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Objective: To investigate the effects of human bone marrow mesenchymal stem cells (hMSCs)-derived exosome circCDK13 on liver fibrosis and its mechanism., Methods: Exosomes derived from hMSCs were extracted and identified by flow cytometry and osteogenic and adipogenic induction, and the expressions of marker proteins on the surface of exosomes were detected by western blot. Cell proliferation was measured by CCK8 assay, the expression of active markers of HSCs by immunofluorescence, and the expressions of fibrosis-related factors by western blot. A mouse model of liver fibrosis was established by intraperitoneal injection of thioacetamide (TAA). Fibrosis was detected by HE staining, Masson staining, and Sirius red staining. Western blot was utilized to test the expressions of PI3K/AKT and NF-κB pathway related proteins, dual-luciferase reporter assay and RIP assay to validate the binding between circCDK13 and miR-17-5p as well as between miR-17-5p and KAT2B, and ChIP to validate the effect of KAT2B on H3 acetylation and MFGE8 transcription., Results: hMSCs-derived exosomes inhibited liver fibrosis mainly through circCDK13. Dual-luciferase reporter assay and RIP assay demonstrated the binding between circCDK13 and miR-17-5p as well as between miR-17-5p and KAT2B. Further experimental results indicated that circCDK13 mediated liver fibrosis by regulating the miR-17-5p/KAT2B axis, and KAT2B promoted MFGE8 transcription by H3 acetylation. Exo-circCDK13 inhibited PI3K/AKT and NF-κB signaling pathways activation through regulating the miR-17-5p/KAT2B axis., Conclusion: hMSCs-derived exosome circCDK13 inhibited liver fibrosis by regulating the expression of MFGE8 through miR-17-5p/KAT2B axis., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Accumulation of aggregated and misfolded proteins, leading to endoplasmic reticulum stress and activation of the unfolded protein response, is a hallmark of several neurodegenerative disorders, including Alzheimer's and Parkinson's disease. Genetic screens are powerful tools that are proving invaluable in identifying novel modulators of disease associated processes. Here, we performed a loss-of-function genetic screen using a human druggable genome library, followed by an arrayed-screen validation, in human iPSC-derived cortical neurons. We identified and genetically validated 13 genes, whose knockout was neuroprotective against Tunicamycin, a glycoprotein synthesis inhibitor widely used to induce endoplasmic reticulum stress. We also demonstrated that pharmacological inhibition of KAT2B, a lysine acetyltransferase identified by our genetic screens, by L-Moses, attenuates Tunicamycin-mediated neuronal cell death and activation of CHOP, a key pro-apoptotic member of the unfolded protein response in both cortical and dopaminergic neurons. Follow-up transcriptional analysis suggested that L-Moses provided neuroprotection by partly reversing the transcriptional changes caused by Tunicamycin. Finally, L-Moses treatment attenuated total protein levels affected by Tunicamycin, without affecting their acetylation profile. In summary, using an unbiased approach, we identified KAT2B and its inhibitor, L-Moses, as potential therapeutic targets for neurodegenerative diseases., (© 2023. The Author(s).)

Impaired calcium uptake resulting from reduced expression and activity of the cardiac sarco-endoplasmic reticulum Ca 2+ ATPase (SERCA2a) is a hallmark of heart failure (HF). Recently, new mechanisms of SERCA2a regulation, including post-translational modifications (PTMs), have emerged. Our latest analysis of SERCA2a PTMs has identified lysine acetylation as another PTM which might play a significant role in regulating SERCA2a activity. SERCA2a is acetylated, and that acetylation is more prominent in failing human hearts. In this study, we confirmed that p300 interacts with and acetylates SERCA2a in cardiac tissues. Several lysine residues in SERCA2a modulated by p300 were identified using in vitro acetylation assay. Analysis of in vitro acetylated SERCA2a revealed several lysine residues in SERCA2a susceptible to acetylation by p300. Among them, SERCA2a Lys514 (K514) was confirmed to be essential for SERCA2a activity and stability using an acetylated mimicking mutant. Finally, the reintroduction of an acetyl-mimicking mutant of SERCA2a (K514Q) into SERCA2 knockout cardiomyocytes resulted in deteriorated cardiomyocyte function. Taken together, our data demonstrated that p300-mediated acetylation of SERCA2a is a critical PTM that decreases the pump's function and contributes to cardiac impairment in HF. SERCA2a acetylation can be targeted for therapeutic aims for the treatment of HF.

Background: Rheumatoid arthritis (RA) is an autoimmune condition that causes progressive inflammation. It seems that alternations in epigenetic modifications contribute to RA development. The present study aimed to assess the expression pattern of K (lysine) acetyltransferase 1 (KAT1; HAT1) and lysine acetyltransferase 2B (KAT2B; PCAF), and the establishment of sister chromatid cohesion N-acetyltransferase 2 (ESCO2) in peripheral blood mononuclear cells (PBMCs) from RA patients., Method and Material: In this case-control study, we studied 50 cases with RA in comparison to 50 age- and gender-matched healthy subjects. Separation of PBMCs samples from whole blood, extraction of RNA, and reverse transcription were performed. Gene transcript levels of KAT1, KAT2B, and ESCO2 were determined using SYBR green real-time quantitative PCR., Results: Our results exhibited a significant upregulation in the expression levels of ESCO2 and KAT2B genes in patients with RA compared to normal individuals (P-value < 0.0001). Similarly, we observed higher expression of KAT1 in the patients' group when compared to the healthy controls, although the difference in expression level failed to show any significant changes (P-value = 0.485). Also, we found a positive correlation between ESCO2 and the level of erythrocyte sedimentation rate (ESR) in patients., Conclusion: Collectively, our results suggest that upregulated expression of KAT2B and ESCO2 genes may be correlated to RA development. Further studies with larger sample sizes are required for understanding the potential contribution of these enzymes in the pathology of RA. Key Points • Dysregulated expression level of epigenetics enzymes was observed in PBMCs from RA patients. • The expression of KAT2B was 2.44 times higher in the PBMCs of RA patients than in the healthy subjects. • The expression of ESCO2 was upregulated (2.75 times) in the PBMCs of RA patients compared to the control group. • There was a positive correlation between ESCO2 expression and the ESR level in patients., (© 2022. The Author(s), under exclusive licence to International League of Associations for Rheumatology (ILAR).)

Increasing evidence has shown that vascular aging has a key role in the pathogenesis of vascular diseases. P300/CBP-associated factor (PCAF) is involved in many vascular pathological processes, but the role of PCAF in vascular aging is unknown. This study aims to explore the role and underlying mechanism of PCAF in vascular aging. The results demonstrated that the expression of PCAF was associated with age and aging, and remarkably increased expression of PCAF was present in human atherosclerotic coronary artery. Downregulation of PCAF could reduce angiotensin II (AngII)-induced senescence of rat aortic endothelial cells (ECs) in vitro. In addition, inhibition of PCAF with garcinol alleviated AngII-induced vascular senescence phenotype in mice. Downregulation of PCAF could alleviate AngII-induced oxidative stress injury in ECs and vascular tissue. Moreover, PCAF and nuclear factor erythroid-2-related factor 2 (Nrf2) could interact directly, and downregulation of PCAF alleviated vascular aging by promoting the activation of Nrf2 and enhancing the expression of its downstream anti-aging factors. The silencing of Nrf2 with small interfering RNA attenuated the protective effect of PCAF downregulation from vascular aging. These findings indicate that downregulation of PCAF alleviates oxidative stress by activating the Nrf2 signaling pathway and ultimately inhibits vascular aging. Thus, PCAF may be a promising target for aging-related cardiovascular disease.

Environmental factors and life experiences impinge on brain circuits triggering adaptive changes. Epigenetic regulators contribute to this neuroadaptation by enhancing or suppressing specific gene programs. The paralogous transcriptional coactivators and lysine acetyltransferases CREB binding protein (CBP) and p300 are involved in brain plasticity and stimulus-dependent transcription, but their specific roles in neuroadaptation are not fully understood. Here we investigated the impact of eliminating either CBP or p300 in excitatory neurons of the adult forebrain of mice from both sexes using inducible and cell type-restricted knock-out strains. The elimination of CBP, but not p300, reduced the expression and chromatin acetylation of plasticity genes, dampened activity-driven transcription, and caused memory deficits. The defects became more prominent in elderly mice and in paradigms that involved enduring changes in transcription, such as kindling and environmental enrichment, in which CBP loss interfered with the establishment of activity-induced transcriptional and epigenetic changes in response to stimulus or experience. These findings further strengthen the link between CBP deficiency in excitatory neurons and etiopathology in the nervous system. SIGNIFICANCE STATEMENT How environmental conditions and life experiences impinge on mature brain circuits to elicit adaptive responses that favor the survival of the organism remains an outstanding question in neurosciences. Epigenetic regulators are thought to contribute to neuroadaptation by initiating or enhancing adaptive gene programs. In this article, we examined the role of CREB binding protein (CBP) and p300, two paralogous transcriptional coactivators and histone acetyltransferases involved in cognitive processes and intellectual disability, in neuroadaptation in adult hippocampal circuits. Our experiments demonstrate that CBP, but not its paralog p300, plays a highly specific role in the epigenetic regulation of neuronal plasticity gene programs in response to stimulus and provide unprecedented insight into the molecular mechanisms underlying neuroadaptation., (Copyright © 2022 Lipinski, Niñerola et al.)

