Nonsense Variant PRDM16-Q187X Causes Impaired Myocardial Development and TGF-ß Signaling Resulting in Noncompaction Cardiomyopathy in Humans and Mice.

BACKGROUND: PRDM16 plays a role in myocardial development through TGF-ß (transforming growth factor-beta) signaling. Recent evidence suggests that loss of PRDM16 expression is associated with cardiomyopathy development in mice, although its role in human cardiomyopathy development is unclear. This study aims to determine the impact of PRDM16 loss-of-function variants on cardiomyopathy in humans. METHODS: Individuals with PRDM16 variants were identified and consented. Induced pluripotent stem cell-derived cardiomyocytes were generated from a proband hosting a Q187X nonsense variant as an in vitro model and underwent proliferative and transcriptional analyses. CRISPR (clustered regularly interspaced short palindromic repeats)-mediated knock-in mouse model hosting the Prdm16Q187X allele was generated and subjected to ECG, histological, and transcriptional analysis. RESULTS: We report 2 probands with loss-of-function PRDM16 variants and pediatric left ventricular noncompaction cardiomyopathy. One proband hosts a PRDM16-Q187X variant with left ventricular noncompaction cardiomyopathy and demonstrated infant-onset heart failure, which was selected for further study. Induced pluripotent stem cell-derived cardiomyocytes prepared from the PRDM16-Q187X proband demonstrated a statistically significant impairment in myocyte proliferation and increased apoptosis associated with transcriptional dysregulation of genes implicated in cardiac maturation, including TGF-ß-associated transcripts. Homozygous Prdm16Q187X/Q187X mice demonstrated an underdeveloped compact myocardium and were embryonically lethal. Heterozygous Prdm16Q187X/WT mice demonstrated significantly smaller ventricular dimensions, heightened fibrosis, and age-dependent loss of TGF-ß expression. Mechanistic studies were undertaken in H9c2 cardiomyoblasts to show that PRDM16 binds TGFB3 promoter and represses its transcription. CONCLUSIONS: Novel loss-of-function PRDM16 variant impairs myocardial development resulting in noncompaction cardiomyopathy in humans and mice associated with altered TGF-ß signaling.

Human embryo models: the importance of national policy and governance review.

Integrated and non-integrated stem cell-based embryo models are becoming widely adopted tools in biomedical research with distinct advantages over animal models for studying human development. Although SCB-EMs have tremendous benefits for research, they raise a number of social, ethical and legal questions that affect future research and widespread adoption in industry and clinical settings. The 2021 International Society for Stem Cell Research Guidelines for Stem Cell Research and Clinical Translation provide helpful guidance on many of these issues but do not have force in domestic law. Careful appraisal and development of national legal and ethical frameworks is crucial. Paving the way to better regulation provides an ethical and social foundation to continue using human embryo models and to fully realise their potential benefits for reproductive medicine.

Cardiac gene therapy treats diabetic cardiomyopathy and lowers blood glucose.

Diabetic cardiomyopathy, an increasingly global epidemic and a major cause of heart failure with preserved ejection fraction (HFpEF), is associated with hyperglycemia, insulin resistance, and intracardiomyocyte calcium mishandling. Here we identify that, in db/db mice with type 2 diabetes-induced HFpEF, abnormal remodeling of cardiomyocyte transverse-tubule microdomains occurs with downregulation of the membrane scaffolding protein cardiac bridging integrator 1 (cBIN1). Transduction of cBIN1 by AAV9 gene therapy can restore transverse-tubule microdomains to normalize intracellular distribution of calcium-handling proteins and, surprisingly, glucose transporter 4 (GLUT4). Cardiac proteomics revealed that AAV9-cBIN1 normalized components of calcium handling and GLUT4 translocation machineries. Functional studies further identified that AAV9-cBIN1 normalized insulin-dependent glucose uptake in diabetic cardiomyocytes. Phenotypically, AAV9-cBIN1 rescued cardiac lusitropy, improved exercise intolerance, and ameliorated hyperglycemia in diabetic mice. Restoration of transverse-tubule microdomains can improve cardiac function in the setting of diabetic cardiomyopathy and can also improve systemic glycemic control.

