoxia induced cardiac cell death based on TUNEL staining and cleaved caspase 3 level, while inactivation of RBFox1 promoted cardiac cell death. To further understand the molecular mechanism underlying RBFox1 mediated cardiac protection, we performed RNA-seq analysis to determine the transcriptome changes in vivo. RNA-seq showed insulin secretion, cAMP signaling and muscle contraction pathways to be top significantly changed pathways in RBFox1 expressed rat hearts post MI. Lastly, we have identified Mbnl1 mRNA alternative splicing to be regulated by RBFox1 through promoting a 36bp exon exclusion at the C-terminal of Mbnl1 protein, potentially affecting the function of Mbnl1. Conclusion: In summary, we have identified a previously uncharacterized role of RBFox1 in myocardial infarction injury. RBFox1 expression is critical to preserve cardiac function post MI, potentially through regulating downstream targets alternative splicing, including Mbnl1.
Abstract We011: The role of hsa-miR-9-5p in hypercontractility: insights from patients with hypertrophic cardiomyopathy
Authors: Doris Adao, Daniela Grothe, Ludger Hauck, Zahra Mirzaei, Craig Simmons, Filio Billia
Journal: Circulation Research (2024)

Background: Hypertrophic cardiomyopathy (HCM) is an inherited disease characterized by the thickening of the heart muscle. Mutations in contractile proteins, such as myosin binding protein C ( MYBPC3 ) and β-myosin heavy chain ( MYH7 ), account for over half of patients with familial HCM. HCM is the leading cause of sudden cardiac death among young adults and athletes, with these mutations potentially leading to hypercontractility and arrhythmias culminating in sudden cardiac death. MicroRNAs (miRNAs) are pivotal regulators of gene expression that may influence disease progression. Despite their potential significance, there is a scarcity of published data on miRNA expression in HCM. Induced pluripotent stem cells (iPSCs) have emerged as valuable tools for modeling various cardiovascular diseases, including HCM. However, the miRNA expression profiles associated with HCM remain largely unexplored within iPSC models. Investigating the differential expression of miRNAs in HCM patients offers a promising avenue to identify potential therapeutic targets for individuals affected by this condition. Methods: We performed an unbiased screen using a microarray (NanoString Technologies) that contained 798 miRNAs to identify differentially expressed miRNAs in induced pluripotent stem cell (iPSC)-CM and myocardial tissues derived from healthy donors and HCM patients with MYBPC3 and MYH7 mutations. Results: We identified 5 differentially expressed miRNAs that are significantly downregulated in both mutant MYBPC3 iPSC-CM and myocardial tissue (miR-9-5p, -4443, -367-3p, -302c-3p, and -129-2-3p) (p ≤ 0.05). In mutant MYH7 iPSC-CM and myocardial tissue, 3 miRNAs that were significantly downregulated (miR-9-5p, -151a-3p, -129-2-3p), and 1 was significantly upregulated (miR-331-5p) (p ≤ 0.05). KEGG pathway analysis of gene targets using miRTarBase and g:Profiler revealed that miR-9-5p regulates genes in the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance pathway (p = 3.99x10 -9 ), which is involved in hypercontractility associated with HCM. Conclusion: This work represents the first description of miRNA expression patterns in iPSC-CMs derived from patients with HCM with additional validation from primary myocardial tissue, the current gold standard. We identified the miR-9-5p/EGFR tyrosine kinase inhibitor resistance axis as a potential therapeutic target responsible for mitigating the hypercontractile phenotype exhibited in HCM.
Abstract We002: A natural loss-of-function deletion of the cytohesin 1 (Cyth1) gene in BALB/cByJ mice does not impact cardiomyocyte polyploidy
Authors: Ruolan Song, Henry Sucov
Journal: Circulation Research (2024)

