Explore the vast range of titles available.

B-cell non-Hodgkin’s lymphoma comprises biologically and clinically distinct diseases the pathogenesis of which is associated with genetic lesions affecting oncogenes and tumour-suppressor genes. We report here that the two most common types—follicular lymphoma and diffuse large B-cell lymphoma—harbour frequent structural alterations inactivating CREBBP and, more rarely, EP300 , two highly related histone and non-histone acetyltransferases (HATs) that act as transcriptional co-activators in multiple signalling pathways. Overall, about 39% of diffuse large B-cell lymphoma and 41% of follicular lymphoma cases display genomic deletions and/or somatic mutations that remove or inactivate the HAT coding domain of these two genes. These lesions usually affect one allele, suggesting that reduction in HAT dosage is important for lymphomagenesis. We demonstrate specific defects in acetylation-mediated inactivation of the BCL6 oncoprotein and activation of the p53 tumour suppressor. These results identify CREBBP/EP300 mutations as a major pathogenetic mechanism shared by common forms of B-cell non-Hodgkin’s lymphoma, with direct implications for the use of drugs targeting acetylation/deacetylation mechanisms. CREBBP and EP300 mutations in B-cell lymphoma In three different subtypes of B-cell lymphomas, two papers report frequent somatic mutations in the genes CREBBP and EP300 , which are present in primary tumours or acquired at relapse. These genes encode related acetyltransferases that mainly function to regulate gene expression by acetylating histones and other transcriptional regulators. The mutations disrupt these activities and thus alter chromatin regulation of gene expression, as well as proliferation and potentially the response to anticancer drugs. These studies may provide a rationale for the use of histone deacetylase inhibitors in certain B-cell lymphomas. In three different subtypes of B-cell lymphomas, two papers now report frequent somatic mutations in CREBBP and EP300 , present in primary tumours or acquired at relapse. These genes encode related acetyltransferases that mainly function to regulate gene expression by acetylating histones and other transcriptional regulators. The mutations found inactivate these activities and thus alter chromatin regulation of gene expression, as well as proliferation and potentially the response to therapeutic drugs.

Runt-related transcription factor 2 (Runx2) transactivates many genes required for osteoblast differentiation. The role of N -α-acetyltransferase 10 (NAA10, arrest-defective-1), originally identified in yeast, remains poorly understood in mammals. Here we report a new NAA10 function in Runx2-mediated osteogenesis. Runx2 stabilizes NAA10 in osteoblasts during BMP-2-induced differentiation, and NAA10 in turn controls this differentiation by inhibiting Runx2. NAA10 delays bone healing in a rat calvarial defect model and bone development in neonatal mice. Mechanistically, NAA10 acetylates Runx2 at Lys225, and this acetylation inhibits Runx2-driven transcription by interfering with CBFβ binding to Runx2. Our study suggests that NAA10 acts as a guard ensuring balanced osteogenesis by fine-tuning Runx2 signalling in a feedback manner. NAA10 inhibition could be considered a potential strategy for facilitating bone formation. N -alpha-acetyltransferase 10 (NAA10) regulates cell growth and proliferation. Here the authors show that NAA10 also has a role in osteogenesis, by fine-tuning the activity of the osteogenic transcription factor Runx2.

Posttranslational modifications add tremendous complexity to proteomes; however, gaps remain in knowledge regarding the function and regulatory mechanism of newly discovered lysine acylation modifications. Here, we compared a panel of non-histone lysine acylation patterns in metastasis models and clinical samples, and focused on 2-hydroxyisobutyrylation (Khib) due to its significant upregulation in cancer metastases. By the integration of systemic Khib proteome profiling in 20 paired primary esophageal tumor and metastatic tumor tissues with CRISPR/Cas9 functional screening, we identified N-acetyltransferase 10 (NAT10) as a substrate for Khib modification. We further showed that Khib modification at lysine 823 in NAT10 functionally contribute to metastasis. Mechanistically, NAT10 Khib modification enhances its interaction with deubiquitinase USP39, resulting in increased NAT10 protein stability. NAT10 in turn promotes metastasis by increasing NOTCH3 mRNA stability in an N4-acetylcytidine-dependent manner. Furthermore, we discovered a lead compound #7586-3507 that inhibited NAT10 Khib modification and showed efficacy in tumor models in vivo at a low concentration. Together, our findings bridge newly identified lysine acylation modifications with RNA modifications, thus providing novel insights into epigenetic regulation in human cancer. We propose that pharmacological inhibition of NAT10 K823 Khib modification constitutes a potential anti-metastasis strategy.

