Activation Of Transcription Factors Research Articles

Cell stretching devices integrated with live cell imaging: a powerful approach to study how cells react to mechanical cues

Cell stretching devices integrated with live cell imaging: a powerful approach to study how cells react to mechanical cues

Pseudokinase STK40 promotes TH1 and TH17 cell differentiation by targeting FOXO transcription factors.

Inappropriate CD4+ T helper (TH) cell differentiation leads to progression of inflammatory and autoimmune diseases, yet the regulatory mechanisms governing stability and activity of transcription factors controlling TH cell differentiation remain elusive. Here, we describe how pseudokinase serine threonine kinase 40 (STK40) facilitates TH1/TH17 differentiation under pathological conditions. STK40 in T cells is dispensable for immune homeostasis in resting mice. However, mice with T cell-specific deletion of STK40 exhibit attenuated symptoms of experimental autoimmune encephalomyelitis and colitis, accompanied by diminished TH1 and TH17 cell differentiation. Mechanistically, STK40 facilitates K48-linked polyubiquitination and proteasomal degradation of FOXO1/4 through promoting their interaction with E3 ligase COP1. Inhibition of FOXO4 or FOXO1, respectively, restores differentiation potential of STK40-deficient TH1/TH17 cells. Together, our data suggest a crucial role of STK40 in TH1 and TH17 cell differentiation, thereby enabling better understanding of the molecular regulatory network of CD4+ T cell differentiation and providing effective targets for the treatment of autoimmune diseases.

Protein moonlighting by a target gene dominates phenotypic divergence of the Sef1 transcriptional regulatory network in yeasts.

Transcriptional rewiring generates phenotypic novelty, acting as an important mechanism contributing to evolutionary development, speciation, and adaptation in all organisms. The phenotypic outcomes (functions) of transcription factor (TF) activity are determined by the combined effects of all target genes in the TF's regulatory network. Plastic rewiring of target genes accumulates during species divergence and ultimately alters phenotypes, indicating a TF functional switch. We define this phenomenon as 'disruptive rewiring', where the rewiring process disrupts the link between a TF and its original target genes that determine phenotypes. Here, we investigate if 'complete' disruptive rewiring is a prerequisite for a TF functional switch by employing chromatin immunoprecipitation sequencing, RNA expression, and phenotypic assays across yeast species. In yeasts where Sef1 targets TCA (tricarboxylic acid)cycle genes, we demonstrate that Sef1 orthologs can promote and inhibit respiratory growth by modulating the moonlighting function of their conserved target, NDE1. This modulation occurs without changing the overall association of Sef1 with TCA cycle genes. We propose that phenotypic masking by NDE1 promotes 'deceptive' disruptive rewiring of the Sef1 regulatory network in Saccharomyces cerevisiae, thereby potentially constraining future evolutionary trajectories.

Single-molecule states link transcription factor binding to gene expression.

The binding of multiple transcription factors (TFs) to genomic enhancers drives gene expression in mammalian cells1. However, the molecular details that link enhancer sequence to TF binding, promoter state and transcription levels remain unclear. Here we applied single-molecule footprinting2,3 to measure the simultaneous occupancy of TFs, nucleosomes and other regulatory proteins on engineered enhancer-promoter constructs with variable numbers of TFbinding sites for both a synthetic TF and an endogenous TF involved in thetype I interferon response. Although TF binding events on nucleosome-free DNAare independent, activation domains recruit cofactors that destabilize nucleosomes, driving observed TF binding cooperativity. Average TF occupancy linearly determines promoter activity, and we decompose TF strength into separable binding and activation terms. Finally, we develop thermodynamic and kinetic models that quantitatively predict both the enhancer binding microstates and gene expression dynamics. This work provides a template for the quantitative dissection of distinct contributors to gene expression, including TF activation domains, concentration, binding affinity, binding site configuration and recruitment of chromatin regulators.

ScCancerExplorer: a comprehensive database for interactively exploring single-cell multi-omics data of human pan-cancer.