Objectives: The molecular mechanistic actions of tumor-derived extracellular vesicles (EVs) in modulating macrophage polarization in the tumor microenvironment of epithelial ovarian cancer (EOC) is largely unknown. The study was performed to clarify the effect and downstream mechanism of microRNA-181c-5p (miR-181c-5p)-containing EVs from EOC cells in the M2 polarization of tumor-associated macrophages (TAMs)., Methods: EVs were isolated from normoxic and hypoxic human EOC cells SKOV3. Human mononuclear cell THP-1 was induced by phorbol-12-myristate-13-acetate to differentiate into TAMs. The targeting relationship between miR-181c-5p and KAT2B was verified by dual luciferase reporter gene assay. The interaction between KAT2B and HOXA10 was detected by immunofluorescence, Co-IP and ChIP assays. EdU staining, the scratch test and Transwell assay were used to assess the resultant cell proliferation, migration and invasion. The mouse xenograft model and the pulmonary metastasis model were developed through intraperitoneal injection of SKOV3 cells and tail vein injection of THP-1 cells, respectively., Results: Hypoxic SKOV3 cell-derived EVs could be internalized by TAMs. SKOV3 cell-derived EVs induced by hypoxia (H-EVs) promoted M2 polarization of TAMs and facilitated the proliferation, migration and invasion of SKOV3 cells. miR-181c-5p was highly expressed in H-EVs and promoted the M2 polarization of TAMs. Further, miR-181c-5p targeted KAT2B, upregulated HOXA10 and activated the JAK1/STAT3 pathway, thereby promoting the M2 polarization of TAMs. In both mouse models, H-EV-derived miR-181c-5p promoted growth and metastasis of EOC cells., Conclusion: The miR-181c-5p-containing EVs from hypoxic EOC cells may upregulate HOXA10 by targeting KAT2B and activate the JAK1/STAT3 pathway to promote the M2 polarization of TAMs, ultimately promoting growth and metastasis of EOC cells in vitro and in vivo., (© 2022 John Wiley & Sons Ltd.)

Histone acetyltransferases (HATs) are involved in the epigenetic positive control of gene expression in eukaryotes. CREB-binding proteins (CBP)/p300, a subfamily of highly conserved HATs, have been shown to function as acetylases on both histones and non-histone proteins. In the model plant Arabidopsis thaliana among the five CBP/p300 HATs, HAC1, HAC5 and HAC12 have been shown to be involved in the ethylene signaling pathway. In addition, HAC1 and HAC5 interact and cooperate with the Mediator complex, as in humans. Therefore, it is potentially difficult to discriminate the effect on plant development of the enzymatic activity with respect to their Mediator-related function. Taking advantage of the homology of the human HAC catalytic domain with that of the Arabidopsis, we set-up a phenotypic assay based on the hypocotyl length of Arabidopsis dark-grown seedlings to evaluate the effects of a compound previously described as human p300/CBP inhibitor, and to screen previously described cinnamoyl derivatives as well as newly synthesized analogues. We selected the most effective compounds, and we demonstrated their efficacy at phenotypic and molecular level. The in vitro inhibition of the enzymatic activity proved the specificity of the inhibitor on the catalytic domain of HAC1, thus substantiating this strategy as a useful tool in plant epigenetic studies.

More than 90% of ovarian cancer deaths are due to relapse following development of chemoresistance. Our main objective is to better understand the molecular mechanism underlying paclitaxel resistance (taxol resistance, Txr) in ovarian cancer. Here, we observed that the linker histone H1.0 is upregulated in paclitaxel-resistant ovarian cancer cells. Knockdown of H1.0 significantly downregulates the androgen receptor (AR) and sensitizes paclitaxel-resistant SKOV3/Txr and 2774/Txr cell lines to paclitaxel. Conversely, ectopic expression of H1.0 upregulates AR and increases Txr in parental SKOV3 and MDAH2774 cells. Notably, H1.0 upregulation is associated with disease recurrence and poor survival in a subset of ovarian cancer subjects. Inhibition of PI3K significantly reduces H1.0 mRNA and protein levels in paclitaxel-resistant cells, suggesting the involvement of the PI3K/AKT signaling pathway. Knockdown of H1.0 and AR also downregulates the Txr genes ABCB1 and ABCG2 in paclitaxel-resistant cells. Our data show that H1.0 induces GCN5 expression and histone acetylation, thereby enhancing Txr gene transactivation. These findings suggest that Txr in ovarian cancer involves the PI3K/AKT pathway and leads to upregulation of histone H1.0, recruitment of GCN5 and AR, followed by upregulation of a subgroup of Txr genes that include ABCB1 and ABCG2. This study is the first report describing the relationship between histone H1.0 and GCN5 that cooperate to induce AR-dependent Txr in ovarian cancer cells., (© 2022 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Dysregulation of multiple genes is an important risk factor for acute kidney injury (AKI). Numerous genes, such as proinflammatory cytokines, intracellular cell adhesion molecules (ICAMs), and nitric oxide synthases (NOSs), are implicated in AKI pathogenesis. However, the molecular mechanisms involved in the dysregulation of these genes are still obscure. Herein, we discovered that two subunits of NF-κB (p50 and p65) couple with lysine acetyltransferase 2B (KAT2B) and nuclear receptor coactivator 2 (NOCA2) to assemble a transcriptional complex in a LPS-induced mouse model of AKI. The NCOA2-KAT2B-NF-κB complex bound to the promoters of some NF-κB target genes, such as interleukin 1 beta (IL-1B), IL-6, tumor necrosis factor alpha (TNFA), ICAM1, vascular cell adhesion molecule 1 (VCAM1), cluster of differentiation 38 (CD38), CD40, CD80, and NOS2, and transactivated their expression. In vitro knockdown of components of the NCOA2-KAT2B-NF-κB complex or blockage of KAT2B by its inhibitors (5-chloro-2-(4-nitrophenyl)-3(2H)-isothiazolone [CNIT] and garcinol) significantly decreased the expression of these NF-κB target genes following LPS treatment. The administration of CNIT and garcinol significantly improved the in vivo outcomes of the AKI mice. Our findings reveal the underlying mechanism of NF-κB target upregulation in the pathogenesis of LPS-induced AKI and identify a new therapeutic strategy for AKI that involves targeting the NCOA2-KAT2B-NF-κB complex., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Vascular smooth muscle cell (VSMC) phenotypic switching contributes to cardiovascular diseases. Epigenetic regulation is emerging as a key regulatory mechanism, with the methylcytosine dioxygenase TET2 acting as a master regulator of smooth muscle cell phenotype. The histone acetyl-transferases p300 and CREB-binding protein (CBP) are highly homologous and often considered to be interchangeable, and their roles in smooth muscle cell phenotypic regulation are not known., Methods: We assessed the roles of p300 and CBP in human VSMC with knockdown, in inducible smooth muscle-specific knockout mice (inducible knockout [iKO]; p300 iKO or CBP iKO ), and in samples of human intimal hyperplasia., Results: P300, CBP, and histone acetylation were differently regulated in VSMCs undergoing phenotypic switching and in vessel remodeling after vascular injury. Medial p300 expression and activity were repressed by injury, but CBP and histone acetylation were induced in neointima. Knockdown experiments revealed opposing effects of p300 and CBP in the VSMC phenotype: p300 promoted contractile protein expression and inhibited migration, but CBP inhibited contractile genes and enhanced migration. p300 iKO mice exhibited severe intimal hyperplasia after arterial injury compared with controls, whereas CBP iKO mice were entirely protected. In normal aorta, p300 iKO reduced, but CBP iKO enhanced, contractile protein expression and contractility compared with controls. Mechanistically, we found that these histone acetyl-transferases oppositely regulate histone acetylation, DNA hydroxymethylation, and PolII (RNA polymerase II) binding to promoters of differentiation-specific contractile genes. Our data indicate that p300 and TET2 function together, because p300 was required for TET2-dependent hydroxymethylation of contractile promoters, and TET2 was required for p300-dependent acetylation of these loci. TET2 coimmunoprecipitated with p300, and this interaction was enhanced by rapamycin but repressed by platelet-derived growth factor (PDGF) treatment, with p300 promoting TET2 protein stability. CBP did not associate with TET2, but instead facilitated recruitment of histone deacetylases (HDAC2, HDAC5) to contractile protein promoters. Furthermore, CBP inhibited TET2 mRNA levels. Immunostaining of cardiac allograft vasculopathy samples revealed that p300 expression is repressed but CBP is induced in human intimal hyperplasia., Conclusions: This work reveals that p300 and CBP serve nonredundant and opposing functions in VSMC phenotypic switching and coordinately regulate chromatin modifications through distinct functional interactions with TET2 or HDACs. Targeting specific histone acetyl-transferases may hold therapeutic promise for cardiovascular diseases.

