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At least 19 recordsLinked to original sources
PubMed2024

Adaptation for Staphylococcus aureus to hosts via insertion mutation in the accessory gene regulator agrC gene: decreased virulence and enhanced persistence capacity.

UNLABELLED: Staphylococcus aureus is an important human pathogen due to its vast array of virulence factors regulated by multiple regulatory mechanisms, including the accessory gene regulator. In this study, two S. aureus strains were simultaneously isolated from the blood of a febrile patient, belonging to the same clone, designated as 23H with a complete hemolytic phenotype, and 23B, exhibiting an incomplete hemolytic phenotype. The genomic comparison between strains 23B and 23H revealed that 23B had a single adenine base insertion at position 923 in the agrC gene, leading to a functional loss of the encoded AgrC. Experimental findings showed that strain 23B had decreased hemolytic activity, lower cytotoxicity against human alveolar epithelial A549 cells and in the Galleria mellonella model, and a reduced ability to survive intracellularly after infecting macrophages, in comparison to 23H. Conversely, 23B exhibited enhanced biofilm formation, greater adherence to A549 cells, and increased persistence in the face of vancomycin and daptomycin treatment. Transcriptomic analysis revealed that 23B upregulated surface protein-encoding genes while simultaneously reducing the expression levels of virulence factors, highlighting the intricate regulatory adjustments facilitating its persistence and reducing pathogenic potential. ATP assay results indicated that 23B maintained elevated ATP levels during the exponential phase yet exhibited reduced levels in the stationary phase when compared with 23H. Our findings suggested that the mutation in the agrC gene of S. aureus results in diminished virulence but markedly enhances persistence. This mutated strain warrants clinical attention because it may lead to treatment failures and persist in patients. IMPORTANCE: In clinical antimicrobial therapy, bacterial strains often develop resistance to antimicrobial agents. Additionally, mutations in their gene regulatory networks can increase their persistence, especially in immunocompromised patients. This study identified an insertion mutation in the accessory gene regulator, agrC gene, carried by a Staphylococcus aureus strain isolated from the blood of a febrile patient, leading to the functional loss of AgrC. Further research revealed that despite the reduced virulence of the mutated strain, it significantly bolstered the capacity to adapt and endure within the host during prolonged infections. This was evidenced by increased adhesion and biofilm formation capabilities, development of antimicrobial tolerance, and decreased ATP levels linked to persistence. Therefore, monitoring these mutations in S. aureus is crucial clinically, as they can complicate treatment strategies.

Staphylococcus aureus↗
PubMed2026

How advances in chromosome conformation capture (3C) methods are reshaping our understanding of gene regulation in hematopoiesis.

The three-dimensional organization of the DNA within the nucleus plays a key role in regulating gene expression. Over the past two decades, advances in chromosome conformation capture (3C) technologies, in tandem with other methods, have shown that the genome forms a complex structure at multiple scales. Early studies identified large-scale structures such as chromosome territories, compartments and topologically associating domains (TADs). As the resolution of 3C techniques has improved, it has become possible to identify contacts between regulatory elements in detail and more recently, it has become possible to define intricate structures within cis-regulatory elements. In this chapter, we review the development of 3C-based methodologies and discuss the strengths and limitations of the different approaches. We examine how these technologies have refined our understanding of genome organization and gene regulation. Recent high-resolution studies reveal that chromatin architecture extends beyond classical domain structures to include nanoscale organization. Integration of 3C data with super-resolution imaging and molecular dynamics simulations supports a model in which genome folding is governed by the biophysical properties of chromatin.

Animals↗
PubMed2025

Self-regulating gene therapy ameliorates phenotypes and overcomes gene dosage sensitivity in a mouse model of Rett syndrome.

