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Background: The human heart primarily metabolizes fatty acids, and this decreases as alternative fuel use rises in heart failure with reduced ejection fraction (HFrEF). Patients with severe obesity and diabetes are thought to have increased myocardial fatty acid metabolism, but whether this is found in those who also have heart failure with preserved ejection fraction (HFpEF) is unknown. Methods: Plasma and endomyocardial biopsies were obtained from HFpEF (n=38), HFrEF (n=30), and nonfailing donor controls (n=20). Quantitative targeted metabolomics measured organic acids, amino acids, and acylcarnitines in myocardium (72 metabolites) and plasma (69 metabolites). The results were integrated with reported RNA sequencing data. Metabolomics were analyzed using agnostic clustering tools, Kruskal-Wallis test with Dunn test, and machine learning. Results: Agnostic clustering of myocardial but not plasma metabolites separated disease groups. Despite more obesity and diabetes in HFpEF versus HFrEF (body mass index, 39.8 kg/m 2 versus 26.1 kg/m 2 ; diabetes, 70% versus 30%; both P Conclusions: Despite marked obesity and diabetes, HFpEF myocardium exhibited lower fatty acid metabolites compared with HFrEF. Ketones and metabolites of the tricarboxylic acid cycle and BCAA were also lower in HFpEF, suggesting insufficient use of alternative fuels. These differences were not detectable in plasma and challenge conventional views of myocardial fuel use in HFpEF with marked diabetes and obesity and suggest substantial fuel inflexibility in this syndrome.

Cardiovascular complications of pregnancy have risen substantially over the past decades, and now account for the majority of pregnancy-induced maternal deaths, as well as having substantial long-term consequences on maternal cardiovascular health. The causes and pathophysiology of these complications remain poorly understood, and therapeutic options are limited. Preclinical models represent a crucial tool for understanding human disease. We review here advances made in preclinical models of cardiovascular complications of pregnancy, including preeclampsia and peripartum cardiomyopathy, with a focus on pathological mechanisms elicited by the models and on relevance to human disease.

BACKGROUND: Hypertensive disorders of pregnancy (HDP) are associated with increased risk of cardiovascular disease (CVD) 20–30 years later; however, cardiovascular (CV) risk in the decade after HDP is less studied. OBJECTIVES: The purpose of this study was to evaluate differences in CV risk factors as well as subclinical CVD among a well-characterized group of racially diverse patients with and without a history of HDP 10 years earlier. METHODS: This is a prospective study of patients with and without a diagnosis of HDP ≥10 years earlier (2005–2007) who underwent in-person visits with echocardiography, arterial tonometry, and flow-mediated dilation of the brachial artery. RESULTS: A total of 135 patients completed assessments (84 with and 51 without a history of HDP); 85% self-identified as Black. Patients with a history of HDP had a 2.4-fold increased risk of new hypertension compared with those without HDP (56.0% vs. 23.5%; adjusted relative risk: 2.4; 95% CI: 1.39–4.14) with no differences in measures of left ventricular structure, global longitudinal strain, diastolic function, arterial stiffness, or endothelial function. Patients who developed hypertension, regardless of HDP history, had greater left ventricular remodeling, including greater relative wall thickness; worse diastolic function, including lower septal and lateral e’ and E/A ratio; more abnormal longitudinal strain; and higher effective arterial elastance than patients without hypertension. CONCLUSIONS: We found a 2.4-fold increased risk of hypertension 10 years after HDP. Differences in noninvasive measures of CV risk were driven mostly by the hypertension diagnosis, regardless of HDP history, suggesting that the known long-term risk of CVD after HDP may primarily be a consequence of hypertension development.

