Minor histocompatibility antigens to predict, monitor or manipulate GvL and GvHD after allogeneic hematopoietic cell transplantation.

Allogeneic hematopoietic cell transplantation (alloHCT) provides a potential curative treatment for haematological malignancies. The therapeutic Graft-versus-Leukaemia (GvL) effect is induced by donor T cells attacking patient hematopoietic (malignant) cells. However, if healthy non-hematopoietic tissues are targeted, Graft-versus-Disease (GvHD) may develop. After HLA-matched alloHCT, GvL and GvHD are induced by donor T cells recognizing polymorphic peptides presented by HLA on patient cells, so-called minor histocompatibility antigens (MiHAs). The balance between GvL and GvHD depends on the tissue distribution of MiHAs and T-cell frequencies targeting these MiHAs. T cells against broadly expressed MiHAs induce GvL and GvHD, whereas those targeting MiHAs with hematopoietic-restricted expression induce GvL without GvHD. Recently, the MiHA repertoire identified in natural immune responses after alloHCT was expanded to 159 total HLA-I-restricted MiHAs, including 14 hematopoietic-restricted MiHAs. This review explores their potential relevance to predict, monitor, and manipulate GvL and GvHD for improving clinical outcome after HLA-matched alloHCT.

Structural basis of the obligatory exchange mode of human neutral amino acid transporter ASCT2.

ASCT2 is an obligate exchanger of neutral amino acids, contributing to cellular amino acid homeostasis. ASCT2 belongs to the same family (SLC1) as Excitatory Amino Acid Transporters (EAATs) that concentrate glutamate in the cytosol. The mechanism that makes ASCT2 an exchanger rather than a concentrator remains enigmatic. Here, we employ cryo-electron microscopy and molecular dynamics simulations to elucidate the structural basis of the exchange mechanism of ASCT2. We establish that ASCT2 binds three Na+ ions per transported substrate and visits a state that likely acts as checkpoint in preventing Na+ ion leakage, both features shared with EAATs. However, in contrast to EAATs, ASCT2 retains one Na+ ion even under Na+-depleted conditions. We demonstrate that ASCT2 cannot undergo the structural transition in TM7 that is essential for the concentrative transport cycle of EAATs. This structural rigidity and the high-affinity Na+ binding site effectively confine ASCT2 to an exchange mode.

The effect of rs2910686 on ERAP2 expression in IBD and epithelial inflammatory response.

BACKGROUND: ERAP2 is an aminopeptidase involved in antigen processing and presentation, and harbor genetic variants linked to several inflammatory diseases such as Inflammatory Bowel Disease (IBD). The lack of an ERAP2 gene homologue in mice has hampered functional studies, and most human studies have focused on cells of hematopoietic origin. Using an IBD biobank as vantage point, this study explores how genetic variation in ERAP2 affects gene expression in human-derived epithelial organoids upon proinflammatory stimulation. METHODS: An IBD patient cohort was genotyped with regards to two single nucleotide polymorphisms (SNP) (rs2910686/rs2248374) associated with ERAP2 expression levels, and we examined the correlation between colon gene expression and genotype, specifically aiming to establish a relationship with ERAP2 expression proficiency. Human-derived colon organoids (colonoids) with known ERAP2 genotype were established and used to explore differences in whole genome gene expression between ERAP2-deficient (n = 4) and -proficient (n = 4) donors upon pro-inflammatory encounter. RESULTS: When taking rs2910686 genotype into account, ERAP2 gene expression is upregulated in the inflamed colon of IBD patients. Colonoids upregulate ERAP2 upon IFNÉ£ stimulation, and ERAP2 expression proficiency is dependent on rs2910686 genotype. Colonoid genotyping confirms that mechanisms independent of the frequently studied SNP rs2248374 can cause ERAP2-deficiency. A total of 586 genes involved in various molecular mechanisms are differentially expressed between ERAP2 proficient- and deficient colonoids upon proinflammatory stimulation, including genes encoding proteins with the following molecular function: catalytic activity (AOC1, CPE, ANPEP and MEP1A), regulator activity (TNFSF9, MDK, GDF15, ILR6A, LGALS3 and FLNA), transmembrane transporter activity (SLC40A1 and SLC5A1), and extracellular matrix structural constituents (FGL2, HMCN2, and MUC17). CONCLUSIONS: ERAP2 is upregulated in the inflamed IBD colon mucosa, and expression proficiency is highly correlated with genotype of rs2910686. While the SNP rs2248374 is commonly used to determine ERAP2 expressional proficiency, our data confirms that mechanisms independent of this SNP can lead to ERAP2 deficiency. Our data demonstrates that epithelial ERAP2 presence affects the inflammatory response in colonoids, suggesting a pleiotropic role of ERAP2 beyond MHC class I antigen processing.

