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The farnesoid X receptor activates transcription independently of RXR at non-canonical response elements.

The farnesoid X receptor (FXR) is a nuclear receptor (NR) known to obligately heterodimerize with the retinoid X receptor (RXR). FXR is expressed as four isoforms (α1-α4) that drive transcription from IR-1 (inverted repeat-1) response elements (REs). Recently, we found that FXR isoforms α2/α4 also activate transcription from non-canonical ER-2 (everted repeat-2) REs, mediating most metabolic effects of general FXR activation. Here, we explored molecular determinants of regulation by FXRα2 from ER-2 REs through quantitative interaction proteomics, site-directed mutagenesis and transcriptomics. We discovered FXRα2 binds to and activates ER-2 elements in vitro and in reporter assays independently of RXR. Genome-wide binding analysis in mouse liver revealed higher ER-2 motif enrichment in FXR sites lacking RXR. Abrogation of FXRα2:RXR heterodimerization abolished IR-1, but preserved ER-2 transactivation. Transcriptome-wide, RXR overexpression inhibited 25% of FXRα2 targets in HepG2. These genes were specifically activated by the heterodimerization-deficient mutant FXRα2L434R, enriched for ER-2 motifs at their promoters, and involved in lipid metabolism and ammonia detoxification. In conclusion, RXR acts as a molecular switch, inhibiting FXRα2 activation from ER-2 while enhancing it from canonical IR-1 REs. Our results showcase FXR as the first NR with isoform-specific RXR-independent REs, highlighting a new layer of regulation and complexity for RXR-heterodimerizing NRs.

Humans

Upregulation of TLR2 expression is induced by estrogen via an estrogen-response element (ERE).

TLR2 and estrogen are both thought to be involved in the pathogenesis of RA; however, it is unknown if there is an association between estrogen and TLR2. In this report, we treated PMA-differentiated THP-1 cells with 17β-estradiol (E2) and observed increases in TLR2 mRNA and protein levels by real-time quantitative PCR and western blot. Transfection of THP-1 cells with a series of 5'-deleted TLR2 promoter-luciferase constructs revealed that E2 enhanced TLR2 transcriptional activity in an estrogen receptor alpha (ERα)-dependent pattern. An estrogen receptor response element (ERE) was identified 251 bases upstream of the TLR2 promoter, and electrophoretic mobility shift assay and chromatin immunoprecipitations showed ERα binding was increased by E2. In summary, this work demonstrated that TLR2 is a new estrogen-regulated gene whose expression is upregulated through the interaction of ERα with an ERE in the promoter region.

Cell Line

A python based automated computational framework to classify and comparative genomics analysis of the global diversity of chili leaf curl virus (ChiLCV) strains to understand virus host interactions.

Chili leaf curl virus (ChiLCV) is a Begomovirus chillicapsici that is one of the most devastating viruses impacted on the production of chili in the world, especially in South Asia. In the present study, we combined high-throughput computational genomics with experimental analysis of global diversity. A workflow was created using automated Python scripts to download, curate and process ChiLCV genomes from public database. About 410 complete ChiLCV genomes download from public databases. Using a phylogenetic approach, these isolates were subdivided into 34 strains, belonging to 10 major clades, showing significant genetic diversity. Geographic analysis revealed that Pakistan (207 isolates) and India (148 isolates) were the main sources of ChiLCV diversity and the remainder of the isolates were from Oman, Bangladesh, Iran, Saudi Arabia and Sri Lanka. Recombination was observed as a major evolutionary force as more than twenty recombination events were detected. Analysis of cis-regulatory elements showed a complex structure of the viral promoter, including multiple binding sites for transcription factors, hormone-response elements, light-responsive elements, and stress-responsive elements, indicating a high number of interactions between viral regulatory elements and host signaling pathways. Pangenome analysis showed the presence of a highly dynamic open pangenome made up of strain-specific orthologous groups (species-specific orthogroups). Experimental inoculation of chili plants was also carried out to assess the biological effects of infection, along with phytochemical, FTIR, HPLC, and qPCR analyses.

