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Breast cancer is the most common cancer in women diagnosed in the U.S. and worldwide. Obesity increases breast cancer risk without clear underlying molecular mechanisms. Our studies demonstrate that circulating adipose fatty acid binding protein (A-FABP,or FABP4) links obesity-induced dysregulated lipid metabolism and breast cancer risk,thus potentially offering a new target for breast cancer treatment. We immunized FABP4 knockout mice with recombinant human FABP4 and screened hybridoma clones with specific binding to FABP4. The potential effects of antibodies on breast cancer cells in vitro were evaluated using migration,invasion,and limiting dilution assays. Tumor progression in vivo was evaluated in various types of tumorigenesis models including C57BL/6 mice,Balb/c mice,and SCID mice. The phenotype and function of immune cells in tumor microenvironment were characterized with multi-color flow cytometry. Tumor stemness was detected by ALDH assays. To characterize antigen-antibody binding capacity,we determined the dissociation constant of selected anti-FABP4 antibodies via surface plasmon resonance. Further analyses in tumor tissue were performed using 10X Genomics Visium spatial single cell technology. Herein,we report the generation of humanized monoclonal antibodies blocking FABP4 activity for breast cancer treatment in mouse models. One clone,named 12G2,which significantly reduced circulating levels of FABP4 and inhibited mammary tumor growth,was selected for further characterization. After confirming the therapeutic efficacy of the chimeric 12G2 monoclonal antibody consisting of mouse variable regions and human IgG1 constant regions,16 humanized 12G2 monoclonal antibody variants were generated by grafting its complementary determining regions to selected human germline sequences. Humanized V9 monoclonal antibody showed consistent results in inhibiting mammary tumor growth and metastasis by affecting tumor cell mitochondrial metabolism. Our current evidence suggests that targeting FABP4 with humanized monoclonal antibodies may represent a novel strategy for the treatment of breast cancer and possibly other obesity- associated diseases. The online version contains supplementary material available at 10.1186/s13058-024-01873-y. View Publication

Heme oxygenase-1 (HO-1,HMOX1 ) degrades heme protecting cells from heme-induced oxidative damage. Beyond its well-established cellular functions,heme has emerged as a stabilizer of G-quadruplexes. These secondary DNA structures interfere with DNA replication. We recently revealed that nuclear HO-1 colocalizes with DNA G-quadruplexes and promotes their removal. Here,we investigate whether HO-1 safeguards cells against replication stress. Experiments were conducted in control and HMOX1 -deficient HEK293T cell lines. Immunostaining unveiled that DNA G-quadruplexes accumulated in the absence of HO-1,the effect that was further enhanced in response to δ-aminolevulinic acid (ALA),a substrate in heme synthesis. This was associated with replication stress,as evidenced by an elevated proportion of stalled forks analyzed by fiber assay. We observed the same effects in hematopoietic stem cells isolated from Hmox1 knockout mice and in a lymphoblastoid cell line from an HMOX1 -deficient patient. Interestingly,in the absence of HO-1,the speed of fork progression was higher,and the response to DNA conformational hindrance less stringent,indicating dysfunction of the PARP1-p53-p21 axis. PARP1 activity was not decreased in the absence of HO-1. Instead,we observed that HO-1 deficiency impairs the nuclear import and accumulation of p53,an effect dependent on the removal of excess heme. We also demonstrated that administering ALA is a more specific method for increasing intracellular free heme compared to treatment with hemin,which in turn induces strong lipid peroxidation. Our results indicate that protection against replication stress is a universal feature of HO-1,presumably contributing to its widely recognized cytoprotective activity. View Publication

