Downregulation of GSTK1 Is a Common Mechanism Underlying Hypertrophic Cardiomyopathy

Pervasive nuclear envelope ruptures precede ECM signaling and disease onset without activating cGAS-STING in Lamin-cardiomyopathy mice

Nuclear envelope (NE) ruptures are emerging observations in Lamin-related dilated cardiomyopathy, an adult-onset disease caused by loss-of-function mutations in Lamin A/C, a nuclear lamina component. Here, we test a prevailing hypothesis that NE ruptures trigger the pathological cGAS-STING cytosolic DNA-sensing pathway using a mouse model of Lamin cardiomyopathy. The reduction of Lamin A/C in cardio-myocyte of adult mice causes pervasive NE ruptures in cardiomyocytes, preceding inflammatory transcription, fibrosis, and fatal dilated cardiomyopathy. NE ruptures are followed by DNA damage accumulation without causing immediate cardiomyocyte death. However, cGAS-STING-dependent inflammatory signaling remains inactive. Deleting cGas or Sting does not rescue cardiomyopathy in the mouse model. The lack of cGAS-STING activation is likely due to the near absence of cGAS expression in adult cardiomyocytes at baseline. Instead, extracellular matrix (ECM) signaling is activated and predicted to initiate pro-inflammatory communication from Lamin-reduced cardiomyocytes to fibroblasts. Our work nominates ECM signaling, not cGAS-STING, as a potential inflammatory contributor in Lamin cardiomyopathy.

Paeoniflorin alleviates AngII-induced cardiac hypertrophy in H9c2 cells by regulating oxidative stress and Nrf2 signaling pathway

Cardiac hypertrophy is frequently associated with ventricular dysfunction and heart failure. Paeoniflorin, has been widely used to treat cardiovascular dysfunction-related diseases. However, the underlying mechanism has been unclear. Here, we investigated the potential inhibitory effects and mechanism of paeoniflorin on oxidative stress of cardiac hypertrophy induced by angiotensin II (AngII) in vitro. Using MTS assay, qRT-PCR, WGA staining assay, and western blot, different dosages (50-400 μM) of paeoniflorin were utilized to examine the antihypertrophy effects on H9c2 cells. Western blot examination revealed the presence of apoptosis-related proteins Bax, Bcl2, and Cytc, antioxidative stress-related proteins Nrf2, HO-1, SOD, and CAT, and mitophagy-related proteins PINK1 and Parkin. qRT-PCR was used to detect the mRNA expression of Bax, Bcl2, Nrf2, and HO-1. TUNEL, caspase3/9 enzyme viability, and MDA, T-AOC, and superoxide levels were all evaluated using commercial kits.The fluorescent probes DCFH-DA and JC-1 were employed to measure cellular ROS and MMP levels. Nrf2 siRNA was utilized to investigate Nrf2's role in paeoniflorin-treated cardiac hypertrophy. Paeoniflorin dramatically reduced cell section area (CSA) and hypertrophic marker (ANP, BNP) expression while inhibiting oxidative stress by modulating ROS and MDA, CAT, SOD, and T-AOC levels. Furthermore, in AngII-induced cardiomyocyte hypertrophy, paeoniflorin restores H9c2 apoptosis by restoring Bax, Bcl-2 Cyt-C, Caspase 3, and Caspase 9 levels. Paeoniflorin also restored Nrf2/HO-1 and PINK1/Parkin expression, and its anti-AngII activities were mediated by Nrf2, which was regulated by Nrf2 knockdown. In conclusion, Our data confirm that paeoniflorin alleviates cardiac hypertrophy through modulating oxidative stress and Nrf2 signaling pathway in vitro.

Apoptosis and heart failure: The role of non-coding RNAs and exosomal non-coding RNAs

Heart failure is a condition that affects the cardio vascular system and occurs if the heart cannot adequately pump the oxygen and blood to the body. Myocardial infarction, reperfusion injury, and this disease is the only a few examples of the numerous cardiovascular illnesses that are impacted by the closely controlled cell deletion process known as apoptosis. Attention has been paid to the creation of alternative diagnostic and treatment modalities for the condition. Recent evidences have shown that some non-coding RNAs (ncRNAs) influence the stability of proteins, control of transcription factors, and HF apoptosis through a variety of methods. Exosomes make a significant paracrine contribution to the regulation of illnesses as well as to the communication between nearby and distant organs. However, it has not yet been determined whether exosomes regulate the cardiomyocyte-tumor cell interaction in ischemia HF to limit the vulnerability of malignancy to ferroptosis. Here, we list the numerous ncRNAs in HF that are connected to apoptosis. In addition, we emphasize the significance of exosomal ncRNAs in the HF.

Functional Analysis of GSTK1 in Peroxisomal Redox Homeostasis in HEK-293 Cells

Peroxisomes serve as important centers for cellular redox metabolism and communication. However, fundamental gaps remain in our understanding of how the peroxisomal redox equilibrium is maintained. In particular, very little is known about the function of the nonenzymatic antioxidant glutathione in the peroxisome interior and how the glutathione antioxidant system balances with peroxisomal protein thiols. So far, only one human peroxisomal glutathione-consuming enzyme has been identified: glutathione S-transferase 1 kappa (GSTK1). To study the role of this enzyme in peroxisomal glutathione regulation and function, a GSTK1-deficient HEK-293 cell line was generated and fluorescent redox sensors were used to monitor the intraperoxisomal GSSG/GSH and NAD⁺/NADH redox couples and NADPH levels. We provide evidence that ablation of GSTK1 does not change the basal intraperoxisomal redox state but significantly extends the recovery period of the peroxisomal glutathione redox sensor po-roGFP2 upon treatment of the cells with thiol-specific oxidants. Given that this delay (i) can be rescued by reintroduction of GSTK1, but not its S16A active site mutant, and (ii) is not observed with a glutaredoxin-tagged version of po-roGFP2, our findings demonstrate that GSTK1 contains GSH-dependent disulfide bond oxidoreductase activity.

Nogo-A reduces ceramide de novo biosynthesis to protect from heart failure

AIMS

Growing evidence correlate the accrual of the sphingolipid ceramide in plasma and cardiac tissue with heart failure (HF). Regulation of sphingolipid metabolism in the heart and the pathological impact of its derangement remain poorly understood. Recently, we discovered that Nogo-B, a membrane protein of endoplasmic reticulum, abundant in the vascular wall, down-regulates the sphingolipid de novo biosynthesis via serine palmitoyltransferase (SPT), first and rate liming enzyme, to impact vascular functions and blood pressure. Nogo-A, a splice isoform of Nogo, is transiently expressed in cardiomyocyte (CM) following pressure overload. Cardiac Nogo is up-regulated in dilated and ischaemic cardiomyopathies in animals and humans. However, its biological function in the heart remains unknown.