Begomovirus

An XRE-type regulator in Streptococcus mutans plays an important role in brpA expression and oxidative stress tolerance response.

This study used a functional genomics approach to explore the role of a xenobiotic response element (XRE)-type regulator (SMU.405c) in Streptococcus mutans physiology, including the expression of biofilm regulatory protein BrpA. Results showed that deletional mutation of xre significantly reduced the ability of the deficient mutant to grow in the presence of methyl viologen, a commonly used oxidative stressor (P < 0.001). When challenged in a hydrogen peroxide killing assay, the survival rate of the &#x2206;xre mutant was >2-log less than the parent strain after 60 min (P < 0.001). Luciferase reporter fusion assays showed that xre deficiency had no significant effect on luciferase expression when it was under the control of the intact brpA promoter, but the reporter activity increased by >6-fold (P < 0.001) when the reporter gene was fused to a brpA promoter derivative with deletion of a putative XRE-binding box. Electrophoretic mobility shift assay (EMSA) showed that recombinant XRE interacted with the brpA promoter, resulting in an electrophoretic shift of the promoter probes. In vitro transcription assay also showed that inclusion of XRE caused transcription to fall off, significantly reducing full-length brpA transcripts. RNA-seq analysis revealed that deficiency of XRE led to altered expression of >102 genes by >2-fold (P < 0.05), including 28 with increased expression, and 74 with decreased expression. Among the down-regulated were genes for DNA repair and oxidative stress tolerance response. These results suggest that XRE (SMU.405c) in S. mutans plays an important role in brpA expression and oxidative stress tolerance response.IMPORTANCEStreptococcus mutans, a keystone pathogen in human dental caries, primarily lives in the highly diverse microbiota on tooth surfaces, where the conditions are often harsh and fluctuate frequently. Locus SMU.405c was annotated to encode a xenobiotic response element (XRE)-like transcriptional regulator, but no information is available concerning the role of this protein in S. mutans pathophysiology. This study used a functional genomics approach along with molecular and transcriptomic analysis to characterize a deletional xre mutant, and the results showed that xre deficiency in S. mutans resulted in weakened oxidative stress tolerance response and alterations in transcription of >102 genes, including those known to play an important role in cell envelope biogenesis and stress tolerance response. Reporter fusion assay, electrophoretic mobility shift assay (EMSA), and in vitro transcription further demonstrated that the XRE-like regulator encoded by SMU.405c is a repressor of brpA expression and plays an important role in oxidative stress tolerance response.

Streptococcus mutans

BHLHE40 and ChREBP associate with hepatic enhancer clusters containing PPAR&#x3b1;, RXR&#x3b1;, and HNF4 nuclear receptors.

BHLHE40/DEC1 is a basic helix-loop-helix transcription factor (TF) that regulates circadian rhythm and T-cell responses. In hepatocytes, its function and interplay with other TFs are poorly understood. Employing a genome-wide approach, we show that its genomic binding strongly overlapped with that of carbohydrate response-element binding protein, a sugar-sensing TF and known inducer of BHLHE40 expression. Transcriptomic analysis of primary mouse hepatocytes revealed reduced expression of genes involved in genomic stability on Bhlhe40 knockdown by siRNA. Bhlhe40 depletion potentiated fructose responsiveness of genes involved in cell-cycle regulation. Strikingly, genomic binding of BHLHE40 extensively overlapped with enhancers occupied by PPAR&#x3b1;, RXR&#x3b1;, and HNF4 nuclear receptors and BHLHE40 fine-tuned the expression of PPAR&#x3b1; target genes. Using HEK293 cells, we further observed that BHLHE40 physically interacted with RXR&#x3b1; and PPAR&#x3b1; cofactors. Collectively, our data suggest that through cooperation with carbohydrate response-element binding protein and nuclear receptors, BHLHE40 is a central regulator of hepatic gene expression with potential to integrate inputs from nutrient signals contributing to the metabolic flexibility of the liver.

