Mechanistic Insights into Lead Acetate-Induced Neurotoxicity Using RNA-Seq Analysis
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE285507 | GEO | 2025/03/31
REPOSITORIES: GEO
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Project description:The unfolded protein response maintains endoplasmic reticulum (ER) homeostasis by sensing protein-folding stress and orchestrating cellular adaptation via the ER-transmembrane proteins IRE1, PERK and ATF6. Malignant cells can co-opt IRE1 and PERK to sustain growth; however, the importance of ATF6 in cancer remains poorly deciphered. We observed elevated ATF6 transcriptional activity in several cancers including colorectal carcinoma (CRC). Genetic silencing or small molecule inhibition of ATF6 blocked cell cycle progression and reduced viability of several human CRC cell lines in vitro and disrupted tumor progression in vivo. Unexpectedly, ATF6 interference disabled Wnt and Myc signaling and reduced stemness. ATF6 inhibition attenuated growth of organoids derived from malignant but not normal human intestinal tissue, decreasing Wnt-pathway activity and driving cellular differentiation. Wnt-surrogate agonism in a Wnt-dependent CRC organoid restored pathway activity and rescued growth under ATF6 blockade. Our findings identify ATF6 as an unexpected facilitator of oncogenic Wnt signaling in CRC.
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Project description:Heavy metal toxicity is a worldwide health problem. Lead exposure is of particular concern due to the adverse effects of low concentrations on cognitive development in children. Although the mechanism of lead neurotoxicity has been well studied, the analysis and molecular mechanism of the transgenerational effects of lead exposure-induced neurotoxicity are lacking. To address this, Drosophila, a powerful developmental animal model, was exposed to lead acetate. We found that Pb exposure during the developmental stage affected the neurodevelopment of F0 fruit flies, resulting in a loss of the correlation between the motor terminal area and muscle fiber area and the increased frequency of β-lobe midline crossing phenotype in Mushroom bodies. We also found that Pb exposure led to an increase in BRP expression, suggesting an increase in synaptic vesicle release sites and a decrease in synaptic vesicle protein SYN expression in F0 generation. This explained the results of our electrophysiological data that Pb exposure led to an increase in the amplitude of evoked excitatory junctional potential (EJP) and an increase in the frequency of spontaneous excitatory junctional potential (mEJP). Our results further confirmed that the developmental neurotoxicity of parental Pb exposure has a transgenerational effect. Neurodevelopmental defects, abnormalities in synaptic function, and repetitive behavior also were observed in the F3 offspring of F0 exposed to lead. Our Medip-seq analysis showed that Pb exposure altered the DNA methylation levels of many neurodevelopmentally associated genes (eg, hppy, nrg, baz, and spn) in the F3 offspring of the F0 generation with Pb exposure. Our findings suggest that epigenetic mechanisms may underlie the transgenerational inheritance of acquired phenotypic traits resulting from exposure to environmental factors.
2023-12-09 | GSE249281 | GEO
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2024-08-12 | MSV000095581 | MassIVE
Project description:Lead (Pb) is a widespread environmental toxicant that can elicit a wide variety of adverse effects in aquatic species. In fish, exposure to Pb can induce oxidative stress and reduce antioxidant capacity and there is evidence that Pb-induced developmental abnormalities are the result of dysregulated metabolism pathways but to date, no studies have characterised the molecular mechanisms of lead toxicity in amphibians. To investigate this, we coupled transcriptomic responses and early-life stage toxicity testing to identify specific molecular mechanisms that drive the adverse effects of lead, in Xenopus laevis. Embryos were exposed to one of the concentrations (0, 70, 210 and 630 ng/L) of lead (II) nitrate starting from 2 days post fertilization (dpf) until 6 dpf and 21 dpf to examine the transcriptomic and apical responses, respectively. We observed common dysregulated pathways and with similar magnitude at medium and high lead concentrations, but a phenotypic response only with the highest lead level. RNA Seq analysis showed about ~250 differentially expressed genes that could be further categorized into KEGG pathways based on their involvement in key biological processes. The most dysregulated pathways were Glutathione metabolism, Cytochrome P450 (drug/ xenobiotic metabolism) and Steroid hormone biosynthesis. Developmental studies showed that tadpoles exposed to the highest Pb concentration (630 ug/L) had significantly decreased total length and higher proportion of developmental abnormalities. Therefore, evaluating gene expression responses can provide early indication of toxicological mechanisms of lead effects in amphibians. As with fish, dysregulated metabolic pathways are most likely the molecular mechanisms underlying lead toxicity in ELS amphibians and contribute to the altered growth and developmental abnormalities observed in this study.