The ability of cells to store and rapidly mobilize energy reserves in response to nutrient availability is essential for survival. Breakdown of carbon stores produces acetyl-coenzyme-A (acetyl-CoA), which fuels various metabolic pathways and is also the acyl donor for protein lysine acetylation. Notably, histone acetylation is sensitive to acetyl-CoA availability and nutrient replete conditions induce a substantial accumulation of acetylation on histones. Deacetylation releases acetate, which can be recycled to acetyl-CoA, suggesting that deacetylation could be mobilized as an acetyl-CoA source to feed downstream metabolic processes under nutrient depletion. While the notion of histones as a metabolic reservoir has been frequently proposed, experimental evidence has been lacking. Therefore, to test this concept directly, we developed an experimental system to trace deacetylation-derived acetate and its incorporation into acetyl-CoA, using13C2-acetate in ATP citrate lyase-deficient fibroblasts (Acly-/-MEFs), which are primarily dependent on acetate for protein acetylation. We find that dynamic protein deacetylation inAcly-/-MEFs contributes carbons to acetyl-CoA and proximal downstream metabolites. However, there is no significant effect on acyl-CoA pool sizes, and even at maximal acetylation, deacetylation transiently supplies approximately 9% of cellular acetyl-CoA. Together, our data reveal that although protein acetylation is dynamic and sensitive to nutrient availability, its potential for maintaining cellular acetyl-CoA-dependent metabolic pathways is limited compared to cellular demand.

Background Skeletomuscular diseases result in significant muscle loss and decreased performance, paralleled by a loss in mitochondrial and oxidative capacity. Insulin and insulin‐like growth factor‐1 (IGF‐1) are two potent anabolic hormones that activate a host of signalling intermediates including the serine/threonine kinase AKT to influence skeletal muscle physiology. Defective AKT signalling is associated with muscle pathology, including cachexia, sarcopenia, and disuse; however, the mechanistic underpinnings remain unresolved. Methods To elucidate the role of AKT signalling in muscle mass and physiology, we generated both congenital and inducible mouse models of skeletal muscle‐specific AKT deficiency. To understand the downstream mechanisms mediating AKT's effects on muscle biology, we generated mice lacking AKT1/2 and FOXO1 (M‐AKTFOXO1TKO and M‐indAKTFOXO1TKO) to inhibit downstream FOXO1 signalling, AKT1/2 and TSC1 (M‐AKTTSCTKO and M‐indAKTTSCTKO) to activate mTORC1, and AKT1/2, FOXO1, and TSC1 (M‐QKO and M‐indQKO) to simultaneously activate mTORC1 and inhibit FOXO1 in AKT‐deficient skeletal muscle. Muscle proteostasis and physiology were assessed using multiple assays including metabolic labelling, mitochondrial function, fibre typing, ex vivo physiology, and exercise performance. Results Here, we show that genetic ablation of skeletal muscle AKT signalling resulted in decreased muscle mass and a loss of oxidative metabolism and muscle performance. Specifically, deletion of muscle AKT activity during development or in adult mice resulted in a significant reduction in muscle growth by 30–40% (P

Assessing mammalian gene function in vivo has traditionally relied on manipulation of the mouse genome in embryonic stem cells or perizygotic embryos. These approaches are time-consuming and require extensive breeding when simultaneous mutations in multiple genes is desired. The aim of this study is to introduce a rapid in vivo multiplexed editing (RIME) method and provide proof of concept of this system.RIME, a system wherein CRISPR/caspase 9 technology, paired with adeno-associated viruses (AAVs), permits the inactivation of one or more genes in the adult mouse liver. The method is quick, requiring as little as 1 month from conceptualization to knockout, and highly efficient, enabling editing in95% of target cells. To highlight its use, we used this system to inactivate, alone or in combination, genes with functions spanning metabolism, mitosis, mitochondrial maintenance, and cell proliferation.RIME enables the rapid, efficient, and inexpensive analysis of multiple genes in the mouse liver in vivo.