METHODS AND RESULTS

We discovered that Nogo-A is a negative regulator of SPT activity and refrains ceramide de novo biosynthesis in CM exposed to haemodynamic stress, hence limiting ceramide accrual. At 7 days following transverse aortic constriction (TAC), SPT activity was significantly up-regulated in CM lacking Nogo-A and correlated with ceramide accrual, particularly very long-chain ceramides, which are the most abundant in CM, resulting in the suppression of 'beneficial' autophagy. At 3 months post-TAC, mice lacking Nogo-A in CM showed worse pathological cardiac hypertrophy and dysfunction, with ca. 50% mortality rate.

CONCLUSION

Mechanistically, Nogo-A refrains ceramides from accrual, therefore preserves the 'beneficial' autophagy, mitochondrial function, and metabolic gene expression, limiting the progression to HF under sustained stress.

Identification of biomarkers, pathways, and potential therapeutic targets for heart failure using next-generation sequencing data and bioinformatics analysis

BACKGROUND

Heart failure (HF) is the most common cardiovascular diseases and the leading cause of cardiovascular diseases related deaths. Increasing molecular targets have been discovered for HF prognosis and therapy. However, there is still an urgent need to identify novel biomarkers. Therefore, we evaluated biomarkers that might aid the diagnosis and treatment of HF.

METHODS

We searched next-generation sequencing (NGS) dataset (GSE161472) and identified differentially expressed genes (DEGs) by comparing 47 HF samples and 37 normal control samples using limma in R package. Gene ontology (GO) and pathway enrichment analyses of the DEGs were performed using the g: Profiler database. The protein-protein interaction (PPI) network was plotted with Human Integrated Protein-Protein Interaction rEference (HiPPIE) and visualized using Cytoscape. Module analysis of the PPI network was done using PEWCC1. Then, miRNA-hub gene regulatory network and TF-hub gene regulatory network were constructed by Cytoscape software. Finally, we performed receiver operating characteristic (ROC) curve analysis to predict the diagnostic effectiveness of the hub genes.

RESULTS

A total of 930 DEGs, 464 upregulated genes and 466 downregulated genes, were identified in HF. GO and REACTOME pathway enrichment results showed that DEGs mainly enriched in localization, small molecule metabolic process, SARS-CoV infections, and the citric acid tricarboxylic acid (TCA) cycle and respiratory electron transport. After combining the results of the PPI network miRNA-hub gene regulatory network and TF-hub gene regulatory network, 10 hub genes were selected, including heat shock protein 90 alpha family class A member 1 (HSP90AA1), arrestin beta 2 (ARRB2), myosin heavy chain 9 (MYH9), heat shock protein 90 alpha family class B member 1 (HSP90AB1), filamin A (FLNA), epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), cullin 4A (CUL4A), YEATS domain containing 4 (YEATS4), and lysine acetyltransferase 2B (KAT2B).

CONCLUSIONS

This discovery-driven study might be useful to provide a novel insight into the diagnosis and treatment of HF. However, more experiments are needed in the future to investigate the functional roles of these genes in HF.

Single-cell transcriptomics provides insights into hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic heart disease that is characterized by unexplained segmental hypertrophy that is usually most pronounced in the septum. While sarcomeric gene mutations are often the genetic basis for HCM, the mechanistic origin for the heterogeneous remodeling remains largely unknown. A better understanding of the gene networks driving the cardiomyocyte (CM) hypertrophy is required to improve therapeutic strategies. Patients suffering from HCM often receive a septal myectomy surgery to relieve outflow tract obstruction due to hypertrophy. Using single-cell RNA sequencing (scRNA-seq) on septal myectomy samples from patients with HCM, we identify functional links between genes, transcription factors, and cell size relevant for HCM. The data show the utility of using scRNA-seq on the human hypertrophic heart, highlight CM heterogeneity, and provide a wealth of insights into molecular events involved in HCM that can eventually contribute to the development of enhanced therapies.

Mutant CHCHD10 causes an extensive metabolic rewiring that precedes OXPHOS dysfunction in a murine model of mitochondrial cardiomyopathy

Mitochondrial cardiomyopathies are fatal diseases, with no effective treatment. Alterations of heart mitochondrial function activate the mitochondrial integrated stress response (ISR^mt), a transcriptional program affecting cell metabolism, mitochondrial biogenesis, and proteostasis. In humans, mutations in CHCHD10, a mitochondrial protein with unknown function, were recently associated with dominant multi-system mitochondrial diseases, whose pathogenic mechanisms remain to be elucidated. Here, in CHCHD10 knockin mutant mice, we identify an extensive cardiac metabolic rewiring triggered by proteotoxic ISR^mt. The stress response arises early on, before the onset of bioenergetic impairments, triggering a switch from oxidative to glycolytic metabolism, enhancement of transsulfuration and one carbon (1C) metabolism, and widespread metabolic imbalance. In parallel, increased NADPH oxidases elicit antioxidant responses, leading to heme depletion. As the disease progresses, the adaptive metabolic stress response fails, resulting in fatal cardiomyopathy. Our findings suggest that early interventions to counteract metabolic imbalance could ameliorate mitochondrial cardiomyopathy associated with proteotoxic ISR^mt.

Sayles et al. report that mutant CHCHD10 proteotoxicity activates the mitochondrial integrated stress response (ISR^mt) in a mouse model of mitochondrial cardiomyopathy. Chronic ISR^mt causes profound metabolic imbalances, culminating in oxidative stress and iron dysregulation, ultimately resulting in mitochondrial dysfunction and contributing to disease pathogenesis.