2024-08-31 | GSE190080 | GEO
Project description:Limited studies on comparison of developmental (neuro)toxicity of parabens have been conducted and unharmonized concentrations between phenotypic observations and transcriptomic analysis hamper understanding of their differential molecular mechanism. Developmental toxicity testing was conducted with commonly used methyl- (MtP), ethyl- (EtP) and propyl-paraben (PrP) in zebrafish embryos. Based on benchmark dose 5% (BMD5), embryonic mortality based-point of departure (M-PoD) values of three parabens were determined and changes in locomotor behavior were evaluated at concentrations of 0, M-PoD/50, M-PoD/10, and M-PoD in which transcriptomic analysis was conducted to explore the underlying neurotoxicity mechanism. Higher long-chained parabens were more toxic than short-chained parabens, as determined by M-PoD values of 154.1, 72.6, and 24.2 µM for MtP, EtP, and PrP, respectively. While exposure to EtP resulted in hyperactivity, no behavior effect was observed by MtP and PrP. Transcriptomics analysis revealed that abnormal behaviors in EtP-exposed group are associated with the distinctly enriched pathways in signal, transport, calcium ion binding, and metal-binding. In contrast, exposure to MtP and PrP mainly disrupted the membrane and transmembrane, which are closely linked to abnormal embryonic development rather than neurobehavior changes. According to the changes in expression of signature mRNAs, tentative transcriptomic-based PoD (T-PoD) values for each paraben were determined as MtP (2.68 µM), EtP (3.85 µM), and PrP (1.4 µM).
2023-08-07 | GSE239773 | GEO
Project description:The unfolded protein response (UPR) maintains endoplasmic reticulum (ER) proteostasis through the activation of transcription factors such as XBP1s and ATF6. The functional consequences of these transcription factors for ER proteostasis remain poorly defined. Here, we describe methodology that enables orthogonal, small molecule-mediated activation of the UPR-associated transcription factors XBP1s and/or ATF6 in the same cell independent of stress. We employ transcriptomics and quantitative proteomics to evaluate ER proteostasis network remodeling owing to the XBP1s and/or ATF6 transcriptional programs. Furthermore, we demonstrate that the three ER proteostasis environments accessible by activating XBP1s and/or ATF6 differentially influence the folding, trafficking, and degradation of destabilized ER client proteins without globally affecting the endogenous proteome. Our data reveal how the ER proteostasis network is remodeled by the XBP1s and/or ATF6 transcriptional programs at the molecular level and demonstrate the potential for selectively restoring aberrant ER proteostasis of pathologic, destabilized proteins through arm-selective UPR-activation. The unfolded protein response adapts endoplasmic reticulum (ER) proteostasis via stress-responsive transcription factors including XBP1s and ATF6. Here, R. Luke Wiseman and colleagues implement technology for the orthogonal, ligand-dependent activation of XBP1s and/or ATF6 in a single cell. They characterize how XBP1s and/or ATF6 activation impacts ER proteostasis pathway composition and function. Adapted ER environments influence the proteostasis of destabilized protein variants without affecting the endogenous proteome. The work informs the development of proteostasis environment-adapting therapeutics for protein misfolding-related diseases. In order to activate both XBP1s and ATF6 in the same cell, we incorporated DHFR.ATF6 and tet-inducible XBP1s into a HEK293T-REx cell line stably expressing the tet-repressor. The HEK293DYG control cell line expresses tet-inducible eGFP and DHFR.YFP and is used as a control to demonstrate that the addition of doxycycline (dox) and trimethoprim (TMP) do not induce UPR genes. HEK293DYG cells were treated for 12 h with vehicle or 1 μg/mL dox and 10 μM TMP in biological triplicate. Cells were harvested and RNA was extracted using the RNeasy Mini Kit (Qiagen). Genomic DNA was removed by on-column digestion using the RNase-free DNase Set (Qiagen). Data from HEK293DYG cells showed no significant overlap in the ligand-treated transcriptomes obtained from HEK293DAX cells.
