Acetylation of H3K4, H3K9, and H3K27 mediated by p300 regulates the expression of GATA4 in cardiocytes

Genetic and Epigenetic Mechanisms Regulating Blood Pressure and Kidney Dysfunction

The pioneering work of Dr Lewis K. Dahl established a relationship between kidney, salt, and high blood pressure (BP), which led to the major genetic-based experimental model of hypertension. BP, a heritable quantitative trait affected by numerous biological and environmental stimuli, is a major cause of morbidity and mortality worldwide and is considered to be a primary modifiable factor in renal, cardiovascular, and cerebrovascular diseases. Genome-wide association studies have identified monogenic and polygenic variants affecting BP in humans. Single nucleotide polymorphisms identified in genome-wide association studies have quantified the heritability of BP and the effect of genetics on hypertensive phenotype. Changes in the transcriptional program of genes may represent consequential determinants of BP, so understanding the mechanisms of the disease process has become a priority in the field. At the molecular level, the onset of hypertension is associated with reprogramming of gene expression influenced by epigenomics. This review highlights the specific genetic variants, mutations, and epigenetic factors associated with high BP and how these mechanisms affect the regulation of hypertension and kidney dysfunction.

Uncovering the Genetic Basis of Congenital Heart Disease: Recent Advancements and Implications for Clinical Management

Congenital heart disease (CHD) is the most prevalent hereditary disorder, affecting approximately 1% of all live births. A reduction in morbidity and mortality has been achieved with advancements in surgical intervention, yet challenges in managing complications, extracardiac abnormalities, and comorbidities still exist. To address these, a more comprehensive understanding of the genetic basis underlying CHD is required to establish how certain variants are associated with the clinical outcomes. This will enable clinicians to provide personalized treatments by predicting the risk and prognosis, which might improve the therapeutic results and the patient's quality of life. We review how advancements in genome sequencing are changing our understanding of the genetic basis of CHD, discuss experimental approaches to determine the significance of novel variants, and identify barriers to use this knowledge in the clinics. Next-generation sequencing technologies are unravelling the role of oligogenic inheritance, epigenetic modification, genetic mosaicism, and noncoding variants in controlling the expression of candidate CHD-associated genes. However, clinical risk prediction based on these factors remains challenging. Therefore, studies involving human-induced pluripotent stem cells and single-cell sequencing help create preclinical frameworks for determining the significance of novel genetic variants. Clinicians should be aware of the benefits and implications of the responsible use of genomics. To facilitate and accelerate the clinical integration of these novel technologies, clinicians should actively engage in the latest scientific and technical developments to provide better, more personalized management plans for patients.

A novel trans-acting lncRNA of ACTG1 that induces the remodeling of ovarian follicles

Previous studies have implicated the attractive role of long noncoding RNAs (lncRNAs) in the remodeling of mammalian tissues. The migration of granulosa cells (GCs), which are the main supporting cells in ovarian follicles, stimulates the follicular remodeling. Here, with the cultured GCs as the follicular model, the actin gamma 1 (ACTG1) was observed to significantly promote the migration and proliferation while inhibit the apoptosis of GCs, suggesting that ACTG1 was required for ovarian remodeling. Moreover, we identified the trans-regulatory lncRNA of ACTG1 (TRLA), which was epigenetically targeted by histone H3 lysine 4 acetylation (H3K4ac). Mechanistically, the 2-375 nt of TRLA bound to ACTG1's mRNA to increase the expression of ACTG1. Furthermore, TRLA facilitated the migration and proliferation while inhibited the apoptosis of GCs, thereby accelerating follicular remodeling. Besides, TRLA acted as a ceRNA for miR-26a to increase the expression of high-mobility group AT-hook 1 (HMGA1). Collectively, TRLA induces the remodeling of ovarian follicles via complementary to ACTG1's mRNA and regulating miR-26a/HMGA1 axis in GCs. These observations revealed a novel and promising trans-acting lncRNA mechanism mediated by H3K4ac, and TRLA might be a new target to restore follicular remodeling and development.