ERAP Inhibitors in Autoimmunity and Immuno-Oncology: Medicinal Chemistry Insights.

Endoplasmic reticulum aminopeptidases ERAP1 and 2 are intracellular aminopeptidases that trim antigenic precursors and generate antigens presented by major histocompatibility complex class I (MHC-I) molecules. They thus modulate the antigenic repertoire and drive the adaptive immune response. ERAPs are considered as emerging targets for precision immuno-oncology or for the treatment of autoimmune diseases, in particular MHC-I-opathies. This perspective covers the structural and biological characterization of ERAP, their relevance to these diseases and the ongoing research on small-molecule inhibitors. We describe the chemical and pharmacological space explored by medicinal chemists to exploit the potential of these targets given their localization, biological functions, and family depth. Specific emphasis is put on the binding mode, potency, selectivity, and physchem properties of inhibitors featuring diverse scaffolds. The discussion provides valuable insights for the future development of ERAP inhibitors and analysis of persisting challenges for the translation for clinical applications.

UBE2C-induced crosstalk between mono- and polyubiquitination of SNAT2 promotes lymphatic metastasis in bladder cancer.

Ubiquitination plays an essential role in protein stability, subcellular localization, and interactions. Crosstalk between different types of ubiquitination results in distinct biological outcomes for proteins. However, the role of ubiquitination-related crosstalk in lymph node (LN) metastasis and the key regulatory factors controlling this process have not been determined. Using high-throughput sequencing, we found that ubiquitin-conjugating enzyme E2 C (UBE2C) was overexpressed in bladder cancer (BCa) and was strongly associated with an unfavorable prognosis. Overexpression of UBE2C increased BCa lymphangiogenesis and promoted LN metastasis both in vitro and in vivo. Mechanistically, UBE2C mediated sodium-coupled neutral amino acid transporter 2 (SNAT2) monoubiquitination at lysine 59 to inhibit K63-linked polyubiquitination at lysine 33 of SNAT2. Crosstalk between monoubiquitination and K63-linked polyubiquitination increased SNAT2 membrane protein levels by suppressing epsin 1-mediated (EPN1-mediated) endocytosis. SNAT2 facilitated glutamine uptake and metabolism to promote VEGFC secretion, ultimately leading to lymphangiogenesis and LN metastasis in patients with BCa. Importantly, inhibition of UBE2C significantly attenuated BCa lymphangiogenesis in a patient-derived xenograft model. Our results reveal the mechanism by which UBE2C mediates crosstalk between the monoubiquitination and K63-linked polyubiquitination of SNAT2 to promote BCa metastasis and identify UBE2C as a promising target for treating LN-metastatic BCa.

Congenital Heart Disease and Genetic Changes in Folate/Methionine Cycles.

Congenital heart disease is one of the most common congenital malformations and thus represents a considerable public health burden. Hence, the identification of individuals and families with an increased genetic predisposition to congenital heart disease (CHD) and its possible prevention is important. Even though CHD is associated with the lack of folate during early pregnancy, the genetic background of folate and methionine metabolism perturbations and their influence on CHD risk is not clear. While some genes, such as those coding for cytosolic enzymes of folate/methionine cycles, have been extensively studied, genetic studies of folate transporters (de)glutamation enzymes and mitochondrial enzymes of the folate cycle are lacking. Among genes coding for cytoplasmic enzymes of the folate cycle, MTHFR, MTHFD1, MTR, and MTRR have the strongest association with CHD, while among genes for enzymes of the methionine cycle BHMT and BHMT2 are the most prominent. Among mitochondrial folate cycle enzymes, MTHFD2 plays the most important role in CHD formation, while FPGS was identified as important in the group of (de)glutamation enzymes. Among transporters, the strongest association with CHD was demonstrated for SLC19A1.

