Selective modulation of local linkages between active transcription and oxidative demethylation activity shapes cardiomyocyte-specific gene-body epigenetic status in mice.

BACKGROUND: Cell-type-specific genes exhibit heterogeneity in genomic contexts and may be subject to different epigenetic regulations through different gene transcriptional processes depending on the cell type involved. The gene-body regions (GBRs) of some cardiomyocyte (CM)-specific genes are long and highly hypomethylated in CMs. To explore the cell-type specificities of epigenetic patterns and functions, multiple epigenetic modifications of GBRs were compared among CMs, liver cells and embryonic stem cells (ESCs). RESULTS: We found that most genes show a moderately negative correlation between transcript levels and gene lengths. As CM-specific genes are generally longer than other cell-type-specific genes, we hypothesized that the gene-body epigenetic features of CMs may support the transcriptional regulation of CM-specific genes. We found gene-body DNA hypomethylation in a CM-specific gene subset co-localized with rare gene-body marks, including RNA polymerase II (Pol II) and p300. Interestingly, 5-hydroxymethylcytosine (5hmC) within the gene body marked cell-type-specific genes at neonatal stages and active gene-body histone mark H3K36 trimethylation declined and overlapped with cell-type-specific gene-body DNA hypomethylation and selective Pol II/p300 accumulation in adulthood. Different combinations of gene-body epigenetic modifications were also observed with genome-wide scale cell-type specificity, revealing the occurrence of dynamic epigenetic rearrangements in GBRs across different cell types. CONCLUSIONS: As 5hmC enrichment proceeded to hypomethylated GBRs, we considered that hypomethylation may not represent a static state but rather an equilibrium state of turnover due to the balance between local methylation linked to transcription and Tet oxidative modification causing demethylation. Accordingly, we conclude that demethylation in CMs can be a used to establish such cell-type-specific epigenetic domains in relation to liver cells. The establishment of cell-type-specific epigenetic control may also change genomic contexts of evolution and may contribute to the development of cell-type-specific transcriptional coordination.

Investigation of June 2020 giant Saharan dust storm using remote sensing observations and model reanalysis.

This paper investigates the characteristics and impact of a major Saharan dust storm during June 14th-19th 2020 on atmospheric radiative and thermodynamics properties over the Atlantic Ocean. The event witnessed the highest ever aerosol optical depth for June since 2002. The satellites and high-resolution model reanalysis products well captured the origin and spread of the dust storm. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measured total attenuated backscatter and aerosol subtype profiles, lower angstrom exponent values (~ 0.12) from Modern-Era Retrospective Analysis for Research and Application-version 2 (MERRA-2) and higher aerosol index value from Ozone monitoring instrument (> 4) tracked the presence of elevated dust. It was found that the dust AOD was as much as 250-300% higher than their climatology resulting in an atmospheric radiative forcing ~ 200% larger. As a result, elevated warming (8-16%) was observed, followed by a drop in relative humidity (2-4%) in the atmospheric column, as evidenced by both in-situ and satellite measurements. Quantifications such as these for extreme dust events provide significant insights that may help in understanding their climate effects, including improvements to dust simulations using chemistry-climate models.

Intramyocardial Injection for the Study of Cardiac Lymphatic Function in Zebrafish.

Zebrafish have proved to be an important model for studying cardiovascular formation and function during postembryonic development and regeneration. The present protocol describes a method for injecting fluorescent tracers into the zebrafish myocardium to study interstitial fluid and debris uptake into cardiac lymphatic vessels. To do so, microspheres (200 nm diameter) and quantum dots (<10 nm diameter) are introduced into the myocardium of live zebrafish, which can be tracked using ex vivo confocal microscopy. These tracers are then tracked intermittently over several hours to follow clearance from the myocardium into cardiac lymphatic vessels. Quantum dots are transported through cardiac lymphatic vessels away from the heart, while larger microspheres remain at the injection site for over three weeks. This method of intramyocardial injection can be extended to other uses, including the injection of encapsulated MS or hydrogels to locally release cells, proteins, or compounds of interest to a targeted region of the heart.

Dilated cardiomyopathy-linked heat shock protein family D member 1 mutations cause up-regulation of reactive oxygen species and autophagy through mitochondrial dysfunction.

AIMS: During heart failure, the levels of circulatory heat shock protein family D member 1 (HSP60) increase. However, its underlying mechanism is still unknown. The apical domain of heat shock protein family D member 1 (HSPD1) is conserved throughout evolution. We found a point mutation in HSPD1 in a familial dilated cardiomyopathy (DCM) patient. A similar point mutation in HSPD1 in the zebrafish mutant, nbl, led to loss of its regenerative capacity and development of pericardial oedema under heat stress condition. In this study, we aimed to determine the direct involvement of HSPD1 in the development of DCM. METHODS AND RESULTS: By Sanger method, we found a point mutation (Thr320Ala) in the apical domain of HSPD1, in one familial DCM patient, which was four amino acids away from the point mutation (Val324Glu) in the nbl mutant zebrafish. The nbl mutants showed atrio-ventricular block and sudden death at 8-month post-fertilization. Histological and microscopic analysis of the nbl mutant hearts showed decreased ventricular wall thickness, elevated level of reactive oxygen species (ROS), increased fibrosis, mitochondrial damage, and increased autophagosomes. mRNA and protein expression of autophagy-related genes significantly increased in nbl mutants. We established HEK293 stable cell lines of wild-type, nbl-type, and DCM-type HSPD1, with tetracycline-dependent expression. Compared to wild-type, both nbl- and DCM-type cells showed decreased cell growth, increased expression of ROS and autophagy-related genes, inhibition of the activity of mitochondrial electron transport chain complexes III and IV, and decreased mitochondrial fission and fusion. CONCLUSION: Mutations in HSPD1 caused mitochondrial dysfunction and induced mitophagy. Mitochondrial dysfunction caused increased ROS and cardiac atrophy.