Effects of ketamine-induced H3K9 hypoacetylation during pregnancy on cardiogenesis of mouse offspring

BACKGROUND

Prenatal exposure to adverse factors can cause congenital heart defects. Ketamine, a widely used anesthetic drug, produces several adverse reactions such as tachycardia, hypertension, and laryngospasm, especially in pediatric patients. This study aimed to detect the effects of ketamine exposure during pregnancy on the cardiogenesis of mouse offspring and the potential mechanisms.

METHODS

In this study, ketamine at an addictive dose (5 mg/kg) was administered to mice during early gestation to explore the epigenetic mechanism of its causing cardiac dysplasia. The cardiac morphology of the mouse offspring was observed through hematoxylin-eosin staining and transmission electron microscopy. The heart function of one-month-old neonates was detected by echocardiography. The expression of cardiomyogenesis-related genes was detected by western blot and RT-qPCR. The acetylation level of histone H3K9 at the Mlc2 promoter and its deacetylase level and activity were detected by CHIP-qPCR, RT-qPCR, and ELISA, respectively.

RESULTS

Our data revealed that ketamine exposure during pregnancy could cause cardiac enlargement, myocardial sarcomere disorganization, and decreased cardiac contractile function in mouse offspring. Moreover, ketamine reduced the expression of Myh6, Myh7, Mlc2, Mef2c, and cTnI. The histone H3K9 acetylation level at the Mlc2 promoter was down-regulated by increasing the histone deacetylase activity and HDAC3 level upon ketamine administration.

CONCLUSIONS

Our work indicates that H3K9 acetylation is a vital player in cardiac dysplasia in offspring caused by prenatal ketamine exposure and HDAC3 is a key regulatory factor.

Roles of histone acetylation sites in cardiac hypertrophy and heart failure

Heart failure results from various physiological and pathological stimuli that lead to cardiac hypertrophy. This pathological process is common in several cardiovascular diseases and ultimately leads to heart failure. The development of cardiac hypertrophy and heart failure involves reprogramming of gene expression, a process that is highly dependent on epigenetic regulation. Histone acetylation is dynamically regulated by cardiac stress. Histone acetyltransferases play an important role in epigenetic remodeling in cardiac hypertrophy and heart failure. The regulation of histone acetyltransferases serves as a bridge between signal transduction and downstream gene reprogramming. Investigating the changes in histone acetyltransferases and histone modification sites in cardiac hypertrophy and heart failure will provide new therapeutic strategies to treat these diseases. This review summarizes the association of histone acetylation sites and histone acetylases with cardiac hypertrophy and heart failure, with emphasis on histone acetylation sites.

The Role of PGK1 in Promoting Ischemia/Reperfusion Injury-Induced Microglial M1 Polarization and Inflammation by Regulating Glycolysis

Stroke is a leading cause of death, with a continuously increasing incidence. As a metabolic process that catabolizes glucose pyruvate and provides adenosine triphosphate (ATP), glycolysis plays a crucial role in different diseases. Phosphoglycerate kinase 1 (PGK1) facilitates energy production with biosynthesis in many diseases, including stroke. However, the exact role of PGK1/glycolysis in stroke remains to be elucidated. A rat model of middle cerebral artery occlusion (MCAO) was used to mimic ischemia/reperfusion injuries. Oxygen glucose deprivation/re-oxygenation (OGD/R) was used to induce injury to highly aggressively proliferating immortalized (HAPI) rat microglial cells. The extracellular acidification rate (ECAR) was determined using an XFe24 Extracellular Flux Analyzer. ATP, lactate dehydrogenase, tumor necrosis factor-alpha, and interleukin-6 levels were measured using commercial kits. Chromatin immunoprecipitation assay was performed to examine the interaction between H3K27ac or p300 and the PGK1 promoter region. PGK1 was either knocked down or overexpressed by lentivirus. Thus, to examine its role in stroke, real-time polymerase chain reaction and immunoblotting were used to measure gene expression. The expression of PGK1 was increased and associated with M1 polarization and glycolysis in MCAO rat models. OGD/R promoted M1 polarization and HAPI microglial cell inflammation by regulating glycolysis. Silencing PGK1 reduced OGD/R-increased M1 polarization, inflammation, and glycolysis. Conversely, the overexpression of PGK1 promoted HAPI microglial cell inflammation by regulating glycolysis. The mechanism showed that histone acetyltransferase p300 promoted PGK1 expression through H3K27 acetylation. Finally, data indicated that silencing PGK1 inhibited microglia M1 polarization, inflammation, and glycolysis in MCAO rat models. PGK1 could promote ischemia/reperfusion injury-induced microglial M1 polarization and inflammation by regulating glycolysis, which might provide a novel direction in developing new therapeutic medications for preventing or treating stroke.