Reprogramming of Glutamine Amino Acid Transporters Expression and Prognostic Significance in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the most prevalent primary liver malignancy and is a major cause of cancer-related mortality in the world. This study aimed to characterize glutamine amino acid transporter expression profiles in HCC compared to those of normal liver cells. In vitro and in vivo models of HCC were studied using qPCR, whereas the prognostic significance of glutamine transporter expression levels within patient tumors was analyzed through RNAseq. Solute carrier (SLC) 1A5 and SLC38A2 were targeted through siRNA or gamma-p-nitroanilide (GPNA). HCC cells depended on exogenous glutamine for optimal survival and growth. Murine HCC cells showed superior glutamine uptake rate than normal hepatocytes (p < 0.0001). HCC manifested a global reprogramming of glutamine transporters compared to normal liver: SLC38A3 levels decreased, whereas SLC38A1, SLC7A6, and SLC1A5 levels increased. Also, decreased SLC6A14 and SLC38A3 levels or increased SLC38A1, SLC7A6, and SLC1A5 levels predicted worse survival outcomes (all p < 0.05). Knockdown of SLC1A5 and/or SLC38A2 expression in human Huh7 and Hep3B HCC cells, as well as GPNA-mediated inhibition, significantly decreased the uptake of glutamine; combined SLC1A5 and SLC38A2 targeting had the most considerable impact (all p < 0.05). This study revealed glutamine transporter reprogramming as a novel hallmark of HCC and that such expression profiles are clinically significant.

Regulation of MAIT cells through host-derived antigens.

Mucosal-associated invariant T (MAIT) cells are a major subset of innate-like T cells that function at the interface between innate and acquired immunity. MAIT cells recognize vitamin B2-related metabolites produced by microbes, through semi-invariant T cell receptor (TCR) and contribute to protective immunity. These foreign-derived antigens are presented by a monomorphic antigen presenting molecule, MHC class I-related molecule 1 (MR1). MR1 contains a malleable ligand-binding pocket, allowing for the recognition of compounds with various structures. However, interactions between MR1 and self-derived antigens are not fully understood. Recently, bile acid metabolites were identified as host-derived ligands for MAIT cells. In this review, we will highlight recent findings regarding the recognition of self-antigens by MAIT cells.

Specific association of MTHFD1 expressions with small cell lung cancer development and chemoradiotherapy outcome.

OBJECTIVES: To identify biomarkers that can discriminated small cell lung cancer (SCLC) from non-SCLC (NSCLC), and explore their association with the prognosis of SCLC under chemoradiotherapy. METHODS: The GSE40275 dataset was used to identify potential targets in SCLC. There were 196 patients of lung cancer (LC) in cohort 1 of this study. MTHFD1 levels in tissues were determined by immunohistochemistry assay in cohort 1. Lung cancer patients who were all underwent local chemoradiotherapy (CRT) were included in cohort 2, and the association of MTHFD1 levels with CRT treatment outcome were determined in cohort 2. Cell experiments were used to determine the function of MTHFD1 on the radio-sensitivity of SCLC and NSCLC cells. RESULTS: The MTHFD1 levels in LC tissues were increased, and could discriminate SCLC from both lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD). Small cell lung cancer patients with MTHFD1 high phenotype had a poorer prognosis after CRT treatment, whereas no significant correlation was found between MTHFD1 levels and prognosis in LUSC and LUAD group. Cell experiments demonstrated that overexpression of MTHFD1 increases radio-resistance in both SCLC and NSCLC in vitro. CONCLUSION: MTHFD1 expressions might be a novel specifically prognostic biomarker for SCLC and the CRT treatment outcome.

Association of Endoplasmic Reticulum Aminopeptidase 1 Gene Polymorphism with Susceptibility and Severity of Axial Spondyloarthritis in Egyptian Population: A Single-center Case-Control Study.