Genomic, epigenomicand transcriptomic alterations are hallmarks of cancer cells, and are closely connected. Especially, epigenetic regulation plays a critical role in tumorigenesis and progression. The growing single-cell epigenome data in cancer research provide new opportunities for data mining from a more comprehensive perspective. However, there is still a lack of databases designed for interactively exploring the single-cell multi-omics data of human pan-cancer, especially for the single-cell epigenome data. To fill in the gap, we developed scCancerExplorer, a comprehensive and user-friendly database to facilitate the exploration of the single-cell genome, epigenome (chromatin accessibility and DNA methylation), and transcriptome data of 50 cancer types. Five major modules were provided to explore those data interactively, including 'Integrated multi-omics analysis', 'Single-cell transcriptome', 'Single-cell epigenome', 'Single-cell genome' and 'TCGA analysis'. By simple clicking, users can easily investigate gene expression features, chromatin accessibility patterns, transcription factor activities, DNA methylation states, copy number variationsand TCGA survival analysis results. Taken together, scCancerExplorer is distinguished from previous databases with rich and interactive functions for exploring the single-cell multi-omics data of human pan-cancer. It bridges the gap between single-cell multi-omics data and the end-users, and will facilitate progress in the field of cancer research. scCancerExplorer is freely accessible via https://bianlab.cn/scCancerExplorer.

Abstract B040: Cell-free DNA captures inter- and intra-patient heterogeneity in advanced bladder cancer

Abstract Metastatic bladder cancer (BLCA) is an aggressive disease complicated by the emergence of variant histological subtypes. The UW/Fred Hutch metastatic BLCA rapid autopsy program is a first-of-its-kind program collecting cell-free DNA (cfDNA) and matched normal tissue, primary tumor, and metastatic tumor samples from advanced BLCA patients, with a focus on these variant subtype tumors. This dataset, consisting of 20 patients with up to five metastases per patient, is a unique opportunity to assess how cfDNA is able to capture heterogeneity across BLCA. We assessed both inter-patient heterogeneity between BLCA subtypes and inter-tumoral heterogeneity within each patient using epigenetic and genomic profiling. Using nucleosome profiling, we identified the activity of lineage markers and transcription factors that distinguish healthy individuals from BLCA patients, and between BLCA subtypes. Furthermore, we conducted a detailed analysis of whole genome (30X) and targeted (4,000X) cfDNA sequencing in their ability to capture the evolutionary history of tumor mutations. Detection of tumor mutations by cfDNA is highly dependent on clonality, with >90% of founder tumor mutations captured by either sequencing method, while capture is decreased for either subclonal mutations or those private to a single metastasis. Importantly, deleterious mutations in BLCA driver genes had close to 100% detection using targeted panel sequencing, even for subclonal mutations. These findings lay the groundwork for the use of cfDNA in clinical BLCA decision-making, including tracking the emergence of pathogenic, targetable mutations and variant subtypes. Citation Format: Samantha L Schuster, Pushpa Itagi, Sonali Arora, Patricia C Galipeau, Thomas W Persse, Michael Yang, Allie Kreitman, Alan Min, Funda Vakar-Lopez, John K Lee, Petros Grivas, Robert B Montgomery, Jonathan L Wright, Andrew C Hsieh, Hung- Ming Lam, Gavin Ha. Cell-free DNA captures inter- and intra-patient heterogeneity in advanced bladder cancer [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B040.

Identification and functional validation of variants in the promoter region of HAND1 gene in sporadic tetralogy of Fallot.

Tetralogy of Fallot (TOF) is a common congenital heart disease (CHD) but the impact of the variants of the HAND1 gene promoter region has not been explored. DNA from blood samples of 612 subjects (300 sporadic TOF patients and 312 healthy controls) was sequenced to identify variants in the HAND1 gene promoter region that were further tested by cellular function experiments including dual-luciferase reporter gene assays, electrophoretic mobility shift analysis (EMSA), and bioinformatics analysis using JASPAR, a transcription factor binding site database. Eight variants in HAND1 gene promoter region were identified with 3 only found in TOF patients including one novel g.3639 G > T. All 3 variants significantly reduced the transcriptional activity of HAND1 gene promoter in an in vitro reporter assay (p < 0.05). JASPAR analysis indicated that these variants may alter the binding sites of transcription factors, potentially associated with TOF formation. In the promoter region of HAND1gene of TOF patients, 3 variants were found only in the patients including one found for the first time. These variants decreased transcription factor activity. Therefore, the present study implies the role of HAND1 gene in the pathogenesis of TOF and further provides new insights into the genetic basis of TOF formation. Sequencing of DNA from 612 human subjects (300 TOF patients and 312 healthy controls) identified 8 variants in the promoter region of HAND1 gene with 3 found only in TOF including 1 newly identified. Reduced transcriptional activity at these 3 variants was confirmed by dual-luciferase reporter gene assay and EMSA assay. Predictions from the JASPAR database suggest altered binding sites of transcription factors by the variants. We for the first time demonstrate variants in the HAND1 promoter and that cause cellular dysfunction. The variants identified may have a pathological role in the formation of TOF.

