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At least 127 records · Page 7Linked to original sources

Deep learning-based cell-specific gene regulatory networks inferred from single-cell multiome data.

Gene regulatory networks (GRNs) provide a global representation of how genetic/genomic information is transferred in living systems and are a key component in understanding genome regulation. Single-cell multiome data provide unprecedented opportunities to reconstruct GRNs at fine-grained resolution. However, the inference of GRNs is hindered by insufficient single omic profiles due to the characteristic high loss rate of single-cell sequencing data. In this study, we developed scMultiomeGRN, a deep learning framework to infer transcription factor (TF) regulatory networks via unique integration of single-cell genomic (single-cell RNA sequencing) and epigenomic (single-cell ATAC sequencing) data. We create scMultiomeGRN to elucidate these networks by conceptualizing TF network graph structures. Specifically, we build modality-specific neighbor aggregators and cross-modal attention modules to learn latent representations of TFs from single-cell multi-omics. We demonstrate that scMultiomeGRN outperforms state-of-the-art models on multiple benchmark datasets involved in diseases and health. Via scMultiomeGRN, we identified Alzheimer's disease-relevant regulatory network of SPI1 and RUNX1 for microglia. In summary, scMultiomeGRN offers a deep learning framework to identify cell type-specific gene regulatory network from single-cell multiome data.

Deep Learning↗

Regulation of intestinal epithelial barrier function by TGF-beta 1. Evidence for its role in abrogating the effect of a T cell cytokine.

Maintenance of the integrity of the single-cell-thick intestinal epithelium as an in vivo barrier between environmental Ags and mucosal immunocytes is pivotal for health. The T cell cytokine IFN-gamma consistently disrupts this epithelial barrier in vitro, but the substances in mucosa that may be responsible for sustaining or enhancing barrier function have not been clearly identified. Therefore, we characterized the effect on the epithelial barrier of TGF-beta 1 and three prominent neuropeptides (VIP, substance P, somatostatin) by using a model system in which barrier function of a mature polar human colonic epithelial (T84) cell monolayer is reflected in 1) the electrical potential difference across the apical to basolateral surface of each cell, 2) the transmonolayer permeability to macromolecules such as horseradish peroxidase, and 3) lactate dehydrogenase release into the medium indicating epithelial cell cytolysis. Whereas T84 monolayers exposed to TGF-beta 1 alone demonstrated a modest increase in electrical resistance and barrier integrity, TGF-beta 1 showed a striking ability to reduce the capacity of IFN-gamma to disrupt epithelial barrier function. Characterization studies demonstrated that this TGF-beta 1 effect was prolonged (e.g., days) after a single exposure, progressive over the dose range 0.1 to 2.5 ng/ml, reversible with increased concentrations of IFN-gamma, and more pronounced when TGF-beta 1 exposure was to basolateral rather than to apical epithelial membranes. Macromolecular (horseradish peroxidase) penetration of epithelium was not simultaneously altered by TGF-beta 1 and epithelial cellular injury was minimal as gauged by lactate dehydrogenase release. Additional studies using a human pathogen demonstrated that TGF-beta 1 delayed and decreased the barrier disruption caused by exposure to Cryptosporidium parvum. TGF-beta 1 may be the first of a new class of cytokines that maintains and/or enhances barrier function of human enterocytes, in part by countering the effect of a T cell cytokine.

Animals↗

Simultaneous optical measurements of cytosolic Ca2+ and cAMP in single cells.

Understanding the temporal and spatial integration of the Ca2+ and adenosine 3',5'-monophosphate (cAMP) signaling pathways requires concurrent measurements of both second messengers. Here, we describe an optical technique to simultaneously image cAMP and Ca2+ concentration gradients in MIN6 mouse insulinoma cells using Epac1-camps, a Förster (or fluorescence) resonance energy transfer (FRET)-based cAMP biosensor, and Fura-2, a fluorescent indicator of Ca2+. This real-time imaging method allows investigation of the dynamic organization and integration of multiple levels of signal processing in single living cells.

Animals↗

A Moloney MLV-rat somatotropin fusion gene produces biologically active somatotropin in a transgenic pig.