BACKGROUND: Axial spondyloarthritis (axSpA) is a systemic, progressive, autoimmune disease. Complex interactions between environmental factors and host immune responses are the origin of axSpA. Together with human leukocyte antigen (HLA-B27), endoplasmic reticulum aminopeptidase 1 (ERAP1) gene is a potential non-HLA contributor to axSpA susceptibility. AIM: This study aimed to identify the role of ERAP1 single-nucleotide polymorphisms (SNPs) (rs30187, rs27044, and rs27037) in susceptibility to and severity of axSpA in Egyptian patients. METHODS: In this case-control study, we enrolled 120 patients with axSpA and 120 healthy individuals as controls. Real-time polymerase chain reaction was used to identify ERAP1 polymorphisms. RESULTS: The present study revealed no significant association between ERAP1 SNPs (rs30187, rs27044, and rs27037) and axSpA susceptibility in Egyptian patients. A significant relationship was found only between the ERAP1 SNP rs27037 "GT" genotype and axSpA HLA-B27-positive cases, demonstrating a functional interaction between ERAP1 and HLA-B27-positive cases. Our analysis revealed a significant association between the ERAP1 SNP rs27037 "GT and TT" genotypes and Bath Ankylosing Spondylitis Disease Activity Index, in addition to an association between the ERAP1 SNP rs27037 "TT" genotype and active enthesitis. The ERAP1 SNP rs27044 "GG" genotype was significantly associated with active enthesitis, but not with clinical axial involvement. Finally, we did not observe a significant relationship between HLA-B27 positivity and disease severity in the studied cases. CONCLUSION: Three SNPs (rs30187, rs27044, and rs27037) in ERAP1 do not confer susceptibility to axSpA in Egyptian patients. This association existed exclusively between the ERAP1 SNP (rs27037) "GT" genotype and axSpA HLA-B27-positive cases.

Résumé Contexte:la spondyloarthrite axiale (SpAx) est une maladie auto-immune systémique et progressive. Les interactions complexes entre les facteurs environnementaux et les réponses immunitaires de l'hôte sont à l'origine de la SpAx. En plus de l'antigène leucocytaire humain (HLAB27), le gène de l'aminopeptidase du réticulum endoplasmique 1 (ERAP1) est un contributeur potentiel non-HLA à la susceptibilité à la SpAx.Objectif:cette étude visait à identifier le rôle des polymorphismes mononucléotidiques (SNP) de l'ERAP1 (rs30187, rs27044 et rs27037) dans la susceptibilité et la gravité de la SpAx chez les patients égyptiens.Méthodes:dans cette étude cas-témoins, nous avons inclus 120 patients atteints de SpAx et 120 individus en bonne santé comme témoins. La réaction en chaîne de la polymérase en temps réel a été utilisée pour identifier les polymorphismes de l'ERAP1.Résultats:cette étude a révélé qu'il n'y avait pas d'association significative entre les SNP de l'ERAP1 (rs30187, rs27044 et rs27037) et la susceptibilité à la SpAx chez les patients égyptiens. Une relation significative a été trouvée uniquement entre le génotype "GT" du SNP rs27037 de l'ERAP1 et les cas de SpAx positifs pour le HLA-B27, démontrant une interaction fonctionnelle entre l'ERAP1 et les cas positifs pour le HLA-B27. Notre analyse a révélé une association significative entre les génotypes "GT et TT" du SNP rs27037 de l'ERAP1 et l'indice d'activité de la maladie de spondylarthrite ankylosante de Bath, ainsi qu'une association entre le génotype "TT" du SNP rs27037 de l'ERAP1 et l'enthésite active. Le génotype "GG" du SNP rs27044 de l'ERAP1 était significativement associé à l'enthésite active, mais non à l'atteinte axiale clinique. Enfin, nous n'avons pas observé de relation significative entre la positivité du HLA-B27 et la gravité de la maladie dans les cas étudiés.Conclusion:trois SNP (rs30187, rs27044 et rs27037) dans l'ERAP1 ne confèrent pas de susceptibilité à la SpAx chez les patients égyptiens. Cette association existait exclusivement entre le génotype "GT" du SNP rs27037 de l'ERAP1 et les cas de SpAx positifs pour le HLA-B27.

Hypoxia-induced cysteine metabolism reprogramming is crucial for the tumorigenesis of colorectal cancer.