Metabolomic and transcriptomic signatures of chemogenetic heart failure

The failing heart is characterized by elevated levels of reactive oxygen species. We have developed an animal model of heart failure induced by chemogenetic production of oxidative stress in the heart using a recombinant adeno-associated virus (AAV9) expressing yeast d-amino acid oxidase (DAAO) targeted to cardiac myocytes. When DAAO-infected animals are fed the DAAO substrate d-alanine, the enzyme generates hydrogen peroxide (H₂O₂) in the cardiac myocytes, leading to dilated cardiomyopathy. However, the underlying mechanisms of oxidative stress-induced heart failure remain incompletely understood. Therefore, we investigated the effects of chronic oxidative stress on the cardiac transcriptome and metabolome. Rats infected with recombinant cardiotropic AAV9 expressing DAAO or control AAV9 were treated for 7 wk with d-alanine to stimulate chemogenetic H₂O₂ production by DAAO and generate dilated cardiomyopathy. After hemodynamic assessment, left and right ventricular tissues were processed for RNA sequencing and metabolomic profiling. DAAO-induced dilated cardiomyopathy was characterized by marked changes in the cardiac transcriptome and metabolome both in the left and right ventricle. Downregulated transcripts are related to energy metabolism and mitochondrial function, accompanied by striking alterations in metabolites involved in cardiac energetics, redox homeostasis, and amino acid metabolism. Upregulated transcripts are involved in cytoskeletal organization and extracellular matrix. Finally, we noted increased metabolite levels of antioxidants glutathione and ascorbate. These findings provide evidence that chemogenetic generation of oxidative stress leads to a robust heart failure model with distinct transcriptomic and metabolomic signatures and set the basis for understanding the underlying pathophysiology of chronic oxidative stress in the heart.NEW & NOTEWORTHY We have developed a "chemogenetic" heart failure animal model that recapitulates a central feature of human heart failure: increased cardiac redox stress. We used a recombinant DAAO enzyme to generate H₂O₂ in cardiomyocytes, leading to cardiomyopathy. Here we report striking changes in the cardiac metabolome and transcriptome following chemogenetic heart failure, similar to changes observed in human heart failure. Our findings help validate chemogenetic approaches for the discovery of novel therapeutic targets in heart failure.

Exploring the Communal Pathogenesis, Ferroptosis Mechanism, and Potential Therapeutic Targets of Dilated Cardiomyopathy and Hypertrophic Cardiomyopathy via a Microarray Data Analysis

Background

Cardiomyopathies are a heterogeneous group of heart diseases that can gradually cause severe heart failure. In particular, dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) are the two main types of cardiomyopathies, yet the independent and communal biological mechanisms of both remain far from elucidated. Meanwhile, ferroptosis is a non-apoptotic form of cell death that has been proven to be associated with cardiomyopathies, but the concrete nature of the interaction remains unclear. Hence, this study explored the pathogenesis and ferroptosis mechanism of HCM and DCM via a bioinformatics analysis.

Methods

Six datasets were downloaded from the Gene Expression Omnibus (GEO) database based on the study inclusion/exclusion criteria. After screening the differentially expressed genes (DEGs) and hub genes of HCM and DCM, subsequent analyses, including functional annotation, co-expression, validation, and transcription factors (TF)–mRNA–microRNA (miRNA) regulatory network construction, were performed. In addition, ferroptosis-related DEGs were also identified and verified in HCM and DCM.

Results

We found 171 independent DEGs of HCM mainly enriched in the regulation of ERK1 and ERK2 cascade, while 171 independent DEGs of DCM were significantly involved in cell adhesion. Meanwhile, 32 communal DEGs (26 upregulated genes and 6 downregulated genes) and 3 hub genes [periostin (POSTN), insulin-like growth factor-binding protein-5 (IGFBP5), and fibromodulin (FMOD)] were determined to be shared between HCM and DCM and the functional annotation of these genes highlighted the important position of growth hormone in HCM and DCM. Moreover, we identified activating transcription factor 3 (ATF3), lysophosphatidylcholine acyltransferase 3 (LPCAT3), and solute carrier family 1 member 5 (SLC1A5) as ferroptosis-related genes in HCM and STAT3 as a ferroptosis-related gene in DCM.

Conclusion

The identified independent and communal DEGs contribute to uncover a potentially distinct and common mechanism of HCM and DCM and ferroptosis-related genes could provide us with a novel direction for exploration. In addition, 3 hub genes could be potential biomarkers or therapeutic targets in patients with cardiomyopathy.

Involvement of homeobox transcription factor Mohawk in palatogenesis

Palatogenesis is affected by many factors, including gene polymorphisms and exposure to toxic chemicals during sensitive developmental periods. Cleft palate is one of the most common congenital anomalies, and ongoing efforts to elucidate the molecular mechanisms underlying palatogenesis are providing useful insights to reduce the risk of this disorder. To identify novel potential regulators of palatogenesis, we analyzed public transcriptome datasets from a mouse model of cleft palate caused by selective deletion of transforming growth factor-β (TGFβ) receptor type 2 in cranial neural crest cells. We identified the homeobox transcription factor Mohawk (Mkx) as a gene downregulated in the maxilla of TGFβ knockout mice compared with wild-type mice. To examine the role of mkx in palatogenesis, we used CRISPR/Cas9 editing to generate zebrafish with impaired expression of mkxa and mkxb, the zebrafish homologs of Mkx. We found that mkx crispants expressed reduced levels of gli1, a critical transcription factor in the Sonic hedgehog (SHH) signaling pathway that plays an important role in the regulation of palatogenesis. Furthermore, we found that mkxa^-/- zebrafish were more susceptible than mkxa^+/+ zebrafish to the deleterious effects of cyclopamine, an inhibitor of SHH signaling, on upper jaw development. These results suggest that Mkx may be involved in palatogenesis regulated by TGFβ and SHH signaling, and that impairment in Mkx function may be related to the etiology of cleft palate.

Vitamin D Modulation of Mitochondrial Oxidative Metabolism and mTOR Enforces Stress Adaptations and Anticancer Responses