Expression of a Moloney murine leukemia virus (MLV) rat somatotropin fusion gene was examined in a transgenic pig. The fusion gene was integrated in a single site within the genome in a tandem array with approximately eight copies per cell. The integrated in a single site within the genome in a tandem array with approximately eight copies per cell. The integrated MLV-rat somatotropin fusion gene produced high levels of circulating rat somatotropin and resulted in an elevation in the circulating levels of insulin-like growth factor I. Although there was no increase in the rate of growth of the transgenic animal during the rapid growth phase, several phenotypic changes were evident. Skeletal growth was markedly increased and fat deposition was reduced throughout the animal. Blood glucose levels were elevated without ketosis. Northern blot analyses of rat somatotropin RNA revealed that expression of the fusion gene was highest in the spleen, lung, intestine, lymph nodes, and bone marrow. These results show that the MLV promoter can be used to express high levels of biologically active rat somatotropin in transgenic swine.

Animals↗

Integration of synaptic responses to neighboring whiskers in rat barrel cortex in vivo.

Characterizing input integration at the single-cell level is a critical step to understanding cortical function, particularly when sensory stimuli are represented over wide cortical areas and single cells exhibit large receptive fields. To study synaptic integration of sensory inputs, we made intracellular recordings from the barrel cortex of anesthetized rats in vivo. For each cell, we deflected the principal whisker (PW) either alone or preceded by the deflection of a single adjacent whisker (AW) at an interval of 20 or 3 ms. At the 20-ms interval in all cases, prior AW deflection significantly suppressed the PW-evoked spike output and caused the underlying synaptic response to reach a peak Vm less depolarized than that arising from PW deflection alone. The decrease in peak Vm was not attributed to hyperpolarizing inhibition but to a divisive reduction in PW-evoked PSP amplitude. The reduction in amplitude was not a result of shunting inhibition but was mostly a result of removal of the synaptic drive, or disfacilitation. When the AW-PW interval was shortened to 3 ms, spike suppression was observed in a subset of the cells studied. In most cases, a divisive reduction in synaptic response amplitude was offset by summation with the preceding AW-evoked depolarization. To determine whether suppression is a general feature of synaptic integration by barrel cortex neurons, we also characterized the interaction of responses evoked by local electrical stimulation. In contrast to the whisker data, we found that responses to paired stimulation at the same intervals produced more spikes and reached a peak Vm more depolarized than the individual responses alone, suggesting that whisker-evoked suppression is not a result of postsynaptic mechanisms. Instead, we propose that cross-whisker response suppression depends on sensory-specific mechanisms at cortical and subcortical levels.

Action Potentials↗

In situ analysis of single-stranded and duplex siRNA integrity in living cells.

To attain the full therapeutic promise of short interfering RNA (siRNA), it is believed that improvements such as increased biostability are critical. Regrettably, thus far, insufficient in situ data are on hand regarding the intracellular stability of siRNAs. We report on the use of an advanced fluorescence-based method to probe the nucleolytic decay of double labeled siRNAs, which are subject to fluorescence resonance energy transfer (FRET). In vitro measurements with RNAse A and cellular extracts demonstrate that the ratio of acceptor (5'-Cy5) to donor (3'-rhodamine green) fluorescence can be used to study the degradation of the labeled siRNA substrates upon donor excitation. Intracellular FRET analysis showed substantial degradation of single-stranded siRNA, whereas duplex siRNA stayed intact during the measured time period. These data underline the high intrinsic nuclease resistance of unmodified duplex siRNA and prove that cellular persistence is much more critical for the single-stranded structure. For the first time, the stability of siRNA is investigated in real-time inside living cells. The fluorescence-based method presented here is a straightforward technique to gain direct information on siRNA integrity inside living cells and provides a bright outlook to learn more about the intracellular fate of siRNA therapeutics.

Animals↗

Increased somatic recombination in methylation tolerant human cells with defective DNA mismatch repair.