Metabolic reprogramming is a hallmark of human cancer, and cancer-specific metabolism provides opportunities for cancer diagnosis, prognosis, and treatment. However, the underlying mechanisms by which metabolic pathways affect the initiation and progression of colorectal cancer (CRC) remain largely unknown. Here, we demonstrate that cysteine is highly enriched in colorectal tumors compared to adjacent non-tumor tissues, thereby promoting tumorigenesis of CRC. Synchronously importing both cysteine and cystine in colorectal cancer cells is necessary to maintain intracellular cysteine levels. Hypoxia-induced reactive oxygen species (ROS) and ER stress regulate the co-upregulation of genes encoding cystine transporters (SLC7A11, SLC3A2) and genes encoding cysteine transporters (SLC1A4, SLC1A5) through the transcription factor ATF4. Furthermore, the metabolic flux from cysteine to reduced glutathione (GSH), which is critical to support CRC growth, is increased due to overexpression of glutathione synthetase GSS in CRC. Depletion of cystine/cysteine by recombinant cyst(e)inase effectively inhibits the growth of colorectal tumors by inducing autophagy in colorectal cancer cells through mTOR-ULK signaling axis. This study demonstrates the underlying mechanisms of cysteine metabolism in tumorigenesis of CRC, and evaluates the potential of cysteine metabolism as a biomarker or a therapeutic target for CRC.

[Relationship between maternal and fetal ERAP-1 gene polymorphism and pre-eclampsia].

Objective: To investigate the relationship between the polymorphism of endoplasmic reticulum aminopeptidase 1 (ERAP-1) gene and the occurrence of pre-eclampsia (PE). Methods: A case-control study was conducted in Beijing Obstetrics and Gynecology Hospital from October 2018 to October 2021. A total of 51 PE pregnant women with onset gestational age<34 weeks were selected as the PE group, and 48 normal pregnant women during the same period were selected as the control group. Venous blood samples were collected from the pregnant women before delivery and umbilical cord within 5 minutes after delivery. Single nucleotide polymorphisms (SNP) of ERAP-1 gene in the pregnant women and their fetus were detected by next-generation sequencing. Univariate analysis and multivariate logistic regression analysis were used to analyze all the SNP loci and alleles detected in the two groups, and the significant SNP were screened. Results: (1) A total of 13 target SNP loci of maternal ERAP-1 gene were selected by univariate analysis. Among them, the frequency distribution of genotypes at 96096828, 96121524, 96121715, 96122260 and 96122281 showed statistically significant differences between PE group and control group (all P<0.05). Multivariate logistic regression analysis showed that the risk of PE in pregnant women with TC genotype at locus 96121524 was 2.002 times higher than those with TT genotype (95%CI: 0.687-5.831, P=0.020). (2) A total of 4 target SNP loci of ERAP-1 gene in fetal were selected by univariate analysis, and there was no statistical significance in gene polymorphism of the 4 loci between PE group and control group (all P>0.05). Multivariate logistic regression analysis showed that the risk of PE in fetus with genotype AA at locus 96121406 was 0.236 times that of fetus with genotype GG (95%CI: 0.055-1.025, P=0.016). Conclusion: ERAP-1 gene with TC genotype at 96121524 in the mother and GG genotype at 96121406 in the fetus might be related to the incidence of PE.

Co-Expression Network Analysis and Molecular Docking Demonstrate That Diosgenin Inhibits Gastric Cancer Progression via SLC1A5/mTORC1 Pathway.

Background: Tumor-Node-Metastasis (TNM) stage of gastric cancer (GC) is one of the main factors affecting clinical outcome. The aim of this study was to explore the targets related to TNM stage of GC, and screening natural bioactive drug. Methods: RNA sequencing data of the TCGA-STAD cohort were downloaded from UCSC database. Genes associated with TNM staging were identified by weighted gene co-expression network analysis (WGCNA). Univariate Cox regression, least absolute shrinkage and selection operator (LASSO), extreme gradient boosting (Xgboost), random forest (RF) and cytohubba plug-in of cytoscope were applied to screen hub genes. Natural bioactive ingredients were available from the HERB database. Molecular docking was used to evaluate the binding activity of active ingredients to the hub protein. CCK-8, flow cytometry, transwell and Western blot assays were used to analyze the effects of diosgenin on GC cells. Results: 898 TNM-related genes were screened out through WGCNA. Three genes associated with GC progression/prognosis were identified, including nuclear receptor subfamily 3 group C member 2 (NR3C2), solute carrier family 1 member 5 (SLC1A5) and FAT atypical cadherin 1 (FAT1) based on the machine learning algorithms and hub co-expression network analysis. Diosgenin had good binding activity with SLC1A5. SLC1A5 was highly expressed in GC and was closely associated with tumor stage, overall survival and immune infiltration of GC patients. Diosgenin could inhibit cell viability and invasive ability, promote apoptosis and induce cell cycle arrest in G0/G1 phase. In addition, diosgenin promoted cleaved caspase 3 expression and inhibited Ki67, cyclin D1, p-S6K1, and SLC1A5 expression levels, while the mTORC1 activator (MHY1485) reversed this phenomenon. Conclusion: For the first time, this work reports diosgenin may inhibit the activation of mTORC1 signaling through targeting SLC1A5, thereby inhibiting the malignant behaviors of GC cells.