Conventional methods of gene transfer lead to inconsistent transgene expression within cells. This variability can be problematic, particularly in conditions like Rett syndrome (RTT), a neurological disorder caused by mutations in the MECP2 (methyl-CpG binding protein 2) gene, because overexpression of MECP2 can also cause adverse effects. To address these challenges, we devised a gene regulation system called Expression Attenuation via Construct Tuning (EXACT), which uses a self-contained, microRNA-based feed-forward loop that not only ensures more consistent transgene expression but also protects against excessive expression. Through cell-based screening assays, we demonstrated the ability of the EXACT circuit to modulate the expression of full-length human MeCP2. Compared with a conventional construct, an EXACT-MECP2 construct exhibited a narrower range of cellular protein abundance. Furthermore, the degree of regulation by the EXACT circuit increased with higher transgene doses in vitro and in wild-type mice and mice modeling RTT. On the basis of cellular and in vivo testing, we identified an optimal configuration for the adeno-associated virus serotype 9 (AAV9) construct for self-regulated MECP2 gene therapy, designated NGN-401. Delivery of NGN-401 to neonatal male Mecp2-/y hemizygous mice via intracerebroventricular injection resulted in prolonged survival and amelioration of RTT-like phenotypes compared with vehicle-treated animals. NGN-401 was also well tolerated by female Mecp2+/- mice and healthy juvenile nonhuman primates, in contrast with a conventional construct, which caused toxicity. The results from these studies underpin a first-in-human pediatric trial of NGN-401 in RTT (ClinicalTrials.gov, NCT05898620).

Animals↗
PubMed2004

Ternary complex factor-serum response factor complex-regulated gene activity is required for cellular proliferation and inhibition of apoptotic cell death.

Members of the ternary complex factor (TCF) subfamily of the ETS-domain transcription factors are activated through phosphorylation by mitogen-activated protein kinases (MAPKs) in response to a variety of mitogenic and stress stimuli. The TCFs bind and activate serum response elements (SREs) in the promoters of target genes in a ternary complex with a second transcription factor, serum response factor (SRF). The association of TCFs with SREs within immediate-early gene promoters is suggestive of a role for the ternary TCF-SRF complex in promoting cell cycle entry and proliferation in response to mitogenic signaling. Here we have investigated the downstream gene regulatory and phenotypic effects of inhibiting the activity of genes regulated by TCFs by expressing a dominantly acting repressive form of the TCF, Elk-1. Inhibition of ternary complex activity leads to the downregulation of several immediate-early genes. Furthermore, blocking TCF-mediated gene expression leads to growth arrest and triggers apoptosis. By using mutant Elk-1 alleles, we demonstrated that these effects are via an SRF-dependent mechanism. The antiapoptotic gene Mcl-1 is identified as a key target for the TCF-SRF complex in this system. Thus, our data confirm a role for TCF-SRF-regulated gene activity in regulating proliferation and provide further evidence to indicate a role in protecting cells from apoptotic cell death.

Alleles↗
PubMed2026

Nuclear speckles: a fundamental layer of gene regulation.

Within the cell nucleus, non-DNA structures called nuclear bodies interact with chromatin to regulate gene expression and organize our genetic material. Among nuclear bodies, nuclear speckles are prominent. They interact with broad genomic regions, serve as major gene-activating structures, and are implicated in viral infection, cancer, neurodegeneration, stress response, and development. Advances that integrate genomics with imaging are leading to a deeper understanding of how nuclear speckles fit into our current knowledge of chromatin biology, genome organization, and the central dogma of biology. Collectively, these recent studies emphasize nuclear speckles as key gene regulatory structures within the cell nucleus, offering new perspectives on how gene expression dysregulation is linked to disease.

Humans↗
PubMed2024

Chromatin and gene regulation in archaea.

The chromatinisation of DNA by nucleoid-associated proteins (NAPs) in archaea 'formats' the genome structure in profound ways, revealing both striking differences and analogies to eukaryotic chromatin. However, the extent to which archaeal NAPs actively regulate gene expression remains poorly understood. The dawn of quantitative chromatin mapping techniques and first NAP-specific occupancy profiles in different archaea promise a more accurate view. A picture emerges where in diverse archaea with very different NAP repertoires chromatin maintains access to regulatory motifs including the gene promoter independently of transcription activity. Our re-analysis of genome-wide occupancy data of the crenarchaeal NAP Cren7 shows that these chromatin-free regions are flanked by increased Cren7 binding across the transcription start site. While bacterial NAPs often form heterochromatin-like regions across islands with xenogeneic genes that are transcriptionally silenced, there is little evidence for similar structures in archaea and data from Haloferax show that the promoters of xenogeneic genes remain accessible. Local changes in chromatinisation causing wide-ranging effects on transcription restricted to one chromosomal interaction domain (CID) in Saccharolobus islandicus hint at a higher-order level of organisation between chromatin and transcription. The emerging challenge is to integrate results obtained at microscale and macroscale, reconciling molecular structure and function with dynamic genome-wide chromatin landscapes.