We have studied whether spontaneous intrachromosomal recombination is altered in methylation tolerant human cells with a defect in mismatch repair. Somatic recombination was analysed in HeLaMR cells containing the vector pTPSN, which carries two copies of the gene for hygromycin resistance. The hygromycin genes are both inactivated by an inserted HindIII linker but hygromycin-resistant clones can arise by recombination. The spontaneous rate of recombination in a clone of HeLaMR cells containing a single integrated copy of pTPSN (HeLaG1) was 3.1x10(-6)/cell per generation. Two methylation tolerant variants from HeLaG1 cells (clone 12 and clone 15) were isolated by exposure to MNNG. Clone 12 cells exhibited a 16-fold increase in spontaneous mutation rate at the HPRT gene and extensive microsatellite instability at both mono- and dinucleotide repeats. Microsatellite instability limited to mononucleotide repeats was found in clone 15, whereas the mutation rate at HPRT was not significantly affected. A mismatch binding defect in extracts of clone 15 could be complemented by exogenous GTBP but not by purified hMSH2 protein. These data suggest that clone 15 is defective in GTBP. Extracts of clone 12 were unable to correct a single C:T mispair and complementation by extracts of human colorectal carcinoma cells with known deficiencies in mismatch repair indicated a defect in hMutLalpha. Western blotting with antibodies against different human mismatch repair proteins showed that clone 12 cells did not express hPMS2 protein, but expression of hMLH1, hMSH2 and GTBP appeared normal. The spontaneous recombination rate of clone 12 was 19-fold higher than the parental HeLaG1 cells, whereas no increase was observed in clone 15. Analysis of individual recombinants showed that hygromycin resistance arose exclusively by gene conversion. Our data indicate that mismatch correction regulates somatic recombination in human cells.

Base Sequence↗

Feline immunodeficiency virus integration in B-cell lymphoma identifies a candidate tumor suppressor gene on human chromosome 15q15.

Infection with immunosuppressive lentiviruses is associated with increased cancer risk,but most studies have implicated indirect mechanisms as the tumor cells generally lack integrated viral sequences. An exception wasfound in a B-cell lymphoma (Q254) where the tumor cells contained a single integrated feline immunodeficiency virus genome. Additional analysis now indicates that feline immunodeficiency virus integration in lymphoma Q254 resulted in promoter insertion and truncation of a conserved gene on feline chromosome B3, whereas the unaffected allele of the gene appeared to be transcriptionally down-regulated. The orthologous human gene (FLJ12973), is expressed ubiquitously and encodes a WD-repeat protein with structural similarity to DDB2, the small subunit of the xeroderma pigmentosum XP-E complex. Moreover, the gene is located within a region of frequent tumor-specific deletions on chromosome 15q15. These observations demonstrate the direct mutagenic potential of the lentiviruses and identify a new candidate tumor suppressor gene.

Amino Acid Sequence↗

Stromal ARHGEF15 Correlates With Inflammatory EMT and Stromal-Immune Crosstalk During Inflammatory Bowel Disease-To-Colorectal Cancer Progression.

Patients with inflammatory bowel disease (IBD) have an increased risk of colorectal cancer (CRC), but how chronic intestinal inflammation drives malignant transformation remains unclear. We retrospectively reanalyzed published single-cell transcriptomic datasets from intestinal biopsies of healthy individuals and patients with IBD; differential expression was assessed using independent t tests with Benjamini-Hochberg false discovery rate correction. We then integrated those single-cell findings with the Cancer Genome Atlas bulk transcriptomes and pharmacogenomic cohorts to trace stromal programs across the IBD-to-cancer continuum. ARHGEF15 emerged as a stromal gene enriched in CD74hi HLA-DRB1hi arterial pericytes within inflamed tissue. Its expression rose steadily from IBD to CRC and tracked with epithelial-mesenchymal transition (EMT) activity. In CRC, higher ARHGEF15 expression was associated with shorter overall and progression-free survival. These retrospective, in silico findings identify ARHGEF15 as an exploratory stromal biomarker associated with inflammatory EMT and stromal-immune remodeling during IBD-to-CRC progression. Prospective experimental and clinical validation is required to establish its prognostic or therapeutic relevance.

ARHGEF15↗

Establishment of a human in vitro mesothelial cell model system for investigating mechanisms of asbestos-induced mesothelioma.