Effect of nHA/CS/PLGA delivering adipose stem cell-derived exosomes and bone marrow stem cells on bone healing—in vitro and in vivo studies

Adipose stem cell-derived exosomes (ADSC-EXO) have been demonstrated to promote osteogenic differentiation of bone marrow stem cells (BMSCs) and facilitate bone regeneration. The present study aims to investigate the effect of ADSC-EXO-loaded nano-hydroxyapatite/chitosan/poly-lactide-co-glycolide (nHA/CS/PLGA) scaffolds on maxillofacial bone regeneration using tissue engineering. ADSC-EXO was isolated and co-cultured with BMSCs, and the osteogenic differentiation of BMSCs was assessed through the detection of mineralized nodule formation, alkaline phosphatase (ALP) activity, and mRNA expression of COL1A1 and runt-related transcription factor 2 (RUNX2). The nHA/CS/PLGA scaffolds were fabricated and loaded with ADSC-EXO and BMSCs, and these tissue engineering complexes were applied to the maxillofacial bone defect region of rabbits to elucidate their bone regeneration effect. The osteogenic differentiation of BMSCs was markedly enhanced when they were co-cultured with ADSC-EXO. This was evidenced by an increase in the formation of mineralized nodule formation, ALP activity, and mRNA expression of COL1A1 and runt-related transcription factor 2 (RUNX2). In vivo experiments demonstrated that the application of ADSC-EXO and BMSCs loaded nHA/CS/PLGA scaffolds effectively repaired maxillofacial bone defects in rabbits. ADSC-EXO has been demonstrated to promote the osteogenic differentiation of BMSCs. The ADSC-EXO and BMSCs loaded nHA/CS/PLGA scaffolds have been shown to facilitate the regeneration of maxillofacial bone defects. This may serve as a potential therapeutic strategy for large-scale bone defects.

PSTAT3 Expression is Increased in Advanced Prostate Cancer in Post-Initiation of Androgen Deprivation Therapy.

The transcription factor Signal Transducer and Activator of Transcription 3 (STAT3) plays a role in carcinogenesis and is involved in processes, such as proliferation, differentiation, drug resistance and immunosuppression. STAT3 can be activated by phosphorylation of tyrosine at position 705 (pSTAT3Tyr705) or serine at 727 (pSTAT3Ser727). High expression levels of pSTAT3 are implicated in advanced stages of prostate cancer (PCa) and are known to interact with the androgen receptor signaling pathway. However, not much is known about how androgen deprivation therapy (ADT) in advanced disease affects pSTAT3 expression. The aim of this study was to determine the influence of ADT on pSTAT3 expression in PCa tissue. The study cohort came from a PCa tissue microarray resource containing prostate specimens from patients before and post-initiation of ADT. Tissue samples from 111 patients were immunostained for pSTAT3Tyr705 and pSTAT3Ser727. H-score was used to evaluate the intensity and the percentage of pSTAT3 expression in malignant epithelial and stromal compartments. Univariate and multivariable Cox regression analyses were used to assess pSTAT3Tyr705 and pSTAT3Ser727 as biomarkers of oncological outcome in patients undergoing ADT. Post-ADT PCa samples demonstrated increased nuclear and cytoplasmic levels of pSTAT3Ser727 in the stroma compared to pre-ADT samples, whereas pSTAT3Tyr705 expression was increased significantly in both stromal and malignant epithelial compartments except for stromal cytoplasm. High cytoplasmic pSTAT3Ser727 in stromal compartments correlated with reduced overall survival, shorter time to castration-resistant PCa development, and decreased metastasis-free survival. An increase in nuclear and cytoplasmic pSTAT3Ser727 expression within the stromal compartment of post-ADT samples corresponded to a shorter time to CRPC development, which was not observed for pSTAT3Tyr705. Multivariable survival analysis using Cox's regression identified that high cytoplasmic pSTAT3Ser727 expression in the stroma of post-ADT samples and pT3 or pT4-stage were associated with worse overall survival and 5-year metastasis-free survival (MFS). This study presents novel insights into the impact of ADT on the expression levels of pSTAT3Tyr705 and pSTAT3Ser727 in PCa. Cytoplasmic pSTAT3Ser727 status of cancer-associated stromal cells in post-ADT samples may serve as an independent prognostic marker for OS and 5-year MFS, identifying prostate cancer patients prone to developing resistance to ADT.