Animals

Impact of AGT rs5050(T>G) variants on associations between estradiol and angiotensinogen levels: Multi-Ethnic Study of Atherosclerosis (MESA).

AIMS: Angiotensinogen plays an essential role in maintaining circulatory homeostasis. AGT rs5050(T&#x2009;>&#x2009;G) has been identified as a regulator of the transcription of AGT mRNA, with differential expression between sexes. We sought to determine if rs5050(T&#x2009;>&#x2009;G), an estrogen response element, modifies the relationship between estrogen and angiotensinogen levels. METHODS: rs5050(T&#x2009;>&#x2009;G) was genotyped, and plasma angiotensinogen levels were measured in 4,831 MESA participants, including postmenopausal women, on hormone therapy (n&#x2009;=&#x2009;709) or not (n&#x2009;=&#x2009;1,551), and 2,581 men. Linear regression models were employed to determine the associations of angiotensinogen with rs5050(T&#x2009;>&#x2009;G) allele dosage; and to evaluate whether rs5050(T&#x2009;>&#x2009;G) modifies the association between estradiol and angiotensinogen, with a main effect term and interaction term between rs5050(T&#x2009;>&#x2009;G)*estradiol. Estimated marginal means (EMMs) were used to further evaluate the effect of estradiol on angiotensinogen across different rs5050 alleles (T&#x2009;>&#x2009;G). RESULTS: rs5050TT had the highest median levels of angiotensinogen, followed by TG and GG. Adjusted main effect model showed positive associations between estradiol and angiotensinogen, with each rs5050T allele associated with 0.329 SD higher log-angiotensinogen levels (CI 95% 0.293, 0.365). The interaction rs5050(T&#x2009;>&#x2009;G)*estradiol was not significant, with EMMs exhibiting overlapping slope confidence intervals across genotypes. The proportion of the variance in angiotensinogen explained by modeling increases from 47.9% to 51.6% when including rs5050(T&#x2009;>&#x2009;G) or interation rs5050(T&#x2009;>&#x2009;G)*estradiol in the model. CONCLUSIONS: rs5050(T&#x2009;>&#x2009;G) is associated with circulating angiotensinogen levels, but rs5050(T&#x2009;>&#x2009;G) alleles do not influence the relationship between estradiol and angiotensinogen. This suggests that estrogen's effect on angiotensinogen regulation occurs independently of rs5050(T&#x2009;>&#x2009;G), despite its location within an estrogen-responsive element.

Angiotensinogen

Mechanistic insights into steroid hormone-mediated regulation of the androgen receptor gene.

Expression of the androgen receptor is key to the response of cells and tissues to androgenic steroids, such as testosterone or dihydrotestosterone, as well as impacting the benefit of hormone-dependent therapies for endocrine diseases and hormone-dependent cancers. However, the mechanisms controlling androgen receptor expression are not fully understood, limiting our ability to effectively promote or inhibit androgenic signalling therapeutically. An autoregulatory loop has been described in which androgen receptor may repress its own expression in the presence of hormone, although the molecular mechanisms are not fully understood. In this work, we elucidate the mechanisms of autoregulation and demonstrate, for the first time, that a similar repression of the AR gene is facilitated by the progesterone receptor. We show that the progesterone receptor, like the androgen receptor binds to response elements within the AR gene to effect transcriptional repression in response to hormone treatment. Mechanistically, this repression involves hormone-dependent histone deacetylation within the AR 5'UTR region and looping between sequences in intron 2 and the transcription start site (TSS). This novel pathway controlling AR expression in response to hormone stimulation may have important implications for understanding cell or tissue selective receptor signalling.

Receptors, Androgen

Targeting PRAME directly or via EZH2 inhibition overcomes retinoid resistance and represents a novel therapy for keratinocyte carcinoma.