The relationship between the active form of vitamin D3 (1,25-dihydroxyvitamin D, 1,25(OH)2D) and reactive oxygen species (ROS), two integral signaling molecules of the cell, is poorly understood. This is striking, given that both factors are involved in cancer cell regulation and metabolism. Mitochondria (mt) dysfunction is one of the main drivers of cancer, producing more mitochondria, higher cellular energy, and ROS that can enhance oxidative stress and stress tolerance responses. To study the effects of 1,25(OH)2D on metabolic and mt dysfunction, we used the vitamin D receptor (VDR)-sensitive MG-63 osteosarcoma cell model. Using biochemical approaches, 1,25(OH)2D decreased mt ROS levels, membrane potential (ΔΨmt), biogenesis, and translation, while enforcing endoplasmic reticulum/mitohormetic stress adaptive responses. Using a mitochondria-focused transcriptomic approach, gene set enrichment and pathway analyses show that 1,25(OH)2D lowered mt fusion/fission and oxidative phosphorylation (OXPHOS). By contrast, mitophagy, ROS defense, and epigenetic gene regulation were enhanced after 1,25(OH)2D treatment, as well as key metabolic enzymes that regulate fluxes of substrates for cellular architecture and a shift toward non-oxidative energy metabolism. ATACseq revealed putative oxi-sensitive and tumor-suppressing transcription factors that may regulate important mt functional genes such as the mTORC1 inhibitor, DDIT4/REDD1. DDIT4/REDD1 was predominantly localized to the outer mt membrane in untreated MG-63 cells yet sequestered in the cytoplasm after 1,25(OH)2D and rotenone treatments, suggesting a level of control by membrane depolarization to facilitate its cytoplasmic mTORC1 inhibitory function. The results show that 1,25(OH)2D activates distinct adaptive metabolic responses involving mitochondria to regain redox balance and control the growth of osteosarcoma cells. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Identification of atrial-enriched lncRNA Walras linked to cardiomyocyte cytoarchitecture and atrial fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in humans. Genetic and genomic analyses have recently demonstrated that the homeobox transcription factor Pitx2 plays a fundamental role regulating expression of distinct growth factors, microRNAs and ion channels leading to morphological and molecular alterations that promote the onset of AF. Here we address the plausible contribution of long non-coding (lnc)RNAs within the Pitx2>Wnt>miRNA signaling pathway. In silico analyses of annotated lncRNAs in the vicinity of the Pitx2, Wnt8 and Wnt11 chromosomal loci identified five novel lncRNAs with differential expression during cardiac development. Importantly, three of them, Walaa, Walras, and Wallrd, are evolutionarily conserved in humans and displayed preferential atrial expression during embryogenesis. In addition, Walrad displayed moderate expression during embryogenesis but was more abundant in the right atrium. Walaa, Walras and Wallrd were distinctly regulated by Pitx2, Wnt8, and Wnt11, and Wallrd was severely elevated in conditional atrium-specific Pitx2-deficient mice. Furthermore, pro-arrhythmogenic and pro-hypertrophic substrate administration to primary cardiomyocyte cell cultures consistently modulate expression of these lncRNAs, supporting distinct modulatory roles of the AF cardiovascular risk factors in the regulation of these lncRNAs. Walras affinity pulldown assays revealed its association with distinct cytoplasmic and nuclear proteins previously involved in cardiac pathophysiology, while loss-of-function assays further support a pivotal role of this lncRNA in cytoskeletal organization. We propose that lncRNAs Walaa, Walras and Wallrd, distinctly regulated by Pitx2>Wnt>miRNA signaling and pro-arrhythmogenic and pro-hypertrophic factors, are implicated in atrial arrhythmogenesis, and Walras additionally in cardiomyocyte cytoarchitecture.

MiR-590-5p inhibits pathological hypertrophy mediated heart failure by targeting RTN4

Heart failure (HF) is a rising epidemic and public health burden in modern society. It is of great need to find new biomarkers to ensure a timely diagnosis and to improve treatment and prognosis of the disease. The mouse model of HF was established by thoracic aortic constriction. Color Doppler ultrasound was performed to detect left ventricular end-diastolic diameter. Hematoxylin and eosin staining was conducted to observe the pathological changes of mouse myocardium. The RT-qPCR analysis was performed to detect miR-590-5p and RTN4 expression levels. Western blot was conducted to detect protein levels of the indicated genes. We found that the expression of miR-590-5p was downregulated in cardiac tissues of HF mice. Injection of AAV-miR-590-5p attenuated myocardium hypertrophy and myocyte apoptosis. Additionally, miR-590-5p overexpression promoted viability, inhibited apoptosis, and decreased ANF, BNP and beta-MHC protein levels in H9c2 cell. Mechanistically, miR-590-5p binds to RTN4 3'-untranslated region, as predicted by starBase online database and evidenced by luciferase reporter assay. Furthermore, miR-590-5p negatively regulates RTN4 mRNA expression and suppresses its translation. The final rescue experiments revealed that miR-590-5p modulated cardiomyocyte phenotypes by binding to RTN4. In conclusion, miR-590-5p modulates myocardium hypertrophy and myocyte apoptosis in HF by downregulating RTN4.

Sub-chronic exposure to PhIP induces oxidative damage and DNA damage, and disrupts the amino acid metabolism in the colons of Wistar rats

Heterocyclic amines (HCAs) are a group of mutagenic compounds produced during thermal processing of protein-rich foods. One of the most abundant HCAs, 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) has potential carcinogenic and mutagenic effects on human organs, especially the colon. This study aimed to explore the toxic effects of PhIP on amino acid metabolism in the colon of Wistar rats using RNA-seq and LC-MS/MS. Exposure to PhIP for 4 weeks induced oxidative damage and DNA damage in the colons, and disrupted the expression of related genes involved in tryptophan metabolism, beta(β)-alanine metabolism, valine, leucine, and isoleucine degradation, and glutathione metabolic pathways. Moreover, the levels of fecal metabolites related to amino acid metabolism were affected by PhIP. Cumulatively, these results indicate that PhIP can induce colonic oxidative injury and disorders related to amino acid metabolism, thereby providing a new theoretical basis for the study of PhIP toxicity.

Oxidative stress in cardiac hypertrophy: From molecular mechanisms to novel therapeutic targets

When faced with increased workload the heart undergoes remodelling, where it increases its muscle mass in an attempt to preserve normal function. This is referred to as cardiac hypertrophy and if sustained, can lead to impaired contractile function. Experimental evidence supports oxidative stress as a critical inducer of both genetic and acquired forms of cardiac hypertrophy, a finding which is reinforced by elevated levels of circulating oxidative stress markers in patients with cardiac hypertrophy. These observations formed the basis for using antioxidants as a therapeutic means to attenuate cardiac hypertrophy and improve clinical outcomes. However, the use of antioxidant therapies in the clinical setting has been associated with inconsistent results, despite antioxidants having been shown to exert protection in several animal models of cardiac hypertrophy. This has forced us to revaluate the mechanisms, both upstream and downstream of oxidative stress, where recent studies demonstrate that apart from conventional mediators of oxidative stress, metabolic disturbances, mitochondrial dysfunction and inflammation as well as dysregulated autophagy and protein homeostasis contribute to disease pathophysiology through mechanisms involving oxidative stress. Importantly, novel therapeutic targets have been identified to counteract oxidative stress and attenuate cardiac hypertrophy but more interestingly, the repurposing of drugs commonly used to treat metabolic disorders, hypertension, peripheral vascular disease, sleep disorders and arthritis have also been shown to improve cardiac function through suppression of oxidative stress. Here, we review the latest literature on these novel mechanisms and intervention strategies with the aim of better understanding the complexities of oxidative stress for more precise targeted therapeutic approaches to prevent cardiac hypertrophy.

Zebrafish as an animal model for biomedical research

Zebrafish have several advantages compared to other vertebrate models used in modeling human diseases, particularly for large-scale genetic mutant and therapeutic compound screenings, and other biomedical research applications. With the impactful developments of CRISPR and next-generation sequencing technology, disease modeling in zebrafish is accelerating the understanding of the molecular mechanisms of human genetic diseases. These efforts are fundamental for the future of precision medicine because they provide new diagnostic and therapeutic solutions. This review focuses on zebrafish disease models for biomedical research, mainly in developmental disorders, mental disorders, and metabolic diseases.