EPCO-54. MULTIOMIC ANALYSIS OF SPINAL EPENDYMOMAS REVEALS MECHANISMS OF TUMOR AGGRESSIVENESS WITH MYCN AMPLIFICATION

Abstract Grade-3 spinal ependymomas, particularly those harboring MYCN amplification, have dismal prognoses despite optimal treatment regimens. MYCN functions as a transcription factor (TF) to drive the expression of key tumor driver genes. Our aim is to identify mechanisms underlying tumor aggressiveness and treatment resistance in MYCN-amplified ependymomas. MYCN amplification in spinal ependymomas was identified with custom next generation sequencing panels and bulk methylation analysis. We then conducted paired single-nucleus RNA (snRNA-seq) and chromatin accessibility (snATAC-seq) sequencing of grade-2 (n=2, 1 patient) and grade-3 spinal ependymomas (n=6, 6 patients, 4 MYCN-amplified). Comparator snRNA-seq datasets (grade-2/grade-3; 8/2) were included from a publicly available dataset (GSE163686; all non-MYCN-amplified). Canonical cell classes were identified with a combination of cluster- and cell-based strategies. Downstream analysis was conducted using R 4.3 (Seurat, Signac, clusterProfiler, CellChat), and Python 3.11 (scanpy) packages. We identified ependymoma tumor cells distinct from canonical immune cell classes with gene expression analysis and confirmed a distinct copy-number-variation pattern in these cells with chromosome 1 and 2p gain, and chromosome 6p and 22q loss. MYCN-amplified tumor cells (compared to non-MYCN-amplified grade2/3 tumor cells) showed increased differential accessibility at genes including VEGFA. Increased MYCN TF activity was confirmed with gene overexpression of downstream targets including NOTCH3, CREB5, PLK1, and VEGFA. Other genes that were highly accessible and overexpressed in MYCN-amplified tumor cells were related to oxidative stress, differentiation, and anti-apoptotic pathways. MYCN-amplified tumor cells modified the tumor microenvironment with increased VISTA signaling between MYCN-amplified tumor cells and tumor-associated macrophages, creating an immunosuppressive environment. We confirmed these effects by observing a higher proportion of M2-like macrophages in MYCN-amplified tumors (29.6% vs 18.2%). In conclusion, MYCN amplification in spinal ependymomas upregulates tumor cell proliferation, angiogenesis, and M2-like macrophage recruitment/programming.

STEM-12. A NEURONAL STEM-LIKE PHENOTYPE IN GRADE 4 IDH-MUTANT ASTROCYTOMA WITH CDKN2A/B LOSS IS ASSOCIATED WITH CUX2 DEFICIENCY