Retinoids have demonstrated efficacy as preventative/treatment agents for keratinocyte carcinomas (KCs): basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (SCC). However, retinoid resistance mechanisms limit the efficacy of these compounds. A subset of KCs expresses Preferentially Expressed Antigen in Melanoma (PRAME): a retinoid signaling corepressor. PRAME is proposed to repress retinoid signaling by guiding enhancer of zeste homolog 2 (EZH2) to retinoic acid response elements (RARE) in promoters. We investigated the effects of PRAME on KC pathogenesis and retinoid response. High-PRAME expression in tumors was negatively correlated with epidermal differentiation gene signatures. PRAME overexpression downregulated epidermal differentiation gene signatures and impaired differentiation in 3D culture. PRAME overexpression attenuated retinoid-induced RARE activation, growth suppression, and differentiation responses. Conversely, low-PRAME tumors and PRAME-depleted KC cells demonstrated enriched epidermal differentiation gene signatures. PRAME downregulation restored retinoid-induced RARE activation, growth suppression, keratinization in SCC, and cell death signaling in BCC. Furthermore, combined retinoid and EZH2 inhibitor treatment augmented RARE activation and suppressed PRAME-expressing KC cell growth. Hence, PRAME confers retinoid resistance in KC, which may be overcome by EZH2 inhibition.

Enhancer of Zeste Homolog 2 Protein

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

Genome-wide identification of HCT gene family in sugarcane (Saccharum spp. hybrid) and characterization of putative cis-elements in gene regulation.

BACKGROUND: Sugarcane (Saccharum spp. hybrid) is a globally important crop, and its bagasse can be converted into bioethanol and other industrial products. Lignin, a core component of sugarcane cell walls, plays a crucial role in bagasse quality and lodging resistance. Shikimic acid hydroxycinnamyl transferase (HCT) is the key enzyme in lignin biosynthesis. However, the HCT gene family in sugarcane and its regulatory roles in sugarcane remain poorly understood. RESULTS: A total of 663 HCT genes (including alleles) were identified in the Saccharum hybrid R570 genome, which were classified into six groups (I-VI) and were unevenly distributed across 77 chromosomes. Bioinformatics analysis revealed that the subgroups of R570HCTs had similar gene structures, suggesting conserved functions. Moreover, the different subgroups presented unique putative cis&#x2011;element distribution patterns. Transcriptome data indicated that some R570HCTs exhibited significant spatiotemporal and tissue&#x2011;specific expression patterns. Further Pearson correlation analysis between putative cis&#x2011;element distribution and normalized expression values at the subgroup level revealed that light-responsive elements (L&#x2011;box and GA&#x2011;motif) were positively correlated with R570HCT expression, and different subgroups formed a complex regulatory network by integrating hormone response and stress elements. Importantly, this subgroup-level correlation was cross-validated by comparing the cis&#x2011;element clustering heatmap with the expression heatmap, revealing consistent enrichment patterns. CONCLUSIONS: The study's findings provide novel insights into the correlation among motifs, putative cis&#x2011;elements, and gene expression, and propose a cross-validated framework for understanding regulatory divergence among HCT subfamilies in polyploid sugarcane, serving as a hypothesis generating resource for future research on R570HCT expression.

Saccharum

Anthracyclines attenuate Nrf1-dependent proteolytic pathways and potentiate proteasome inhibitor cytotoxicity.

Proteasome inhibitors such as bortezomib, carfilzomib, and ixazomib are FDA-approved treatments for multiple myeloma, but resistance frequently limits their effectiveness. The transcription factor Nrf1 (NFE2L1) upregulates proteasome and autophagy genes upon proteasome inhibition, contributing to adaptive resistance. In this study, we identified anthracyclines, including doxorubicin, as suppressors of the Nrf1-driven transcriptional response. Mechanistically, doxorubicin impaired Nrf1 binding to antioxidant response elements (AREs) within promoter regions of target genes without affecting Nrf1 processing or nuclear localization. Importantly, aclarubicin, a non-DNA-damaging anthracycline, also attenuated Nrf1 transcriptional activity, indicating that DNA damage is not required for this inhibition. Doxorubicin cotreatment delayed proteasome recovery after pulse inhibition and partially restored sensitivity to carfilzomib in bortezomib-resistant U266 myeloma cells, consistent with genetic knockout of Nrf1. These findings identify a DNA-damage-independent mechanism by which anthracyclines directly obstruct Nrf1-mediated transcriptional induction. Thus, anthracyclines serve as chemical tools to probe the molecular control of proteostasis and suggest a strategy to mitigate Nrf1-driven adaptive response to proteasome inhibition.