Carnosic Acid: A Novel Selective Inhibitor of ERAP1 by Direct Binding and Its Modulation of Antigen Processing and Presentation.

ERAP1 is an emerging target for a large subclass of severe autoimmune diseases known as "MHC-I-opathy", together with tumor immunity. Nevertheless, effective inhibitors targeting ERAP1 remain a challenge. In this study, a novel food-derived natural product ERAP1-targeting inhibitor, carnosic acid, was identified, and to our knowledge, it is one of the best active compounds among the highly selective inhibitors targeting the orthosteric site of ERAP1. The results reveal that carnosic acid could bind strongly, like a key to the ERAP1 active site in the biased S1' pocket, which is different from the binding mode of the existing orthosteric site inhibitors. HLA-B27-mediated cell modeling validated that carnosic acid has the activity to reverse the AS-associated cellular phenotype brought on by ERAP1 through inhibition. Our findings provide insights into the design of potent inhibitors against the ERAP1 orthosteric site and the discovery of a key direct target of carnosic acid.

The cytidine deaminase APOBEC3C has unique sequence and genome feature preferences.

APOBEC proteins are cytidine deaminases that restrict the replication of viruses and transposable elements. Several members of the APOBEC3 family, APOBEC3A, APOBEC3B, and APOBEC3H-I, can access the nucleus and cause what is thought to be indiscriminate deamination of the genome, resulting in mutagenesis and genome instability. Although APOBEC3C is also present in the nucleus, the full scope of its deamination target preferences is unknown. By expressing human APOBEC3C in a yeast model system, I have defined the APOBEC3C mutation signature, as well as the preferred genome features of APOBEC3C targets. The APOBEC3C mutation signature is distinct from those of the known cancer genome mutators APOBEC3A and APOBEC3B. APOBEC3C produces DNA strand-coordinated mutation clusters, and APOBEC3C mutations are enriched near the transcription start sites of active genes. Surprisingly, APOBEC3C lacks the bias for the lagging strand of DNA replication that is seen for APOBEC3A and APOBEC3B. The unique preferences of APOBEC3C constitute a mutation profile that will be useful in defining sites of APOBEC3C mutagenesis in human genomes.

Comparing the roles of sex chromosome-encoded protein homologs in gene regulation.

The X and Y chromosomes play important roles outside of human reproduction; namely, their potential contribution to human sex biases in physiology and disease. While sex biases are often thought to be an effect of hormones and environmental exposures, genes encoded on the sex chromosomes also play a role. Seventeen homologous gene pairs exist on the X and Y chromosomes whose proteins have critical functions in biology, from direct regulation of transcription and translation to intercellular signaling and formation of extracellular structures. In this review, we cover the current understanding of several of these sex chromosome-encoded protein homologs that are involved in transcription and chromatin regulation: SRY/SOX3, ZFX/ZFY, KDM5C/KDM5D, UTX/UTY, and TBL1X/TBL1Y. Their mechanisms of gene regulation are discussed, including any redundancies or divergent roles of the X- and Y-chromosome homologs. Additionally, we discuss associated diseases related to these proteins and any sex biases that exist therein in an effort to drive further research into how these pairs contribute to sexually dimorphic gene regulation in health and disease.

Cutting Edge: Redundant Roles for MHC Class II-, CD1d-, and MR1-restricted T Cells in Clearing Bartonella Infection.

The importance of unconventional T cells for mucosal immunity is firmly established but for systemic bacterial infection remains less well defined. In this study, we explored the role of various T cell subsets in murine Bartonella infection, which establishes persistent bacteremia unless controlled by antibacterial Abs. We found that αß T cells are essential for Ab production against and clearance of B. taylorii, whereas MHC class I (MHC-I)- or MHC class II (MHC-II)-deficient mice eliminated B. taylorii infection with normal kinetics. Similarly, animals lacking either CD1d or MR1 suppressed bacteremia with normal kinetics. Interestingly, mice with a combined deficiency of either MHC-II and CD1d or MHC-II and MR1 failed to clear the infection, indicating that the combination of CD1d- and MR1-restricted T cells can compensate for the lack of MHC-II in this model. Our data document a previously underappreciated contribution of unconventional T cells to the control of systemic bacterial infection, supposedly as helper cells for antibacterial Ab production.