Pathological cardiac hypertrophy is a process of abnormal remodeling of cardiomyocytes in response to pressure overload or other stress stimuli, resulting in myocardial injury, which is a major risk factor for heart failure, leading to increased morbidity and mortality. General control nonrepressed protein 5 (GCN5)/lysine acetyltransferase 2 A, a member of the histone acetyltransferase and lysine acetyltransferase families, regulates a variety of physiological and pathological events. However, the function of GCN5 in pathological cardiac hypertrophy remains unclear. This study aimed to explore the role of GCN5 in the development of pathological cardiac hypertrophy. GCN5 expression was increased in isolated neonatal rat cardiomyocytes (NRCMs) and mouse hearts of a hypertrophic mouse model. GCN5 overexpression aggravated the cardiac hypertrophy triggered by transverse aortic constriction surgery. In contrast, inhibition of GCN5 impairs the development of pathological cardiac hypertrophy. Similar results were obtained upon stimulation of NRCMs (having GCN5 overexpressed or knocked down) with phenylephrine. Mechanistically, our results indicate that GCN5 exacerbates cardiac hypertrophy via excessive activation of the transforming growth factor β-activated kinase 1 (TAK1)-c-Jun N-terminal kinase (JNK)/p38 signaling pathway. Using a TAK1-specific inhibitor in rescue experiments confirmed that the activation of TAK1 is essential for GCN5-mediated cardiac hypertrophy. In summary, the current study elucidated the role of GCN5 in promotion of cardiac hypertrophy, thereby implying it to be a potential target for treatment., (© 2022. The Author(s).)

The histone acetyltransferase p300 (also known as KAT3B) is a general transcriptional coactivator that introduces the H3K27ac mark on enhancers triggering their activation and gene transcription. Genome-wide screenings demonstrated that a large fraction of long non-coding RNAs (lncRNAs) plays a role in cellular processes and organ development although the underlying molecular mechanisms remain largely unclear (1,2). We found 122 lncRNAs that interacts directly with p300. In depth analysis of one of these, lncSmad7, is required to maintain ESC self-renewal and it interacts to the C-terminal domain of p300. lncSmad7 also contains predicted RNA-DNA Hoogsteen forming base pairing. Combined Chromatin Isolation by RNA precipitation followed by sequencing (ChIRP-seq) together with CRISPR/Cas9 mutagenesis of the target sites demonstrate that lncSmad7 binds and recruits p300 to enhancers in trans, to trigger enhancer acetylation and transcriptional activation of its target genes. Thus, these results unveil a new mechanism by which p300 is recruited to the genome., (© The Author(s) 2022. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Inhibition of P300 acetyltransferase activity by specific inhibitor C646 has been shown to improve insulin signaling. However, the underlying molecular mechanism of this improvement remains unclear. In this study, we analyzed P300 levels of obese patients and found that they were significantly increased in liver hepatocytes. In addition, large amounts of P300 appeared in the cytoplasm. Inhibition of P300 acetyltransferase activity by C646 drastically increased tyrosine phosphorylation of the insulin receptor protein substrates (IRS1/2) without affecting the tyrosine phosphorylation of the beta subunit of the insulin receptor (IRβ) in hepatocytes in the absence of insulin. Since IRS1/2 requires membrane translocation and binding to inositol compounds for normal functions, we also examined the role of acetylation on binding to phosphatidylinositol(4,5)P2 and found that IRS1/2 acetylation by P300 reduced this binding. In contrast, we show that inhibition of IRS1/2 acetylation by C646 facilitates IRS1/2 membrane translocation. Intriguingly, we demonstrate that C646 activates IRβ's tyrosine kinase activity and directly promotes IRβ interaction with IRS1/2, leading to the tyrosine phosphorylation of IRS1/2 and subsequent activation of insulin signaling even in the absence of insulin. In conclusion, these data reveal the unique effects of C646 in activating insulin signaling in patients with obesity and diabetes., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest with the contents of this article., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Protein lysine acetylation is a post-translational modification that regulates protein structure and function. It is targeted to proteins by lysine acetyltransferases (KATs) or removed by lysine deacetylases. This work identifies a role for the KAT enzyme general control of amino acid synthesis protein 5 (GCN5; KAT2A) in regulating muscle integrity by inhibiting DNA binding of the transcription factor/repressor Yin Yang 1 (YY1). Here we report that a muscle-specific mouse knockout of GCN5 (Gcn5skm-/-) reduces the expression of key structural muscle proteins, including dystrophin, resulting in myopathy. GCN5 was found to acetylate YY1 at two residues (K392 and K393), disrupting the interaction between the YY1 zinc finger region and DNA. These findings were supported by human data, including an observed negative correlation between YY1 gene expression and muscle fiber diameter. Collectively, GCN5 positively regulates muscle integrity through maintenance of structural protein expression via acetylation-dependent inhibition of YY1. This work implicates the role of protein acetylation in the regulation of muscle health and for consideration in the design of novel therapeutic strategies to support healthy muscle during myopathy or aging., (© 2022 Addicks et al.)

Background: Persistent hyperglycemia decreases the sensitivity of insulin-sensitive organs to insulin, owing to which cells fail to take up and utilize glucose, which exacerbates the progression of type 2 diabetes mellitus (T2DM). lncRNAs' abnormal expression is reported to be associated with the progression of diabetes and plays a significant role in glucose metabolism. Herein, we study the detailed mechanism underlying the functions of lncRNA EPB41L4A-AS1in T2DM., Methods: Data from GEO datasets were used to analyze the expression of EPB41L4A-AS1 between insulin resistance or type 2 diabetes patients and the healthy people. Gene expression was evaluated by qRT-PCR and western blotting. Glucose uptake was measured by Glucose Uptake Fluorometric Assay Kit. Glucose tolerance of mice was detected by Intraperitoneal glucose tolerance tests. Cell viability was assessed by CCK-8 assay. The interaction between EPB41L4A-AS1 and GCN5 was explored by RNA immunoprecipitation, RNA pull-down and RNA-FISH combined immunofluorescence. Oxygen consumption rate was tested by Seahorse XF Mito Stress Test., Results: EPB41L4A-AS1 was abnormally increased in the liver of patients with T2DM and upregulated in the muscle cells of patients with insulin resistance and in T2DM cell models. The upregulation was associated with increased TP53 expression and reduced glucose uptake. Mechanistically, through interaction with GCN5, EPB41L4A-AS1 regulated histone H3K27 crotonylation in the GLUT4 promoter region and nonhistone PGC1β acetylation, which inhibited GLUT4 transcription and suppressed glucose uptake by muscle cells. In contrast, EPB41L4A-AS1 binding to GCN5 enhanced H3K27 and H3K14 acetylation in the TXNIP promoter region, which activated transcription by promoting the recruitment of the transcriptional activator MLXIP. This enhanced GLUT4/2 endocytosis and further suppressed glucose uptake., Conclusion: Our study first showed that the EPB41L4A-AS1/GCN5 complex repressed glucose uptake via targeting GLUT4/2 and TXNIP by regulating histone and nonhistone acetylation or crotonylation. Since a weaker glucose uptake ability is one of the major clinical features of T2DM, the inhibition of EPB41L4A-AS1 expression seems to be a potentially effective strategy for drug development in T2DM treatment., (© 2022 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Constrained peptides have proven to be a rich source of ligands for protein surfaces, but are often limited in their binding potency. Deployment of nonnatural side chains that access unoccupied crevices on the receptor surface offers a potential avenue to enhance binding affinity. We recently described a computational approach to create topographic maps of protein surfaces to guide the design of nonnatural side chains [ J. Am. Chem. Soc. 2017 , 139 , 15560]. The computational method, AlphaSpace, was used to predict peptide ligands for the KIX domain of the p300/CBP coactivator. KIX has been the subject of numerous ligand discovery strategies, but potent inhibitors of its interaction with transcription factors remain difficult to access. Although the computational approach provided a significant enhancement in the binding affinity of the peptide, fine-tuning of nonnatural side chains required an experimental screening method. Here we implement a peptide-tethering strategy to screen fragments as nonnatural side chains on conformationally defined peptides. The combined computational-experimental approach offers a general framework for optimizing peptidomimetics as inhibitors of protein-protein interactions.