SMYD1a protects the heart from ischemic injury by regulating OPA1-mediated cristae remodeling and supercomplex formation.

SMYD1, a striated muscle-specific lysine methyltransferase, was originally shown to play a key role in embryonic cardiac development but more recently we demonstrated that loss of Smyd1 in the murine adult heart leads to cardiac hypertrophy and failure. However, the effects of SMYD1 overexpression in the heart and its molecular function in the cardiomyocyte in response to ischemic stress are unknown. In this study, we show that inducible, cardiomyocyte-specific overexpression of SMYD1a in mice protects the heart from ischemic injury as seen by a > 50% reduction in infarct size and decreased myocyte cell death. We also demonstrate that attenuated pathological remodeling is a result of enhanced mitochondrial respiration efficiency, which is driven by increased mitochondrial cristae formation and stabilization of respiratory chain supercomplexes within the cristae. These morphological changes occur concomitant with increased OPA1 expression, a known driver of cristae morphology and supercomplex formation. Together, these analyses identify OPA1 as a novel downstream target of SMYD1a whereby cardiomyocytes upregulate energy efficiency to dynamically adapt to the energy demands of the cell. In addition, these findings highlight a new epigenetic mechanism by which SMYD1a regulates mitochondrial energetics and functions to protect the heart from ischemic injury.

Identification of Two Homozygous Variants in MYBPC3 and SMYD1 Genes Associated with Severe Infantile Cardiomyopathy.

Mutations in cardiac genes are one of the primary causes of infantile cardiomyopathy. In this study, we report the genetic findings of two siblings carrying variations in the MYBPC3 and SMYD1 genes. The first patient is a female proband exhibiting hypertrophic cardiomyopathy (HCM) and biventricular heart failure carrying a truncating homozygous MYBPC3 variant c.1224-52G>A (IVS13-52G>A) and a novel homozygous variant (c.302A>G; p.Asn101Ser) in the SMYD1 gene. The second patient, the proband's sibling, is a male infant diagnosed with hypertrophic cardiomyopathy and carries the same homozygous MYBPC3 variant. While this specific MYBPC3 variant (c.1224-52G>A, IVS13-52G>A) has been previously reported to be associated with adult-onset hypertrophic cardiomyopathy, this is the first report linking it to infantile cardiomyopathy. In addition, this work describes, for the first time, a novel SMYD1 variant (c.302A>G; p.Asn101Ser) that has never been reported. We performed a histopathological evaluation of tissues collected from both probands and show that these variants lead to myofibrillar disarray, reduced and irregular mitochondrial cristae and cardiac fibrosis. Together, these results provide critical insight into the molecular functionality of these genes in human cardiac physiology.

Correction to "Histone H4K20 Trimethylation Is Decreased in Murine Models of Heart Disease".

[This corrects the article DOI: 10.1021/acsomega.2c00984.].

Distinct Transcriptomic and Proteomic Profile Specifies Patients Who Have Heart Failure With Potential of Myocardial Recovery on Mechanical Unloading and Circulatory Support.

BACKGROUND: Extensive evidence from single-center studies indicates that a subset of patients with chronic advanced heart failure (HF) undergoing left ventricular assist device (LVAD) support show significantly improved heart function and reverse structural remodeling (ie, termed "responders"). Furthermore, we recently published a multicenter prospective study, RESTAGE-HF (Remission from Stage D Heart Failure), demonstrating that LVAD support combined with standard HF medications induced remarkable cardiac structural and functional improvement, leading to high rates of LVAD weaning and excellent long-term outcomes. This intriguing phenomenon provides great translational and clinical promise, although the underlying molecular mechanisms driving this recovery are largely unknown. METHODS: To identify changes in signaling pathways operative in the normal and failing human heart and to molecularly characterize patients who respond favorably to LVAD unloading, we performed global RNA sequencing and phosphopeptide profiling of left ventricular tissue from 93 patients with HF undergoing LVAD implantation (25 responders and 68 nonresponders) and 12 nonfailing donor hearts. Patients were prospectively monitored through echocardiography to characterize their myocardial structure and function and identify responders and nonresponders. RESULTS: These analyses identified 1341 transcripts and 288 phosphopeptides that are differentially regulated in cardiac tissue from nonfailing control samples and patients with HF. In addition, these unbiased molecular profiles identified a unique signature of 29 transcripts and 93 phosphopeptides in patients with HF that distinguished responders after LVAD unloading. Further analyses of these macromolecules highlighted differential regulation in 2 key pathways: cell cycle regulation and extracellular matrix/focal adhesions. CONCLUSIONS: This is the first study to characterize changes in the nonfailing and failing human heart by integrating multiple -omics platforms to identify molecular indices defining patients capable of myocardial recovery. These findings may guide patient selection for advanced HF therapies and identify new HF therapeutic targets.