Abstract Diffuse gliomas represent the most common type of primary adult malignant brain tumor historically diagnosed and graded from histologic criteria alone. Gliomas harboring isocitrate dehydrogenase (IDH) 1 or 2 mutations are associated with lower grade tumors and portend a favorable prognosis relative to IDH-wildtype glioma. However, the loss of CDKN2A/B in IDH-mutant astrocytoma confers an aggressive high grade phenotype and is the strongest implicated molecular alteration associated poor clinical survival, thus is now sufficient to define a grade 4 tumor regardless of histologic grade. However, there remains no effective therapies targeted at molecular subgroups in aggressive gliomas to date. Here, we sought to elucidate the biologic pathways and functional outcomes associated with the acquisition of high-grade behavior under loss of CDKN2A/B in IDH-mutant astrocytoma to inform future therapeutic strategies. We analyzed a cohort of patient IDH-mutant astrocytomas with RNA sequencing data and found the increased expression of regulators of embryonic nervous system development and signaling concurrent with CDKN2A/B loss. Using grade 4 IDH-mutant astrocytoma patient-derived (PDX) and cell-lines harboring CDKN2A/B homozygous deletion, we stably re-expressed p14ARF, p15INK4B, and p16INK4A using a Tet-inducible system. IDH-mutant cell lines with re-expression of p14, p15, or p16 displayed differential transcription factor activation, impaired neurosphere capability, decreased colony formation, and lower neurosphere proliferation. Intriguingly, RNA-seq data revealed CUX2, a transcription factor known to control neuronal precursor behavior, as the likely candidate regulating the differential expression profile across CDKN2A/B status. We observed increased CUX2 expression in cell lines stably re-expressing p14, p15, and p16. We validated the CUX2 signature across publicly available datasets of IDH-mutant astrocytoma where CUX2 expression negatively correlated with loss of CDKN2A/B in patient tumors. Together our work suggests CUX2 deficiency in IDH-mutant astrocytoma with CDKN2A/B deletion enables an increased neuronal stem-like phenotype in these grade 4 tumors.

Carboxylic Acids as Activators of NRF2: Antioxidant and Antiinflammatory Effects

Abstract: The complex interaction between carboxylic acids and molecular signaling pathways, particularly the nuclear factor erythroid 2-related factor 2 (NRF2) pathway, is of growing interest in medicinal chemistry due to its potential therapeutic benefits. Carboxylic acids, which are widely distributed in nature, are versatile regulators of cellular responses due to their ability to interact with multiple signaling pathways, especially those involved in combating oxidative stress and inflammation. Several carboxylic acids exhibit significant antioxidant and anti-inflammatory activities. They have been identified as potential activators of the NRF2 transcription factor, a key regulator of endogenous antioxidants that maintains cellular redox homeostasis and modulates the production of several antioxidant proteins and detoxifying enzymes. The potential effects of carboxylic acid-NRF2 crosstalk are exhibited in a variety of physiological processes, such as attenuation of oxidative stress and inflammation, detoxification of xenobiotics, and modulation of the immune system. The molecular docking of some carboxylic acids with NRF2 protein showed that their binding affinities were comparable to dimethyl fumarate, a reference drug. The current review explores the evolving landscape of carboxylic acid-NRF2 interactions and their mechanisms of action, highlighting the possible impact of their antioxidant and anti-inflammatory effects on inflammation and oxidative stress-mediated diseases. The natural and synthetic sources of NRF2-activating carboxylic acids and the role of their chemical and physical properties in influencing NRF2-inducing activities were discussed. Their potential challenges as future drugs and clinical trial prospects were also highlighted. Carboxylic acid-NRF2 interactions offer potential for developing therapies that will attenuate oxidative stress and inflammation.

MiRNAs in the diagnosis and therapy of cardiac and mediastinal tumors: a new dawn for cardio-oncology?

Dysfunctions in miRNA production have been recently investigated as predictors of neoplasms and their therapeutic strategies. In this review, we summarize the available knowledge on miRNAs and cardiac tumors (such as myxoma) and mediastinal tumors (such as thymoma) and propose new avenues for future research. MiRNAs are crucial for cardiac development through the expression of cardiac transcription factors (miR-335-5p), hinder the cell cycle by modulating the activity of transcription factors (miR-126-3p, miR-320a), modulate the production of inflammatory factors such as interleukins (miR-217), and interfere with cell proliferation or apoptosis (miR-218, miR-634 and miR-122). Current and future research on miRNAs is essential, as a deep understanding could lead to a revolution in the field of diagnostics and prevention of neoplastic diseases.