Doxorubicin (DOX) is an efficacious chemotherapy compound used to treat various cancers which elicits severe side effects, including heart failure. Uptake of DOX by cardiomyocytes causes metabolic dysfunction and cell death but causal mechanisms remain largely undefined. We applied genome-wide CRISPR/Cas9 knockout screens to discover genetic modifiers of DOX-induced cardiomyocyte cell death, and independently, DOX uptake and clearance. Both screens discovered known and novel factors. In cell death screens and validation studies, loss of retinoic acid receptor-α (RARA) predisposed cardiomyocytes to DOX-mediated cell death. Conversely, RARA activation reduced DOX cytotoxicity in wild type cardiomyocytes. RNA-Seq analysis revealed that whilst DOX caused large-scale suppression of metabolic and mitochondrial gene expression, RARA activation mitigated this effect. In DOX accumulation screens, an essential role for lysosomes in DOX clearance was observed. Loss of Sphingolipid Transporter 1 (SPNS1) led to DOX hyperaccumulation, suppression of autophagy, increased DNA damage, and increased cell death. Hence, SPNS1 plays a key role in buffering against DOX accumulation and toxicity. Collectively, our study nominated hundreds of drug-gene interactions, providing a springboard for exploration of causal mechanisms, and a technical framework for future screening campaigns.

We report a case series of six women with peripartum cardiomyopathy (PPCM) who incidentally underwent echocardiography prior to the clinical presentation of PPCM. For comparison, we identified controls, matched 2:1 on age, race, body mass index, gestational age, and hypertensive disorder. Among the six cases, all were diagnosed with PPCM during the post‐partum period. Pre‐PPCM echocardiograms were performed between 17.7 weeks of gestation and 13 days post‐partum. Baseline left ventricular ejection fraction and size were normal and similar to the 12 matched controls (60% ± 6.6% vs. 61.4% ± 6.3%, P = 0.63) or left ventricular end‐diastolic dimension (4.6 cm ± 0.2 cm vs. 4.5 cm ± 0.4 cm, P = 0.689). There was a trend towards a less negative (more abnormal) mean global longitudinal strain in cases compared with controls (−14% ± 4% vs. −18.3% ± 4.5%, P = 0.0658). Mean global circumferential strain was significantly less negative (more abnormal) in cases compared with controls (−21.5% ± 5% vs. −29.3% ± 7.6%, P = 0.0329). We conclude that women who develop PPCM have normal left ventricular ejection fraction during gestation preceding PPCM, indicating that the disease develops acutely in the peripartum period. Abnormal strain can be detected, however, suggesting that strain imaging could represent a screening method in populations at high risk for PPCM if confirmed in future studies.

Oxidation of branched-chain amino acids (BCAAs) is tightly regulated in mammals. We review here the distribution and regulation of whole-body BCAA oxidation. Phosphorylation and dephosphorylation of the rate-limiting enzyme, branched-chain α-ketoacid dehydrogenase complex directly regulates BCAA oxidation, and various other indirect mechanisms of regulation also exist. Most tissues throughout the body are capable of BCAA oxidation, and the flux of oxidative BCAA disposal in each tissue is influenced by three key factors: 1. tissue-specific preference for BCAA oxidation relative to other fuels, 2. the overall oxidative activity of mitochondria within a tissue, and 3. total tissue mass. Perturbations in BCAA oxidation have been implicated in many disease contexts, underscoring the importance of BCAA homeostasis in overall health.

Background: Defects in energetics are thought to be central to the pathophysiology of hypertrophic cardiomyopathy (HCM); yet, the determinants of ATP availability are not known. The purpose of this study is to ascertain the nature and extent of metabolic reprogramming in human HCM, and its potential impact on contractile function. Methods: We conducted proteomic and targeted, quantitative metabolomic analyses on heart tissue from patients with HCM and from nonfailing control human hearts. Results: In the proteomic analysis, the greatest differences observed in HCM samples compared with controls were increased abundances of extracellular matrix and intermediate filament proteins and decreased abundances of muscle creatine kinase and mitochondrial proteins involved in fatty acid oxidation. These differences in protein abundance were coupled with marked reductions in acyl carnitines, byproducts of fatty acid oxidation, in HCM samples. Conversely, the ketone body 3-hydroxybutyrate, branched chain amino acids, and their breakdown products, were all significantly increased in HCM hearts. ATP content, phosphocreatine, nicotinamide adenine dinucleotide and its phosphate derivatives, NADP and NADPH, and acetyl CoA were also severely reduced in HCM compared with control hearts. Functional assays performed on human skinned myocardial fibers demonstrated that the magnitude of observed reduction in ATP content in the HCM samples would be expected to decrease the rate of cross-bridge detachment. Moreover, left atrial size, an indicator of diastolic compliance, was inversely correlated with ATP content in hearts from patients with HCM. Conclusions: HCM hearts display profound deficits in nucleotide availability with markedly reduced capacity for fatty acid oxidation and increases in ketone bodies and branched chain amino acids. These results have important therapeutic implications for the future design of metabolic modulators to treat HCM.