Chromatin↗
PubMed2026

Noncoding transcription controls the developmental dynamics of long-range gene regulation.

The genomic regions regulating gene expression are often themselves transcribed into a variety of noncoding RNAs (ncRNAs). However, the regulatory roles of this noncoding transcription remain largely unknown. By using live imaging, we reveal that the sequential transcription of ncRNAs emanating from distinct regulatory elements underlies gene activation in Drosophila embryos. Single-allele co-visualization uncovers that optimal gene activation is achieved by only moderate levels of enhancer activity. Disrupting enhancer-associated ncRNAs causes precocious gene activation, providing evidence that ncRNAs control the timing of gene expression in development. We further show that enhancer transcription can regulate long-range interactions within complex regulatory landscapes. We propose that ncRNAs locally modulate regulatory element activity in cis to shape genome organization and orchestrate the temporal control of gene expression in development.

Journal Article↗
PubMed2025

Gene regulation technologies for gene and cell therapy.

Gene therapy stands at the forefront of medical innovation, offering unique potential to treat the underlying causes of genetic disorders and broadly enable regenerative medicine. However, unregulated production of therapeutic genes can lead to decreased clinical utility due to various complications. Thus, many technologies for controlled gene expression are under development, including regulated transgenes, modulation of endogenous genes to leverage native biological regulation, mapping and repurposing of transcriptional regulatory networks, and engineered systems that dynamically react to cell state changes. Transformative therapies enabled by advances in tissue-specific promoters, inducible systems, and targeted delivery have already entered clinical testing and demonstrated significantly improved specificity and efficacy. This review highlights next-generation technologies under development to expand the reach of gene therapies by enabling precise modulation of gene expression. These technologies, including epigenome editing, antisense oligonucleotides, RNA editing, transcription factor-mediated reprogramming, and synthetic genetic circuits, have the potential to provide powerful control over cellular functions. Despite these remarkable achievements, challenges remain in optimizing delivery, minimizing off-target effects, and addressing regulatory hurdles. However, the ongoing integration of biological insights with engineering innovations promises to expand the potential for gene therapy, offering hope for treating not only rare genetic disorders but also complex multifactorial diseases.

Humans↗
PubMed1978

Gene regulation in adaptive evolution.

It has been suggested that gene regulation may play a critical role in adaptive evolution. However, gene regulation has proved to be most refractory to experimental investigation in multicellular organisms. Using specially constructed stocks of Drosophila melanogaster, we have demonstrated the following. (1) The existence in natural populations of ample variation in regulatory genes that modify the activity of alcohol dehydrogenase (ADH), an enzyme coded by a structural gene locus, Adh, located on the second chromosome; the regulatory genes are located on the third chromosome, and thus are not adjacent to the structural locus. (2) The regulatory genes act not by means of post-transcriptional or post-translational modification of the gene product, but rather by controlling the number of ADH molecules; this is consistent with the hypothesis of gene regulation by means of macromolecules specifically binding at control sites adjacent to the structural gene locus. (3) The variation in regulatory genes is adaptively significant; adaptation to higher levels of environmental alcohol takes place not by changes in the Adh structural locus, but by changes in regulatory genes that control the number of ADH molecules in the organisms. Our results provide direct evidence of the importance of gene regulation in eucaryotic evolution.

Alcohol Oxidoreductases↗
PubMed2026

Chronic nitric oxide mediates dual-layer gene regulation through mRNA m6A positional remodeling and parallel transcriptional reprogramming.

Nitric oxide (NO) is a pleiotropic free radical that functions as a master regulator of gene expression, and its sustained production within the tumor microenvironment reshapes the epitranscriptomic state of cancer cells. We previously demonstrated that NO inhibits the m6A mRNA demethylases FTO and ALKBH5 through dinitrosyliron complex formation while leaving the methyltransferase METTL3 intact, a demethylase-specific perturbation that increases global m6A on mRNA. Here, integrating m6A-RIP-seq and RNA-seq from triple-negative breast cancer cells, we show that chronic NO does not produce the uniform hypermethylation anticipated from demethylase inhibition. Instead, it redistributes m6A on mRNA, enriching the 5'UTR and coding sequence while depleting the 3'UTR and departing from the canonical stop-codon and 3'UTR topology. We found that the position of m6A, rather than its intensity or mere presence, shapes the outcome, in part by determining which reader protein is predicted to recognize it. In parallel, NO drives a canonical NF-κB and inflammatory transcriptional program. The transcriptional program is independent of the m6A methylome in both which genes respond and how strongly they respond, ruling out a linear methylome-to-transcriptome cascade; even so, m6A position remains associated with the direction of change among responding transcripts. The 3'UTR is the primary site of m6A loss and shows a suggestive computational link to miRNA-mediated regulation. Sense-antisense coordination reinforces the transcriptional response without bridging the two programs. These findings demonstrate that NO not only increases m6A abundance, but it also rewrites the m6A positional code, establishing spatial reprogramming of the epitranscriptome as a previously unrecognized mode of gene regulation.