Emerging epigenetic therapies of cardiac fibrosis and remodelling in heart failure: from basic mechanisms to early clinical development

Cardiovascular diseases and specifically heart failure (HF) impact global health and impose a significant economic burden on society. Despite current advances in standard of care, the risks for death and readmission of HF patients remain unacceptably high and new therapeutic strategies to limit HF progression are highly sought. In disease settings, persistent mechanical or neurohormonal stress to the myocardium triggers maladaptive cardiac remodelling, which alters cardiac function and structure at both the molecular and cellular levels. The progression and magnitude of maladaptive cardiac remodelling ultimately leads to the development of HF. Classical therapies for HF are largely protein-based and mostly are targeted to ameliorate the dysregulation of neuroendocrine pathways and halt adverse remodelling. More recently, investigation of novel molecular targets and the application of cellular therapies, epigenetic modifications, and regulatory RNAs has uncovered promising new avenues to address HF. In this review, we summarize the current knowledge on novel cellular and epigenetic therapies and focus on two non-coding RNA-based strategies that reached the phase of early clinical development to counteract cardiac remodelling and HF. The current status of the development of translating those novel therapies to clinical practice, limitations, and future perspectives are additionally discussed.

Microglial immune regulation by epigenetic reprogramming through histone H3K27 acetylation in neuroinflammation

Epigenetic reprogramming is the ability of innate immune cells to form memories of environmental stimuli (priming), allowing for heightened responses to secondary stressors. Herein, we explored microglial epigenetic marks using the known inflammagen LPS as a memory priming trigger and Parkinsonian-linked environmental neurotoxic stressor manganese (Mn) as the secondary environmental trigger. To mimic physiological responses, the memory priming trigger LPS treatment was removed by triple-washing to allow the cells' acute inflammatory response to reset back before applying the secondary insult. Our results show that after the secondary Mn insult, levels of key proinflammatory markers, including nitrite release, iNOS mRNA and protein expression, Il-6, Il-α and cytokines were exaggerated in LPS-primed microglia. Our paradigm implies primed microglia retain immune memory that can be reprogrammed to augment inflammatory response by secondary environmental stress. To ascertain the molecular underpinning of this neuroimmune memory, we further hypothesize that epigenetic reprogramming contributes to the retention of a heightened immune response. Interestingly, Mn-exposed, LPS-primed microglia showed enhanced deposition of H3K27ac and H3K4me3 along with H3K4me1. We further confirmed the results using a PD mouse model (MitoPark) and postmortem human PD brains, thereby adding clinical relevance to our findings. Co-treatment with the p300/H3K27ac inhibitor GNE-049 reduced p300 expression and H3K27ac deposition, decreased iNOS, and increased ARG1 and IRF4 levels. Lastly, since mitochondrial stress is a driver of environmentally linked Parkinson's disease (PD) progression, we examined the effects of GNE-049 on primary trigger-induced mitochondrial stress. GNE-049 reduced mitochondrial superoxide, mitochondrial circularity and stress, and mitochondrial membrane depolarization, suggesting beneficial consequences of GNE-049 on mitochondrial function. Collectively, our findings demonstrate that proinflammatory primary triggers can shape microglial memory via the epigenetic mark H3K27ac and that inhibiting H3K27ac deposition can prevent primary trigger immune memory formation and attenuate subsequent secondary inflammatory responses.

