Bromodomain and Extra-Terminal Proteins in Brain Physiology and Pathology: BET-ing on Epigenetic Regulation

Design and Development of a Novel BET Protein-Targeted PET Imaging Probe for In Vivo Characterization of Alzheimer's Disease Pathophysiology

BET proteins are essential epigenetic regulators involved in gene transcription and have been linked to neurodegenerative disorders, such as Alzheimer's disease (AD). In vivo imaging of BET proteins may provide insights into disease pathophysiology and help identify potential therapeutic targets. We developed a carbon-11-labeled radiotracer, [11C]YL9, which exhibits high binding affinity for BET proteins. It was synthesized via standard methylation and evaluated for brain uptake, binding specificity, and pharmacokinetics in wild-type and AD mouse models using PET imaging and autoradiography. [11C]YL9 demonstrated excellent blood-brain barrier penetration, prolonged retention, and strong BET protein binding. In AD mice, [11C]YL9 uptake was significantly higher than in wild-type mice, suggesting increased BET protein availability. These findings suggest that [11C]YL9 is a promising PET radioligand for noninvasive BET protein imaging. Its high specificity and favorable pharmacokinetics make it a valuable tool for studying BET protein involvement in neurodegeneration.

Untangling the Role of MYC in Sarcomas and Its Potential as a Promising Therapeutic Target

MYC plays a pivotal role in the biology of various sarcoma subtypes, acting as a key regulator of tumor growth, proliferation, and metabolic reprogramming. This oncogene is frequently dysregulated across different sarcomas, where its expression is closely intertwined with the molecular features unique to each subtype. MYC interacts with critical pathways such as cell cycle regulation, apoptosis, and angiogenesis, amplifying tumor aggressiveness and resistance to standard therapies. Furthermore, MYC influences the tumor microenvironment by modulating cell-extracellular matrix interactions and immune evasion mechanisms, further complicating therapeutic management. Despite its well-established centrality in sarcoma pathogenesis, targeting MYC directly remains challenging due to its "undruggable" protein structure. However, emerging therapeutic strategies, including indirect MYC inhibition via epigenetic modulators, transcriptional machinery disruptors, and metabolic pathway inhibitors, offer new hope for sarcoma treatment. This review underscores the importance of understanding the intricate roles of MYC across sarcoma subtypes to guide the development of effective targeted therapies. Given MYC's central role in tumorigenesis and progression, innovative approaches aiming at MYC inhibition could transform the therapeutic landscape for sarcoma patients, providing a much-needed avenue to overcome therapeutic resistance and improve clinical outcomes.

Basic Epigenetic Mechanisms

The human genome consists of 23 chromosome pairs (22 autosomes and one pair of sex chromosomes), with 46 chromosomes in a normal cell. In the interphase nucleus, the 2 m long nuclear DNA is assembled with proteins forming chromatin. The typical mammalian cell nucleus has a diameter between 5 and 15 μm in which the DNA is packaged into an assortment of chromatin assemblies. The human brain has over 3000 cell types, including neurons, glial cells, oligodendrocytes, microglial, and many others. Epigenetic processes are involved in directing the organization and function of the genome of each one of the 3000 brain cell types. We refer to epigenetics as the study of changes in gene function that do not involve changes in DNA sequence. These epigenetic processes include histone modifications, DNA modifications, nuclear RNA, and transcription factors. In the interphase nucleus, the nuclear DNA is organized into different structures that are permissive or a hindrance to gene expression. In this chapter, we will review the epigenetic mechanisms that give rise to cell type-specific gene expression patterns.

Precision Targeting of BET Proteins - Navigating Disease Pathways, Inhibitor Insights, and Shaping Therapeutic Frontiers: A Comprehensive Review

The family of proteins known as Bromodomain and Extra-Terminal (BET) proteins has become a key participant in the control of gene expression, having a significant impact on numerous physiological and pathological mechanisms. This review offers a thorough investigation of the BET protein family, clarifying its various roles in essential cellular processes and its connection to a variety of illnesses, from inflammatory disorders to cancer. The article explores the structural and functional features of BET proteins, emphasizing their special bromodomain modules that control chromatin dynamics by identifying acetylated histones. BET proteins' complex roles in the development of cardiovascular, neurodegenerative, and cancer diseases are carefully investigated, providing insight into possible treatment avenues. In addition, the review carefully examines the history and relevance of BET inhibitors, demonstrating their capacity to modify gene expression profiles and specifically target BET proteins. The encouraging outcomes of preclinical and clinical research highlight BET inhibitors' therapeutic potential across a range of disease contexts. The article summarizes the state of BET inhibitors today and makes predictions about the challenges and future directions of the field. This article provides insights into the changing field of BET protein-targeted interventions by discussing the potential of personalized medicine and combination therapies involving BET inhibitors. This thorough analysis combines many aspects of BET proteins, such as their physiological roles and their roles in pathophysiological conditions. As such, it is an invaluable tool for scientists and medical professionals who are trying to figure out how to treat patients by using this fascinating protein family.