Histone H4K20 Trimethylation Is Decreased in Murine Models of Heart Disease.

Heart disease is the leading cause of death in the developed world, and its comorbidities such as hypertension, diabetes, and heart failure are accompanied by major transcriptomic changes in the heart. During cardiac dysfunction, which leads to heart failure, there are global epigenetic alterations to chromatin that occur concomitantly with morphological changes in the heart in response to acute and chronic stress. These epigenetic alterations include the reversible methylation of lysine residues on histone proteins. Lysine methylations on histones H3K4 and H3K9 were among the first methylated lysine residues identified and have been linked to gene activation and silencing, respectively. However, much less is known regarding other methylated histone residues, including histone H4K20. Trimethylation of histone H4K20 has been shown to repress gene expression; however, this modification has never been examined in the heart. Here, we utilized immunoblotting and mass spectrometry to quantify histone H4K20 trimethylation in three models of cardiac dysfunction. Our results show that lysine methylation at this site is differentially regulated in the cardiomyocyte, leading to increased H4K20 trimethylation during acute hypertrophic stress in cell models and decreased H4K20 trimethylation during sustained ischemic injury and cardiac dysfunction in animal models. In addition, we examined publicly available data sets to analyze enzymes that regulate H4K20 methylation and identified two demethylases (KDM7B and KDM7C) and two methyltransferases (KMT5A and SMYD5) that were all differentially expressed in heart failure patients. This is the first study to examine histone H4K20 trimethylation in the heart and to determine how this post-translational modification is differentially regulated in multiple models of cardiac disease.

Mitochondrial calcium uniporter stabilization preserves energetic homeostasis during Complex I impairment.

Calcium entering mitochondria potently stimulates ATP synthesis. Increases in calcium preserve energy synthesis in cardiomyopathies caused by mitochondrial dysfunction, and occur due to enhanced activity of the mitochondrial calcium uniporter channel. The signaling mechanism that mediates this compensatory increase remains unknown. Here, we find that increases in the uniporter are due to impairment in Complex I of the electron transport chain. In normal physiology, Complex I promotes uniporter degradation via an interaction with the uniporter pore-forming subunit, a process we term Complex I-induced protein turnover. When Complex I dysfunction ensues, contact with the uniporter is inhibited, preventing degradation, and leading to a build-up in functional channels. Preventing uniporter activity leads to early demise in Complex I-deficient animals. Conversely, enhancing uniporter stability rescues survival and function in Complex I deficiency. Taken together, our data identify a fundamental pathway producing compensatory increases in calcium influx during Complex I impairment.

The role of demethylases in cardiac development and disease.