The human N-terminal acetyltransferase E (NatE) contains NAA10 and NAA50 catalytic, and NAA15 auxiliary subunits and associates with HYPK, a protein with intrinsic NAA10 inhibitory activity. NatE co-translationally acetylates the N-terminus of half the proteome to mediate diverse biological processes, including protein half-life, localization, and interaction. The molecular basis for how NatE and HYPK cooperate is unknown. Here, we report the cryo-EM structures of human NatE and NatE/HYPK complexes and associated biochemistry. We reveal that NAA50 and HYPK exhibit negative cooperative binding to NAA15 in vitro and in human cells by inducing NAA15 shifts in opposing directions. NAA50 and HYPK each contribute to NAA10 activity inhibition through structural alteration of the NAA10 substrate-binding site. NAA50 activity is increased through NAA15 tethering, but is inhibited by HYPK through structural alteration of the NatE substrate-binding site. These studies reveal the molecular basis for coordinated N-terminal acetylation by NatE and HYPK. The chaperone HYPK regulates the human N-terminal acetyltransferase E (NatE) complex, but the mechanism is not fully understood. Here, the authors study the interplay of NatE and HYPK by cryo-EM and biochemical approaches, providing insights into the molecular basis of N-terminal acetylation of human proteins.

Although a substantial increase in the survival of patients with other cancers has been observed in recent decades, pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest diseases. No effective screening approach exists. Differential exosomal long noncoding RNAs (lncRNAs) isolated from the serum of patients with PDAC and healthy individuals were profiled to screen for potential markers in liquid biopsies. The functions of LINC00623 in PDAC cell proliferation, migration and invasion were confirmed through in vivo and in vitro assays. RNA pulldown, RNA immunoprecipitation (RIP) and coimmunoprecipitation (Co-IP) assays and rescue experiments were performed to explore the molecular mechanisms of the LINC00623/NAT10 signaling axis in PDAC progression. A novel lncRNA, LINC00623, was identified, and its diagnostic value was confirmed, as it could discriminate patients with PDAC from patients with benign pancreatic neoplasms and healthy individuals. Moreover, LINC00623 was shown to promote the tumorigenicity and migratory capacity of PDAC cells in vitro and in vivo. Mechanistically, LINC00623 bound to N-acetyltransferase 10 (NAT10) and blocked its ubiquitination-dependent degradation by recruiting the deubiquitinase USP39. As a key regulator of N4-acetylcytidine (ac4C) modification of mRNA, NAT10 was demonstrated to maintain the stability of oncogenic mRNAs and promote their translation efficiency through ac4C modification. Our data revealed the role of LINC00623/NAT10 signaling axis in PDAC progression, showing that it is a potential biomarker and therapeutic target for PDAC.

Acute myeloid leukaemia (AML) is a heterogeneous disease characterized by transcriptional dysregulation that results in a block in differentiation and increased malignant self-renewal. Various epigenetic therapies aimed at reversing these hallmarks of AML have progressed into clinical trials, but most show only modest efficacy owing to an inability to effectively eradicate leukaemia stem cells (LSCs) 1 . Here, to specifically identify novel dependencies in LSCs, we screened a bespoke library of small hairpin RNAs that target chromatin regulators in a unique ex vivo mouse model of LSCs. We identify the MYST acetyltransferase HBO1 (also known as KAT7 or MYST2) and several known members of the HBO1 protein complex as critical regulators of LSC maintenance. Using CRISPR domain screening and quantitative mass spectrometry, we identified the histone acetyltransferase domain of HBO1 as being essential in the acetylation of histone H3 at K14. H3 acetylated at K14 (H3K14ac) facilitates the processivity of RNA polymerase II to maintain the high expression of key genes (including Hoxa9 and Hoxa10 ) that help to sustain the functional properties of LSCs. To leverage this dependency therapeutically, we developed a highly potent small-molecule inhibitor of HBO1 and demonstrate its mode of activity as a competitive analogue of acetyl-CoA. Inhibition of HBO1 phenocopied our genetic data and showed efficacy in a broad range of human cell lines and primary AML cells from patients. These biological, structural and chemical insights into a therapeutic target in AML will enable the clinical translation of these findings. The MYST acetyltransferase HBO1 is a critical regulator in maintaining leukaemia stem cells, and a small-molecule inhibitor of HBO1 is developed that shows efficacy against a range of acute myeloid leukaemia cells.

The SAGA (Spt–Ada–Gcn5 acetyltransferase) complex is an important chromatin modifying complex that can both acetylate and deubiquitinate histones. Sgf29 is a novel component of the SAGA complex. Here, we report the crystal structures of the tandem Tudor domains of Saccharomyces cerevisiae and human Sgf29 and their complexes with H3K4me2 and H3K4me3 peptides, respectively, and show that Sgf29 selectively binds H3K4me2/3 marks. Our crystal structures reveal that Sgf29 harbours unique tandem Tudor domains in its C‐terminus. The tandem Tudor domains in Sgf29 tightly pack against each other face‐to‐face with each Tudor domain harbouring a negatively charged pocket accommodating the first residue alanine and methylated K4 residue of histone H3, respectively. The H3A1 and K4me3 binding pockets and the limited binding cleft length between these two binding pockets are the structural determinants in conferring the ability of Sgf29 to selectively recognize H3K4me2/3. Our in vitro and in vivo functional assays show that Sgf29 recognizes methylated H3K4 to recruit the SAGA complex to its targets sites and mediates histone H3 acetylation, underscoring the importance of Sgf29 in gene regulation. The SAGA complex is a large histone acetyltransferase complex. Here, the crystal structure of the Sgf29 subunits tandem Tudor domains demonstrates how Sgf29 recognizes methylated H3K4 to recruit the SAGA complex to its targets sites and mediate histone H3 acetylation.