Epigenetics in Congenital Heart Disease

Embryonic heart development is an intricate process that mainly involves morphogens, transcription factors, and cardiac genes. The precise spatiotemporal expression of these genes during different developmental stages underlies normal heart development. Thus, mutation or aberrant expression of these genes may lead to congenital heart disease (CHD). However, evidence demonstrates that the mutation of genes accounts for only a small portion of CHD cases, whereas the aberrant expression regulated by epigenetic modification plays a predominant role in the pathogenesis of CHD. In this review, we provide essential knowledge on the aberrant epigenetic modification involved in the pathogenesis of CHD. Then, we discuss recent advances in the identification of novel epigenetic biomarkers. Last, we highlight the epigenetic roles in some adverse intrauterine environment‐related CHD, which may help the prevention, diagnosis, and treatment of these kinds of CHD.

[Coactivator p300-induced H3K27 acetylation mediates lipopolysaccharide-induced inflammatory mediator synthesis]

OBJECTIVE

To investigate the role of acetylated modification induced by coactivator p300 in lipopolysaccharide (LPS)- induced inflammatory mediator synthesis and its molecular mechanism.

METHODS

Agilent SurePrint G3 Mouse Gene Expression V2 microarray chip and Western blotting were used to screen the molecules whose expression levels in mouse macrophages (RAW246.7) were correlated with the stimulation intensity of LPS. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (chip-qPCR) were used to verify the binding of the molecules to the promoters of IL-6 and TNF-α genes. The effects of transfection of RAW246.7 cells with overexpression or interfering plasmids on IL-6 and TNF-α synthesis were evaluated with ELISA, and the binding level of the target molecules and acetylation level of H3K27 in the promoter region of IL-6 and TNF-α genes were analyzed by chromatin immunoprecipitation sequencing technique (chip-seq).

RESULTS

Gene microarray chip data and Western blotting both confirmed a strong correlation of p300 expression with the stimulation intensity of LPS. Immunocoprecipitation confirmed the binding between p300 and c-myb. The results of EMSA demonstrated that c-myb (P < 0.05), but not p300, could directly bind to the promoter region of IL-6 and TNF-α genes; p300 could bind to the promoters only in the presence of c-myb (P < 0.05). The expressions of p65, p300 and c-myb did not show interactions. Both p300 overexpression and LPS stimulation could increase the level of promoter-binding p300 and H3K27 acetylation level, thus promoting p65 binding and inflammatory gene transcription; such effects were obviously suppressed by interference of c-myb expression (P < 0.05). Interference of p65 resulted in inhibition of p65 binding to the promoters and gene transcription (P < 0.05) without affecting p300 binding or H3K27 acetylation level.

CONCLUSION

LPS can stimulate the synthesis of p300, whose binding to the promoter region of inflammatory genes via c-myb facilitates the cohesion of p65 by inducing H3K27 acetylation, thus promoting the expression of the inflammatory genes.