Interleukin-6 (IL-6) overproduction has been considered to contribute to inflammatory damage of glomerular mesangial cells (GMCs) in human mesangial proliferative glomerulonephritis (MsPGN) and its rat model called Thy-1 nephritis (Thy-1N). However, the regulatory mechanisms of IL-6 expression in GMCs upon sublytic C5b-9 timulation remain poorly understood. We found that Krüppel-like factor 4 (KLF4) bound to the IL-6 promoter (-618 to -126 nt) and activated IL-6 gene transcription. Furthermore, lysine residue 224 of KLF4 was acetylated by p300/CBP-associated factor (PCAF), which was important for KLF4-mediated transactivation. Moreover, lysine residue 5 on histone H2B and lysine residue 9 on histone H3 at the IL-6 promoter were also acetylated by PCAF, which resulted in an increase in IL-6 transcription. Besides, NF-κB activation promoted IL-6 expression by elevating the expression of PCAF. Overall, these findings suggest that sublytic C5b-9-induced the expression of IL-6 involves KLF4-mediated transactivation, PCAF-mediated acetylation of KLF4 and histones, and NF-κB activation in GMCs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Xia, Liu, Zhang, Gong, Yu, Zhao, Qiu, Wang and Zhang.)

B lymphocyte development has two DNA recombination processes: V(D)J recombination of the immunoglobulin ( Igh ) gene variable region, and class switching of the Igh constant regions from IgM to IgG, IgA, or IgE. V(D)J recombination is required for the successful maturation of B cells from pro-B to pre-B to immature-B and then to mature B cells in the bone marrow. CSR occurs outside of the bone marrow when mature B cells migrate to peripheral lymphoid organs, such as spleen and lymph nodes. Both V(D)J recombination and CSR depend on an open chromatin state that makes DNA accessible to specific enzymes, recombination activating gene (RAG), and activation-induced cytidine deaminase (AID). Acetyltransferases GCN5 and PCAF possess redundant functions acetylating histone H3 lysine 9 (H3K9). Here, we generated a mouse model that lacked both GCN5 and PCAF in B cells. Double-deficient mice possessed low levels of mature B cells in the bone marrow and peripheral organs, an accumulation of pro-B cells in bone marrow, and reduced CSR levels. We concluded that both GCN5 and PCAF are required for B-cell development in vivo.

Histone acetylation is one of the most essential parts of epigenetic modification, mediating a variety of complex biological functions. In these procedure, p300/CBP could catalyze the acetylation of lysine 27 on histone 3 (H3K27ac), and had been reported to mediate tumorigenesis and development in a variety of tumors by enhancing chromatin transcription activity. Ovarian cancer, as an extremely malignant tumor, has also been observed to undergo abnormal acetylation of histones. However, whether the treatment of ovarian cancer could be achieved by inhibiting the acetylation activity of p300/CBP on H3K27 has not been well investigated. In this article, we modified the structure of p300/CBP HAT domain inhibitor A-485 and obtained a highly active small molecule known as 13f, which has an IC 50 value of 0.49 nM for inhibiting the in vitro enzyme activity of p300, as well as the anti-proliferation IC 50 value on ovarian cancer cell line OVCAR-3 was 153 nM. In addition, 13f had strong acetylase family selectivity, good metabolic stability and promising in vivo anti-tumor activity in OVCAR-3 xenograft model. The discovery of 13f revealed a more active chemical entity of the HATs domain of p300/CBP and provided a novel idea for the application of epigenetic inhibitors in the treatment of ovarian cancer., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Fascin is crucial for cancer cell filopodium formation and tumor metastasis, and is functionally regulated by post-translational modifications. However, whether and how Fascin is regulated by acetylation remains unclear. This study explored the regulation of Fascin acetylation and its corresponding roles in filopodium formation and tumor metastasis., Methods: Immunoprecipitation and glutathione-S-transferase pull-down assays were performed to examine the interaction between Fascin and acetyltransferase P300/CBP-associated factor (PCAF), and immunofluorescence was used to investigate their colocalization. An in vitro acetylation assay was performed to identify Fascin acetylation sites by using mass spectrometry. A specific antibody against acetylated Fascin was generated and used to detect the PCAF-mediated Fascin acetylation in esophageal squamous cell carcinoma (ESCC) cells using Western blotting by overexpressing and knocking down PCAF expression. An in vitro cell migration assay was performed, and a xenograft model was established to study in vivo tumor metastasis. Live-cell imaging and fluorescence recovery after photobleaching were used to evaluate the function and dynamics of acetylated Fascin in filopodium formation. The clinical significance of acetylated Fascin and PCAF in ESCC was evaluated using immunohistochemistry., Results: Fascin directly interacted and colocalized with PCAF in the cytoplasm and was acetylated at lysine 471 (K471) by PCAF. Using the specific anti-AcK471-Fascin antibody, Fascin was found to be acetylated in ESCC cells, and the acetylation level was consequently increased after PCAF overexpression and decreased after PCAF knockdown. Functionally, Fascin-K471 acetylation markedly suppressed in vitro ESCC cell migration and in vivo tumor metastasis, whereas Fascin-K471 deacetylation exhibited a potent oncogenic function. Moreover, Fascin-K471 acetylation reduced filopodial length and density, and lifespan of ESCC cells, while its deacetylation produced the opposite effect. In the filipodium shaft, K471-acetylated Fascin displayed rapid dynamic exchange, suggesting that it remained in its monomeric form owing to its weakened actin-bundling activity. Clinically, high levels of AcK471-Fascin in ESCC tissues were strongly associated with prolonged overall survival and disease-free survival of ESCC patients., Conclusions: Fascin interacts directly with PCAF and is acetylated at lysine 471 in ESCC cells. Fascin-K471 acetylation suppressed ESCC cell migration and tumor metastasis by reducing filopodium formation through the impairment of its actin-bundling activity., (© 2021 The Authors. Cancer Communications published by John Wiley & Sons Australia, Ltd. on behalf of Sun Yat-sen University Cancer Center.)

ULK1 (unc-51 like autophagy activating kinase) has a central role in initiating macroautophagy/autophagy, a process that contributes to atherosclerosis and neointima hyperplasia, or excessive tissue growth that leads to vessel dysfunction. However, the role of ULK1 in neointima formation remains unclear. We aimed to determine how Ulk1 deletion affected neointima formation and to investigate the underlying mechanisms. We measured autophagy activity, vascular smooth muscle cell (VSMC) migration and neointima hyperplasia in cultured VSMCs and ligation-injured mouse carotid arteries from male wild-type (WT, C57BL/6 J) and VSMC-specific ulk1 knockout ( ulk1 KO) mice. Carotid artery ligation in WT mice increased ULK1 protein expression, and concurrently increased autophagic flux and neointima formation. Treating human aortic smooth muscle cells (HASMCs) with PDGF (platelet derived growth factor) increased ULK1 expression, activated autophagy, and promoted cell migration. Further, smooth muscle cell-specific deletion of Ulk1 suppressed autophagy, inhibited VSMC migration, and impeded neointima hyperplasia. Mechanistically, Ulk1 deletion inhibited autophagic degradation of histone acetyltransferase protein KAT2A/GCN5 (K[lysine] acetyltransferase 2A), resulting in accumulation of KAT2A that directly acetylated TUBA/α-tubulin and subsequently increased protein levels of acetylated TUBA. The acetylation of TUBA increased microtubule stability and inhibited VSMC directional migration and neointima formation. Finally, local transfection of Kat2a siRNA decreased TUBA acetylation and prevented the attenuation of vascular injury-induced neointima formation in ulk1 KO mice. These findings suggest that Ulk1 deletion inhibits neointima formation by reducing autophagic degradation of KAT2A and increasing TUBA acetylation in VSMCs. Abbreviations: ACTA2/α-SMA: actin, alpha 2, smooth muscle, aorta; ACTB: actin beta; ATAT1: alpha tubulin acetyltransferase 1; ATG: autophagy related; BECN1: beclin 1; BP: blood pressure; CAL: carotid artery ligation; CQ: chloroquine diphosphate; EC: endothelial cells; EEL: external elastic layer; FBS: fetal bovine serum; GAPDH: glyceraldehyde 3-phosphate dehydrogenase; HASMCs: human aortic smooth muscle cells; HAT1: histone acetyltransferase 1; HDAC: histone deacetylase; IEL: inner elastic layer; IP: immunoprecipitation; KAT2A/GCN5: K(lysine) acetyltransferase 2A; KAT8/hMOF: lysine acetyltransferase 8; MAP1LC3: microtubule associated protein 1 light chain 3; MYH11: myosin heavy chain 11; PBS: phosphate-buffered saline; PDGF: platelet derived growth factor; PECAM1/CD31: platelet and endothelial cell adhesion molecule 1; RAC3: Rac family small GTPase 3; SIRT2: sirtuin 2; SPP1/OPN: secreted phosphoprotein 1; SQSTM1/p62: sequestosome 1; TAGLN/SM22: transgelin; TUBA: tubulin alpha; ULK1: unc-51 like autophagy activating kinase; VSMC: vascular smooth muscle cell; VVG: Verhoeff Van Gieson; WT: wild type.