INTRODUCTION: As many as 100 million people in the US have nonalcoholic fatty liver disease (NAFLD), characterized by increased liver lipid accumulation, which often leads to hepatocyte injury and fibrosis, characteristics of nonalcoholic steatohepatitis (NASH). NASH in turn can progress to cirrhosis and hepatocellular carcinoma. There are currently no US Food and Drug Administration–approved therapies for NAFLD or NASH. NAFLD occurs when there is disequilibrium between the processes of hepatic lipid synthesis and consumption. The nutrient sensor mechanistic target of rapamycin complex 1 (mTORC1) regulates several of these pathways. mTORC1 is thus an attractive target to modulate lipid homeostasis in the liver. However, mTORC1 also regulates numerous other cellular pathways, and blunting of mTORC1 modulation can lead to unexpected feedback loops and unwanted effects. RATIONALE: We hypothesized that selective modulation of hepatic mTORC1 signaling could benefit liver lipid metabolism and prevent NAFLD. In non-liver cell types, the protein folliculin (FLCN) has been shown to confer substrate specificity to mTORC1. Deletion of FLCN inhibits mTORC1-mediated phosphorylation of the transcription factor E3/B (TFE3/B) family of transcription factors, without affecting mTORC1-driven phosphorylation of its canonical substrates ribosomal protein S6 kinase beta-1 (S6K1) and eukaryotic translation initiation factor 4E–binding protein 1 (4E-BP1). Unphosphorylated TFE3 translocates to the nucleus and activates genes that promote lysosomal biogenesis, mitochondrial biogenesis, and oxidative metabolism. We reasoned that suppression of FLCN in the liver might promote fatty acid oxidation and lipid clearance without untoward effects of generalized mTORC1 inhibition. RESULTS: Hepatocyte-specific genetic deletion of Flcn in adult mice selectively inhibited mTORC1-mediated cytoplasmic sequestration of TFE3, with little effect on other mTORC1 targets, including S6K, 4E-BP1, and Lipin1. Hepatocyte loss of Flcn protected mice from both NAFLD and NASH and partially reversed these processes when already established. The protection against NAFLD and NASH required TFE3, which activated lipid clearance. Unleashed TFE3 additionally suppressed de novo lipogenesis. The latter was mediated in part by TFE3-mediated induction of insulin-induced gene 2 (Insig2) to inhibit proteolytic activation of sterol regulatory element–binding protein-1c (SREBP-1c), a critical lipogenic transcription factor. CONCLUSION: Our data establish FLCN as a critical regulator of lipid homeostasis in the liver. Flcn deletion affords selective inhibition of mTORC1, leading to nuclear translocation and activation of the transcription factor TFE3, which coordinates hepatic lipid metabolic pathways to protect against NAFLD and NASH in mice. Thus, our data reveal FLCN as a promising target for the treatment of NAFLD and NASH. The data also illuminate previously published and seemingly conflicting data, which likely reflected different effects on each arm of mTORC1 signaling. There have been numerous attempts by many to develop disease-specific treatments for NAFLD and NASH, thus far without success. A recurrent problem has been the many compensatory responses by the liver to targeting any one pathway; for example, inhibitors of acetyl–coenzyme A carboxylase led to compensatory activation of SREBP-1c and consequent hyperlipidemia. Targeting FLCN is thus particularly attractive, in that loss of FLCN simultaneously and favorably affects multiple aspects of hepatic lipid homeostasis, including promoting fatty acid oxidation and lysosomal biogenesis and inhibiting de novo lipogenesis.

