Novel Roles for the Transcriptional Repressor E4BP4 in Both Cardiac Physiology and Pathophysiology
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE240149 | GEO | 2023/08/11
REPOSITORIES: GEO
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Project description:Circadian clocks temporally orchestrate biological processes critical for cellular/organ function. For example, the cardiomyocyte circadian clock modulates cardiac metabolism, signaling, and electrophysiology over the course of the day, such that, disruption of the clock leads to age-onset cardiomyopathy (through unknown mechanisms). Here, we report that genetic disruption of the cardiomyocyte clock results in chronic induction of the transcriptional repressor E4BP4. Importantly, E4BP4 deletion prevents age-onset cardiomyopathy following clock disruption. These studies also indicate that E4BP4 regulates both cardiac metabolism (eg, fatty acid oxidation) and electrophysiology (eg, QT interval). Collectively, these studies reveal that E4BP4 is a novel regulator of both cardiac physiology and pathophysiology.
2023-08-16 | GSE240710 | GEO
Project description:The heart is a highly metabolic organ that uses multiple energy sources to meet its demand for ATP production. Diurnal feeding-fasting cycles result in substrate availability fluctuations which, together with increased energetic demand during the active period, impose a need for rhythmic cardiac metabolism. The nuclear receptors REV-ERBa and b are essential repressive components of the molecular circadian clock and major regulators of metabolism. To investigate their role in the heart, we generated mice with cardiomyocyte (CM)-specific deletion of both Rev-erbs, which died prematurely due to dilated cardiomyopathy. Loss of Rev-erbs markedly downregulated fatty acid oxidation genes prior to overt pathology, which was mediated by induction of the transcriptional repressor E4BP4, a direct target of cardiac REV-ERBs. E4BP4 directly controls circadian expression of Nampt and its biosynthetic product NAD+ via distal cis-regulatory elements. Thus, REV-ERB-mediated E4BP4 repression is required for Nampt expression and NAD+ production by the salvage pathway. Together, these results highlight the indispensable role of circadian REV-ERBs in cardiac gene expression, metabolic homeostasis and function.
2021-09-28 | GSE153014 | GEO
Project description:Circadian clocks are cell autonomous timekeeping mechanisms that govern critical biological processes. Regarding the heart, the cardiomyocyte circadian clock regulates a diverse array of processes, ranging from transcription and translation, to signaling, metabolism, electrophysiology, and contractility. The importance of this mechanism is underscored by observations that genetic disruption of the cardiomyocyte circadian clock in murine models leads to adverse cardiac remodeling, heart failure, and reduced lifespan. However, the precise molecular links between the cardiomyocyte circadian clock and cardiac physiology/pathology have not been characterized fully. Given that recent studies have highlighted that small RNA species (such as miRNAs) influence both cardiac physiology and pathology, we sought to determine the extent to which cardiomyocyte circadian clock disruption impacts cardiac small RNA species. Accordingly, hearts were collected from cardiomyocyte-specific Bmal1 knockout (CBK) and littermate control (CON) mice at distinct times of the day. Small RNA-seq revealed 47 differentially expressed miRNA species in CBK hearts (in the absence of significant time-of-day-dependent effects). Subsequent bioinformatic analyses predicted that differentially expressed miRNA species in CBK hearts potentially influence processes such as circadian rhythmicity, cellular signaling, and metabolism. Of the induced miRNAs in CBK hearts, 7 were predicted to be targeted by the transcriptional repressors REV-ERB/ (integral circadian clock components that are directly regulated by BMAL1). Similar to CBK hearts, cardiomyocyte-specific Rev-erb/ double knockout (CM-RevDKO) mouse hearts exhibited increased let-7c-1-3p, miR-23b-5p, miR-139-3p, miR-5123, and miR-7068-3p levels. Importantly, 19 putative targets of these 5 miRNAs were commonly repressed in both CBK and CM-RevDKO heart (of which 16 are targeted by let-7c-1-3p). These observations suggest that disruption of the BMAL1–REV-ERB/ axis in the heart leads to induction of a subset of miRNAs, whose predicted mRNA targets have established functions in biological processes such as metabolism and cellular signaling.