Lysine Acetyltransferase 2B (KAT2B) functions pivotally in regulating chromatin organization as well as function, and is a key regulator of signal transduction during development of many diseases, like tumors. This research intends to exploit expression, clinical significance as well as how KAT2B functions in cervical cancer. Our study showed that the KAT2B expression in cervical carcinoma tissues was inferior to that in normal tissues; decreased KAT2B expression was signally related to increased T staging, lymph node metastasis together with tissue differentiation; patients with high KAT2B expression had better prognosis. After knocking down KAT2B, cell proliferation diminished with decreased cell migration and invasion. Additionally, knocking down KAT2B made for increasing EMT-related proteins N-cadherin and Vimentin expression, while ZO-1 expression decreased; overexpression had the opposite effect. Dual luciferase analysis affirmed that miR-93-5p could in specifical bind to KAT2B, and thus reducing its expression and activity. KAT2B may be a new cervical tumor-suppressor gene, which is closely concerned with poor prognosis of patients, and under negative regulation by miR-93-5p.

Vascular endothelial cells are exposed to shear stresses with disturbed vs. laminar flow patterns, which lead to proinflammatory vs. antiinflammatory phenotypes, respectively. Effective treatment against endothelial inflammation and the consequent atherogenesis requires the identification of new therapeutic molecules and the development of drugs targeting these molecules. Using Connectivity Map, we have identified vitexin, a natural flavonoid, as a compound that evokes the gene-expression changes caused by pulsatile shear, which mimics laminar flow with a clear direction, vs. oscillatory shear (OS), which mimics disturbed flow without a clear direction. Treatment with vitexin suppressed the endothelial inflammation induced by OS or tumor necrosis factor-α. Administration of vitexin to mice subjected to carotid partial ligation blocked the disturbed flow-induced endothelial inflammation and neointimal formation. In hyperlipidemic mice, treatment with vitexin ameliorated atherosclerosis. Using SuperPred, we predicted that apurinic/apyrimidinic endonuclease1 (APEX1) may directly interact with vitexin, and we experimentally verified their physical interactions. OS induced APEX1 nuclear translocation, which was inhibited by vitexin. OS promoted the binding of acetyltransferase p300 to APEX1, leading to its acetylation and nuclear translocation. Functionally, knocking down APEX1 with siRNA reversed the OS-induced proinflammatory phenotype, suggesting that APEX1 promotes inflammation by orchestrating the NF-κB pathway. Animal experiments with the partial ligation model indicated that overexpression of APEX1 negated the action of vitexin against endothelial inflammation, and that endothelial-specific deletion of APEX1 ameliorated atherogenesis. We thus propose targeting APEX1 with vitexin as a potential therapeutic strategy to alleviate atherosclerosis., Competing Interests: The authors declare no competing interest.

The anti-apoptotic myeloid cell leukemia 1 (MCL1) protein belongs to the pro-survival BCL2 family and is frequently amplified or elevated in human cancers. MCL1 is highly unstable, with its stability being regulated by phosphorylation and ubiquitination. Here, we identify acetylation as another critical post-translational modification regulating MCL1 protein stability. We demonstrate that the lysine acetyltransferase p300 targets MCL1 at K40 for acetylation, which is counteracted by the deacetylase sirtuin 3 (SIRT3). Mechanistically, acetylation enhances MCL1 interaction with USP9X, resulting in deubiquitination and subsequent MCL1 stabilization. Therefore, ectopic expression of acetylation-mimetic MCL1 promotes apoptosis evasion of cancer cells, enhances colony formation potential, and facilitates xenografted tumor progression. We further demonstrate that elevated MCL1 acetylation sensitizes multiple cancer cells to pharmacological inhibition of USP9X. These findings reveal that acetylation of MCL1 is a critical post-translational modification enhancing its oncogenic function and provide a rationale for developing innovative therapeutic strategies for MCL1-dependent tumors., Competing Interests: Declaration of interests W.W. is a co-founder and consultant for ReKindle Therapeutics., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Cardiomyocyte apoptosis is the main reason of cardiac injury after myocardial ischaemia-reperfusion (I/R) injury (MIRI), but the role of p300/CBP-associated factor (PCAF) on myocardial apoptosis in MIRI is unknown. The aim of this study was to investigate the main mechanism of PCAF modulating cardiomyocyte apoptosis in MIRI. The MIRI model was constructed by ligation of the rat left anterior descending coronary vessel for 30 min and reperfusion for 24 h in vivo. H9c2 cells were harvested after induced by hypoxia for 6 h and then reoxygenation for 24 h (H/R) in vitro. The RNA interference PCAF expression adenovirus was transfected into rat myocardium and H9c2 cells. The area of myocardial infarction, cardiac function, myocardial injury marker levels, apoptosis, inflammation and oxidative stress were detected respectively. Both I/R and H/R remarkably upregulated the expression of PCAF, and downregulation of PCAF significantly attenuated myocardial apoptosis, inflammation and oxidative stress caused by I/R and H/R. In addition, downregulation of PCAF inhibited the activation of NF-κB signalling pathway in cardiomyocytes undergoing H/R. Pretreatment of lipopolysaccharide, a NF-κB pathway activator, could blunt these protective effects of PCAF downregulation on myocardial apoptosis in MIRI. These results highlight that downregulation of PCAF could reduce cardiomyocyte apoptosis by inhibiting the NF-κB pathway, thereby providing protection for MIRI. Therefore, PCAF might be a promising target for protecting against cardiac dysfunction induced by MIRI., (© 2021 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Suppression of excessive hepatic gluconeogenesis is an effective strategy for controlling hyperglycemia in type 2 diabetes (T2D). In the present study, we screened our compounds library to discover the active molecules inhibiting gluconeogenesis in primary mouse hepatocytes. We found that SL010110 (5-((4-allyl-2-methoxyphenoxy) methyl) furan-2-carboxylic acid) potently inhibited gluconeogenesis with 3 μM and 10 μM leading to a reduction of 45.5% and 67.5%, respectively. Moreover, SL010110 caused suppression of gluconeogenesis resulted from downregulating the protein level of phosphoenolpyruvate carboxykinase 1 (PEPCK1), but not from affecting the gene expressions of PEPCK, glucose-6-phosphatase, and fructose-1,6-bisphosphatase. Furthermore, SL010110 increased PEPCK1 acetylation, and promoted PEPCK1 ubiquitination and degradation. SL010110 activated p300 acetyltransferase activity in primary mouse hepatocytes. The enhanced PEPCK1 acetylation and suppressed gluconeogenesis caused by SL010110 were blocked by C646, a histone acetyltransferase p300 inhibitor, suggested that SL010110 inhibited gluconeogenesis by activating p300. SL010110 decreased NAD + /NADH ratio, inhibited SIRT2 activity, and further promoted p300 acetyltransferase activation and PEPCK1 acetylation. These effects were blocked by NMN, an NAD + precursor, suggested that SL010110 inhibited gluconeogenesis by inhibiting SIRT2, activating p300, and subsequently promoting PEPCK1 acetylation. In type 2 diabetic ob/ob mice, single oral dose of SL010110 (100 mg/kg) suppressed gluconeogenesis accompanied by the suppressed hepatic SIRT2 activity, increased p300 activity, enhanced PEPCK1 acetylation and degradation. Chronic oral administration of SL010110 (15 or 50 mg/kg) significantly reduced the blood glucose levels in ob/ob and db/db mice. This study reveals that SL010110 is a lead compound with a distinct mechanism of suppressing gluconeogenesis via SIRT2-p300-mediated PEPCK1 degradation and potent anti-hyperglycemic activity for the treatment of T2D., (© 2021. The Author(s), under exclusive licence to CPS and SIMM.)

Cardiovascular disease is the leading cause of accelerated as well as chronological aging-related human morbidity and mortality worldwide. Genetic, immunologic, unhealthy lifestyles including daily consumption of high-carb/high-fat fast food, lack of exercise, drug addiction, cigarette smoke, alcoholism, and exposure to environmental pollutants like particulate matter (PM)-induced stresses contribute profoundly to accelerated and chronological cardiovascular aging and associated life threatening diseases. All these stressors alter gene expression epigenetically either through activation or repression of gene transcription via alteration of chromatin remodeling enzymes and chromatin landscape by DNA methylation or histone methylation or histone acetylation. Acetyltransferase p300, a major epigenetic writer of acetylation on histones and transcription factors, contributes significantly to modifications of chromatin landscape of genes involved in cellular aging and cardiovascular diseases. In this review, the key findings those implicate acetyltransferase p300 as a major contributor to cellular senescence or aging related cardiovascular pathologies including vascular dysfunction, cardiac hypertrophy, myocardial infarction, cardiac fibrosis, systolic/diastolic dysfunction, and aortic valve calcification are discussed. The efficacy of natural or synthetic small molecule inhibitor targeting acetyltransferase p300 in amelioration of stress-induced dysregulated gene expression, cellular aging, and cardiovascular disease in preclinical study is also discussed.