Per capita fructose consumption has increased 100-fold over the last century1. Epidemiological studies suggest that excessive fructose consumption, and especially consumption of sweet drinks, is associated with hyperlipidaemia, non-alcoholic fatty liver disease, obesity and diabetes2–7. Fructose metabolism begins with its phosphorylation by the enzyme ketohexokinase (KHK), which exists in two alternatively spliced forms8. The more active isozyme, KHK-C, is expressed most strongly in the liver, but also substantially in the small intestine9,10 where it drives dietary fructose absorption and conversion into other metabolites before fructose reaches the liver11–13. It is unclear whether intestinal fructose metabolism prevents or contributes to fructose-induced lipogenesis and liver pathology. Here we show that intestinal fructose catabolism mitigates fructose-induced hepatic lipogenesis. In mice, intestine-specific KHK-C deletion increases dietary fructose transit to the liver and gut microbiota and sensitizes mice to fructose’s hyperlipidaemic effects and hepatic steatosis. In contrast, intestine-specific KHK-C overexpression promotes intestinal fructose clearance and decreases fructose-induced lipogenesis. Thus, intestinal fructose clearance capacity controls the rate at which fructose can be safely ingested. Consistent with this, we show that the same amount of fructose is more strongly lipogenic when drunk than eaten, or when administered as a single gavage, as opposed to multiple doses spread over 45 min. Collectively, these data demonstrate that fructose induces lipogenesis when its dietary intake rate exceeds the intestinal clearance capacity. In the modern context of ready food availability, the resulting fructose spillover drives metabolic syndrome. Slower fructose intake, tailored to intestinal capacity, can mitigate these consequences. Modulating the capacity of the intestinal epithelium to catabolize fructose is shown to alter fructose-induced lipogenesis in the mouse liver, suggesting that fructose clearance in the small intestine protects from steatosis.

Nonalcoholic steatohepatitis (NASH) is a progressive disorder with aberrant lipid accumulation and subsequent inflammatory and profibrotic response. Therapeutic efforts at lipid reduction via increasing cytoplasmic lipolysis unfortunately worsens hepatitis due to toxicity of liberated fatty acid. An alternative approach could be lipid reduction through autophagic disposal, i.e., lipophagy. We engineered a synthetic adaptor protein to induce lipophagy, combining a lipid droplet-targeting signal with optimized LC3-interacting domain. Activating hepatocyte lipophagy in vivo strongly mitigated both steatosis and hepatitis in a diet-induced mouse NASH model. Mechanistically, activated lipophagy promoted the excretion of lipid from hepatocytes via lysosomal exocytosis, thereby suppressing harmful intracellular accumulation of nonesterified fatty acid. A high-content compound screen identified alpelisib and digoxin, clinically-approved compounds, as effective activators of lipophagy. Administration of alpelisib or digoxin in vivo strongly inhibited the transition to steatohepatitis. These data thus identify lipophagy as a promising therapeutic approach to prevent NASH progression.

OBJECTIVE: To determine predictors of adverse outcomes in peripartum cardiomyopathy (PPCM). METHODS AND RESULTS: We conducted a multi-center cohort study across four centers to identify subjects with PPCM with the following criteria: LVEF

How SARS-CoV-2 causes the observed range of clinical manifestations and disease severity remains poorly understood. SARS-CoV-2 encodes for two proteases (3CLPro and PLPro), vital for viral production, but also promiscuous with respect to host protein targets, likely contributing to the range of disease. Pharmacological inhibition of the 3C-like3 protease has revealed remarkable reduction in hospitalization and death in phase 2/3 clinical studies. However, the mechanisms responsible for the pathology mediated by those proteases are still unclear. In this study, we develop a bioinformatic algorithm, leveraging experimental data from SARS-CoV, to predict host cleavage targets of the SARS-CoV-2 3C-like protease, or 3CLPro. We capture targets of the 3CL protease described previously for SARS-CoV, and we identify hundreds of new putative targets. We experimentally validate a number of these predicted targets, including the giant sarcomeric protein Obscurin, and show that expression of 3CL protease alone recapitulates the sarcomeric disorganization seen by SARS-CoV-2 infection of hiPSC-derived cardiomyocytes. Our data provide a resource to identify putative host cleavage targets of 3CL protease that contribute to mechanisms and heterogeneity of disease in COVID-19 and future coronavirus outbreaks.