Hypoxia inducible factor-3α promotes osteosarcoma progression by activating KDM3A-mediated demethylation of SOX9

Hypoxia/oxygen-sensing signally is closely associated with many tumor progressions, including osteosarcoma (OS). Previous research principally focused on the function of hypoxia-inducible factor (HIF)-1α and HIF-2α as the major hypoxia-associated transcription factors in OS, however, the role of HIF-3α has not been investigated. Our study found that HIF-3α was upregulated in OS tissues and cell lines. HIF-3α overexpression facilitated cell proliferation and invasion, and inhibited apoptosis, whereas HIF-3α knockdown showed the opposite results. Chromatin immunoprecipitation analysis revealed that lysine demethylase 3A (KDM3A) expression was transcriptionally activated by HIF-3α under hypoxia, and KDM3A occupied the SRY-box transcription factor 9 (SOX9) gene promoter region through H3 lysine 9 dimethylation (H3K9me2). Additionally, rescue results revealed that KDM3A or SOX9 overexpression reversed the effects of HIF-3α silence on cell functions. The Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway inhibitor cucurbitacin I suppressed the promotive effects of HIF-3α overexpression on cell proliferation, invasion and TAK2/STAT3 pathway. Finally, OS cell line MG-63 transfected with HIF-3α short hairpin RNA (HIF-3α shRNA) were subcutaneously injected into nude mice, and the results found that HIF-3α knockdown significantly inhibited the xenograft tumor growth of OS in vivo. In conclusion, this study reveals that HIF-3α promotes OS progression in vitro and in vivo by activating KDM3A-mediated SOX9 promoter demethylation, which may provide a potential therapeutic mechanism for OS.

Curcumin attenuates renal ischemia reperfusion injury via JNK pathway with the involvement of p300/CBP-mediated histone acetylation

Apoptosis is proved responsible for renal damage during ischemia/reperfusion. The regulation for renal apoptosis induced by ischemia/reperfusion injury (IRI) has still been unclearly characterized to date. In the present study, we investigated the regulation of histone acetylation on IRI-induced renal apoptosis and the molecular mechanisms in rats with the application of curcumin possessing a variety of biological activities involving inhibition of apoptosis. Sprague–Dawley rats were randomized into four experimental groups (SHAM, IRI, curcumin, SP600125). Results showed that curcumin significantly decreased renal apoptosis and caspase-3/-9 expression and enhanced renal function in IRI rats. Treatment with curcumin in IRI rats also led to the decrease in expression of p300/cyclic AMP response element-binding protein (CBP) and activity of histone acetyltransferases (HATs). Reduced histone H3 lysine 9 (H3K9) acetylation was found near the promoter region of caspase-3/-9 after curcumin treatment. In a similar way, SP600125, an inhibitor of c-Jun N-terminal kinase (JNK), also attenuated renal apoptosis and enhanced renal function in IRI rats. In addition, SP600125 suppressed the binding level of p300/CBP and H3K9 acetylation near the promoter region of caspase-3/-9, and curcumin could inhibit JNK phosphorylation like SP600125. These results indicate that curcumin could attenuate renal IRI via JNK/p300/CBP-mediated anti-apoptosis signaling.

Fetal Gene Reactivation in Pulmonary Arterial Hypertension: GOOD, BAD, or BOTH?

Pulmonary arterial hypertension is a debilitating chronic disorder marked by the progressive obliteration of the pre-capillary arterioles. This imposes a pressure overload on the right ventricle (RV) pushing the latter to undergo structural and mechanical adaptations that inexorably culminate in RV failure and death. Thanks to the advances in molecular biology, it has been proposed that some aspects of the RV and pulmonary vascular remodeling processes are orchestrated by a subversion of developmental regulatory mechanisms with an upregulation of a suite of genes responsible for the embryo's early growth and normally repressed in adults. In this review, we present relevant background regarding the close relationship between overactivation of fetal genes and cardiopulmonary remodeling, exploring whether the reawakening of developmental factors plays a causative role or constitutes a protective mechanism in the setting of PAH.

H3K9ac modification was involved in doxorubicin induced apoptosis by regulating Pik3ca transcription in H9C2 cells

AIM

We evaluated the effect of H3K9ac modification on the transcriptional level of Pik3ca and the apoptosis induction effects of Pik3ca in the PI3K/AKT pathway in rat H9C2 cells.