Discovery of a Covalent Inhibitor That Overcame Resistance to Venetoclax in AML Cells Overexpressing BFL-1.

Clinical and biological studies have shown that overexpression of BFL-1 is one contributing factor to venetoclax resistance. The resistance might be overcome by a potent BFL-1 inhibitor, but such an inhibitor is rare. In this study, we show that 56, featuring an acrylamide moiety, inhibited the BFL-1/BID interaction with a Ki value of 105 nM. More interestingly, 56 formed an irreversible conjugation adduct at the C55 residue of BFL-1. 56 was a selective BFL-1 inhibitor, and its MCL-1 binding affinity was 10-fold weaker, while it did not bind BCL-2 and BCL-xL. Mechanistic studies showed that 56 overcame venetoclax resistance in isogenic AML cell lines MOLM-13-OE and MV4-11-OE, which both overexpressed BFL-1. More importantly, 56 and venetoclax combination promoted stronger apoptosis induction than either single agent. Collectively, our data show that 56 overcame resistance to venetoclax in AML cells overexpressing BFL-1. These attributes make 56 a promising candidate for future optimization.

Design of a Lead-Like Cysteine-Targeting Covalent Library and the Identification of Hits to Cys55 of Bfl-1.

Covalent hit identification is a viable approach to identify chemical starting points against difficult-to-drug targets. While most researchers screen libraries of <2k electrophilic fragments, focusing on lead-like compounds can be advantageous in terms of finding hits with improved affinity and with a better chance of identifying cryptic pockets. However, due to the increased molecular complexity, larger numbers of compounds (>10k) are desirable to ensure adequate coverage of chemical space. Herein, the approach taken to build a library of 12k covalent lead-like compounds is reported, utilizing legacy compounds, robust library chemistry, and acquisitions. The lead-like covalent library was screened against the antiapoptotic protein Bfl-1, and six promising hits that displaced the BIM peptide from the PPI interface were identified. Intriguingly, X-ray crystallography of lead-like compound 8 showed that it binds to a previously unobserved conformation of the Bfl-1 protein and is an ideal starting point for the optimization of Bfl-1 inhibitors.

New insights into ATR inhibition in muscle invasive bladder cancer: The role of apolipoprotein B mRNA editing catalytic subunit 3B.

Background: Apolipoprotein B mRNA editing catalytic polypeptide (APOBEC), an endogenous mutator, induces DNA damage and activates the ataxia telangiectasia and Rad3-related (ATR)-checkpoint kinase 1 (Chk1) pathway. Although cisplatin-based therapy is the mainstay for muscle-invasive bladder cancer (MIBC), it has a poor survival rate. Therefore, this study aimed to evaluate the efficacy of an ATR inhibitor combined with cisplatin in the treatment of APOBEC catalytic subunit 3B (APOBEC3B) expressing MIBC. Methods: Immunohistochemical staining was performed to analyze an association between APOBEC3B and ATR in patients with MIBC. The APOBEC3B expression in MIBC cell lines was assessed using real-time polymerase chain reaction and western blot analysis. Western blot analysis was performed to confirm differences in phosphorylated Chk1 (pChk1) expression according to the APOBEC3B expression. Cell viability and apoptosis analyses were performed to examine the anti-tumor activity of ATR inhibitors combined with cisplatin. Conclusion: There was a significant association between APOBEC3B and ATR expression in the tumor tissues obtained from patients with MIBC. Cells with higher APOBEC3B expression showed higher pChk1 expression than cells expressing low APOBEC3B levels. Combination treatment of ATR inhibitor and cisplatin inhibited cell growth in MIBC cells with a higher APOBEC3B expression. Compared to cisplatin single treatment, combination treatment induced more apoptotic cell death in the cells with higher APOBEC3B expression. Conclusion: Our study shows that APOBEC3B's higher expression status can enhance the sensitivity of MIBC to cisplatin upon ATR inhibition. This result provides new insight into appropriate patient selection for the effective application of ATR inhibitors in MIBC.