Humans

Regulation of the bone-specific osteocalcin gene by p300 requires Runx2/Cbfa1 and the vitamin D3 receptor but not p300 intrinsic histone acetyltransferase activity.

p300 is a multifunctional transcriptional coactivator that serves as an adapter for several transcription factors including nuclear steroid hormone receptors. p300 possesses an intrinsic histone acetyltransferase (HAT) activity that may be critical for promoting steroid-dependent transcriptional activation. In osteoblastic cells, transcription of the bone-specific osteocalcin (OC) gene is principally regulated by the Runx2/Cbfa1 transcription factor and is stimulated in response to vitamin D(3) via the vitamin D(3) receptor complex. Therefore, we addressed p300 control of basal and vitamin D(3)-enhanced activity of the OC promoter. We find that transient overexpression of p300 results in a significant dose-dependent increase of both basal and vitamin D(3)-stimulated OC gene activity. This stimulatory effect requires intact Runx2/Cbfa1 binding sites and the vitamin D-responsive element. In addition, by coimmunoprecipitation, we show that the endogenous Runx2/Cbfa1 and p300 proteins are components of the same complexes within osteoblastic cells under physiological concentrations. We also demonstrate by chromatin immunoprecipitation assays that p300, Runx2/Cbfa1, and 1alpha,25-dihydroxyvitamin D(3) receptor interact with the OC promoter in intact osteoblastic cells expressing this gene. The effect of p300 on the OC promoter is independent of its intrinsic HAT activity, as a HAT-deficient p300 mutant protein up-regulates expression and cooperates with P/CAF to the same extent as the wild-type p300. On the basis of these results, we propose that p300 interacts with key transcriptional regulators of the OC gene and bridges distal and proximal OC promoter sequences to facilitate responsiveness to vitamin D(3).

Acetyltransferases

Eugenol-Derived Cytoprotective Action Against Dityrosine-Induced Oxidative Stress in Mice Liver via Akt/Nrf2/ARE Signaling Pathway.

Dityrosine (Dityr), a byproduct of protein oxidation in protein-rich food, induces oxidative stress, inflammation, and apoptosis, jeopardizing human health. Eugenol (EUG), a natural compound with antioxidative and anti-inflammatory properties, was investigated for its protective effects against Dityr-induced hepatotoxicity in this work. In this study, in vivo and in vitro analyses demonstrated EUG's protective effects against Dityr-induced hepatotoxicity. EUG significantly attenuated oxidative stress markers, inflammatory infiltration, fibrotic progression, and apoptotic signaling in mice liver tissues. Mechanistically, EUG activated the Akt/NF-E2-related factor 2/antioxidant response element (Akt/Nrf2/ARE) pathway, enhancing cellular antioxidant capacity while suppressing pro-inflammatory cytokine release. In HepG2 cells, EUG treatment effectively counteracted Dityr-induced ROS overproduction and cell death through Nrf2-mediated antioxidant upregulation. In conclusion, our findings indicate that EUG effectively mitigates Dityr-induced oxidative stress via the Akt/Nrf2/ARE pathway, and this antioxidative impact further inhibits inflammation and apoptosis. These effects ultimately ameliorate liver function impairment caused by Dityr.

Animals

Evidence for orphan nuclear receptor TR4 in the etiology of Cushing disease.