MAIN METHODS

H9C2 cells were cultured with 1uM doxorubicin for 8 h. The acetylation level of histone H3K9 in the transcriptional initiation area of Pik3ca was determined by CHIP-seq. The enrichment of mRNA fragment of Pik3ca transcription initiation region by H3K9ac antibody was detected by CHIP-qPCR, and the expression of Pik3ca was detected by real-time Polymerase Chain Reaction(rt-PCR) and western blot. The transcription efficiency of Pik3ca siRNA was detected by immunofluorescence and western blot. Cell Counting Kit8(CCK8) was used to detect the cell activity and flow cytometry was used to detect the apoptosis rate. Western blot was applied to assess the protein expression level of PI3K, P-AKT, AKT, Bcl2, BAX and cleaved-caspase3 in H9C2 cells.

KEY FINDINGS

In doxorubicin-inducedH9C2 cells, the acetylation levels of histone H3K9 in the Pik3ca transcriptional initiation region significantly increased and promoted the transcription of Pik3ca. After knockdown of Pik3ca, the PI3K/AKT signaling pathway was inhibited, and the protein expression of Bcl2 was increased, the protein expression of BAX and cleaved-caspase3 were decreased. PI3K/AKT pathway activator partially reversed the effect of silencing Pik3ca.

SIGNIFICANCE

In summary, the elevated H3K9ac level in the Pik3ca transcriptional initiation region promoted the transcription of Pik3ca, and Pik3ca promoted doxorubicin induced apoptosis in H9C2 cells by activating the PI3K/AKT pathway, providing a new theoretical basis for the study of doxorubicin cardiomyopathy.

P300-dependent acetylation of histone H3 is required for epidermal growth factor receptor-mediated high-mobility group protein A2 transcription in hepatocellular carcinoma

High‐mobility group protein A2 (HMGA2) is highly expressed in hepatocellular carcinoma (HCC) cells and contributes to tumor metastasis and poor patient survival. However, the molecular mechanism through which HMGA2 is transcriptionally regulated in HCC cells remains largely unclear. Here, we showed that the expression HMGA2 was upregulated in HCC, and that elevated HMGA2 could promote tumor metastasis. Incubation of HCC cells with epidermal growth factor (EGF) could promote the expression of HMGA2 mRNA and protein. Mechanistic studies suggested that EGF can phosphorylate p300 at Ser1834 residue through the PI3K/Akt signaling pathway in HCC cells. Knockdown of p300 can reverse EGF‐induced HMGA2 expression and histone H3‐K9 acetylation, whereas a phosphorylation‐mimic p300 S1834D mutant can stimulate HMGA2 expression as well as H3‐K9 acetylation in HCC cells. Furthermore, we identified that p300‐mediated H3‐K9 acetylation participates in EGF‐induced HMGA2 expression in HCC. In addition, the levels of H3‐K9 acetylation positively correlated with the expression levels of HMGA2 in a chemically induced HCC model in rats and human HCC specimens.

Deacetylation of H4 lysine16 affects acetylation of lysine residues in histone H3 and H4 and promotes transcription of constitutive genes

Histone modification map of H4 N-terminal tail residues in Saccharomyces cerevisiae reveals the prominence of lysine acetylation. Previous reports have indicated the importance of lysine acetylation in maintaining chromatin structure and function. H4K16, a residue with highly regulated acetylation dynamics has unique functions not overlapping with the other H4 N- terminal acetylable residues. The present work unravels the role of H4K16 acetylation in regulating expression of constitutive genes. H4K16 gets distinctly deacetylated over the coding region of constitutively expressed genes. Deacetylation of H4K16 reduces H3K9 acetylation at the cellular and gene level. Reduced H3K9 acetylation however did not negatively correlate with active gene transcription. Significantly, H4K16 deacetylation was found to be associated with hypoacetylated H4K12 throughout the locus of constitutive genes. H4K16 and K12 deacetylation is known to favour active transcription. Sas2, the HAT mutant showed similar patterns of hypoacetylated H3K9 and H4K12 at the active loci, clearly implying that the modifications were associated with deacetylation state of H4K16. Deacetylation of H4K16 was also concurrent with increased H3K56 acetylation in the promoter region and ORF of the constitutive genes. Combination of all these histone modifications significantly reduced H3 occupancy, increased promoter accessibility and enhanced RNAPII recruitment at the constitutively active loci. Consequently, we found that expression of active genes was higher in H4K16R mutant which mimic deacetylated state, but not in H4K16Q mimicking constitutive acetylation. To summarize, H4K16 deacetylation linked with H4K12 and H3K9 hypoacetylation along with H3K56 hyperacetylation generate a chromatin landscape that is conducive for transcription of constitutive genes.