Modulation of oxidative stress/NMDA/nitric oxide pathway by topiramate attenuates morphine dependence in mice

Morphine belongs to the class of opioids and is known for its potential to cause dependence and addiction, particularly with prolonged use. Due to the associated risks, caution must be taken when prescribing and limiting its clinical use. Overexpression of N-methyl-D-aspartate (NMDA) receptors, nitric oxide and cGMP pathway has been implicated in exacerbate the development of morphine dependence and withdrawal. Topiramate, an antiepileptic drug, interacts with various receptors, ion channels and certain enzymes. In this study, we investigated the effects of topiramate on morphine dependence in mice, specifically targeting NMDA/Nitric oxide/cGMP pathway. Mice were administered different doses of topiramate (intraperitoneally) during the development phase, 45 min prior to morphine administration. Topiramate (20 mg/kg) significantly reduced naloxone-induced withdrawal symptoms in morphine-dependent mice. Additionally, subeffective doses of topiramate, when co-administered with NMDA receptor antagonist MK-801 (0.05 mg/kg) or nitric oxide synthase inhibitors such as L-NAME (10 mg/kg, a non-specific NOS inhibitor) and 7-NI (20 mg/kg, a selective nNOS inhibitor), showed a marked reduction in withdrawal signs. However, the effect of topiramate (20 mg/kg) was abolished when co-administered with NMDA (75 mg/kg, an NMDA receptor agonist) or L-arginine (60 mg/kg, a NOS substrate). Ex-vivo analysis revealed that topiramate significantly reduced oxidative stress and downregulated the gene expression of nNOS, NR1, and NR2B in morphine-treated mice. Furthermore, the expression of NR1 and NR2B proteins in the hippocampus and cortex was significantly reduced in topiramate-pretreated mice. Hence, this finding suggest that topiramate mitigates morphine dependence and withdrawal by inhibiting oxidative stress and modulating the NMDA/NO pathway.

The current status and future trends of BET research in oncology

Background

BET family proteins are important epigenetic and transcriptional regulators involved in the control of tumorigenesis and development and have become important targets for cancer therapy. However, there is no systematic bibliometric analysis in this field. A visual analysis of the research hotspots and trends of BET is helpful to understand the future development direction.

Method

We used CiteSpace, VOSviewer, and Excel to visualize and analyze the trends regarding authors, journals, countries or regions, highly cited papers, and keywords in the field.

Result

The results included a total of 946 publications. There are many more papers on BET proteins published since 2013. The papers are mainly from 44 countries, led by the U.S. and China. A total of 7381 authors were identified, among which Bradner, J.E. had the greatest number of articles and the greatest influence. Cancer Discovery was the journal with the most citations per article. Our analysis identified the most influential papers in the field, including highly cited papers and citation burst references. The most frequent keywords included 'expression', 'c-Myc', 'cancer', 'BRD4', 'BET inhibition', 'resistance', 'differentiation', and 'JQ1', which represent the focus of current and developing research fields.

Conclusion

Research on BET is thriving. Collaboration and exchanges between countries and institutions must be strengthened in the future, and the mechanisms of BET-related pathways, the relationship between BET and various diseases, and the development of new BET inhibitors have become the major focus of current research and the trend of future research.

Impact of JQ1 treatment on seizures, hippocampal gene expression, and gliosis in a mouse model of temporal lobe epilepsy

Epilepsy is a neurological disease characterised by recurrent seizures with complex aetiology. Temporal lobe epilepsy, the most common form in adults, can be acquired following brain insults including trauma, stroke, infection or sustained status epilepticus. The mechanisms that give rise to the formation and maintenance of hyperexcitable networks following acquired insults remain unknown, yet an extensive body of literature points towards persistent gene and epigenomic dysregulation as a potential mediator of this dysfunction. While much is known about the function of specific classes of epigenetic regulators (writers and erasers) in epilepsy, much less is known about the enzymes, which read the epigenome and modulate gene expression accordingly. Here, we explore the potential role for the epigenetic reader bromodomain and extra-terminal domain (BET) proteins in epilepsy. Using the intra-amygdala kainic acid model of temporal lobe epilepsy, we initially identified widespread dysregulation of important epigenetic regulators including EZH2 and REST as well as altered BRD4 expression in chronically epileptic mice. BRD4 activity was also notably affected by epilepsy-provoking insults as seen by elevated binding to and transcriptional regulation of the immediate early gene Fos. Despite influencing early aspects of epileptogenesis, blocking BET protein activity with JQ1 had no overt effects on epilepsy development in mice but did alter glial reactivity and influence gene expression patterns, promoting various neurotransmitter signalling mechanisms and inflammatory pathways in the hippocampus. Together, these results confirm that epigenetic reader activity is affected by epilepsy-provoking brain insults and that BET activity may exert cell-specific actions on inflammation in epilepsy.