Amino-terminal acetylation is a ubiquitous modification in eukaryotes that is involved in a growing number of biological processes.There are six known eukaryotic amino-terminal acetyltransferases (NATs), which are differentiated from one another on the basis of substrate specificity. To date, two eukaryotic NATs, NatA and NatE, have been structurally characterized, of which NatA will acetylate the α-amino group of a number of nonmethionine amino-terminal residue substrates such as serine; NatE requires a substrate amino-terminal methionine residue for activity. Interestingly, these two NATs use different catalytic strategies to accomplish substrate-specific acetylation. In archaea, where this modification is less prevalent, only one NAT enzyme has been identified. Surprisingly, this enzyme is able to acetylate NatA and NatE substrates and is believed to represent an ancestral NAT variant from which the eukaryotic NAT machinery evolved. To gain insight into the evolution of NAT enzymes, we determined the X-ray crystal structure of an archaeal NAT from Sulfolobus solfataricus (ssNAT). Through the use of mutagenesis and kinetic analysis, we show that the active site of ssNAT represents a hybrid of the NatA and NatE active sites, and we highlight features of this protein that allow it to facilitate catalysis of distinct substrates through different catalytic strategies, which is a unique characteristic of this enzyme. Taken together, the structural and biochemical data presented here have implications for the evolution of eukaryotic NAT enzymes and the substrate specificities therein.

Background N-terminal acetylation is a common protein modification in human cells and is catalysed by N-terminal acetyltransferases (NATs), mostly cotranslationally. The NAA10-NAA15 (NatA) protein complex is the major NAT, responsible for acetylating ~ 40% of human proteins. Recently, NAA10 germline variants were found in patients with the X-linked lethal Ogden syndrome, and in other familial or de novo cases with variable degrees of developmental delay, intellectual disability (ID) and cardiac anomalies. Methods Here we report a novel NAA10 (NM_003491.3) c.248G > A, p.(R83H) missense variant in NAA10 which was detected by whole exome sequencing in two unrelated boys with intellectual disability, developmental delay, ADHD like behaviour, very limited speech and cardiac abnormalities. We employ in vitro acetylation assays to functionally test the impact of this variant on NAA10 enzyme activity. Results Functional characterization of NAA10-R83H by in vitro acetylation assays revealed a reduced enzymatic activity of monomeric NAA10-R83H. This variant is modelled to have an altered charge density in the acetyl-coenzyme A (Ac-CoA) binding region of NAA10. Conclusions We show that NAA10-R83H has a reduced monomeric catalytic activity, likely due to impaired enzyme-Ac-CoA binding. Our data support a model where reduced NAA10 and/or NatA activity cause the phenotypes observed in the two patients.

Amino-terminal (Nt-) acetylation (NTA) is a common protein modification, affecting 80% of cytosolic proteins in humans. The human essential gene, NAA10, encodes for the enzyme NAA10, which is the catalytic subunit in the N-terminal acetyltransferase A (NatA) complex, also including the accessory protein, NAA15. The full spectrum of human genetic variation in this pathway is currently unknown. Here we reveal the genetic landscape of variation in NAA10 and NAA15 in humans. Through a genotype-first approach, one clinician interviewed the parents of 56 individuals with NAA10 variants and 19 individuals with NAA15 variants, which were added to all known cases (N = 106 for NAA10 and N = 66 for NAA15). Although there is clinical overlap between the two syndromes, functional assessment demonstrates that the overall level of functioning for the probands with NAA10 variants is significantly lower than the probands with NAA15 variants. The phenotypic spectrum includes variable levels of intellectual disability, delayed milestones, autism spectrum disorder, craniofacial dysmorphology, cardiac anomalies, seizures, and visual abnormalities (including cortical visual impairment and microphthalmia). One female with the p.Arg83Cys variant and one female with an NAA15 frameshift variant both have microphthalmia. The frameshift variants located toward the C-terminal end of NAA10 have much less impact on overall functioning, whereas the females with the p.Arg83Cys missense in NAA10 have substantial impairment. The overall data are consistent with a phenotypic spectrum for these alleles, involving multiple organ systems, thus revealing the widespread effect of alterations of the NTA pathway in humans.