Genome editing in cardiovascular diseases

Genetic modification at the molecular level in somatic cells, germline, and animal models requires for different purposes, such as introducing desired mutation, deletion of alleles, and insertion of novel genes in the genome. Various genome-editing tools are available to accomplish these alterations, such as zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated (Cas) system. CRISPR-Cas system is an emerging technology, which is being used in biological and medical sciences, including in the cardiovascular field. It assists to identify the mechanism of various cardiovascular disease occurrence, such as hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and arrhythmogenic cardiomyopathy (ACM). Furthermore, it has been advantages to edit various genes simultaneously and can also be used to treat and prevent several human diseases. This chapter explores the use of the scientific and therapeutic potential of a CRISPR-Cas system to edit the various cardiovascular disease-associated genes to understand the pathways involved in disease progression and treatment.

GLP-1 improves the supportive ability of astrocytes to neurons by promoting aerobic glycolysis in Alzheimer's disease

Objective

Astrocytes actively participate in energy metabolism in the brain, and astrocytic aerobic glycolysis disorder is associated with the pathology of Alzheimer's disease (AD). GLP-1 has been shown to improve cognition in AD; however, the mechanism remains unclear. The objectives of this study were to assess GLP-1's glycolytic regulation effects in AD and reveal its neuroprotective mechanisms.

Methods

The Morris water maze test was used to evaluate the effects of liraglutide (an analog of GLP-1) on the cognition of 4-month-old 5×FAD mice, and a proteomic analysis and Western blotting were used to assess the proteomic profile changes. We constructed an astrocytic model of AD by treating primary astrocytes with Aβ_1-42. The levels of NAD+ and lactate were examined, and the oxidative levels were assessed by a Seahorse examination. Astrocyte-neuron co-culture was performed to evaluate the effects of GLP-1 on astrocytes’ neuronal support.

Results

GLP-1 improved cognition in 4-month-old 5×FAD mice by enhancing aerobic glycolysis and reducing oxidative phosphorylation (OXPHOS) levels and oxidative stress in the brain. GLP-1 also alleviated Aβ-induced glycolysis declines in astrocytes, which resulted in reduced OXPHOS levels and reactive oxygen species (ROS) production. The mechanism involved the activation of the PI3K/Akt pathway by GLP-1. Elevation in astrocytic glycolysis improved astrocyte cells’ support of neurons and promoted neuronal survival and axon growth.

Conclusions

Taken together, we revealed GLP-1's capacity to regulate astrocytic glycolysis, providing mechanistic insight into one of its neuroprotective roles in AD and support for the feasibility of energy regulation treatments for AD.

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GLP-1 mediates a metabolic shift from oxidative phosphorylation to aerobic glycolysis in Alzheimer's disease.

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GLP-1's mechanism of action involves activation of the PI3K/Akt pathway.

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GLP-1 enhances the supportive ability of astrocytes to neurons by promoting aerobic glycolysis.

Gap junction protein beta 4 plays an important role in cardiac function in humans, rodents, and zebrafish

Aims

GJB4 encodes a transmembrane connexin protein (Cx30.3) that is a component of gap junctions. This study investigated whether GJB4 plays an important role in human heart disease and function.

Methods and results

We examined a patient and her older brother who both presented with complicated severe hypertrophic cardiomyopathy (HCM) and whose parents are healthy married cousins. The gene exome analysis showed 340 single nucleotide polymorphisms (SNPs) that caused amino acid changes for which the patient was homozygous and both parents were heterozygous. After excluding all known common (>10%) SNP gene mutations, the gene for GJB4 was the only identified gene that is possibly associated with cardiac muscle. The resultant E204A substitution exists in the 4th transmembrane domain. GJB4-E204A impaired the binding with gap junction protein A1 (GJA1) compared with GJB4-WT. The expression of GJB4 was induced in rat disease models of left and right ventricle hypertrophy and mouse disease models of adriamycin-induced cardiomyopathy and myocardial infarction, while it was not detected at all in control. An immunohistochemical study was performed for autopsied human hearts and the explanted heart of the patient. GJB4 was expressed and colocalized with GJA1 in intercalated discs in human diseased hearts, which was extensively enhanced in the explanted heart of the patient. The abnormal expression and localization of GJB4 were observed in beating spheres of patient’s induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs). We generated knockout zebrafish of GJB4 by CRISPR/Cas9 and the endodiastolic volume and the ventricular ejection fraction were significantly lower in GJB4-deficient than in wild-type zebrafish at five days post-fertilization.

Conclusions

These results indicate both that GJB4 is defined as a new connexin in diseased hearts, of which mutation can cause a familial form of HCM, and that GJB4 may be a new target for the treatment of cardiac hypertrophy and dysfunction.

The mercapturic acid pathway

The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.

Identification of a Multiplex Biomarker Panel for Hypertrophic Cardiomyopathy Using Quantitative Proteomics and Machine Learning

Hypertrophic cardiomyopathy (HCM) is defined by pathological left ventricular hypertrophy (LVH). It is the commonest inherited cardiac condition and a significant number of high risk cases still go undetected until a sudden cardiac death (SCD) event. Plasma biomarkers do not currently feature in the assessment of HCM disease progression, which is tracked by serial imaging, or in SCD risk stratification, which is based on imaging parameters and patient/family history. There is a need for new HCM plasma biomarkers to refine disease monitoring and improve patient risk stratification. To identify new plasma biomarkers for patients with HCM, we performed exploratory myocardial and plasma proteomics screens and subsequently developed a multiplexed targeted liquid chromatography-tandem/mass spectrometry-based assay to validate the 26 peptide biomarkers that were identified. The association of discovered biomarkers with clinical phenotypes was prospectively tested in plasma from 110 HCM patients with LVH (LVH+ HCM), 97 controls, and 16 HCM sarcomere gene mutation carriers before the development of LVH (subclinical HCM). Six peptides (aldolase fructose-bisphosphate A, complement C3, glutathione S-transferase omega 1, Ras suppressor protein 1, talin 1, and thrombospondin 1) were increased significantly in the plasma of LVH+ HCM compared with controls and correlated with imaging markers of phenotype severity: LV wall thickness, mass, and percentage myocardial scar on cardiovascular magnetic resonance imaging. Using supervised machine learning (ML), this six-biomarker panel differentiated between LVH+ HCM and controls, with an area under the curve of ≥ 0.87. Five of these peptides were also significantly increased in subclinical HCM compared with controls. In LVH+ HCM, the six-marker panel correlated with the presence of nonsustained ventricular tachycardia and the estimated five-year risk of sudden cardiac death. Using quantitative proteomic approaches, we have discovered six potentially useful circulating plasma biomarkers related to myocardial substrate changes in HCM, which correlate with the estimated sudden cardiac death risk.