PU.1 eviction at lymphocyte-specific chromatin domains mediates glucocorticoid response in acute lymphoblastic leukemia

The epigenetic landscape plays a critical role in cancer progression, yet its therapeutic potential remains underexplored. Glucocorticoids are essential components of treatments for lymphoid cancers, but resistance, driven in part by epigenetic changes at glucocorticoid-response elements, poses a major challenge to effective therapies. Here we show that glucocorticoid treatment induces distinct patterns of chromosomal organization in glucocorticoid-sensitive and resistant acute lymphoblastic leukemia xenograft models. These glucocorticoid-response elements are primed by the pioneer transcription factor PU.1, which interacts with the glucocorticoid receptor. Eviction of PU.1 promotes receptor binding, increasing the expression of genes involved in apoptosis and facilitating a stronger therapeutic response. Treatment with a PU.1 inhibitor enhances glucocorticoid sensitivity, demonstrating the clinical potential of targeting this pathway. This study uncovers a mechanism involving PU.1 and the glucocorticoid receptor, linking transcription factor activity with drug response, and suggesting potential therapeutic strategies for overcoming resistance.

A small molecule that reshapes the chromatin dynamics of FOXA1

In this issue, Won etal.1 report a covalent ligand binding the pioneer transcription factor FOXA1, altering its function and remodeling chromatin. This important finding highlights the potential of small molecules to modulate transcription factor activity and demonstrates the promise of chemical proteomics in discovering first-in-class ligands.

Palmitic Acid Induced a Dedifferentiation Profile at the Transcriptome Level: A Collagen Synthesis but no Triglyceride Accumulation in Hepatocyte-Like Cells Derived From Human-Induced Pluripotent Stem Cells Cultivated Inside Organ on a Chip.

Nonalcoholic fatty liver disease (NAFLD) is one of the main causes of critical liver diseases leading to steatosis, steatohepatitis, fibrosis, and ultimately to liver cirrhosis and hepatic carcinoma. In this study, the effect of palmitic acid (PA), one of the most abundant dietary fatty acids, was investigated using an organ-on-a-chip (OoC) technology on hepatocyte-like cells derived from human-induced pluripotent stem cells (hiPSCs). After 1 week of hepatic maturation, followed by 1 week of exposure, the transcriptomic analysis showed lower liver transcription factor activity. It also revealed that 318 genes were differentially expressed between the control and 0.5-mM PA conditions. The 0.5-mM PA conditions were characterized by the downregulation of hepatic markers (liver transcription factors, phase I and phase II metabolism genes) of lipidic genes (metabolism and transport). In parallel, the 0.5-mM PA treatment upregulated several extracellular matrix genes (such as collagen genes). The physiopathological staining demonstrated no lipid accumulation in our model and confirmed the secretion of collagen in the 0.5-mM PA conditions. However, the production of albumin, the metabolic biotransformation by the cytochrome P450 enzymes, and the biliary acid concentrations were not altered by the PA treatments. Overall, our data illustrated the response to PA characterized by an early stage of dedifferentiation observed at the transcriptomic levels associated with a modification of the collagenic profile but without lipid accumulation. We believe that our model provides new insight of the onset of palmitic lipotoxicity in the early stage of NAFLD.

BPDCN MYB fusions regulate cell cycle genes, impair differentiation and induce myeloid-dendritic cell leukemia.

MYB fusions are recurrently found in select cancers, including blastic plasmacytoid dendritic cell neoplasm (BPDCN), an acute leukemia with poor prognosis. They are markedly enriched in BPDCN compared to other blood cancers, and in some patients are the only obvious somatic mutation detected. This suggests they may alone be sufficient to drive dendritic cell transformation. MYB fusions are hypothesized to alter the normal transcription factor activity of MYB, but mechanistically how they promote leukemogenesis is poorly understood. Using CUT&RUN chromatin profiling, we found that in BPDCN leukemogenesis, MYB switches from being a regulator of dendritic cell lineage genes to aberrantly regulating G2/M cell cycle control genes. MYB fusions found in BPDCN patients increased the magnitude of DNA binding at these locations, and this was linked to BPDCN-associated gene expression changes. Furthermore, expression of MYB fusions in vivo impaired dendritic cell differentiation and induced transformation to generate a mouse model of myeloid-dendritic acute leukemia. Therapeutically, we present evidence that all-trans retinoic acid (ATRA) may cause loss of MYB protein and cell death in BPDCN.

Jasmonate induces translation of the Arabidopsis tRNA-binding protein YUELAO1, which activates MYC2 in jasmonate signaling.