Normal human mesothelial (NHM) cells were transfected with a plasmid containing SV40 early region DNA. Individual colonies of transformed cells from several donors were subcultured for periods of 5 to 6 months and 60 to 70 population doublings (PDs) before senescence, in contrast to a culture lifespan of approximately 1 month and 15 PDs for NHM cells. One such culture, designated MeT-5A, escaped senescence and has been passaged continuously for more than 2 years. These cells had a single integrated copy of SV40 early region DNA in their genome, expressed SV40 large T antigen, and exhibited features of mesothelial cells including sensitivity to the cytotoxic effects of asbestos fibers. One year after injection subcutaneously or intraperitoneally in athymic nude mice, these cells remain nontumorigenic, and therefore are a potential model system for in vitro fiber carcinogenesis studies.

Animals↗

Single-cell profiling reveals a novel CAF subpopulation linking stromal heterogeneity to immune suppression in breast cancer subtypes.

BACKGROUND: The tumor microenvironment critically influences breast cancer (BC) progression, immune surveillance, and therapeutic response. Cancer-associated fibroblasts (CAFs), a heterogeneous stromal population, are key regulators of these processes, yet their subtype-specific contributions in BC remain insufficiently defined. METHODS: We integrated three single-cell RNA sequencing datasets from 29 BC patients to characterize stromal populations. Bulk RNA-seq data from The Cancer Genome Atlas (TCGA) were analyzed to assess correlations between CAF subsets and immune infiltration. Gene signatures were derived to identify subtype-specific CAF-immune interactions, prognostic markers, and potential predictors of chemotherapy response. RESULTS: Three conserved stromal populations (iCAFs, myCAFs, and pericytes) were identified, along with a previously unrecognized subset, the cluster 3 (CL3) CAF-like cells, referred as metabolic stressed CAF (msCAF). msCAF cells displayed transcriptional programs associated with antigen presentation, stress response, glycolysis, and extracellular matrix remodeling. Their abundance was inversely correlated with T-cell infiltration and function, in a subtype-specific manner: triple negative breast cancer (TNBC) was enriched for msCAFs in immune-infiltrated but functionally constrained microenvironments, whereas Luminal A tumors exhibited weaker immune infiltration with heterogeneous CAF-immune associations. msCAFs were characterized by a conserved gene signature (HLA-A, HLA-C, IL32, EMP3) and subtype-specific genes related to T-cell exhaustion. Several genes demonstrated prognostic relevance with distinct patterns in Luminal A (IER3, TIMP1, TBX3, SEC61G) and TNBC (ADM, C4orf3, LDHA) tumors, as well as shared biomarkers (FN1, LOXL2, P4HA1). Multiple msCAF genes also predicted chemotherapy response, suggesting utility as treatment stratification biomarkers. CONCLUSION: msCAFs represent a clinically relevant CAF subset that drives immune suppression, impacts subtype-specific prognosis, and influences therapy response in BC. These findings highlight msCAFs as promising targets for enhancing immunotherapy and personalizing treatment strategies.

Humans↗

Analysis of phase-specific gene expression at the single-cell level in the white-opaque switching system of Candida albicans.

The opportunistic fungal pathogen Candida albicans can switch spontaneously and reversibly between different cell forms, a capacity that may enhance adaptation to different host niches and evasion of host defense mechanisms. Phenotypic switching has been studied intensively for the white-opaque switching system of strain WO-1. To facilitate the molecular analysis of phenotypic switching, we have constructed homozygous ura3 mutants from strain WO-1 by targeted gene deletion. The two URA3 alleles were sequentially inactivated using the MPA(R)-flipping strategy, which is based on the selection of integrative transformants carrying a mycophenolic acid (MPA) resistance marker that is subsequently deleted again by site-specific, FLP-mediated recombination. To investigate a possible cell type-independent switching in the expression of individual phase-specific genes, two different reporter genes that allowed the analysis of gene expression at the single-cell level were integrated into the genome, using URA3 as a selection marker. Fluorescence microscopic analysis of cells in which a GFP reporter gene was placed under the control of phase-specific promoters demonstrated that the opaque-phase-specific SAP1 gene was detectably expressed only in opaque cells and that the white-phase-specific WH11 gene was detectably expressed only in white cells. When MPA(R) was used as a reporter gene, it conferred an MPA-resistant phenotype on opaque but not white cells in strains expressing it from the SAP1 promoter, which was monitored at the level of single cells by a significantly enlarged size of the corresponding colonies on MPA-containing indicator plates. Similarly, white but not opaque cells became MPA resistant when MPA(R) was placed under the control of the WH11 promoter. The analysis of these reporter strains showed that cell type-independent phase variation in the expression of the SAP1 and WH11 genes did not occur at a detectable frequency. The expression of these phase-specific genes of C. albicans in vitro, therefore, is tightly linked to the cell type.