2023-11-15 | GSE237168 | GEO
Project description:Circadian clocks are cell autonomous, transcriptionally-based, molecular mechanisms that confer the selective advantage of anticipation, enabling cells/organs to respond to environmental factors in a temporally appropriate manner. Critical to circadian clock function are two transcription factors, CLOCK and BMAL1. Previous studies in our laboratory have highlighted roles for CLOCK in cardiac physiology/pathophysiology. Here, we describe transcriptional, metabolic, and functional consequences of cardiomyocyte-specific Bmal1 knockout (CBK). Microarray analysis revealed 2037 differentially expressed genes in CBK hearts, many of which were previously identified in cardiomyocyte-specific Clock mutant (CCM) hearts. Subsequent analysis showed that Beta-hydroxybutyrate dehydrogenase 1 mRNA, protein, and enzymatic activity are markedly depressed in both CBK and CCM hearts, as is myocardial Beta-hydroxybutyrate oxidation, revealing a novel role for the circadian clock in ketone body utilization. A number of genes encoding for collagen isoforms were identified as oscillating in a time-of-day-dependent manner in wild-type, but not CBK, hearts, including col3a1, col4a1, and col4a2. Chronic induction of collagen isoform genes in CBK hearts was associated with severe age-dependent depression of cardiac function. Development of cardiomyopathy in CBK mice was associated with early mortality; all CBK mice die by one year of age. These studies highlight novel critical functions for BMAL1 in the heart, including regulation of ketone body metabolism and the extracellular matrix. RNA from whole hearts collected every 3 hours for 24 hours from wildtype and CBK mice was isolated and analyzed using MouseRef-8_V2 BeadChips (Illumina, Inc.). The 24-hour data were examined for rhythmicity using cosinor analysis and differences in rhythmicity between genotype groups were further examined for differences in the model fitting parameters.
2014-01-01 | E-GEOD-43073 | biostudies-arrayexpress
Project description:Disruption of the Circadian Clock within the Cardiomyocyte
| PRJNA108617 | ENA
Project description:Disruption of the Circadian Clock within the Cardiomyocyte Influences Myocardial Contractie Function, Metabolism, and Gene Expression Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally-based molecular mechanism in cardiovascular biology is poorly understood. We hypothesized that the circadian clock within the cardiomyocyte influences diurnal variations in myocardial biology. We therefore generated a cardiomyocyte-specific circadian clock mutant (CCM) mouse, in order to test this hypothesis. At 12 weeks of age, CCM mice exhibit normal myocardial contractile function in vivo, as assessed by echocardiography. Radiotelemetry studies reveal attenuation of heart rate diurnal variations and bradycardia in CCM mice (in the absence of conduction system abnormalities). Reduced heart rate persisted in CCM hearts perfused ex vivo in the working mode, highlighting the intrinsic nature of this phenotype. Wild-type, but not CCM, hearts exhibited a marked diurnal variation in responsiveness to an elevation in workload (80mmHg plus 1 microM epinephrine) ex vivo, with a greater increase in cardiac power and efficiency during the dark (active) phase versus the light (inactive) phase. Moreover, myocardial oxygen consumption and fatty acid oxidation rates were increased, while cardiac efficiency was decreased, in CCM hearts. These observations were associated with no alterations in mitochondrial content or structure, and modest mitochondrial dysfunction, in CCM hearts. Gene expression microarray analysis identified 548 and 176 genes in atria and ventricles, respectively, whose normal diurnal expression patterns were altered in CCM mice. These studies suggest that the cardiomyocyte circadian clock influences myocardial contractile function, metabolism, and gene expression. Keywords: Comparison of circadian oscillations in gene expression in hearts taken from wildtype and transgenic animals
2008-01-01 | GSE10045 | GEO
Project description:Circadian clocks are cell autonomous, transcriptionally-based, molecular mechanisms that confer the selective advantage of anticipation, enabling cells/organs to respond to environmental factors in a temporally appropriate manner. Critical to circadian clock function are two transcription factors, CLOCK and BMAL1. Previous studies in our laboratory have highlighted roles for CLOCK in cardiac physiology/pathophysiology. Here, we describe transcriptional, metabolic, and functional consequences of cardiomyocyte-specific Bmal1 knockout (CBK). Microarray analysis revealed 2037 differentially expressed genes in CBK hearts, many of which were previously identified in cardiomyocyte-specific Clock mutant (CCM) hearts. Subsequent analysis showed that Beta-hydroxybutyrate dehydrogenase 1 mRNA, protein, and enzymatic activity are markedly depressed in both CBK and CCM hearts, as is myocardial Beta-hydroxybutyrate oxidation, revealing a novel role for the circadian clock in ketone body utilization. A number of genes encoding for collagen isoforms were identified as oscillating in a time-of-day-dependent manner in wild-type, but not CBK, hearts, including col3a1, col4a1, and col4a2. Chronic induction of collagen isoform genes in CBK hearts was associated with severe age-dependent depression of cardiac function. Development of cardiomyopathy in CBK mice was associated with early mortality; all CBK mice die by one year of age. These studies highlight novel critical functions for BMAL1 in the heart, including regulation of ketone body metabolism and the extracellular matrix.