Deletion of Gtpbp3 in zebrafish revealed the hypertrophic cardiomyopathy manifested by aberrant mitochondrial tRNA metabolism

GTPBP3 is a highly conserved tRNA modifying enzyme for the biosynthesis of τm⁵U at the wobble position of mitochondrial tRNA^Glu, tRNA^Gln, tRNA^Lys, tRNA^Trp and tRNA^Leu(UUR). The previous investigations showed that GTPBP3 mutations were associated with hypertrophic cardiomyopathy (HCM). However, the pathophysiology of GTPBP3 deficiency remains elusively. Using the gtpbp3 knockout zebrafish generated by CRISPR/Cas9 system, we demonstrated the aberrant mitochondrial tRNA metabolism in gtpbp3 knock-out zebrafish. The deletion of gtpbp3 may alter functional folding of tRNA, indicated by conformation changes and sensitivity to S1-mediated digestion of tRNA^Glu, tRNA^Lys, tRNA^Trp and tRNA^Leu(UUR). Strikingly, gtpbp3 knock-out zebrafish displayed the global increases in the aminoacylated efficiencies of mitochondrial tRNAs. The aberrant mitochondrial tRNA metabolisms impaired mitochondrial translation, produced proteostasis stress and altered activities of respiratory chain complexes. These mitochondria dysfunctions caused the alterations in the embryonic heart development and reduced fractional shortening of ventricles in mutant zebrafish. Notably, the gtpbp3 knock-out zebrafish exhibited hypertrophy of cardiomyocytes and myocardial fiber disarray in ventricles. These cardiac defects in the gtpbp3 knock-out zebrafish recapitulated the clinical phenotypes in HCM patients carrying the GTPBP3 mutation(s). Our findings highlight the fundamental role of defective nucleotide modifications of tRNAs in mitochondrial biogenesis and their pathological consequences in hypertrophic cardiomyopathy.

C3orf70 Is Involved in Neural and Neurobehavioral Development

Neurogenesis is the process by which undifferentiated progenitor cells develop into mature and functional neurons. Defects in neurogenesis are associated with neurodevelopmental and neuropsychiatric disorders; therefore, elucidating the molecular mechanisms underlying neurogenesis can advance our understanding of the pathophysiology of these disorders and facilitate the discovery of novel therapeutic targets. In this study, we performed a comparative transcriptomic analysis to identify common targets of the proneural transcription factors Neurog1/2 and Ascl1 during neurogenesis of human and mouse stem cells. We successfully identified C3orf70 as a novel common target gene of Neurog1/2 and Ascl1 during neurogenesis. Using in situ hybridization, we demonstrated that c3orf70a and c3orf70b, two orthologs of C3orf70, were expressed in the midbrain and hindbrain of zebrafish larvae. We generated c3orf70 knockout zebrafish using CRISPR/Cas9 technology and demonstrated that loss of c3orf70 resulted in significantly decreased expression of the mature neuron markers elavl3 and eno2. We also found that expression of irx3b, a zebrafish ortholog of IRX3 and a midbrain/hindbrain marker, was significantly reduced in c3orf70 knockout zebrafish. Finally, we demonstrated that neurobehaviors related to circadian rhythm and altered light–dark conditions were significantly impaired in c3orf70 knockout zebrafish. These results suggest that C3orf70 is involved in neural and neurobehavioral development and that defects in C3orf70 may be associated with midbrain/hindbrain-related neurodevelopmental and neuropsychiatric disorders.

Hypertrophic Cardiomyopathy: A Vicious Cycle Triggered by Sarcomere Mutations and Secondary Disease Hits

Significance: Hypertrophic cardiomyopathy (HCM) is a cardiac genetic disease characterized by left ventricular hypertrophy, diastolic dysfunction, and myocardial disarray. Disease onset occurs between 20 and 50 years of age, thus affecting patients in the prime of their life. HCM is caused by mutations in sarcomere proteins, the contractile building blocks of the heart. Despite increased knowledge of causal mutations, the exact path from genetic defect leading to cardiomyopathy is complex and involves additional disease hits. Recent Advances: Laboratory-based studies indicate that HCM development not only depends on the primary sarcomere impairment caused by the mutation but also on secondary disease-related alterations in the heart. Here we propose a vicious mutation-induced disease cycle, in which a mutation-induced energy depletion alters cellular metabolism with increased mitochondrial work, which triggers secondary disease modifiers that will worsen disease and ultimately lead to end-stage HCM. Critical Issues: Evidence shows excessive cellular reactive oxygen species (ROS) in HCM patients and HCM animal models. Oxidative stress markers are increased in the heart (oxidized proteins, DNA, and lipids) and serum of HCM patients. In addition, increased mitochondrial ROS production and changes in endogenous antioxidants are reported in HCM. Mutant sarcomeric protein may drive excessive levels of cardiac ROS via changes in cardiac efficiency and metabolism, mitochondrial activation and/or dysfunction, impaired protein quality control, and microvascular dysfunction. Future Directions: Interventions restoring metabolism, mitochondrial function, and improved ROS balance may be promising therapeutic approaches. We discuss the effects of current HCM pharmacological therapies and potential future therapies to prevent and reverse HCM. Antioxid. Redox Signal. 31, 318-358.

DsbA-L ameliorates high glucose induced tubular damage through maintaining MAM integrity

Background

The mitochondrial associated endoplasmic reticulum (ER) membrane (MAM) provides a platform for communication between the mitochondria and ER, and it plays a vital role in many biological functions. Disulphide-bond A oxidoreductase-like protein (DsbA-L), expressed in the MAM, serves as an antioxidant and reduces ER stress. However, the role of DsbA-L and MAM in kidney pathobiology remains unclear.

Methods

Molecular biology techniques, transmission electron microscopy (TEM), in situ proximity ligation assays (PLAs), confocal microscopy, TUNEL staining and flow cytometry were utilized to analyse apoptosis and status of MAM in DsbA-L mutant mice.

Findings

We showed that MAM was significantly reduced in the kidneys of streptozotocin-induced diabetic mice, which correlated with the extent of renal injury. We also observed a correlation between the loss of MAM integrity and increased apoptosis and renal injury in diabetic nephropathy (DN). These alterations were further exacerbated in diabetic DsbA-L gene-deficient mice (DsbA-L^−/−). In vitro, overexpression of DsbA-L in HK-2 cells restored MAM integrity and reduced apoptosis induced by high-glucose ambience. These beneficial effects were partially blocked by overexpression of FATE-1, a MAM uncoupling protein. Finally, the expression of DsbA-L was positively correlated with MAM integrity in the kidneys of DN patients but negatively correlated with apoptosis and renal injury.