RNA Methylation↗
PubMed1979

Cellular regulation of mammalian sarcoma virus expression: a gene regulation model for oncogenesis.

Investigations aimed at defining cellular functions required for expression of transformation by mammalian sarcoma viruses have led to the isolation of a class of revertants that contain biologically active feline sarcoma virus, yet possess in vitro and in vivo properties of normal cells. The block to expression of the transformed state in these cellular revertants was spontaneously reversible at low frequency. Moreover, infection with certain helper viruses reversed the block at very high efficiency. Helper virus complementation was shown not to be a direct effect of helper virus functions expressed in the initially infected revertant cell. Rather, the helper virus acted indirectly by rescuing sarcoma virus and allowing it to infect and transform another cell within the revertant population. Using biochemical and immunologic techniques, it was possible to demonstrate a specific and very marked reduction in transcriptional and translational products of the sarcoma viral genome in the revertant cells. Findings that the reversal of this block was associated with reacquisition of the transformed phenotype, together with other evidence, suggest that reversion results from cellular transcriptional regulation of the integrated sarcoma virus genome. Reversion in this virus transformation system provides a model for oncogenesis resulting from derepression of cellular genes that possess malignant potential.

Animals↗
PubMed2025

Mechanisms of Globin Gene Regulation in Mammals.

Studies of globin gene clusters have established many paradigms of gene regulation. This review focuses on the α- and β-globin gene clusters of humans and mice, summarizing important insights from high-throughput biochemical assays and directed genetic dissections and emphasizing similarities across the types of gene clusters and between species. The overall arrangements and architectures are similar, with each gene cluster being localized within a topologically constrained unit of chromatin containing a multicomponent enhancer (i.e., a locus control region) and other regulatory elements bound by a similar set of transcription factors and coactivators. Differential expression of the globin genes within each cluster during ontogeny is associated with changes in contacts with the locus control region and involves the action of gene-specific repressors. Detailed study of the fetal β-like HBG1 and HBG2 globin genes has revealed a remarkable diversity of regulatory pathways that provide candidates for therapeutic approaches to reactivate these genes for β-hemoglobinopathies.

Animals↗
PubMed2024

Tailored UPRE2 variants for dynamic gene regulation in yeast.

Genetic elements are foundational in synthetic biology serving as vital building blocks. They enable programming host cells for efficient production of valuable chemicals and recombinant proteins. The unfolded protein response (UPR) is a stress pathway in which the transcription factor Hac1 interacts with the upstream unfolded protein response element (UPRE) of the promoter to restore endoplasmic reticulum (ER) homeostasis. Here, we created a UPRE2 mutant (UPRE2m) library. Several rounds of screening identified many elements with enhanced responsiveness and a wider dynamic range. The most active element m84 displayed a response activity 3.72 times higher than the native UPRE2. These potent elements are versatile and compatible with various promoters. Overexpression of HAC1 enhanced stress signal transduction, expanding the signal output range of UPRE2m. Through molecular modeling and site-directed mutagenesis, we pinpointed the DNA-binding residue Lys60 in Hac1(Hac1-K60). We also confirmed that UPRE2m exhibited a higher binding affinity to Hac1. This shed light on the mechanism underlying the Hac1-UPRE2m interaction. Importantly, applying UPRE2m for target gene regulation effectively increased both recombinant protein production and natural product synthesis. These genetic elements provide valuable tools for dynamically regulating gene expression in yeast cell factories.

Saccharomyces cerevisiae↗
PubMed2025

scPOEM: robust co-embedding of peaks and genes revealing peak-gene regulation.