Versican is crucial for the initiation of cardiovascular lumen development in medaka (Oryzias latipes).

Versican is an evolutionary conserved extracellular matrix proteoglycan, and versican expression loss in mice results in embryonic lethality owing to cardiovascular defects. However, the in utero development of mammals limits our understanding of the precise role of versican during cardiovascular development. Therefore, the use of evolutionarily distant species that develop ex utero is more suitable for studying the mechanistic basis of versican activity. We performed ENU mutagenesis screening to identify medaka mutants with defects in embryonic cardiovascular development. In this study, we described a recessive point mutation in the versican 3'UTR resulting in reduced versican protein expression. The fully penetrant homozygous mutant showed termination of cardiac development at the linear heart tube stage and exhibited absence of cardiac looping, a constricted outflow tract, and no cardiac jelly. Additionally, progenitor cells did not migrate from the secondary source towards the arterial pole of the linear heart tube, resulting in a constricted outflow tract. Furthermore, mutants lacked blood flow and vascular lumen despite continuous peristaltic heartbeats. These results enhance our understanding of the mechanistic basis of versican in cardiac development, and this mutant represents a novel genetic model to investigate the mechanisms of vascular tubulogenesis.

Perturbation of the titin/MURF1 signaling complex is associated with hypertrophic cardiomyopathy in a fish model and in human patients.

Hypertrophic cardiomyopathy (HCM) is a hereditary disease characterized by cardiac hypertrophy with diastolic dysfunction. Gene mutations causing HCM have been found in about half of HCM patients, while the genetic etiology and pathogenesis remain unknown for many cases of HCM. To identify novel mechanisms underlying HCM pathogenesis, we generated a cardiovascular-mutant medaka fish, non-spring heart (nsh), which showed diastolic dysfunction and hypertrophic myocardium. The nsh homozygotes had fewer myofibrils, disrupted sarcomeres and expressed pathologically stiffer titin isoforms. In addition, the nsh heterozygotes showed M-line disassembly that is similar to the pathological changes found in HCM. Positional cloning revealed a missense mutation in an immunoglobulin (Ig) domain located in the M-line-A-band transition zone of titin. Screening of mutations in 96 unrelated patients with familial HCM, who had no previously implicated mutations in known sarcomeric gene candidates, identified two mutations in Ig domains close to the M-line region of titin. In vitro studies revealed that the mutations found both in medaka fish and in familial HCM increased binding of titin to muscle-specific ring finger protein 1 (MURF1) and enhanced titin degradation by ubiquitination. These findings implicate an impaired interaction between titin and MURF1 as a novel mechanism underlying the pathogenesis of HCM.

Effect of Risperidone on the Motor and Functional Disability in Children With Choreoathetoid Cerebral Palsy.

BACKGROUND: Therapeutic options for management of choreoathetoid cerebral palsy, which is a permanent disorder, are limited. Available medications either have significant side effects or are unsuitable for long-term use. Risperidone has shown promise in the management of chorea and has been found to be safe in children less than five years. METHODS: Children with choreoathetoid cerebral palsy were enrolled after parental consent and given risperidone for six-month period along with standard care. The choreoathetoid movements were assessed using Abnormal Involuntary Movement Scale, the upper-limb functions were assessed using Quality of upper extremity skill tests, and the quality of life using Cerebral palsy-Quality of life. Side effects were monitored clinically, by biochemical tests and electrocardiogram. RESULTS: Of 42 children with choreoathetoid cerebral palsy who were screened over a period of one year, 35 subjects meeting the study criteria were enrolled. Thirty children completed six months of risperidone therapy, the remaining five subjects were excluded because of time missed due to intercurrent unrelated illnesses. Data of these 30 children were analyzed as per per-protocol analysis. Their mean age was 6.35 ± 3.17 years. Abnormal movements showed statistically significant decline after risperidone (19.7 vs 14.7, P < 0.0001). Functional ability of upper limbs and quality of life also showed improvement (37.0 vs 43.8, P < 0.0001 and 64.3 vs 70.0, P < 0.0001, respectively) after six months of risperidone therapy. Positive change in the behavior was also noted. It was well tolerated without significant side effects. CONCLUSION: Risperidone is a promising drug to manage children with choreoathetoid cerebral palsy and is well tolerated in children.