Heart failure is a worldwide health condition that currently has limited noninvasive treatments. Heart disease includes both structural and molecular remodeling of the heart which is driven by alterations in gene expression in the cardiomyocyte. Therefore, understanding the regulatory mechanisms which instigate these changes in gene expression and constitute the foundation for pathological remodeling may be beneficial for developing new treatments for heart disease. These gene expression changes are largely preceded by epigenetic alterations to chromatin, including the post-translational modification of histones such as methylation, which alters chromatin to be more or less accessible for transcription factors or regulatory proteins to bind and modify gene expression. Methylation was once thought to be a permanent mark placed on histone or non-histone targets by methyltransferases, but is now understood to be a reversible process after the discovery of the first demethylase, KDM1A/LSD1. Since this time, it has been shown that demethylases play key roles in embryonic development, in maintaining cellular homeostasis and disease progression. However, the role of demethylases in the fetal and adult heart remains largely unknown. In this review, we have compiled data on the 33 mammalian demethylases that have been identified to date and evaluate their expression in the embryonic and adult heart as well as changes in expression in the failing myocardium using publicly available RNA-sequencing and proteomic datasets. Our analysis detected expression of 14 demethylases in the normal fetal heart, and 5 demethylases in the normal adult heart. Moreover, 8 demethylases displayed differential expression in the diseased human heart compared to healthy hearts. We then examined the literature regarding these demethylases and provide phenotypic information of 13 demethylases that have been functionally interrogated in some way in the heart. Lastly, we describe the 6 arginine and lysine residues on histones which have been shown to be methylated but have no corresponding demethylase identified which removes these methyl marks. Overall, this review highlights our current knowledge on the role of demethylases, their importance in cardiac development and pathophysiology and provides evidence for the use of pharmacological inhibitors to combat disease.

The lncRNA Caren antagonizes heart failure by inactivating DNA damage response and activating mitochondrial biogenesis.

In the past decade, many long noncoding RNAs (lncRNAs) have been identified and their in vitro functions defined, although in some cases their functions in vivo remain less clear. Moreover, unlike nuclear lncRNAs, the roles of cytoplasmic lncRNAs are less defined. Here, using a gene trapping approach in mouse embryonic stem cells, we identify Caren (short for cardiomyocyte-enriched noncoding transcript), a cytoplasmic lncRNA abundantly expressed in cardiomyocytes. Caren maintains cardiac function under pathological stress by inactivating the ataxia telangiectasia mutated (ATM)-DNA damage response (DDR) pathway and activating mitochondrial bioenergetics. The presence of Caren transcripts does not alter expression of nearby (cis) genes but rather decreases translation of an mRNA transcribed from a distant gene encoding histidine triad nucleotide-binding protein 1 (Hint1), which activates the ATM-DDR pathway and reduces mitochondrial respiratory capacity in cardiomyocytes. Therefore, the cytoplasmic lncRNA Caren functions in cardioprotection by regulating translation of a distant gene and maintaining cardiomyocyte homeostasis.

Rethinking Human Embryo Research Policies.

It now seems technically feasible to culture human embryos beyond the "fourteen-day limit," which has the potential to increase scientific understanding of human development and perhaps improve infertility treatments. The fourteen-day limit was adopted as a compromise but subsequently has been considered an ethical line. Does it remain relevant in light of technological advances permitting embryo maturation beyond it? Should it be changed and, if so, how and why? What justifications would be necessary to expand the limit, particularly given that doing so would violate some people's moral commitments regarding human embryos? Robust stakeholder engagement preceded adoption of the fourteen-day limit and should arguably be part of efforts to reassess it. Such engagement could also consider the need for enhanced oversight of human embryo research. In the meantime, developing and implementing reliable oversight systems should help foster high-quality research and public confidence in it.

The use of complementary and alternative medicine among hypertensive and type 2 diabetic patients in Western Jamaica: A mixed methods study.

BACKGROUND: The simultaneous or intermittent use of alternative treatments and prescription medications for hypertension and type 2 diabetes mellitus can have adverse health effects. OBJECTIVES: To identify beliefs and practices associated with the use of alternative treatments for hypertension and type 2 diabetes mellitus among patients. METHODS: A mixed-methods study including an investigator-administered survey and focus group discussion sessions using convenience sampling was conducted among patients aged ≥18 years during May to August 2018. Descriptive statistics were used to describe and compare demographic characteristics among groups of survey participants using JMP Pro 14.0. Thematic analysis was conducted to analyze the qualitative data using NVivo. RESULTS: Most study participants (87-90%) were on prescription medication for their condition. Of survey participants, 69% reported taking their medication as prescribed and 70% felt that prescription medicine was controlling their condition. Almost all participants (98%) reported using alternative treatments, mainly herbal medications, and 73-80% felt that herbal medicines controlled their conditions. One-third believed that herbal medicines are the most effective form of treatment and should always be used instead of prescription medication. However, most participants (85%) did not believe that prescription and herbal treatments should be used simultaneously. Most (76-90%) did not discuss herbal treatments with their healthcare providers. Four themes emerged from the focus group sessions: 1) Simultaneous use of herbal and prescription medicine was perceived to be harmful, 2) Patients did not divulge their use of herbal medicine to healthcare providers, 3) Alternative medicines were perceived to be highly effective, and 4) Religiosity and family elders played key roles in herbal use. CONCLUSIONS: This study provides useful insights into perceptions and use of alternative treatments by patients that can be used by healthcare providers in developing appropriate interventions to encourage proper use of prescription medicines and alternative medicines resulting in improved management of these chronic diseases.