Immunodeficiency,Centromeric instability and Facial anomalies (ICF) syndrome is a rare genetic disorder characterized by variable immunodeficiency. More than half of the affected individuals show mild to severe intellectual disability at early onset. This disorder is genetically heterogeneous and ZBTB24 is the causative gene of the subtype 2,accounting for about 30% of the ICF cases. ZBTB24 is a multifaceted transcription factor belonging to the Zinc-finger and BTB domain-containing protein family,which are key regulators of developmental processes. Aberrant DNA methylation is the main molecular hallmark of ICF syndrome. The functional link between ZBTB24 deficiency and DNA methylation errors is still elusive. Here,we generated a novel ICF2 disease model by deriving induced pluripotent stem cells (iPSCs) from peripheral CD34 + -blood cells of a patient homozygous for the p.Cys408Gly mutation,the most frequent missense mutation in ICF2 patients and which is associated with a broad clinical spectrum. The mutation affects a conserved cysteine of the ZBTB24 zinc-finger domain,perturbing its function as transcriptional activator. ICF2-iPSCs recapitulate the methylation defects associated with ZBTB24 deficiency,including centromeric hypomethylation. We validated that the mutated ZBTB24 protein loses its ability to directly activate expression of CDCA7 and other target genes in the patient-derived iPSCs. Upon hematopoietic differentiation,ICF2-iPSCs showed decreased vitality and a lower percentage of CD34 + /CD43 + /CD45 + progenitors. Overall,the ICF2-iPSC model is highly relevant to explore the role of ZBTB24 in DNA methylation homeostasis and provides a tool to investigate the early molecular events linking ZBTB24 deficiency to the ICF2 clinical phenotype. View Publication

Mucus stasis is a pathologic hallmark of muco-obstructive diseases,including cystic fibrosis (CF). Mucins,the principal component of mucus,are extensively modified with hydroxyl (O)-linked glycans,which are largely terminated by sialic acid. Sialic acid is a negatively charged monosaccharide and contributes to the biochemical/biophysical properties of mucins. Reports suggest that mucin sialylation may be altered in CF; however,the consequences of reduced sialylation on mucus clearance have not been fully determined. Here,we investigated the consequences of reduced sialylation on the charge state and conformation of the most prominent airway mucin,MUC5B,and defined the functional consequences of reduced sialylation on mucociliary transport (MCT). Reduced sialylation contributed to a lower charged MUC5B form and decreased polymer expansion. The inhibition of total mucin sialylation de novo impaired MCT in primary human bronchial epithelial cells and rat airways,and specific α-2,3 sialylation blockade was sufficient to recapitulate these findings. Finally,we show that ST3 beta-galactoside alpha-2,3-sialyltransferase (ST3Gal1) expression is downregulated in CF and partially restored by correcting CFTR via Elexacaftor/Tezacaftor/Ivacaftor treatment. Overall,this study demonstrates the importance of mucin sialylation in mucus clearance and identifies decreased sialylation by ST3Gal1 as a possible therapeutic target in CF and potentially other muco-obstructive diseases. Subject terms: Biophysical chemistry,Glycobiology,Respiration View Publication

Human iPSC-derived cardiomyocytes (hiPSC-CMs) have proven invaluable for cardiac disease modeling and regeneration. Challenges with quality,inter-batch consistency,cryopreservation and scale remain,reducing experimental reproducibility and clinical translation. Here,we report a robust stirred suspension cardiac differentiation protocol,and we perform extensive morphological and functional characterization of the resulting bioreactor-differentiated iPSC-CMs (bCMs). Across multiple different iPSC lines,the protocol produces 1.2E6/mL bCMs with ~94% purity. bCMs have high viability after cryo-recovery (>90%) and predominantly ventricular identity. Compared to standard monolayer-differentiated CMs,bCMs are more reproducible across batches and have more mature functional properties. The protocol also works with magnetically stirred spinner flasks,which are more economical and scalable than bioreactors. Minor protocol modifications generate cardiac organoids fully in suspension culture. These reproducible,scalable,and resource-efficient approaches to generate iPSC-CMs and organoids will expand their applications,and our benchmark data will enable comparison to cells produced by other cardiac differentiation protocols. Subject terms: Cardiovascular biology,Induced pluripotent stem cells,Cardiovascular models View Publication

Lymphoid specification in human hematopoietic progenitors is not fully understood. To better associate lymphoid identity with protein-level cell features,we conduct a highly multiplexed single-cell proteomic screen on human bone marrow progenitors. This screen identifies terminal deoxynucleotidyl transferase (TdT),a specialized DNA polymerase intrinsic to VDJ recombination,broadly expressed within CD34 + progenitors prior to B/T cell emergence. While these TdT + cells coincide with granulocyte-monocyte progenitor (GMP) immunophenotype,their accessible chromatin regions show enrichment for lymphoid-associated transcription factor (TF) motifs. TdT expression on GMPs is inversely related to the SLAM family member CD84. Prospective isolation of CD84 lo GMPs demonstrates robust lymphoid potentials ex vivo,while still retaining significant myeloid differentiation capacity,akin to LMPPs. This multi-omic study identifies human bone marrow lymphoid-primed progenitors,further defining the lympho-myeloid axis in human hematopoiesis. Subject terms: Lymphopoiesis,Systems analysis,Proteomic analysis,Myelopoiesis View Publication