Aspartic Acid Endopeptidases↗

Single-cell transcriptomic atlas of Alzheimer's disease middle temporal gyrus reveals region, cell type, and sex specificity of gene expression with novel genetic risk for MERTK in female.

BackgroundAlzheimer's disease (AD), the most common age-related neurodegenerative disease, is closely associated with both amyloid-β plaque and neuroinflammation. Two thirds of AD patients are female, and they have a higher disease risk; women with AD have more extensive brain histological changes than men along with more severe cognitive symptoms and neurodegeneration.ObjectiveThis study aimed to determine how sex difference induces structural brain changes and molecular cell vulnerabilities in AD, with a focus on identifying sex-specific transcriptional alterations and genetic risk factors.MethodsWe performed single nucleus RNA sequencing on postmortem brains from individuals with AD and age- and sex-matched controls, focusing on the middle temporal gyrus, a cortical brain region strongly affected by the disease, and integrated single nucleus RNA sequencing results with genome-wide association study (GWAS) data using cell type-specific enrichment and generalized gene-set analysis approaches. The analysis pipeline is provided with threshold information.ResultsWe identified a selectively vulnerable subpopulation of layer 2/3 excitatory neurons that were RORB-negative and CDH9-expressing in both males and females. Disease-associated, but sex-independent, reactive astrocyte signatures were also present. In clear contrast, the microglia signatures of AD brains differed between males and females. Integrating single cell transcriptomic data with results from GWAS, we identified MERTK genetic variation as a candidate novel risk factor for AD selectively in females.ConclusionsTaken together, our single cell atlas of middle temporal gyrus revealed a unique cellular-level view of sex-specific transcriptional changes in AD, illuminating GWAS identification of sex-specific AD genes. These data serve as a rich resource for interrogation of the molecular and cellular basis of AD.

Alzheimer's disease↗

Microfabricated platform for studying stem cell fates.

Platforms that allow parallel, quantitative analysis of single cells will be integral to realizing the potential of postgenomic biology. In stem cell biology, the study of clonal stem cells in multiwell formats is currently both inefficient and time-consuming. Thus, to investigate low-frequency events of interest, large sample sizes must be interrogated. We report a simple, versatile, and efficient micropatterned arraying system conducive to the culture and dynamic monitoring of stem cell proliferation. This platform enables: 1) parallel, automated, long-term ( approximately days to weeks), live-cell microscopy of single cells in culture; 2) tracking of individual cell fates over time (proliferation, apoptosis); and 3) correlation of differentiated progeny with founder clones. To achieve these goals, we used microfabrication techniques to create an array of approximately 10,000 microwells on a glass coverslip. The dimensions of the wells are tunable, ranging from 20 to >500 microm in diameter and 10-500 microm in height. The microarray can be coated with adhesive proteins and is integrated into a culture chamber that permits rapid (approximately min), addressable monitoring of each well using a standard programmable microscope stage. All cells share the same media (including paracrine survival signals), as opposed to cells in multiwell formats. The incorporation of a coverslip as a substrate also renders the platform compatible with conventional, high-magnification light and fluorescent microscopy. We validated this approach by analyzing the proliferation dynamics of a heterogeneous adult rat neural stem cell population. Using this platform, one can further interrogate the response of distinct stem cell subpopulations to microenvironmental cues (mitogens, cell-cell interactions, and cell-extracellular matrix interactions) that govern their behavior. In the future, the platform may also be adapted for the study of other cell types by tailoring the surface coatings, microwell dimensions, and culture environment, thereby enabling parallel investigation of many distinct cellular responses.

Cell Count↗

Plant cis-regulatory grammar: Decoding the multidimensional code of transcriptional regulation for programmable crop engineering.