Effectiveness of an intrauterine device informative intervention among post-natal women in Western Jamaica.

INTRODUCTION: Intrauterine devices are the most effective long-acting reversible contraceptives, but in many developing countries, such as Jamaica, these devices remain underutilized. METHODS: A cross-sectional informative intervention was conducted among women ≥ 18 years of age attending postnatal clinics in western Jamaica from May to August 2018. Data were collected using an investigator-administered questionnaire/pre-test followed by a 12-slide PowerPoint® presentation and a post-test. RESULTS: Most of the 299 women who participated were 18-29 years of age, with a mean age of 27.1 (SD ± 6.1) years. Most had their first pregnancy between ages 18 and 24 years, with mean age at first pregnancy of 20.2 (SD ± 4.0) years. Only 3.0% of participants reported current use of an intrauterine device; 3.5% reported using an intrauterine device in the past. For nearly every measure of knowledge of intrauterine devices, there was a significant change in the proportion of participants who got the correct answer from the pre-test to the post-test. The mean summed pre-test knowledge score was 9.54 (SD ± 3.46) and the post-test score was 15.23 (SD ± 1.92); the possible total score is 18. The difference between the mean scores (5.69 points) was also significant. CONCLUSION: The intervention resulted in significant change in knowledge of intrauterine devices among the women and cleared up many misconceptions that may have contributed to reluctance of women to use intrauterine devices. Women of reproductive age in Jamaica should be counseled on contraceptive methods including intrauterine devices so that these devices can be considered in their contraceptive choices.

Knowledge, attitudes and practices among healthcare professionals regarding complementary alternative medicine use by patients with hypertension and type 2 diabetes mellitus in Western Jamaica.

OBJECTIVES: This study investigated the knowledge, attitudes, and practices (KAP) of healthcare professionals (HCPs) regarding CAM use for Hypertension (HTN) and Type 2 Diabetes Mellitus (T2DM) among patients in western Jamaica, and to determine HCPs' perceptions of the need for training on CAM. DESIGN: A cross-sectional study was conducted from May to August 2019. SETTING: HCPs serving patients with HTN and T2DM in chronic disease clinics in western Jamaica completed a self-administered questionnaire that provided data on their sociodemographic characteristics, training, and KAP of CAM. MAIN OUTCOME MEASURE: The data identified factors associated with discussion and recommendation of CAM to patients and personal use of CAM by HCPs. RESULTS: Type of profession (physicians vs nurses OR = 2.17; 95 % CI = 1.07-4.42 and pharmacists vs nurses OR = 8.67; 95 % CI = 2.83-26.57) was significantly associated with discussion of CAM. Training on CAM was significantly associated with discussion (OR = 2.36; 95 % CI = 1.26-4.42), recommendation (OR = 2.72; 95 % CI = 1.36-5.42), and personal use of CAM (OR = 2.90; 95 % CI = 1.69-4.97). Dieticians and nutritionists had 4.56 higher odds of personal use of CAM (95 % CI = 1.16-17.86), and personal use of CAM was significantly associated with discussion (OR = 8.94; 95 % CI = 4.76-16.80) and recommendation (OR = 7.17; 95 % CI = 3.54-14.51) of CAM. The majority of HCPs (70-89 %) agreed that there is a need to include CAM in professional training programs. CONCLUSION: The results of this study can be used to guide development of programs for training HCPs on knowledge and safe use of CAM so that they can better serve their patients.