p300 in Cardiac Development and Accelerated Cardiac Aging

The heart is the first functional organ that develops during embryonic development. While a heartbeat indicates life, cessation of a heartbeat signals the end of life. Heart disease, due either to congenital defects or to acquired dysfunctions in adulthood, remains the leading cause of death worldwide. Epigenetics plays a key role in both embryonic heart development and heart disease in adults. Stress-induced vascular injury activates pathways involved in pathogenesis of accelerated cardiac aging that includes cellular dysfunction, pathological cardiac hypertrophy, diabetic cardiomyopathy, cardiac matrix remodeling, cardiac dysfunction and heart failure. Acetyltransferase p300 (p300), a major epigenetic regulator, plays a pivotal role in heart development during embryogenesis, as deficiency or abnormal expression of p300 leads to embryonic death at early gestation periods due to deformation of the heart and neural tube. Acetyltransferase p300 controls heart development through histone acetylation-mediated chromatin remodeling and transcriptional regulation of genes required for cardiac development. In adult hearts, p300 is differentially expressed in different chambers and epigenetically controls cardiac gene expression. Deregulation of p300, in response to prohypertrophic and profibrogenic stress signals, is associated with increased recruitment of p300 to several genes including transcription factors, increased acetylation of specific lysines in histones and transcription factors, altered chromatin organization, and increased hypertrophic and fibrogenic gene expression. Cardiac hypertrophy and myocardial fibrogenesis are common pathological manifestations of several stress-induced accelerated cardiac aging-related pathologies, including high blood pressure-induced or environmentally induced cardiac hypertrophy, myocardial infarction, diabetes-induced cardiomyopathy, and heart failure. Numerous studies using cellular and animal models clearly indicate that pharmacologic or genetic normalization of p300 activity has the potential to prevent or halt the progression of cardiac aging pathologies. Based on these preclinical studies, development of safe, non-toxic, small molecule inhibitors/epidrugs targeting p300 is an ideal approach to control accelerated cardiac aging-related deaths worldwide.

Key Players in HIV-1 Transcriptional Regulation: Targets for a Functional Cure

HIV-1 establishes a life-long infection when proviral DNA integrates into the host genome. The provirus can then either actively transcribe RNA or enter a latent state, without viral production. The switch between these two states is governed in great part by the viral protein, Tat, which promotes RNA transcript elongation. Latency is also influenced by the availability of host transcription factors, integration site, and the surrounding chromatin environment. The latent reservoir is established in the first few days of infection and serves as the source of viral rebound upon treatment interruption. Despite effective suppression of HIV-1 replication by antiretroviral therapy (ART), to below the detection limit, ART is ineffective at reducing the latent reservoir size. Elimination of this reservoir has become a major goal of the HIV-1 cure field. However, aside from the ideal total HIV-1 eradication from the host genome, an HIV-1 remission or functional cure is probably more realistic. The "block-and-lock" approach aims at the transcriptional silencing of the viral reservoir, to render suppressed HIV-1 promoters extremely difficult to reactivate from latency. There are unfortunately no clinically available HIV-1 specific transcriptional inhibitors. Understanding the mechanisms that regulate latency is expected to provide novel targets to be explored in cure approaches.