Acute myeloid leukaemia (AML) is a disease of the haematopoietic stem cells(HSCs) that is characterised by the uncontrolled proliferation and impaired differentiation of normal haematopoietic stem/progenitor cells. Several pathways that control the proliferation and differentiation of HSCs are impaired in AML. Activation of the Wnt/beta-catenin signalling pathway has been shown in AML and beta-catenin,which is thought to be the key element of this pathway,has been frequently highlighted. The present study was designed to determine beta-catenin expression levels and beta-catenin-related genes in AML. In this study,beta-catenin gene expression levels were determined in 19 AML patients and 3 controls by qRT-PCR. Transcriptome analysis was performed on AML grouped according to beta-catenin expression levels. Differentially expressed genes(DEGs) were investigated in detail using the Database for Annotation Visualisation and Integrated Discovery(DAVID),Gene Ontology(GO),Kyoto Encyclopedia of Genes and Genomes(KEGG),STRING online tools. The transcriptome profiles of our AML samples showed different molecular signature profiles according to their beta-catenin levels(high-low). A total of 20 genes have been identified as hub genes. Among these,TTK,HJURP,KIF14,BTF3,RPL17 and RSL1D1 were found to be associated with beta-catenin and poor survival in AML. Furthermore,for the first time in our study,the ELOV6 gene,which is the most highly up-regulated gene in human AML samples,was correlated with a poor prognosis via high beta-catenin levels. It is suggested that the identification of beta-catenin-related gene profiles in AML may help to select new therapeutic targets for the treatment of AML. View Publication

p47 phox -deficient chronic granulomatous disease (p47-CGD) is a primary immunodeficiency caused by mutations in the neutrophil cytosolic factor 1 ( NCF1 ) gene,resulting in defective NADPH oxidase function in phagocytes. Due to its complex genomic context,the NCF1 locus is not suited for safe gene editing with current genome editing technologies. Therefore,we developed a targeted NCF1 coding sequence knock-in by CRISPR-Cas9 ribonucleoprotein and viral vector template delivery,to restore p47 phox expression under the control of the endogenous NCF2 locus. NCF2 encodes for p67 phox,an NADPH oxidase subunit that closely interacts with p47 phox and is predominantly expressed in myeloid cells. This approach restored p47 phox expression and NADPH oxidase function in p47-CGD patient hematopoietic stem and progenitor cells (HSPCs) and in p47 phox -deficient mouse HSPCs,with the transgene expression following a myeloid differentiation pattern. Adeno-associated viral vectors performed favorably over integration-deficient lentiviral vectors for template delivery,with fewer off-target integrations and higher correction efficacy in HSPCs. Such myeloid-directed gene editing is promising for clinical CGD gene therapy,as it leads to the co-expression of p47 phox and p67 phox,ensuring spatiotemporal and near-physiological transgene expression in myeloid cells. View Publication

RNA constitutes a large fraction of chromatin. Spatial distribution and functional relevance of most of RNA-chromatin interactions remain unknown. We established a landscape analysis of RNA-chromatin interactions in human acute myeloid leukemia (AML). In total more than 50 million interactions were captured in an AML cell line. Protein-coding mRNAs and long non-coding RNAs exhibited a substantial number of interactions with chromatin in cis suggesting transcriptional activity. In contrast,small nucleolar RNAs (snoRNAs) and small nuclear RNAs (snRNAs) associated with chromatin predominantly in trans suggesting chromatin specific functions. Of note,snoRNA-chromatin interaction was associated with chromatin modifications and occurred independently of the classical snoRNA-RNP complex. Two C/D box snoRNAs,namely SNORD118 and SNORD3A,displayed high frequency of trans -association with chromatin. The transcription of SNORD118 and SNORD3A was increased upon leukemia transformation and enriched in leukemia stem cells,but decreased during myeloid differentiation. Suppression of SNORD118 and SNORD3A impaired leukemia cell proliferation and colony forming capacity in AML cell lines and primary patient samples. Notably,this effect was leukemia specific with less impact on healthy CD34+ hematopoietic stem and progenitor cells. These findings highlight the functional importance of chromatin-associated RNAs overall and in particular of SNORD118 and SNORD3A in maintaining leukemia propagation. Subject terms: Acute myeloid leukaemia,Cancer epigenetics View Publication