Disrupting the interaction between HIF1α and p300 is a promising strategy to modulate the hypoxia response of tumor cells. Herein, we designed a constrained peptide inhibitor derived from the CITED2/p300 complex to disturb the HIF1α/p300 interaction. Through truncation/mutation screening and a terminal aspartic acid-stabilized strategy, a constrained peptide was constructed with outstanding biochemical/biophysical properties, especially in binding affinity, cell penetration, and serum stability. To date, our study was the first one to showcase that stabilized peptides derived from CITED2 using helix-stabilizing methods acted as a promising candidate for modulating hypoxia-inducible signaling.

The serine synthesis pathway (SSP) involving metabolic enzymes phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH) drives intracellular serine biosynthesis and is indispensable for cancer cells to grow in serine-limiting environments. However, how SSP is regulated is not well understood. Here, we report that activating transcription factor 3 (ATF3) is crucial for transcriptional activation of SSP upon serine deprivation. ATF3 is rapidly induced by serine deprivation via a mechanism dependent on ATF4, which in turn binds to ATF4 and increases the stability of this master regulator of SSP. ATF3 also binds to the enhancers/promoters of PHGDH, PSAT1, and PSPH and recruits p300 to promote expression of these SSP genes. As a result, loss of ATF3 expression impairs serine biosynthesis and the growth of cancer cells in the serine-deprived medium or in mice fed with a serine/glycine-free diet. Interestingly, ATF3 expression positively correlates with PHGDH expression in a subset of TCGA cancer samples., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Isoniazid (INH) is a first-line anti-tuberculosis drug used for nearly 70 years. However, the mechanism underlying the side effects of INH has remained elusive. Here, we report that INH and its metabolites induce a post-translational modification (PTM) of histones, lysine isonicotinylation (K inic ), also called 4-picolinylation, in cells and mice. INH promotes the biosynthesis of isonicotinyl-CoA (Inic-CoA), a co-factor of intracellular isonicotinylation. Mass spectrometry reveals 26 K inic sites in histones in HepG2 cells. Acetyltransferases CREB-binding protein (CBP) and P300 catalyse histone K inic , while histone deacetylase HDAC3 functions as a deisonicotinylase. Notably, MNase sensitivity assay and RNA-seq analysis show that histone K inic relaxes chromatin structure and promotes gene transcription. INH-mediated histone K inic upregulates PIK3R1 gene expression and activates the PI3K/Akt/mTOR signalling pathway in liver cancer cells, linking INH to tumourigenicity in the liver. We demonstrate that K inic is a histone acylation mark with a pyridine ring, which may have broad biological effects. Therefore, INH-induced isonicotinylation potentially accounts for the side effects in patients taking INH long-term for anti-tuberculosis therapy, and this modification may increase the risk of cancer in humans., (© 2021. The Author(s).)

Various heart diseases cause cardiac remodeling, which in turn leads to ineffective contraction. Although it is an adaptive response to injury, cardiac fibrosis contributes to this remodeling, for which the reactivation of quiescent myofibroblasts is a key feature. In the present study, we investigated the role of the p300/CBP-associated factor (PCAF), a histone acetyltransferase, in the activation of cardiac fibroblasts. An intraperitoneal (i.p.) injection of a high dose (160 mg/kg) of isoproterenol (ISP) induced cardiac fibrosis and reduced the amount of the PCAF in cardiac fibroblasts in the mouse heart. However, the PCAF activity was significantly increased in cardiac fibroblasts, but not in cardiomyocytes, obtained from ISP-administered mice. An in vitro study using human cardiac fibroblast cells recapitulated the in vivo results; an treatment with transforming growth factor-β1 (TGF-β1) reduced the PCAF, whereas it activated the PCAF in the fibroblasts. PCAF siRNA attenuated the TGF-β1-induced increase in and translocation of fibrosis marker proteins. PCAF siRNA blocked TGF-β1-mediated gel contraction and cell migration. The PCAF directly interacted with and acetylated mothers against decapentaplegic homolog 2 (SMAD2). PCAF siRNA prevented TGF-β1-induced phosphorylation and the nuclear localization of SMAD2. These results suggest that the increase in PCAF activity during cardiac fibrosis may participate in SMAD2 acetylation and thereby in its activation.

Oncogenic signaling pathway reprograms cancer cell metabolism to promote aerobic glycolysis in favor of tumor growth. The ability of cancer cells to evade immunosurveillance and the role of metabolic regulators in T-cell functions suggest that oncogene-induced metabolic reprogramming may be linked to immune escape. Notch1 signaling, dysregulated in lung cancer, is correlated with increased glycolysis. Herein, we demonstrate in lung cancer that Notch1 promotes glycolytic gene expression through functional interaction with histone acetyltransferases p300 and pCAF. Notch1 signaling forms a positive feedback loop with TAZ. Notch1 transcriptional activity was increased in the presence of TAZ and the activation was TEAD1 independent. Notably, aerobic glycolysis was critical for Notch1/TAZ axis modulation of lung cancer growth in vitro and in vivo. Increased level of extracellular lactate via Notch1/TAZ axis inhibited cytotoxic T-cell activity, leading to the invasive characteristic of lung cancer cells. Interaction between Notch1 and TAZ promoted aerobic glycolysis and immune escape in lung cancer. Our findings provide potential therapeutic targets against Notch1 and TAZ and would be important for clinical translation in lung cancer., (© 2021. The Author(s).)

In response to DNA damage, most factors involved in damage recognition and repair are tightly regulated to ensure proper repair pathway choice. Histone acetylation at DNA double strand breaks (DSBs) by p300 histone acetyltransferase (HAT) is critical for the recruitment of DSB repair proteins to chromatin. Here, we show that phosphorylation of Sp1 by ATM increases its interaction with p300 and that Sp1-dependent recruitment of p300 to DSBs is necessary to modify the histones associated with p300 activity and NHEJ repair factor recruitment and repair. p300 is known to acetylate multiple residues on histones H3 and H4 necessary for NHEJ. Acetylation of H3K18 by p300 is associated with the recruitment of the SWI/SNF chromatin remodeling complex and Ku70 to DSBs for NHEJ repair. Depletion of Sp1 results in decreased acetylation of lysines on histones H3 and H4. Specifically, cells depleted of Sp1 display defects in the acetylation of H3K18, resulting in defective SWI/SNF and Ku70 recruitment to DSBs. These results shed light on mechanisms by which chromatin remodelers are regulated to ensure activation of the appropriate DSB repair pathway., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Endogenous DNA damage is a major contributor to mutations, which are drivers of cancer development. Bromodomain (BRD) proteins are well-established participants in chromatin-based DNA damage response (DDR) pathways, which maintain genome integrity from cell-intrinsic and extrinsic DNA-damaging sources. BRD proteins are most well-studied as regulators of transcription, but emerging evidence has revealed their importance in other DNA-templated processes, including DNA repair and replication. How BRD proteins mechanistically protect cells from endogenous DNA damage through their participation in these pathways remains an active area of investigation. Here, we review several recent studies establishing BRD proteins as key influencers of endogenous DNA damage, including DNA-RNA hybrid (R-loops) formation during transcription and participation in replication stress responses. As endogenous DNA damage is known to contribute to several human diseases, including neurodegeneration, immunodeficiencies, cancer, and aging, the ability of BRD proteins to suppress DNA damage and mutations is likely to provide new insights into the involvement of BRD proteins in these diseases. Although many studies have focused on BRD proteins in transcription, evidence indicates that BRD proteins have emergent functions in DNA repair and genome stability and are participants in the etiology and treatment of diseases involving endogenous DNA damage., (© 2021. The Author(s).)