Cushing disease (CD) is a life-threatening disorder attributed to excess pituitary tumor-derived adrenocorticotrophic hormone (ACTH) and adrenal steroid secretion caused by pituitary tumors. Whereas CD was first described in 1932, the underlying genetic basis driving tumor growth and ACTH secretion remains unsolved. Here, we show that testicular orphan nuclear receptor 4 (TR4, nuclear receptor subfamily 2, group C, member 2) is overexpressed in human corticotroph tumors as well as in human and mouse corticotroph tumor cell lines. Forced overexpression of TR4 in both human and murine tumor cells increased proopiomelanocortin transcription, ACTH secretion, cellular proliferation, and tumor invasion rates in vitro. Conversely, knockdown of TR4 expression reversed all phenotypes. Mechanistically, we show that TR4 transcriptionally activates proopiomelanocortin through binding of a direct repeat 1 response element in the promoter, and that this is enhanced by MAPK-mediated TR4 phosphorylation. In vivo, TR4 overexpression promotes murine corticotroph tumor growth as well as enhances ACTH and corticosterone production, whereas TR4 knockdown decreases circulating ACTH and corticosterone levels in mice harboring ACTH-secreting tumors. Our findings directly link TR4 to the etiology of corticotroph tumors, hormone secretion, and cell growth as well as identify it as a potential target in the treatment of CD.

ACTH-Secreting Pituitary Adenoma

AgRP reflects glucocorticoid action: integrated experimental and clinical evidence.

PURPOSE: Glucocorticoids (GCs) are key regulators of energy homeostasis. Clinically, patients with Cushing's syndrome exhibit obesity, whereas adrenal insufficiency is associated with weight loss. However, circulating biomarkers reflecting GC action have not been established. Agouti-related protein (AgRP), an orexigenic neuropeptide, is upregulated by GC in the rodent hypothalamus. Here, we investigated whether AgRP is a surrogate marker of GC action through in vitro and in vivo experiments as well as a clinical study. METHODS: The GC-dependent transcriptional regulation of AgRP was examined using reporter assays in neuronal BE(2)C cells. In animal experiments, the effects of GC on hypothalamic AgRP mRNA expression in C57BL/6J mice were examined. Circulating AgRP levels were also analyzed in nine patients with adrenal Cushing's syndrome before and after surgery. RESULTS: Two functional glucocorticoid-responsive elements (GREs) were identified in the human AgRP gene promoter, through which GC enhanced AgRP transcriptional activity. In mice, corticosterone (CORT) administration induced hyperphagia and increased hypothalamic AgRP mRNA levels, which positively correlated with plasma CORT levels. In patients with adrenal Cushing's syndrome, circulating AgRP levels significantly decreased after surgery (118.7&#x2009;&#xb1;&#x2009;40.3 vs. 37.7&#x2009;&#xb1;&#x2009;9.5 pg/mL, p&#x2009;<&#x2009;0.01) and positively correlated with serum cortisol levels (r&#x2009;=&#x2009;0.79, p&#x2009;<&#x2009;0.01). CONCLUSION: These findings demonstrate that GC positively regulates AgRP across molecular, animal, and clinical settings, supporting the hypothesis that circulating AgRP may serve as a surrogate indicator of GC action. Further studies are warranted to establish its clinical applicability.

Animals

Identification of genomic features that uniquely impact estrogen receptor alpha binding and its effects on gene expression in endometrial cancer.

Estrogen receptor 1 (ESR1, also known as estrogen receptor alpha or ER) is an established oncogenic transcription factor in breast and endometrial cancer; however, more is known about the mechanisms controlling ER behavior in breast cancer, and therapies targeting ER have been much more successful in breast cancer. To address this disparity, we characterize the genomic features that control ER in endometrial cancer and determine to what extent these factors differ from those in breast cancer. We focus on the locations of estrogen response elements (EREs), ER's preferred DNA-binding motif, throughout the human genome. To identify factors that predict ER genomic binding and effects on target gene expression, we apply machine learning to genomic data for each ERE in Ishikawa cells (ER-positive endometrial cancer) and T-47D cells (ER-positive breast cancer). Many of these factors, such as chromatin accessibility and histone modifications, are predictive of ER activity in both cell lines. However, the transcription factors that predict ER activity are cell type specific, including FOXA1 and GATA3 in T-47D cells and ETV4 and SOX17 in Ishikawa cells. In addition, the features that predict ER binding and effects on gene expression differ, with transcription at EREs in the absence of estrogen being predictive of ER regulatory activity. A CRISPR knockout screen in Ishikawa cells, as well as follow-up experiments, confirms the discovery that SOX17 controls ER activity in endometrial cancer cells. These results identify important genomic features of ER binding and regulatory activity and how these features differ between endometrial cancer and breast cancer cells.