Transgene silencing provides a significant challenge in animal model production via gene engineering using viral vectors or transposons. Selecting an appropriate strategy,contingent upon the species is crucial to circumvent transgene silencing,necessitating long-term observation of in vivo gene expression. This study employed the PiggyBac transposon to create a GFP rat model to address transgene silencing in rats. Surprisingly,transgene silencing occurred while using the CAG promoter,contrary to conventional understanding,whereas the Ef1α promoter prevented silencing. GFP expression remained stable through over five generations,confirming efficacy of the Ef1α promoter for long-term protein expression in rats. Additionally,GFP expression was consistently maintained at the cellular level in various cellular sources produced from the GFP rats,thereby validating the in vitro GFP expression of GFP rats. Whole-genome sequencing identified a stable integration site in Akap1 between exons 1 and 2,mitigating sequence-independent mechanism-mediated transgene silencing. This study established an efficient method for producing transgenic rat models using PiggyBac transposon. Our GFP rats represent the first model to exhibit prolonged expression of foreign genes over five generations,with implications for future research in gene-engineered rat models. The online version contains supplementary material available at 10.1186/s12917-024-04123-7. View Publication

The development of haematopoiesis involves the coordinated action of numerous genes,some of which are implicated in haematological malignancies. However,the biological function of many genes remains elusive and unknown functional genes are likely to remain to be uncovered. Here,we report a previously uncharacterised gene in haematopoiesis,identified by screening mutant embryonic stem cells. The gene,‘ attenuated haematopoietic development ( Ahed )’,encodes a nuclear protein. Conditional knockout (cKO) of Ahed results in anaemia from embryonic day 14.5 onward,leading to prenatal demise. Transplantation experiments demonstrate the incapacity of Ahed -deficient haematopoietic cells to reconstitute haematopoiesis in vivo. Employing a tamoxifen-inducible cKO model,we further reveal that Ahed deletion impairs the intrinsic capacity of haematopoietic cells in adult mice. Ahed deletion affects various pathways,and published databases present cancer patients with somatic mutations in Ahed . Collectively,our findings underscore the fundamental roles of Ahed in lifelong haematopoiesis,implicating its association with malignancies. Subject terms: Lymphopoiesis,Development,Haematopoietic stem cells,Differentiation View Publication

The functional coupling between alternative pre-mRNA splicing (AS) and the mRNA quality control mechanism called nonsense-mediated decay (NMD) can modulate transcript abundance. Previous studies have identified several examples of such a regulation in developing neurons. However,the systems-level effects of AS-NMD in this context are poorly understood. We developed an R package,factR2,which offers a comprehensive suite of AS-NMD analysis functions. Using this tool,we conducted a longitudinal analysis of gene expression in pluripotent stem cells undergoing induced neuronal differentiation. Our analysis uncovers hundreds of AS-NMD events with significant potential to regulate gene expression. Notably,this regulation is significantly overrepresented in specific functional groups of developmentally downregulated genes. Particularly strong association with gene downregulation is detected for alternative cassette exons stimulating NMD upon their inclusion into mature mRNA. By combining bioinformatic analyses with CRISPR/Cas9 genome editing and other experimental approaches we show that NMD-stimulating cassette exons regulated by the RNA-binding protein PTBP1 dampen the expression of their genes in developing neurons. We also provided evidence that the inclusion of NMD-stimulating cassette exons into mature mRNAs is temporally coordinated with NMD-independent gene repression mechanisms. Our study provides an accessible workflow for the discovery and prioritization of AS-NMD targets. It further argues that the AS-NMD pathway plays a widespread role in developing neurons by facilitating the downregulation of functionally related non-neuronal genes. The online version contains supplementary material available at 10.1186/s13059-024-03305-8. View Publication