GAS41 promotes H2A.Z deposition through recognition of the N terminus of histone H3 by the YEATS domain

GAS41 promotes ITGA4-mediated PI3K/Akt/mTOR signaling pathway and glioma tumorigenesis

Glioma Amplified Sequence 41 (GAS41) is a chromatin-associated protein that belongs to the YEATS domain family of proteins and is frequently amplified in various tumors. However, its biological function and carcinogenic mechanism in gliomas are not fully understood. In this study, we revealed that GAS41 was upregulated in human glioma tissues and cell lines, and higher expression of GAS41 was significantly associated with poor clinical prognosis. Genetic depletion and chemical inhibition of GAS41 remarkably inhibited glioma cell proliferation and metastasis abilities and induced cellular apoptosis. Furthermore, functional annotation identified that GAS41 was involved in stimulating the expression of membrane protein ITGA4 to activate the downstream PI3K/Akt/mTOR signaling pathway in glioma cell lines. In addition, we synthesized and evaluated a series of small molecules targeting the GAS41 YEATS domain, which yielded effective anti-proliferative activities in glioma cells. Molecular docking revealed that these compounds bound to the GAS41 YEATS domain pocket in a manner similar to Compounds 9 and 3b, providing a structural basis for exploring the selective inhibition of GAS41 as part of an essential molecular framework. Overall, our study illustrates the crucial role of GAS41 in glioma progression and the malignant phenotype and suggests that targeting GAS41 may be a promising therapeutic treatment strategy for gliomas.

Epigenetics-targeted drugs: current paradigms and future challenges

Epigenetics governs a chromatin state regulatory system through five key mechanisms: DNA modification, histone modification, RNA modification, chromatin remodeling, and non-coding RNA regulation. These mechanisms and their associated enzymes convey genetic information independently of DNA base sequences, playing essential roles in organismal development and homeostasis. Conversely, disruptions in epigenetic landscapes critically influence the pathogenesis of various human diseases. This understanding has laid a robust theoretical groundwork for developing drugs that target epigenetics-modifying enzymes in pathological conditions. Over the past two decades, a growing array of small molecule drugs targeting epigenetic enzymes such as DNA methyltransferase, histone deacetylase, isocitrate dehydrogenase, and enhancer of zeste homolog 2, have been thoroughly investigated and implemented as therapeutic options, particularly in oncology. Additionally, numerous epigenetics-targeted drugs are undergoing clinical trials, offering promising prospects for clinical benefits. This review delineates the roles of epigenetics in physiological and pathological contexts and underscores pioneering studies on the discovery and clinical implementation of epigenetics-targeted drugs. These include inhibitors, agonists, degraders, and multitarget agents, aiming to identify practical challenges and promising avenues for future research. Ultimately, this review aims to deepen the understanding of epigenetics-oriented therapeutic strategies and their further application in clinical settings.

Structures of H2A.Z-associated human chromatin remodelers SRCAP and TIP60 reveal divergent mechanisms of chromatin engagement

H2A.Z is a conserved histone variant that is localized to specific genomic regions where it plays important roles in transcription, DNA repair, and replication. Central to the biochemistry of human H2A.Z are the SRCAP and TIP60 chromatin remodelers, homologs of yeast SWR1 which catalyzes ATP-dependent H2A.Z exchange. Here, we use cryo-electron microscopy to resolve six structural states of the native SRCAP complex, uncovering conformational intermediates interpreted as a stepwise path to full nucleosome engagement. We also resolve the structure of the native TIP60 complex which consists of a structured core from which flexibly tethered chromatin binding domains emerge. Despite the shared subunit composition, the core of TIP60 displays divergent architectures from SRCAP that structurally disfavor nucleosome engagement, suggesting a distinct biochemical function.

Targeting dependency on a paralog pair of CBP/p300 against de-repression of KREMEN2 in SMARCB1-deficient cancers

SMARCB1, a subunit of the SWI/SNF chromatin remodeling complex, is the causative gene of rhabdoid tumors and epithelioid sarcomas. Here, we identify a paralog pair of CBP and p300 as a synthetic lethal target in SMARCB1-deficient cancers by using a dual siRNA screening method based on the "simultaneous inhibition of a paralog pair" concept. Treatment with CBP/p300 dual inhibitors suppresses growth of cell lines and tumor xenografts derived from SMARCB1-deficient cells but not from SMARCB1-proficient cells. SMARCB1-containing SWI/SNF complexes localize with H3K27me3 and its methyltransferase EZH2 at the promotor region of the KREMEN2 locus, resulting in transcriptional downregulation of KREMEN2. By contrast, SMARCB1 deficiency leads to localization of H3K27ac, and recruitment of its acetyltransferases CBP and p300, at the KREMEN2 locus, resulting in transcriptional upregulation of KREMEN2, which cooperates with the SMARCA1 chromatin remodeling complex. Simultaneous inhibition of CBP/p300 leads to transcriptional downregulation of KREMEN2, followed by apoptosis induction via monomerization of KREMEN1 due to a failure to interact with KREMEN2, which suppresses anti-apoptotic signaling pathways. Taken together, our findings indicate that simultaneous inhibitors of CBP/p300 could be promising therapeutic agents for SMARCB1-deficient cancers.

Distinct Histone H3 Lysine 27 Modifications Dictate Different Outcomes of Gene Transcription

Site-specific histone modifications have long been recognized to play an important role in directing gene transcription in chromatin in biology of health and disease. However, concrete illustration of how different histone modifications in a site-specific manner dictate gene transcription outcomes, as postulated in the influential "Histone code hypothesis", introduced by Allis and colleagues in 2000, has been lacking. In this review, we summarize our latest understanding of the dynamic regulation of gene transcriptional activation, silence, and repression in chromatin that is directed distinctively by histone H3 lysine 27 acetylation, methylation, and crotonylation, respectively. This represents a special example of a long-anticipated verification of the "Histone code hypothesis."