The adult mammalian heart has limited regenerative capacity due in part to the low level of diploid cardiomyocytes (CMs). Multiple polymorphic genes determine the final level of diploid CMs, however, the relevant genes need to be identified. There is a large variation in CM ploidy between the highly related sister strains BALB/cJ and BALB/cByJ. We undertook an RNA-Seq comparison of neonatal ventricular heart tissue from BALB/cJ and BALB/cByJ to identify gene expression differences that might underlie this difference in CM ploidy. Cytohesin-1 (Cyth1) and Dynein heavy chain 17 (Dnah17) were particularly different in expression: in BALB/cJ (as in most other mouse strains), Cyth1 is expressed in the heart and Dnah17 isn’t expressed, whereas the opposite profile (Cyth1 off, Dnah17 on) was observed in BALB/cByJ heart. These two genes are immediately adjacent to each other in the mouse genome. We found that the basis of differential expression is a large deletion in the locus of BALB/cByJ mice spanning from the Cyth1 first intron to shortly downstream of the last Cyth1 exon. This creates a complete null Cyth1 allele and at the same time results in ectopic transcription of the downstream gene Dnah17, although this transcript is unlikely to encode a protein. Cyth1 encodes a guanine nucleotide exchange factor that was a plausible candidate for being involved in CM ploidy. Using the natural Cyth1 mutant locus plus an engineered null allele, we found no difference in CM ploidy in the absence of Cyth1 function on a cJ-cByJ F1 background or on an inbred C57BL/6J background. This study successfully identified a natural loss-of-function variant in the Cyth1 gene between BALB/cJ and BALB/cByJ but showed that this does not impact CM ploidy, at least by itself. It may underlie other phenotypic differences between these two strains.
Abstract Mo085: Direct effect of sodium-glucose cotransporter 2 (SGLT2) inhibitors on cardiomyocyte function as a potential therapy for Phospholamban cardiomyopathy
Authors: Anna Hnatiuk, Alexander Li, David Staudt, Ricardo Serrano, Mark Mercola
Journal: Circulation Research (2024)

Introduction: Phospholamban (PLN) cardiomyopathy is a dilated and arrhythmogenic cardiomyopathy caused by a single deletion of arginine in PLN gene (PLN-R14del). Clinically, It presents with heart failure, ventricular arrhythmias and sudden cardiac death, and there is still no effective and/or specific treatment besides the heart transplant. Hypothesis: Sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown cardiovascular outcomes improvement in general heart failure patients in multiple clinical trials. We hypothesize that SGLT2 inhibitors could ameliorate the contractile dysfunction in PLN cardiomyopathy. Goals: Identify whether there is a direct cardiac effect of SGLT2 inhibitors on PLN cardiomyopathy. Approach: We used a human iPSC-derived cardiomyocyte (hiPSC-CMs) model of PLN cardiomyopathy that mimics the impaired contractility of the disease to evaluate the contractile function after 4 days of Empagliflozin treatment by using functional cellular imaging assays. Additionally, we evaluated the effect of Empagliflozin treatment on CaMKII phosphorylation and activation of apoptosis mediators by measuring protein expression. All the experiments were compared to results using a CRISPR-engineered isogenic (healthy) line control hiPSC-CMs. Results: 4 days of Empagliflozin treatment significantly restored contractile function, decreased levels of CaMKII phosphorylation, and decreased apoptotic activity in hiPSC-CMs with PLN cardiomyopathy when compared to their healthy (isogenic) control. Conclusions: Our study provided evidence that SGLT2 inhibitors might serve as a therapeutic strategy to ameliorate contractile dysfunction and suppress arrhythmia in PLN cardiomyopathy.
Abstract We123: Cardiomyocyte Specific Sustained Atg7 Overexpression Activates Mitochondrial Autophagy in the Heart
Authors: Chowdhury S. Abdullah, Richa Aishwarya, Naznin Sultana Remex, Wayne Orr, Junichi Sadoshima, Md Shenuarin Bhuiyan
Journal: Circulation Research (2024)