Jasmonate is ubiquitous in the plant kingdom and regulates multiple physiological processes. Although jasmonate signaling has been thoroughly investigated in Arabidopsis thaliana, most studies have focused on the transcriptional mechanisms underlying various jasmonate responses. It remains unclear whether (and how) translation-related pathways help improve transcription efficiency to modulate jasmonate signaling, which may enable plants to respond to stressful conditions effectively. Here, we demonstrate that jasmonate induces translation of the tRNA-binding protein YUELAO 1 (YL1) via a specific region in its 3' untranslated region (3' UTR). YL1 and its homolog YL2 redundantly stimulate jasmonate responses such as anthocyanin accumulation and root growth inhibition, with the YL1 3' UTR being critical for YL1-promoted jasmonate responses. Once translated, YL1 acts as an activator of the MYC2 transcription factor through direct interaction, and disrupting YL1 3' UTR impairs the YL1-mediated transcriptional activation of MYC2. YL1 enhances jasmonate responses mainly in a MYC2-dependent manner. Together, these findings reveal a translational mechanism involved in jasmonate signaling and advance our understanding of the transcriptional regulation of jasmonate signaling. The YL1 3' UTR acts as a crucial signal transducer that integrates translational and transcriptional regulation, allowing plants to respond to jasmonate in a timely fashion.

Exploring the spatial effects influencing the EGFR/ERK pathway dynamics with machine learning surrogate models

The fate of cells is regulated by biochemical reactions taking place inside of them, known as intracellular pathways. Cells display a variety of characteristics related to their shape, structure and contained fluid, which influences the diffusion of proteins and their interactions. To gain insights into the spatial effects shaping intracellular regulation, we apply machine learning (ML) to explore a previously developed spatial model of the epidermal growth factor receptor (EGFR) signaling. The model describes the reactions between molecular species inside of cells following the transient activation of EGF receptors. To train our ML models, we conduct 10,000 numerical simulations in parallel where we calculate the cumulative activation of molecules and transcription factors under various conditions such as different diffusion speeds, inactivation rates, and cell structures. We take advantage of the low computational cost of ML algorithms to investigate the effects of cell and nucleus sizes, the diffusion speed of proteins, and the inactivation rate of the Ras molecules on the activation strength of transcription factors. Our results suggest that the predictions by both neural networks and random forests yielded minimal mean square error (MSEs), while linear generalized models displayed a significant larger MSE. The exploration of the surrogate models has shown that smaller cell and nucleus radii as well, larger diffusion coefficients, and reduced inactivation rates increase the activation of transcription factors. These results are confirmed by numerical simulations. Our ML algorithms can be readily incorporated within multiscale models of tumor growth to embed the spatial effects regulating intracellular pathways, enabling the use of complex cell models within multiscale models while reducing the computational cost.

Single-cell transcriptomics reveals IRF7 regulation of the tumor microenvironment in isocitrate dehydrogenase wild-type glioma.

Mutations in isocitrate dehydrogenase (IDH) are important markers of glioma prognosis. However, few studies have examined the gene expression regulatory network (GRN) in IDH-mutant and wild-type gliomas. In this study, single-cell RNA sequencing and spatial transcriptome sequencing were used to analyze the GRN of cell subsets in patients with IDH-mutant and wild-type gliomas. Through gene transcriptional regulation analysis, we identified the M4 module, whose transcription factor activity is highly expressed in IDH wild-type gliomas compared to IDH-mutants. Enrichment analysis revealed that these genes were predominantly expressed in microglia and macrophages, with significant enrichment in interferon-related signaling pathways. Interferon regulatory factor 7 (IRF7), a transcription factor within this pathway, showed the highest percentage of enrichment and was primarily localized in the core region of wild-type IDH tumors. A machine-learning prognostic model identified novel subgroups within the wild-type IDH population. Additionally, IRF7 was shown to promote the proliferation and migration of T98G and U251 cells in vitro, and its knockdown affected glioma cell proliferation in vivo. This study systematically established the regulatory mechanism of IDH transcriptional activity in gliomas at the single-cell level and drew a corresponding cell map. The study presents a transcriptional regulatory activity map for IDH wild-type gliomas, involving single-cell RNA sequencing and spatial transcriptomics to identify gene regulatory networks, machine learning models for IDH subtyping, and experimental validation, highlighting the role of IRF7 in glioma progression.