Cis-regulatory elements (CREs) orchestrate the spatiotemporal precision of gene expression that underlies plant development, adaptation, and domestication. Decoding the cis-regulatory grammar of plant genomes remains a central challenge in modern biology, with profound implications for programmable crop engineering. Here, recent conceptual and technological advances are synthesized to reshape our understanding of plant CREs. This review first argues that CRE function is not only an intrinsic property of DNA sequence alone but also emerges from a multidimensional context, including chromatin accessibility, histone modifications, three-dimensional genome topology, and cell type-specific regulatory landscapes. Furthermore, the convergence of single-cell epigenomics, high-throughput functional assays, and CRISPR-based dissection has begun to unravel this contextual grammar, revealing the computational principles governing transcriptional regulation. Critically, we propose that artificial intelligence (AI) platforms are catalyzing an ongoing transition from descriptive discovery to predictive engineering, wherein these platforms outperform natural evolution in designing synthetic CREs. Finally, a roadmap is outlined toward a plant regulatory grammar foundation model, which will enable truly predictive engineering of gene expression when fine-tuned for specific tasks. Collectively, the integration of single-cell resolution maps, precise genome editing, AI-driven design, and regulatory-compliant delivery systems promises to transform our ability to reprogram plant gene regulation for next-generation agriculture, bridging the gap between foundational regulatory biology and tangible crop improvement.

artificial intelligence↗

Genome-wide profiling of histone modifications and transcription factor binding at single-cell resolution by DeChIC-seq.

Mapping of protein-DNA interactions at single-cell resolution remains a central challenge in epigenomics, particularly for transcription factors (TFs), whose sparse binding limits reliable detection. Here, we establish DeChIC-seq (DNA Deaminase-based Chromatin Immuno-Conversion sequencing), a conversion-based strategy that uses a protein A-DddAtox fusion to directly record protein-DNA interactions by inducing localized C-to-U conversions near antibody-bound chromatin. Retaining genome-wide background sequence information without immunoprecipitation, DeChIC-seq enables profiling of histone modifications and sensitive detection of TF binding. Integration with single-cell whole-genome amplification extends DeChIC-seq to single-cell applications (scDeChIC-seq), enabling chromatin profiling of individual cells. Applied to mouse embryogenesis, scDeChIC-seq resolves lineage-specific chromatin states through profiling of H3K4me3, CTCF, and RAD21 and sensitively detects TF binding, including that of NR5A2, TFAP2C, and KLF5, from extremely limited blastomere inputs. This underscores its strong potential for detecting TF-binding sites in scarce biological samples. DeChIC-seq establishes a conversion-based framework for chromatin profiling that enables mechanistic dissection of TF-driven gene regulation across rare cells, developmental systems, and disease contexts.

Animals↗

Single copy heterozygote integration of HPV 33 in chromosomal band 5p14 is found in an epithelial cell clone with selective growth advantage.

Infection with human papillomavirus (HPV) of specific high-risk type triggers a series of events in target cells, which will eventually lead to development of genital neoplasia. The integration of high-risk HPV DNA into the cell genome has been regarded as a crucial event in tumor progression. With respect to different HPV types, the knowledge of HPV integrated loci is still limited. We have now determined the genomic variation and chromosomal location of HPV 33 DNA in the cell line UT-DEC-1, established from a vaginal mild dysplasia lesion. The viral sequence of the cell line was determined, and a variant of the prototype HPV 33 strain was identified, showing nucleotide substitutions resulting in amino acid changes in the E2, L2 and E4 open reading frames. In late passage UT-DEC-1 cells, a deletion of more than half of the 3' part of E1 and major parts of the E2 and E4 genes provided evidence for integration. The flanking sequences of the integration site were completely homologous to published sequences from chromosomal band 5p14, and remained unchanged in all subclones established from late passage cells. There were no chromosomal deletions or gross rearrangements at the integration site, and only a single heterozygotic copy of HPV 33 was detected. The karyotype of late passage cells showed only minor changes compared with early passage cells. During passaging of the cell line, there were progressive changes towards a malignant phenotype, and in parallel to this, the cells carrying episomal HPV 33 of the early passages was completely superseded by cells containing the integrated virus. Thus, our results show that this single copy heterozygote integration of HPV 33 into chromosome band 5p14 appears to be associated with emergence of cells escaping senescence, and with growth advantage compared with cells carrying episomal virus.

Base Sequence↗