MOTIVATION: Identifying regulatory elements in various chromosomal regions that influence gene expression is a fundamental challenge in epigenomics, with profound implications for understanding gene regulation and disease mechanisms. The advent of paired single-cell RNA sequencing and single-cell ATAC sequencing has created unprecedented opportunities to address this challenge by enabling simultaneous profiling of gene expression and chromatin accessibility at single-cell resolution. However, the inherent signals between them are weak due to the highly sparse and noisy nature of data. RESULTS: This article proposes single-cell meta-Path based Omics Embedding (scPOEM), a novel embedding method that jointly projects chromatin accessibility peaks and expressed genes into a shared low-dimensional space. By integrating the relationships among peak-peak, peak-gene, and gene-gene interactions, scPOEM assigns closer representations in the embedding space to related peak-gene pairs. Our experiments demonstrate that scPOEM generates stable representations of peaks and genes, outperforms existing methods in recovering biologically meaningful peak-gene regulatory relationships and enables new insights in subgroup and differential analysis of gene regulation. These results highlight its potential to uncover gene regulatory mechanisms and enhance the understanding of transcriptional regulation at single-cell resolution. AVAILABILITY AND IMPLEMENTATION: The source code of scPOEM is available at https://github.com/Houyt23/scPOEM. The datasets can be obtained from the 10× Genomics (https://www.10xgenomics.com/datasets/pbmc-from-a-healthy-donor-granulocytes-removed-through-cell-sorting-10-k-1-standard-1-0-0) and GEO database under access codes GSE194122 and GSE239916.

Gene Expression Regulation↗
PubMed1976

A constitutive mutation in a posttranscriptional regulator gene for a phenoloxidase and proteases in Podospora anserina.

A recessive mutation in the gene mod-2 results in the synthesis at low temperatures of a phenoloxidase and an arrest of growth, reversible by beta-phenyl-pyruvic acid, a protease inhibitor. Phenoloxidase synthesis is 5-fluorouracil resistant and cycloheximade sensitive. Suppression of both cold sensitivity and phenoloxidase synthesis by common factors (higher NH4+ concentrations or mutations) suggests that the protease, suspected to be responsible for cold sensitivity, also arises from preexisting mRNA molecules. Instead of being recessive and constitutive, the mod-2 mutations is suppressive and dominant when cold sensitivity and phenoloxidases synthesis are induced as the consequence of the nonallelic gene interactions C/D, C/E, or R/V responsible for protoplasmic incompatibility. Combinations of nonallelic incompatibility systems and several mod-2 mutations lead us to hypothesize that the translational control of the above proteins depends on conformational relationships between incompatibility gene products and mod-2.

Ammonia↗
PubMed1978

Cellular and genetic control of antibody responses in vitro. III. Immune response gene regulation of accessory cell function.

The possibility was investigated that Ir genes regulate the function of cells other than T or B cells in the primary IgM responses to the synthetic antigens trinitrophenylated poly-L-(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys [TNP-(T,G)-A--L]and trinitrophenylated poly-,-(His,Glu)-poly-D, L-Ala--poly-L-Lys [TNP-(H,G)-A--L]. The primary responses of (B10 x B10.A)F(1) spleen cells to both antigens were abrogated by Sephadex G-10 passage, and restored by the addition of spleen adherent cells. The cell type in the spleen adherent cell population active in reconstituting the responses to TNP-(T,G)-A--L and TNP-(H,G)-A--L was a non-T, non-B, radiation-resistant, glass-adherent spleen cell. The responses of Sephadex G-10-passed (responder x nonresponder)F(1) spleen cells to TNP-(T,G)-A--L or TNP-(H,G)-A--L were reconstituted by spleen adherent cells from only responder strains. Spleen adherent cells from F(1) mice reconstituted the responses to both antigens. Spleen adherent cells from each of the strains tested reconstituted the non- Ir gene-controlled response to a third antigen, TNP-keyhole limpet hemocyanin. The inability of spleen adherent cells from nonresponder strains to reconstitute the responses to either TNP-(T,G)-A--L or TNP-(H,G)-A--L was not a result of active suppression induced by the presence of nonresponder adherent cells, since a mixture of responder and nonresponder spleen adherent cells reconstituted the responses to both antigens. The use of spleen adherent cells from recombinant strains demonstrated that the autosomal dominant genes controlling the ability of spleen adherent cells to function as accessory cells in the responses to TNP-(T,G)-A--L and TNP-(H,G)-A--L are located in the K or I-A regions of the responder H-2 complex, the same region(s) of H-2 as the Ir genes controlling overall in vitro and in vivo responsiveness to these antigens.

Animals↗