Humans

Genome-Wide Analysis of the AT-Hook Gene Family in Malus sieversii and Functional Characterization of MsAHL13.

AT-hook motif nuclear-localized (AHL) proteins are pivotal in plant growth, development, and stress responses. Nevertheless, there is limited research on AHL proteins in Malus sieversii. Our study identified 25 AHL genes from the M. sieversii genome, named MsAHL1-MsAHL25. The encoded protein sequences had lengths ranging from 195 to 554 amino acids, molecular weights from 19.17 to 58.53 kDa, and isoelectric points from 4.67 to 10.09. Chromosomal mapping revealed that these 25 genes were unevenly distributed across 10 chromosomes. Collinearity analysis of AHL genes in M. sieversii implied that gene loss might have occurred during its evolution. The phylogenetic tree classified the AHL proteins of M. sieversii into two subfamilies, showing a close relationship with multiple proteins of M. domestica. Promoter analysis indicated that the AHL genes in M. sieversii harbored numerous stress- and hormone-responsive elements, suggesting their potential role in various stress responses. qRT-PCR analysis of six representative MsAHLs under biotic and abiotic stresses demonstrated that the expression of MsAHL13, MsAHL15, and MsAHL17 was significantly upregulated under salt, drought, and cold stresses, while MsAHL01 expression was inhibited under low-temperature stress. All six MsAHLs were induced by the pathogen Valsa mali. Subcellular localization analysis of the specifically expressed protein MsAHL13 showed its nuclear location. Furthermore, luciferase and yeast two-hybrid assays confirmed the in vitro physical interaction between the MsAHL13 and MsMYB1 proteins. This research offers an important theoretical basis for further exploration of the functional mechanisms of this gene family in responding to environmental stresses.

Malus sieversii

Integrated methylome and transcriptome analysis provides insight into DNA methylation-mediated networks in sexual dimorphism of Vernicia montana.

BACKGROUND: Sexual dimorphism is fundamental to reproduction in dioecious plants and is regulated by both genetic and epigenetic mechanisms. DNA methylation is a central epigenetic mark known to influence phenotypic variation in plants. However, its specific role in shaping sexual dimorphism in dioecious trees remains poorly understood. To address this question, we performed integrated genome-wide DNA methylome and transcriptome analyses of four tissue types in the dioecious tung tree (Vernicia montana), including male and female flower buds and their corresponding leaves. RESULTS: Our analysis revealed distinct DNA methylation patterns between male and female tissues. Notably, the coordination between DNA methylation reprogramming and transcriptional regulation appeared to be more strongly associated with reproductive development than with vegetative growth in V. montana. We identified a set of sex-biased genes that may reflect different reproductive strategies between the sexes. Further analysis identified several key transcription factors (TFs) potentially associated with promoter differentially methylated regions (DMRs), including flowering-time regulators (e.g., FRS5, REM16, and VRN1) and TFs involved in hormone signaling pathways such as jasmonic acid, auxin, and salicylic acid signaling. Cis-regulatory element analysis showed that some promoter DMRs overlapped with hormone response elements related to abscisic acid, auxin, and gibberellin. Co-expression network analysis further revealed potential regulatory correlations among promoter DMR-mediated TFs, hormone-responsive pathways, and key floral development regulators. CONCLUSIONS: Collectively, our results suggest that interactions among DNA methylation, transcriptional regulation, and hormone-responsive pathways may contribute to the establishment of sexual dimorphism in V. montana. This study provides the first integrated view of these regulatory layers in V. montana and supports a species-specific regulatory framework for understanding the epigenetic basis of sexual dimorphism in this economically important dioecious tree. The proposed framework is based on multi-omics analyses and warrants further validation through targeted functional studies.

DNA Methylation