Interpretation

Our results indicate that DsbA-L exerts an antiapoptotic effect by maintaining MAM integrity, which is apparently disrupted in DN.

Fund

This work was supported by the National Natural Science Foundation of China (81730018), the National Key R&D Program of China (2016YFC1305501) and NIH (DK60635).

Mitochondrial impairment following neonatal overfeeding: A comparison between normal and ischemic-reperfused hearts

Overweight and obesity are established factors underpin several metabolic impairments, including the cardiovascular. Although the diversity of factors involved in overweight/obesity-induced cardiovascular diseases, mitochondria has been highlighted due to its role in cardiac metabolism. As obesity can be originated in early postnatal life, the current study evaluates the effects of neonatal overfeeding on the cardiac mitochondrial bioenergetics and oxidative balance in rats that underwent an ischemia-reperfusion insult. Seventy-two hours after delivery, Wistar rat litters were randomly assigned into the control (C; nine pups per mother) and the Overfed (OF; three pups per mother) groups throughout the lactation period. At weaning, male offspring were fed with laboratory chow ad libitum until sacrifice at 30 and 60 days of life. Mitochondrial heart bioenergetics and oxidative balance showed to be deeply affected by neonatal overfeeding at both ages. Interestingly, after ischemia-reperfusion insult I/R (Langendorff or mineral oil incubation), most parameters evaluated in OF animals were not influenced by additional ischemic-reperfusion injury. Our findings demonstrated that suckling overfeeding deregulates cardiac mitochondrial alike to ischemia-reperfusion insult by disengaging electrical mitochondrial coupling and potentiate oxidative stress, wherein the neonatal overfeeding shows to be so detrimental as I/R. Our findings support the concept that nutritional insults in the critical development periods increase the risk for cardiovascular disease and mitochondria impairments throughout life while oxidative damage change between molecular targets.

G protein-coupled estrogen receptor (GPER) deficiency induces cardiac remodeling through oxidative stress

Oxidative stress has been implicated in the unfavorable changes in cardiac function and remodeling that occur after ovarian estrogen loss. Using ovariectomized rat models, we previously reported that the cardioprotective actions of estrogen are mediated by the G protein-coupled estrogen receptor (GPER). Here, in 9-month-old, female cardiomyocyte-specific GPER knockout (KO) mice vs sex- and age-matched wild-type (WT) mice, we found increased cardiac oxidative stress and oxidant damage, measured as a decreased ratio of reduced glutathione to oxidized glutathione, increased 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine (8-oxo-DG) staining, and increased expression of oxidative stress-related genes. GPER KO mice also displayed increased heart weight, cardiac collagen deposition, and Doppler-derived filling pressure, and decreased percent fractional shortening and early mitral annular velocity compared with WT controls. Treatment of GPER KO mice for 8 weeks with phosphonium [10-(4,5-dimethoxy-2-methyl 3,6-dioxo-1,4-cyclohexadien-1-yl)decyl] triphenyl-,mesylate (MitoQ), a mitochondria-targeted antioxidant, significantly attenuated these measures of cardiac dysfunction, and MitoQ decreased 8-oxo-DG intensity compared with treatment with an inactive comparator compound, (1-decyl)triphenylphosphonium bromide (P <0.05). A real-time polymerase chain reaction array analysis of 84 oxidative stress and antioxidant defense genes revealed that MitoQ attenuates the increase in NADPH oxidase 4 and prostaglandin-endoperoxide synthase 2 and the decrease in uncoupling protein 3 and glutathione S-transferase kappa 1 seen in GPER KO mice. Our findings suggest that the cardioprotective effects of GPER include an antioxidant role and that targeted strategies to limit oxidative stress after early noncancerous surgical extirpation of ovaries or menopause may help limit alterations in cardiac structure and function related to estrogen loss.

CRISPR/Cas9 disease models in zebrafish and Xenopus: The genetic renaissance of fish and frogs

The speed by which clinical genomics is currently identifying novel potentially pathogenic variants is outperforming the speed by which these can be functionally (genotype-phenotype) annotated in animal disease models. However, over the past few years the emergence of CRISPR/Cas9 as a straight-forward genome editing technology has revolutionized disease modeling in vertebrate non-mammalian model organisms such as zebrafish, medaka and Xenopus. It is now finally possible, by CRISPR/Cas9, to rapidly establish clinically relevant disease models in these organisms. Interestingly, these can provide both cost-effective genotype-phenotype correlations for gene-(variants) and genomic rearrangements obtained from clinical practice, as well as be exploited to perform translational research to improve prospects of disease afflicted patients. In this review, we show an extensive overview of these new CRISPR/Cas9-mediated disease models and provide future prospects that will allow increasingly accurate modeling of human disease in zebrafish, medaka and Xenopus.

Biomarkers of Myocardial Fibrosis: Revealing the Natural History of Fibrogenesis in Fabry Disease Cardiomyopathy

Background

Cardiomyopathy is a major determinant of overall Fabry disease (FD) prognosis, with the worst outcomes in patients with myocardial fibrosis. Late gadolinium enhancement is currently the gold standard for evaluation of replacement myocardial fibrosis; however, this event is irreversible, thus identification of biomarkers of earlier diffuse fibrosis is paramount.

Methods and Results

Type I collagen synthesis and degradation biomarkers (PICP [carboxyterminal propeptide of procollagen type I], ICTP [carboxyterminal telopeptide of type I collagen], and MMP1 [matrix metalloproteinase 1] and MMP2) and markers of bone synthesis and degradation were evaluated (to adjust type I collagen metabolism to bone turnover) in FD patients and controls. FD patients were grouped by cardiomyopathy severity, according to echocardiogram: (1) normal, (2) tissue Doppler abnormalities, (3) left ventricular hypertrophy. A significant increase in PICP and a significant decrease in matrix metalloproteinases were observed in FD patients; even the group with normal echocardiogram had a significant increase in PICP. We also found a significant correlation between left ventricular mass and PICP (ρ=0.378, P=0.003) and MMP1 (ρ=−0.484, P<0.001). PICP (adjusted for bone turnover) was the better predictor of left ventricular mass in multivariable regression, and its diagnostic accuracy to predict late gadolinium enhancement was also significant.