Cardiomyocyte hypertrophy is a compensatory phase of chronic heart failure that is induced by the activation of multiple signaling pathways. The extracellular signal‑regulated protein kinase (ERK) signaling pathway is an important regulator of cardiomyocyte hypertrophy. In our previous study, it was demonstrated that phenylephrine (PE)‑induced cardiomyocyte hypertrophy involves the hyperacetylation of histone H3K9ac by P300/CBP‑associated factor (PCAF). However, the upstream signaling pathway has yet to be fully identified. In the present study, the role of the extracellular signal‑regulated protein kinase (ERK)1/2 signaling pathway in PE‑induced cardiomyocyte hypertrophy was investigated. The mice cardiomyocyte hypertrophy model was successfully established by treating cells with PE in vitro . The results showed that phospho‑(p‑)ERK1/2 interacted with PCAF and modified the pattern of histone H3K9ac acetylation. An ERK inhibitor (U0126) and/or a histone acetylase inhibitor (anacardic acid; AA) attenuated the overexpression of phospho‑ERK1/2 and H3K9ac hyperacetylation by inhibiting the expression of PCAF in PE‑induced cardiomyocyte hypertrophy. Moreover, U0126 and/or AA could attenuate the overexpression of several biomarker genes related to cardiac hypertrophy (myocyte enhancer factor 2C, atrial natriuretic peptide, brain natriuretic peptide and β‑myosin heavy chain) and prevented cardiomyocyte hypertrophy. These results revealed a novel mechanism in that AA protects against PE‑induced cardiomyocyte hypertrophy in mice via the ERK1/2 signaling pathway, and by modifying the acetylation of H3K9ac. These findings may assist in the development of novel methods for preventing and treating hypertrophic cardiomyopathy.

Our previous studies have shown that cathepsin L (CTSL) is involved in the ability of tumors to resist ionizing radiation (IR), but the specific mechanisms responsible for this remain unknown. We report here that mutant p53 (mut-p53) is involved in IR-induced transcription of CTSL. We found that irradiation caused activation of CTSL in mut-p53 cell lines, whereas there was almost no activation in p53 wild-type cell lines. Additionally, luciferase reporter gene assay results demonstrated that IR induced the p53 binding region on the CTSL promoter. We further demonstrated that the expression of p300 and early growth response factor-1 (Egr-1) was upregulated in mut-p53 cell lines after IR treatment. Accordingly, the expression of Ac-H3, Ac-H4, AcH3K9 was upregulated after IR treatment in mut-p53 cell lines, whereas histone deacetylase (HDAC) 4 and HDAC6 were reciprocally decreased. Moreover, knockdown of either Egr-1 or p300 abolished the binding of mut-p53 to the promoter of CTSL. Chromatin immunoprecipitation assay results showed that the IR-activated transcription of CTSL was dependent on p300. To further delineate the clinical relevance of interactions between Egr-1/p300, mut-p53, and CTSL, we accessed primary tumor samples to evaluate the relationships between mut-p53, CTSL, and Egr-1/p300 ex vivo. The results support the notion that mut-p53 is correlated with CTSL transcription involving the Egr-1/p300 pathway. Taken together, the results of our study revealed that p300 is an important target in the process of IR-induced transcription of CTSL, which confirms that CTSL participates in mut-p53 gain-of-function. SIGNIFICANCE STATEMENT: Transcriptional activation of cathepsin L by ionizing radiation required the involvement of mutated p53 and Egr-1/p300. Interference with Egr-1 or p300 could inhibit the expression of cathepsin L induced by ionizing radiation. The transcriptional activation of cathepsin L by p300 may be mediated by p53 binding sites on the cathepsin L promoter., (Copyright © 2021 by The American Society for Pharmacology and Experimental Therapeutics.)

Api5, is a known anti-apoptotic and nuclear protein that is responsible for inhibiting cell death in serum-starved conditions. The only known post-translational modification of Api5 is acetylation at lysine 251 (K251). K251 acetylation of Api5 is responsible for maintaining its stability while the de-acetylated form of Api5 is unstable. This study aimed to find out the enzymes regulating acetylation and deacetylation of Api5 and the effect of acetylation on its function. Our studies suggest that acetylation of Api5 at lysine 251 is mediated by p300 histone acetyltransferase while de-acetylation is carried out by HDAC1. Inhibition of acetylation by p300 leads to a reduction in Api5 levels while inhibition of deacetylation by HDAC1 results in increased levels of Api5. This dynamic switch between acetylation and deacetylation regulates the localisation of Api5 in the cell. This study also demonstrates that the regulation of acetylation and deacetylation of Api5 is an essential factor for the progression of the cell cycle., (© 2021. The Author(s).)

Cancer, a fatal disease, is also one of the main causes of death worldwide. Despite various developments to prevent and treat cancer, the side effects of anticancer drugs remain a major concern. Ascorbic acid is an essential vitamin required by our bodies for normal physiological function and also has antioxidant and anticancer activity. Although the body cannot synthesize ascorbic acid, it is abundant in nature through foods and other natural sources and also exists as a nutritional food supplement. In anticancer drug development, ascorbic acid has played an important role by inhibiting the development of cancer through various mechanisms, including scavenging reactive oxygen species (ROS), selectively producing ROS and encouraging their cytotoxicity against tumour cells, preventing glucose metabolism, serving as an epigenetic regulator, and regulating the expression of HIF in tumour cells. Several ascorbic acid analogues have been produced to date for their anticancer and antioxidant activity. The current review summarizes the mechanisms behind ascorbic acid's antitumor activity, presents a compilation of its derivatives and their biological activity as anticancer agents, and discusses delivery systems such as liposomes, nanoparticles against cancer, and patents on ascorbic acid as anticancer agents.

Inhibition of PCAF bromodomain has been validated as a promising strategy for the treatment of cancer. In this study, we report the bioisosteric modification of the first reported potent PCAF bromodomain inhibitor, L-45 to its triazoloquinazoline bioisosteres. Accordingly, three new series of triazoloquinazoline derivatives were designed, synthesized, and assessed for their anticancer activity against a panel of four human cancer cells. Three derivatives demonstrated comparable cytotoxic activity with the reference drug doxorubicin. Among them, compound 22 showed the most potent activity with IC 50 values of 15.07, 9.86, 5.75, and 10.79 µM against Hep-G2, MCF-7, PC3, and HCT-116 respectively. Also, compound 24 exhibited remarkable cytotoxicity effects against the selected cancer cell lines with IC 50 values of 20.49, 12.56, 17.18, and 11.50 µM. Compounds 22 and 25 were the most potent PCAF inhibitors (IC 50 , 2.88 and 3.19 μM, respectively) compared with bromosporine (IC 50 , 2.10 μM). Follow up apoptosis induction and cell cycle analysis studies revealed that the bioisostere 22 could induce apoptotic cell death and arrest the cell cycle of PC3 at the G2/M phase. The in silico molecular docking studies were additionally performed to rationalize the PCAF inhibitory effects of new triazoloquinazoline bioisosteres., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Circadian rhythms help animals synchronize motivated behaviors to match environmental demands. Recent evidence indicates that clock neurons influence the timing of behavior by differentially altering the activity of a distributed network of downstream neurons. Downstream circuits can be remodeled by Hebbian plasticity, synaptic scaling, and, under some circumstances, activity-dependent addition of cell surface receptors; the role of this receptor respecification phenomena is not well studied. We demonstrate that high sleep pressure quickly reprograms the wake-promoting large ventrolateral clock neurons to express the pigment dispersing factor receptor (PDFR). The addition of this signaling input into the circuit is associated with increased waking and early mating success. The respecification of PDFR in both young and adult large ventrolateral neurons requires 2 dopamine (DA) receptors and activation of the transcriptional regulator nejire (cAMP response element-binding protein [CREBBP]). These data identify receptor respecification as an important mechanism to sculpt circuit function to match sleep levels with demand., Competing Interests: The authors have declared that no competing interests exist.

Regulatory T cells (Tregs) play a crucial role in preventing antitumor immune responses in cancer tissues. Cancer tissues produce large amounts of transforming growth factor beta (TGF-β), which promotes the generation of Foxp3 + Tregs from naïve CD4 + T cells in the local tumor microenvironment. TGF-β activates nuclear factor kappa B (NF-κB)/p300 and SMAD signaling, which increases the number of acetylated histones at the Foxp3 locus and induces Foxp3 gene expression. TGF-β also helps stabilize Foxp3 expression. The curcumin analog and antitumor agent, GO-Y030, prevented the TGF-β-induced generation of Tregs by preventing p300 from accelerating NF-κB-induced Foxp3 expression. Moreover, the addition of GO-Y030 resulted in a significant reduction in the number of acetylated histones at the Foxp3 promoter and at the conserved noncoding sequence 1 regions that are generated in response to TGF-β. In vivo tumor models demonstrated that GO-Y030-treatment prevented tumor growth and reduced the Foxp3 + Tregs population in tumor-infiltrating lymphocytes. Therefore, GO-Y030 exerts a potent anticancer effect by controlling Treg generation and stability., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 MaruYama, Kobayashi, Nakatsukasa, Moritoki, Taguchi, Sunagawa, Morimoto, Asao, Jin, Owada, Ishii, Iwabuchi, Yoshimura, Chen and Shibata.)