2014-01-01 | GSE43073 | GEO
Project description:Mutations in the LMNA gene encoding nuclear lamins A/C cause a diverse array of tissue-selective diseases, with the heart being the most commonly affected organ. Despite progress in understanding the molecular perturbations emanating from LMNA mutations, an integrative understanding of the pathogenesis leading to cardiac dysfunction remains elusive. Using a novel cell-type specific Lmna deletion mouse model capable of translatome profiling, we found that cardiomyocyte-specific Lmna deletion in adult mice led to rapid cardiomyopathy with pathological remodeling. Prior to the onset of cardiac dysfunction, lamin A/C-depleted cardiomyocytes displayed nuclear envelope deterioration, disruption of the ER-golgi interface, and ER stress. Translatome profiling identified upregulation of Med25, a transcriptional co-factor involved in unfolded protein responses. Culturing Lmna-deleted cardiomyocytes in stiff hydrogels recapitulated these pathological features, confirming that cardiomyocyte-extrinsic factors contribute to the pathogenesis. Pharmacological activation of autophagy or modulation of ER stress significantly improved the cardiac function. These studies support a unified hypothesis wherein cardiomyopathy develops from autophagic impairment that exacerbates ER stress emanating from nuclear envelope deterioration.
2022-10-11 | GSE185620 | GEO
Project description:Maintenance of circadian alignment between an organism and its environment is essential to ensure metabolic homeostasis. Synchrony is achieved by cell autonomous circadian clocks. Despite a growing appreciation of the integral relation between clocks and metabolism, little is known regarding the direct influence of a peripheral clock on cellular responses to fatty acids. To address this important issue, we utilized a genetic model of disrupted clock function specifically in cardiomyocytes in vivo (termed cardiomyocyte clock mutant (CCM)). CCM mice exhibited altered myocardial response to chronic high fat feeding at the levels of the transcriptome and lipidome as well as metabolic fluxes, providing evidence that the cardiomyocyte clock regulates myocardial triglyceride metabolism. Time-of-day-dependent oscillations in myocardial triglyceride levels, net triglyceride synthesis, and lipolysis were markedly attenuated in CCM hearts. Analysis of key proteins influencing triglyceride turnover suggest that the cardiomyocyte clock inactivates hormone-sensitive lipase during the active/awake phase both at transcriptional and post-translational (via AMP-activated protein kinase) levels. Consistent with increased net triglyceride synthesis during the end of the active/awake phase, high fat feeding at this time resulted in marked cardiac steatosis. These data provide evidence for direct regulation of triglyceride turnover by a peripheral clock and reveal a potential mechanistic explanation for accelerated metabolic pathologies after prevalent circadian misalignment in Western society.
2010-03-24 | GSE21028 | GEO
Project description:Protein-protein interactions are essential for normal cellular processes and signaling events. Defining these interaction networks is therefore crucial for understanding complex cellular functions and interpretation of disease-associated gene variants. We need to build a comprehensive picture of the interactions, their affinities and interdependencies in the specific organ and cell-type to understand hitherto poorly understood signaling mechanism through ion channels and to begin their mechanistic studies. Here, we experimentally identify the ensemble of interacting partners for 13 types of ion channel in murine cardiac tissue to understand their role in cardiomyocyte electrophysiology. Of these, we validated the functional importance of 10 novel interactors on cardiac electrophysiology through genetic knockouts in zebrafish, super resolution microscopy, and patch clamp experiments. Furthermore, we establish a computational framework to reconstruct human cardiomyocyte ion channel networks from deep proteome mapping of human heart tissue and human heart single-cell gene-expression data. Finally, we integrate the ion channel interactome with human population genetics data to identify proteins that influence the electrocardiogram (ECG). The combined channel network is enriched for proteins influencing the ECG; with 44% of the network proteins significantly associated with an ECG phenotype. Altogether, we comprehensively define the interactomes of 13 major cardiac ion channels, contextualize their relevance to human electrophysiology including impact on the ECG, and validate the functional roles of ten novel interactors, thereby creating a roadmap for our understanding of how ion channel interactomes regulate cardiac electrophysiology.
2023-09-18 | PXD028021 | Pride