Peripartum cardiomyopathy (PPCM) is a potentially fatal form of idiopathic heart failure with variable prevalence across different countries and ethnic groups. The cause of PPCM is unclear, but environmental and genetic factors and pregnancy-associated conditions such as pre-eclampsia can contribute to the development of PPCM. Furthermore, animal studies have shown that impaired vascular and metabolic function might be central to the development of PPCM. A better understanding of the pathogenic mechanisms involved in the development of PPCM is necessary to establish new therapies that can improve the outcomes of patients with PPCM. Pregnancy hormones tightly regulate a plethora of maternal adaptive responses, including haemodynamic, structural and metabolic changes in the cardiovascular system. In patients with PPCM, the peripartum period is associated with profound and rapid hormonal fluctuations that result in a brief period of disrupted cardiovascular (metabolic) homeostasis prone to secondary perturbations. In this Review, we discuss the latest studies on the potential pathophysiological mechanisms of and risk factors for PPCM, with a focus on maternal cardiovascular changes associated with pregnancy. We provide an updated framework to further our understanding of PPCM pathogenesis, which might lead to an improvement in disease definition. Peripartum cardiomyopathy (PPCM) is a rare form of heart failure that presents in late pregnancy or early in the postpartum period. In this Review, Hoes and colleagues discuss the known risk factors for PPCM, including genetic variants and pre-eclampsia, and describe the potential pathogenic mechanisms underlying the development of PPCM such as disrupted metabolic homeostasis in the heart owing to pregnancy-induced hormone fluctuations.

Introduction: Myocardial fatty acid oxidation is impaired in heart failure with reduced ejection fraction (HFrEF) but increases with obesity with diabetes. HF with preserved EF (HFpEF) patients are often obese, but their myocardial metabolomic profiling compared to HFrEF is unknown. We hypothesized that HFpEF patients have distinctive metabolomics signatures from HFrEF. Methods: Plasma and endomyocardial biopsies were collected from HFpEF patients with clinical HF, LVEF≥50%, and consensus criteria for HFpEF (n=45). Most were obese (median BMI 39.8 kg/m 2 ). Data were compared to end-stage HFrEF (n=30) and unused donor controls (n=20). Liquid chromatography-mass spectrometry measured 97 metabolites (8 organic acids, 30 amino acids [AA], 59 acylcarnitines [AC]). Metabolites undetectable in ≥25% patients were excluded. Statistical analyses used one-way ANOVA with post-hoc Tukey test, and false discovery rate of 5% (Benjamini-Hochberg). Results: Myocardial metabolomics revealed HFpEF patients had greater pyruvate levels vs controls and HFrEF (2-2.5x, p Conclusions: HFpEF myocardium in obese patients displays metabolic signatures consistent with impaired utilization of fatty acids, glucose, and amino acids in a pattern quite distinct from HFrEF. This is not discerned from plasma metabolomics. These findings identify a unique metabolic phenotype in HFpEF in which obesity and associated insulin desensitization are coupled with compromised fat metabolism and alternate substrate utilization. This likely contributes to metabolic insufficiency in the HFpEF syndrome.