Introduction: Accumulating evidence indicates that autophagy-related protein 7 (Atg7) is essential in cellular autophagy. Our earlier studies showed that Atg7 is required to promote macro-autophagy in the heart. However, it is unknown if the activation of Atg7 has a role in the heart to regulate selective mitochondrial autophagy (mitophagy). Objectives: We employed in vitro and in vivo approaches to delineate the molecular function and mechanisms of Atg7-mediated activation of mitophagy in the heart. Methods and Results: Subcellular fractionation and quantum dot-labeled electron microscopy revealed Atg7’s localization on the mitochondrial fraction in the heart. Atg7 co-localization to Mitotracker-labeled mitochondria was confirmed using isolated heart mitochondria. To quantitate the mitophagy, we overexpressed Atg7 in cultured primary cardiomyocytes, treated with cyanide 3-chlorophenylhydrazone (CCCP) to induce mitophagy, and stained with pH-sensitive fluorescent mitophagy dye to enumerate mitophagy dots by microscopy. We found significantly increased mitophagy dots in Atg7 overexpressed cardiomyocytes than in β-gal expressing control. To assess the activation of mitophagy in vivo , we treated the cardiac-specific Atg7 overexpressing transgenic (αMHC-Atg7 Tg) and their littermate non-transgenic (Ntg) mice with CCCP. We found an increased accumulation of mature autophagolysosomal marker protein LC3-II in isolated mitochondria from Atg7 Tg mice hearts post-CCCP treatment. To assess the extent of mitochondrial lysosomal delivery in Atg7 overexpressing hearts, we crossed αMHC-Atg7 Tg mice with cardiac-specific Mito-Keima transgenic (Mt-Keima Tg) mice. Mt-Keima Tg mice bear mitochondria-targeted pH-dependent fluorescent lysosomal protease-resistance Keima protein, enabling the measurement of mitophagy activation in vivo . We observed increased Mt-Keima high red-to-green areas in αMHC-Atg7xMt-Keima Tg mice hearts compared to Mt-Keima mice. Conclusions: Our biochemical and genetic approaches revealed that Atg7 localizes to the mitochondria, leading to the recruitment and initiation of mitophagy machinery. Our data further confirm that genetic activation of Atg7 leads to increased mitophagy activity in the heart.
Abstract We134: Computational Model Predicts Mechanisms of Low-density Lipoprotein Receptor-related Protein 1 Cardioprotection through the RISK Pathway
Authors: Lavie Ngo, Jamie Saquing, Antonio Abbate, Stefano Toldo, Jeffrey Saucerman
Journal: Circulation Research (2024)

Introduction: Complications after acute myocardial infarction are among the leading causes of mortality in the United States. Ischemia-reperfusion injury occurs after reperfusion which induces more damage to the heart despite the return of blood flow, which can lead to heart failure. Previous work has identified low-density lipoprotein receptor-related protein 1, or LRP1, as a potential therapeutic target to protect cell death from reperfusion injury. In this work, an apoptosis model was expanded to predict the signaling effects of an LRP1 agonist during ischemia. Methods: LRP1 agonist was added as an input to an existing cardiomyocyte apoptosis network to predict LRP1 activity and its effects on cell death during ischemia. New reactions of LRP1 with PKC, Shp2, Shc1, and Src were added for more detail upstream. The model was validated using adult mouse cardiomyocytes with ischemia and reperfusion. SP16, a synthetic LRP1 agonist drug, was delivered to measure outputs such as Akt phosphorylation, caspase3, and apoptosis. Results: LRP1 activation increased Ras/PI3K/Akt and MEK/ERK pathway activity, which is part of the reperfusion-injury salvage kinase (RISK) pathway. Outputs of the model such as apoptosis and cell death were decreased due to LRP1 agonist activity. The model predictions were then validated against the experiments, with 7 out of 8 model predictions (88%) validated. Conclusions: The cardiomyocyte apoptosis model was able to accurately predict pathways by which LRP1 prevents cell death, main pathways involved in LRP1 signaling such as the RISK pathway. This work supports LRP1 as a potential therapeutic target to induce pro-survival signaling in the heart during ischemia-reperfusion.