Conclusions

Collagen type I synthesis is increased in FD cardiomyopathy, even in the earlier stages of the disease, and this profibrotic state has good predictive value for and is likely to be critical to the development of overt left ventricular hypertrophy. Moreover, inhibition of enzymes involved in collagen type I cleavage also seems crucial to myocardial collagen deposition.

Hypertrophic Cardiomyopathy: Genetics, Pathogenesis, Clinical Manifestations, Diagnosis, and Therapy

Hypertrophic cardiomyopathy (HCM) is a genetic disorder that is characterized by left ventricular hypertrophy unexplained by secondary causes and a nondilated left ventricle with preserved or increased ejection fraction. It is commonly asymmetrical with the most severe hypertrophy involving the basal interventricular septum. Left ventricular outflow tract obstruction is present at rest in about one third of the patients and can be provoked in another third. The histological features of HCM include myocyte hypertrophy and disarray, as well as interstitial fibrosis. The hypertrophy is also frequently associated with left ventricular diastolic dysfunction. In the majority of patients, HCM has a relatively benign course. However, HCM is also an important cause of sudden cardiac death, particularly in adolescents and young adults. Nonsustained ventricular tachycardia, syncope, a family history of sudden cardiac death, and severe cardiac hypertrophy are major risk factors for sudden cardiac death. This complication can usually be averted by implantation of a cardioverter-defibrillator in appropriate high-risk patients. Atrial fibrillation is also a common complication and is not well tolerated. Mutations in over a dozen genes encoding sarcomere-associated proteins cause HCM. MYH7 and MYBPC3, encoding β-myosin heavy chain and myosin-binding protein C, respectively, are the 2 most common genes involved, together accounting for ≈50% of the HCM families. In ≈40% of HCM patients, the causal genes remain to be identified. Mutations in genes responsible for storage diseases also cause a phenotype resembling HCM (genocopy or phenocopy). The routine applications of genetic testing and preclinical identification of family members represents an important advance. The genetic discoveries have enhanced understanding of the molecular pathogenesis of HCM and have stimulated efforts designed to identify new therapeutic agents.

Comparative proteomic analysis reveals heart toxicity induced by chronic arsenic exposure in rats

Arsenic is a widespread metalloid in the environment, which poses a broad spectrum of adverse effects on human health. However, a global view of arsenic-induced heart toxicity is still lacking, and the underlying molecular mechanisms remain unclear. By performing a comparative quantitative proteomic analysis, the present study aims to investigate the alterations of proteome profile in rat heart after long-term exposure to arsenic. As a result, we found that the abundance of 81 proteins were significantly altered by arsenic treatment (35 up-regulated and 46 down-regulated). Among these, 33 proteins were specifically associated with cardiovascular system development and function, including heart development, heart morphology, cardiac contraction and dilation, and other cardiovascular functions. It is further proposed that the aberrant regulation of 14 proteins induced by arsenic would disturb cardiac contraction and relaxation, impair heart morphogenesis and development, and induce thrombosis in rats, which is mediated by the Akt/p38 MAPK signaling pathway. Overall, these findings will augment our knowledge of the involved mechanisms and develop useful biomarkers for cardiotoxicity induced by environmental arsenic exposure.

A Systems Biology Approach to Investigating Sex Differences in Cardiac Hypertrophy

BACKGROUND

Heart failure preceded by hypertrophy is a leading cause of death, and sex differences in hypertrophy are well known, although the basis for these sex differences is poorly understood.

METHODS AND RESULTS

This study used a systems biology approach to investigate mechanisms underlying sex differences in cardiac hypertrophy. Male and female mice were treated for 2 and 3 weeks with angiotensin II to induce hypertrophy. Sex differences in cardiac hypertrophy were apparent after 3 weeks of treatment. RNA sequencing was performed on hearts, and sex differences in mRNA expression at baseline and following hypertrophy were observed, as well as within-sex differences between baseline and hypertrophy. Sex differences in mRNA were substantial at baseline and reduced somewhat with hypertrophy, as the mRNA differences induced by hypertrophy tended to overwhelm the sex differences. We performed an integrative analysis to identify mRNA networks that were differentially regulated in the 2 sexes by hypertrophy and obtained a network centered on PPARα (peroxisome proliferator-activated receptor α). Mouse experiments further showed that acute inhibition of PPARα blocked sex differences in the development of hypertrophy.

CONCLUSIONS

The data in this study suggest that PPARα is involved in the sex-dimorphic regulation of cardiac hypertrophy.

Potential protective function of the sterol regulatory element binding factor 1-fatty acid desaturase 1/2 axis in early-stage age-related macular degeneration

Age-related macular degeneration (AMD) is the most common cause of vision loss in elderly individuals throughout the developed world. Inhibitors of vascular endothelial growth factor have been successfully used to treat choroidal neovascularization in late-stage AMD. The pathogenesis of early-stage AMD, however, remains largely unknown, impairing efforts to develop effective therapies that prevent progression to late-stage AMD. To address this, we performed comparative transcriptomics of macular and extramacular retinal pigmented epithelium-choroid (RPE-choroid) tissue from early-stage AMD patients. We found that expression of fatty acid desaturase 1 (FADS1), FADS2, and acetyl-CoA acetyltransferase 2 (ACAT2) is increased in macular but not extramacular tissue, possibly through activation of sterol regulatory element binding factor 1 (SREBF1). Consistent with this, we also found that expression of Fads1 is increased in RPE-choroid in a mouse model of early-stage AMD. In zebrafish, deletion of fads2, which encodes a protein that functions as both Fads1 and Fads2 in other species, enhanced apoptosis in the retina upon exposure to intense light. Similarly, pharmacological inhibition of Srebf1 enhanced apoptosis and reduced fads2 expression in zebrafish exposed to intense light. These results suggest that the SREBF1-FADS1/2 axis may be activated in macular RPE-choroid as a protective response during early-stage AMD and could thus be a therapeutic target for early-stage AMD.

Integrated Approaches to Drug Discovery for Oxidative Stress-Related Retinal Diseases

Excessive oxidative stress induces dysregulation of functional networks in the retina, resulting in retinal diseases such as glaucoma, age-related macular degeneration, and diabetic retinopathy. Although various therapies have been developed to reduce oxidative stress in retinal diseases, most have failed to show efficacy in clinical trials. This may be due to oversimplification of target selection for such a complex network as oxidative stress. Recent advances in high-throughput technologies have facilitated the collection of multilevel omics data, which has driven growth in public databases and in the development of bioinformatics tools. Integration of the knowledge gained from omics databases can be used to generate disease-related biological networks and to identify potential therapeutic targets within the networks. Here, we provide an overview of integrative approaches in the drug discovery process and provide simple examples of how the approaches can be exploited to identify oxidative stress-related targets for retinal diseases.