Introduction: The contribution of common genetic variation to heart failure (HF) risk has not been fully elucidated. Here, we applied multi-ancestry and multivariate methods to summary genetic data from >1 million individuals to improve power to identify common genetic variants, genes, cells, tissues, and circulating proteins/metabolites associated with HF and related cardiac imaging traits. Methods: Trans-ancestry meta-analysis of HF (56,722 cases and 1,133,054 controls) was performed using METAL. Multivariate analysis including GWAS of HF and imaging traits (MRI and echocardiogram) was performed using N-GWAMA. Downstream transcriptome-wide association studies (TWAS; S-PrediXcan), tissue/cell enrichment (LDSC-SEG using RNAseq and snRNAseq of human left ventricle samples from the MAGnet consortium), and Mendelian randomization (MR) analyses were performed. Results: The multi-ancestry HF GWAS identified 15 loci associated with all-cause HF (p < 5 x 10 -8 ). Multivariate analysis identified 48 (16 novel) loci (p < 5 x 10 -8 ), with enrichment for loci near Mendelian cardiomyopathy genes (p < 1 x 10 -4 ). Genetic associations were enriched (FDR < 0.05) for cardiac and musculoskeletal gene expression and chromatin marks. Gene expression (p = 0.007) and splicing events (p = 0.01) were enriched for established cardiomyopathy genes. Branch chain amino acid dehydrogenase ( BCKDHA ) expression was prioritized in TWAS, and MR identified causal associations between circulating branch chain amino acids and cardiac imaging traits: LVEDV MRI (leucine β = -0.137, 95% CI -0.25 to -0.022, p = 0.02; isoleucine β = -0.276, 95% CI -0.38 to -0.17, p = 3 x 10 -7 ) and LVSEV MRI (leucine β = -.131, 95% CI -0.24 to -0.026, p = 0.01; isoleucine β = -0.217, 95% CI -0.33 to -0.11, p = 1 x 10 -4 ). Unbiased proteome-wide MR of 725 circulating proteins identified 18 significant (FDR < 0.05) causal protein-trait associations, including between lipoprotein(a) and HF (OR 1.09 per 1-SD increase in lipoprotein(a), 95% CI 1.06 to 1.11, p = 1.6 x 10 -11 ). Conclusion: These analyses implicate novel common genetic variation in the pathogenesis of HF, highlight Mendelian cardiomyopathy genes in common HF, and identify circulating metabolites and proteins that may represent new treatment targets.

Introduction: Peripartum cardiomyopathy (PPCM) is a rare form of pregnancy-related heart failure associated with preeclampsia. Our understanding of their shared pathophysiology is limited as are treatment options. Hypothesis: We hypothesized that plasma proteomic profiling would identify deleterious circulating proteins and provide insights into shared mechanisms driving preeclampsia and PPCM. Methods: We performed serum proteomic case-control studies in women with preeclampsia or PPCM to identify biological processes common to both conditions. The top candidate was validated in independent preeclampsia (n=58) and PPCM (n=114) cohorts. Preeclamptic placenta was examined as a potential source of circulating proteins. Therapeutic targeting the top candidate was examined in an animal model of PPCM. Results: Paradoxically, we found the senescence-associated secretory phenotype (SASP), a marker of biological aging, to be the most upregulated process in relatively young women with preeclampsia (normalized enrichment score [NES]=3.3;p adj =4.0x10 -6 ) or PPCM (NES=3.2;p adj =1.9x10 -5 ). 28 circulating proteins contributed to this common signal, and were strongly enriched in preeclamptic placenta, which expressed markers of increased senescence. The TGFb family member, Activin-A, was the most highly upregulated SASP gene in preeclamptic placentas (5-fold;p Conclusions: These data implicate placental senescence in the increased deleterious circulating proteins seen in preeclampsia and PPCM. We identify multiple new circulating factors associated with these diseases and demonstrate that targeting SASP proteins, such as Activin-A, can mitigate PPCM in mice.