Development and Evaluation of [11C]I-58: A Novel PET Radiotracer Targeting BRD4 BD2 for Advanced Epigenetic Imaging

The paired bromodomains (BD1 and BD2), located in the bromodomain and extra-terminal (BET) family proteins, perform specific functions in gene transcriptional control and expression. Targeting specific bromodomains with inhibitors holds promise for achieving therapeutic benefits with reduced side effects. However, the comprehension of this target related to the disease is still restricted. Positron emission tomography (PET) imaging is a powerful tool that provides a valuable avenue for exploring the BD2 bromodomain. This investigation introduces a novel radioligand, [11C]I-58, for PET targeting the BET BD2 domain. The synthesis of compound I-58, along with its radiosynthetic process for C11 labeling, is detailed, and the suitability of [11C]I-58 for PET imaging of the BD2 bromodomain is evaluated. Initial PET study findings in mice indicate that [11C]I-58 exhibits suitable biodistribution in peripheral organs and tissues. Additionally, in vitro autoradiography studies and blocking experiments provide compelling evidence supporting the specific binding of [11C]I-58 to the BD2 bromodomain. These results establish [11C]I-58 as a promising instrument for the PET imaging of the BD2 bromodomain. This research not only holds the potential to pave the path for developing PET radioligands precisely targeting the BD2 bromodomain but also adds to a more profound comprehension of the biological mechanisms linked to the BD bromodomain.

Targeting BRD4 with PROTAC degrader ameliorates LPS-induced acute lung injury by inhibiting M1 alveolar macrophage polarization

OBJECTIVES

Acute lung injury (ALI) is a highly inflammatory condition with the involvement of M1 alveolar macrophages (AMs) polarization, eventually leading to the development of non-cardiogenic edema in alveolar and interstitial regions, accompanied by persistent hypoxemia. Given the significant mortality rate associated with ALI, it is imperative to investigate the underlying mechanisms of this condition so as to identify potential therapeutic targets. The therapeutic effects of the inhibition of bromodomain containing protein 4 (BRD4), an epigenetic reader, has been proven with high efficacy in ameliorating various inflammatory diseases through mediating immune cell activation. However, little is known about the therapeutic potential of BRD4 degradation in acute lung injury.

METHODS

This study aimed to assess the protective efficacy of ARV-825, a novel BRD4-targeted proteolysis targeting chimera (PROTAC), against ALI through histopathological examination in lung tissues and biochemical analysis in bronchoalveolar lavage fluid (BALF). Additionally, the underlying mechanism by which BRD4 regulated M1 AMs was elucidated by using CUT & Tag assay.

RESULTS

In this study, we found the upregulation of BRD4 in a lipopolysaccharide (LPS)-induced ALI model. Furthermore, we observed that intraperitoneal administration of ARV-825, significantly alleviated LPS-induced pulmonary pathological changes and inflammatory responses. These effects were accompanied by the suppression of M1 AMs. In addition, our findings revealed that the administration of ARV-825 effectively suppressed M1 AMs by inhibiting the expression of IRF7, a crucial transcriptional factor involved in M1 macrophages.

CONCLUSION

Our study suggested that targeting BRD4 using ARV-825 is a potential therapeutic approach for ALI.

Regulation of cholesterol metabolism: New players for an old physiological process

Identified more than two centuries ago, cholesterol plays a pivotal role in human physiology. Since cholesterol metabolism is a physiologically significant process, it is not surprising that its alterations are associated with several pathologies. The discovery of new molecular targets or compounds able to modulate this sophisticated metabolism has been capturing the attention of research groups worldwide since many years. Endogenous and exogenous compounds are known to regulate cellular cholesterol synthesis and uptake, or reduce cholesterol absorption at the intestinal level, thereby regulating cholesterol homeostasis. However, there is a great need of new modulators and diverse new pathways have been uncovered. Here, after illustrating cholesterol metabolism and its well-known regulators, some new players of this important physiological process are also described.

Transcriptomic Approaches in Studies on and Applications of Chimeric Antigen Receptor T Cells

Chimeric antigen receptor T (CAR-T) cells are specifically modified T cells which bear recombinant receptors, present at the cell surface and devoted to detect selected antigens of cancer cells, and due to the presence of transmembrane and activation domains, able to eliminate the latter ones. The use of CAR-T cells in anti-cancer therapies is a relatively novel approach, providing a powerful tool in the fight against cancer and bringing new hope for patients. However, despite huge possibilities and promising results of preclinical studies and clinical efficacy, there are various drawbacks to this therapy, including toxicity, possible relapses, restrictions to specific kinds of cancers, and others. Studies desiring to overcome these problems include various modern and advanced methods. One of them is transcriptomics, a set of techniques that analyze the abundance of all RNA transcripts present in the cell at certain moment and under certain conditions. The use of this method gives a global picture of the efficiency of expression of all genes, thus revealing the physiological state and regulatory processes occurring in the investigated cells. In this review, we summarize and discuss the use of transcriptomics in studies on and applications of CAR-T cells, especially in approaches focused on improved efficacy, reduced toxicity, new target cancers (like solid tumors), monitoring the treatment efficacy, developing novel analytical methods, and others.