Recently, the novel coronavirus (SARS-CoV-2), which has spread from China to the world, was declared a global public health emergency, which causes lethal respiratory infections. Acetylation of several proteins plays essential roles in various biological processes, such as viral infections. We reported that the nucleoproteins of influenza virus and Zaire Ebolavirus were acetylated, suggesting that these modifications contributed to the molecular events involved in viral replication. Similar to influenza virus and Ebolavirus, the coronavirus also contains single-stranded RNA, as its viral genome interacts with the nucleocapsid (N) proteins. In this study, we report that SARS-CoV and SARS-CoV-2 N proteins are strongly acetylated by human histone acetyltransferases, P300/CBP-associated factor (PCAF), and general control nonderepressible 5 (GCN5), but not by CREB-binding protein (CBP) in vitro. Liquid chromatography-mass spectrometry analyses identified 2 and 12 acetyl-lysine residues from SARS-CoV and SARS-CoV-2 N proteins, respectively. Particularly in the SARS-CoV-2 N proteins, the acetyl-lysine residues were localized in or close to several functional sites, such as the RNA interaction domains and the M-protein interacting site. These results suggest that acetylation of SARS-CoV-2 N proteins plays crucial roles in their functions., Competing Interests: Declaration of competing interest None., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The final stage of Ebola virus (EBOV) replication is budding from host cells, where the matrix protein VP40 is essential for driving this process. Many post-translational modifications such as ubiquitination are involved in VP40 egress, but acetylation has not been studied yet. Here, we characterize NEDD4 is acetylated at a conserved Lys667 mediated by the acetyltransferase P300 which drives VP40 egress process. Importantly, P300-mediated NEDD4 acetylation promotes NEDD4-VP40 interaction which enhances NEDD4 E3 ligase activity and is essential for the activation of VP40 ubiquitination and subsequent egress. Finally, we find that Zaire ebolavirus production is dramatically reduced in P300 knockout cell lines, suggesting that P300-mediated NEDD4 acetylation may have a physiological effect on Ebola virus life cycle. Thus, our study identifies an acetylation-dependent regulatory mechanism that governs VP40 ubiquitination and provides insights into how acetylation controls EBOV VP40 egress., Competing Interests: The authors have declared that no competing interests exist.

Factor inhibiting hypoxia-inducible factor (FIH) is a JmjC domain 2-oxogluarate and Fe(II)-dependent oxygenase that catalyzes hydroxylation of specific asparagines in the C-terminal transcriptional activation domain of hypoxia-inducible factor alpha (HIF-α) isoforms. This modification suppresses the transcriptional activity of HIF by reducing its interaction with the transcriptional coactivators p300/CBP. By contrast with inhibition of the HIF prolyl hydroxylases (PHDs), inhibitors of FIH, which accepts multiple non-HIF substrates, are less studied; they are of interest due to their potential ability to alter metabolism (either in a HIF-dependent and/or -independent manner) and, provided HIF is upregulated, to modulate the course of the HIF-mediated hypoxic response. Here we review studies on the mechanism and inhibition of FIH. We discuss proposed biological roles of FIH including its regulation of HIF activity and potential roles of FIH-catalyzed oxidation of non-HIF substrates. We highlight potential therapeutic applications of FIH inhibitors.

Interferon lambda 3 (IFN-λ3 or IFNL3, formerly IL28B), a type III interferon, modulates immune responses during infection/inflammation. Several human studies have reported an association of single nucleotide polymorphisms (SNP) in the IFNL3 locus with expression level of IFNL3. Previous genetic studies, in the context of hepatitis C virus infections, had predicted three regulatory SNPs: rs4803219, rs28416813 and rs4803217 that could have functional/causal roles. Subsequent studies confirmed this prediction for rs28416813 and rs4803217. A dinucleotide TA-repeat variant (rs72258881) has also been reported to be regulating the IFN-λ3 promoter. In this study, we tested all these genetic variants using a sensitive reporter assay. We show that the minor/ancestral alleles of both rs28416813 and rs4803217, together have a strong inhibitory effect on reporter gene expression. We also show an interaction between the two principal transcription factors regulating IFNL3 promoter: IRF7 and NF-kB RelA/p65. We show that IRF7 and p65 physically interact with each other. By using a transient ChIP assay, we show that presence of p65 increases the promoter occupancy of IRF7, thereby leading to synergistic activation of the IFNL3 promoter. We reason that, in contrast to p65, a unique nature of IRF7 binding to its specific DNA sequence makes it more sensitive to changes in DNA phasing. As a result, we see that IRF7, but not p65-mediated transcriptional activity is affected by the phase changes introduced by the TA-repeat polymorphism. Overall, we see that three genetic variants: rs28416813, rs4803217 and rs72258881 could have functional roles in controlling IFNL3 gene expression., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

To separate causal effects of histone acetylation on chromatin accessibility and transcriptional output, we used integrated epigenomic and transcriptomic analyses following acute inhibition of major cellular lysine acetyltransferases P300 and CBP in hematological malignancies. We found that catalytic P300/CBP inhibition dynamically perturbs steady-state acetylation kinetics and suppresses oncogenic transcriptional networks in the absence of changes to chromatin accessibility. CRISPR-Cas9 screening identified NCOR1 and HDAC3 transcriptional co-repressors as the principal antagonists of P300/CBP by counteracting acetylation turnover kinetics. Finally, deacetylation of H3K27 provides nucleation sites for reciprocal methylation switching, a feature that can be exploited therapeutically by concomitant KDM6A and P300/CBP inhibition. Overall, this study indicates that the steady-state histone acetylation-methylation equilibrium functions as a molecular rheostat governing cellular transcription that is amenable to therapeutic exploitation as an anti-cancer regimen., Competing Interests: Declaration of interests The Johnstone laboratory receives funding support from Roche, Bristol Myers Squibb (BMS), AstraZeneca, and MecRx. R.W.J. is a shareholder in and consultant for MecRx. A.L. and K.D.B. are employees of and shareholders in AbbVie. A.S. has participated on advisory boards for and received research funding from Celgene, Juno, BMS, Janssen-Cilag, Novartis, Amgen, Haemalogix, Abbvie, and Takeda. J.S. has participated on advisory boards for and received honoraria from Celgene. O.A.-W. has served as a consultant for H3B Biomedicine, Foundation Medicine Inc., Merck, Prelude Therapeutics, and Janssen; is on the scientific advisory boards of Envisagenics Inc., Pfizer Boulder, and AIChemy Inc.; and has received prior research funding from Loxo Oncology and H3 Biomedicine. J.D.L. is a scientific adviser to the Samuel Waxman Cancer Research Foundation. All other authors declare no competing interests., (Crown Copyright © 2021. Published by Elsevier Inc. All rights reserved.)

The metazoan-specific acetyltransferase p300/CBP is involved in activating signal-induced, enhancer-mediated transcription of cell-type-specific genes. However, the global kinetics and mechanisms of p300/CBP activity-dependent transcription activation remain poorly understood. We performed genome-wide, time-resolved analyses to show that enhancers and super-enhancers are dynamically activated through p300/CBP-catalyzed acetylation, deactivated by the opposing deacetylase activity, and kinetic acetylation directly contributes to maintaining cell identity at very rapid (minutes) timescales. The acetyltransferase activity is dispensable for the recruitment of p300/CBP and transcription factors but essential for promoting the recruitment of TFIID and RNAPII at virtually all enhancers and enhancer-regulated genes. This identifies pre-initiation complex assembly as a dynamically controlled step in the transcription cycle and reveals p300/CBP-catalyzed acetylation as the signal that specifically promotes transcription initiation at enhancer-regulated genes. We propose that p300/CBP activity uses a "recruit-and-release" mechanism to simultaneously promote RNAPII recruitment and pause release and thereby enables kinetic activation of enhancer-mediated transcription., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Traumatic brain injury (TBI) is the largest non-genetic, non-aging related risk factor for Alzheimer's disease (AD). We report here that TBI induces tau acetylation (ac-tau) at sites acetylated also in human AD brain. This is mediated by S-nitrosylated-GAPDH, which simultaneously inactivates Sirtuin1 deacetylase and activates p300/CBP acetyltransferase, increasing neuronal ac-tau. Subsequent tau mislocalization causes neurodegeneration and neurobehavioral impairment, and ac-tau accumulates in the blood. Blocking GAPDH S-nitrosylation, inhibiting p300/CBP, or stimulating Sirtuin1 all protect mice from neurodegeneration, neurobehavioral impairment, and blood and brain accumulation of ac-tau after TBI. Ac-tau is thus a therapeutic target and potential blood biomarker of TBI that may represent pathologic convergence between TBI and AD. Increased ac-tau in human AD brain is further augmented in AD patients with history of TBI, and patients receiving the p300/CBP inhibitors salsalate or diflunisal exhibit decreased incidence of AD and clinically diagnosed TBI., Competing Interests: Declaration of interests A.A.P. is an inventor on patents related to P7C3. L.G. is a founder of Aeton Therapeutics. No other authors declare competing interests., (Published by Elsevier Inc.)