Rationale: In diabetic animals as well as high glucose cell culture conditions, eNOS (endothelial NO synthase) is heavily O-linked-N-acetylglucosaminylated (O-GlcNAcylated), which inhibits its phosphorylation and NO production. It is unknown, however, whether varied blood flow conditions, which affect eNOS phosphorylation, modulate eNOS activity via O-GlcNAcylation-dependent mechanisms. Objective: The goal of this study was to test if steady laminar flow, but not oscillating disturbed flow, decreases eNOS O-GlcNAcylation, thereby elevating eNOS phosphorylation and NO production. Methods and Results: Human umbilical vein endothelial cells were exposed to either laminar flow (20 dynes/cm 2 shear stress) or oscillating disturbed flow (4±6 dynes/cm 2 shear stress) for 24 hours in a cone-and-plate device. eNOS O-GlcNAcylation was almost completely abolished in cells exposed to steady laminar but not oscillating disturbed flow. Interestingly, there was no change in protein level or activity of key O-GlcNAcylation enzymes (OGT [O-GlcNAc transferase], OGA [O-GlcNAcase], or GFAT [glucosamine-fructose-6-phosphate aminotransferase]). Instead, metabolomics data suggest that steady laminar flow decreases glycolysis and hexosamine biosynthetic pathway activity, thereby reducing UDP-GlcNAc (uridine diphosphate N-acetylglucosamine) pool size and consequent O-GlcNAcylation. Inhibition of glycolysis via 2-deoxy-2-glucose in cells exposed to disturbed flow efficiently decreased eNOS O-GlcNAcylation, thereby increasing eNOS phosphorylation and NO production. Finally, we detected significantly higher O-GlcNAcylated proteins in endothelium of the inner aortic arch in mice, suggesting that disturbed flow increases protein O-GlcNAcylation in vivo. Conclusions: Our data demonstrate that steady laminar but not oscillating disturbed flow decreases eNOS O-GlcNAcylation by limiting glycolysis and UDP-GlcNAc substrate availability, thus enhancing eNOS phosphorylation and NO production. This research shows for the first time that O-GlcNAcylation is regulated by mechanical stimuli, relates flow-induced glycolytic reductions to macrovascular disease, and highlights targeting hexosamine biosynthetic pathway metabolic enzymes in endothelial cells as a novel therapeutic strategy to restore eNOS activity and prevent endothelial cell dysfunction in cardiovascular disease.

Endothelial cells (EC) lining blood vessels are exposed to mechanical forces, such as shear stress exerted by the flowing blood. These forces control many aspects of EC biology, including vascular tone, cell migration and proliferation in addition to cell size and shape. Despite a good understanding of the genes and signaling pathways responding to shear stress, our insights into the transcriptional regulation of these responses is much more limited. In particular, we do not know the different sets of regulatory elements (enhancers) that might control increases or decreases in gene expression. Here, we set out to study changes in the chromatin landscape of human umbilical vein endothelial cells (HUVEC) exposed to laminar shear stress. To do so, we performed ChIP-Seq for H3K27 acetylation, indicative of active enhancer elements and ATAC-Seq to mark regions of open chromatin in addition to RNA-Seq on HUVEC exposed to 6 hours of laminar shear stress. Our results show a correlation of gained and lost enhancers with up- and downregulated genes, respectively. DNA motif analysis revealed an over-representation of KLF transcription factor (TF) binding sites in gained enhancers, while lost enhancers contained more ETV/ETS motifs. We validated a subset of flow responsive enhancers using luciferase-based reporter constructs and CRISPR-Cas9 mediated genome editing. Lastly, we characterized shear stress responsive genes in ECs of zebrafish embryos using RNA-Seq. Together, our results reveal the presence of shear stress responsive DNA regulatory elements and lay the groundwork for the future exploration of these elements and the TFs binding to them in controlling EC biology.

Pharmacologic activation of branched-chain amino acid (BCAA) catabolism is protective in models of heart failure (HF). How protection occurs remains unclear, although a causative block in cardiac BCAA oxidation is widely assumed. Here, we use in vivo isotope infusions to show that cardiac BCAA oxidation in fact increases, rather than decreases, in HF. Moreover, cardiac-specific activation of BCAA oxidation does not protect from HF even though systemic activation does. Lowering plasma and cardiac BCAAs also fails to confer significant protection, suggesting alternative mechanisms of protection. Surprisingly, activation of BCAA catabolism lowers blood pressure (BP), a known cardioprotective mechanism. BP lowering occurred independently of nitric oxide and reflected vascular resistance to adrenergic constriction. Mendelian randomization studies revealed that elevated plasma BCAAs portend higher BP in humans. Together, these data indicate that BCAA oxidation lowers vascular resistance, perhaps in part explaining cardioprotection in HF that is not mediated directly in cardiomyocytes.