2013-04-23 | E-GEOD-44950 | biostudies-arrayexpress
Project description:The unfolded protein response (UPR) maintains endoplasmic reticulum (ER) proteostasis through the activation of transcription factors such as XBP1s and ATF6. The functional consequences of these transcription factors for ER proteostasis remain poorly defined. Here, we describe methodology that enables orthogonal, small molecule-mediated activation of the UPR-associated transcription factors XBP1s and/or ATF6 in the same cell independent of stress. We employ transcriptomics and quantitative proteomics to evaluate ER proteostasis network remodeling owing to the XBP1s and/or ATF6 transcriptional programs. Furthermore, we demonstrate that the three ER proteostasis environments accessible by activating XBP1s and/or ATF6 differentially influence the folding, trafficking, and degradation of destabilized ER client proteins without globally affecting the endogenous proteome. Our data reveal how the ER proteostasis network is remodeled by the XBP1s and/or ATF6 transcriptional programs at the molecular level and demonstrate the potential for selectively restoring aberrant ER proteostasis of pathologic, destabilized proteins through arm-selective UPR-activation. The unfolded protein response adapts endoplasmic reticulum (ER) proteostasis via stress-responsive transcription factors including XBP1s and ATF6. Here, R. Luke Wiseman and colleagues implement technology for the orthogonal, ligand-dependent activation of XBP1s and/or ATF6 in a single cell. They characterize how XBP1s and/or ATF6 activation impacts ER proteostasis pathway composition and function. Adapted ER environments influence the proteostasis of destabilized protein variants without affecting the endogenous proteome. The work informs the development of proteostasis environment-adapting therapeutics for protein misfolding-related diseases. In order to activate both XBP1s and ATF6 in the same cell, we incorporated DHFR.ATF6 and tet-inducible XBP1s into a HEK293T-REx cell line stably expressing the tet-repressor. Selection of a single colony resulted in the HEK293DAX cell line in which XBP1s is induced by doxycycline and DHFR.ATF6 is activated by trimethoprim (TMP; TMP-dependent DHFR.ATF6 activation in HEK293DAX cells will henceforth be referred to as ATF6 activation for simplicity). HEK293DAX cells were treated for 12 h with vehicle, 1 ?g/mL dox, 10 ?M TMP, or both in biological triplicate. Cells were harvested and RNA was extracted using the RNeasy Mini Kit (Qiagen). Genomic DNA was removed by on-column digestion using the RNase-free DNase Set (Qiagen). Data from HEK293DYG cells showed no significant overlap in the ligand-treated transcriptomes obtained from the control HEK293DYG cells.
2013-04-23 | E-GEOD-44949 | biostudies-arrayexpress
Project description:We recently found that the endoplasmic reticulum (ER) stress response (ERSR) is activated in surviving cardiac myocytes in a mouse model of in vivo myocardial infarction. ATF6 is an ER stress-activated transcription factor that induces ERSR genes, some of which encode proteins that may protect against ischemic damage. However, few ERSR genes have been identified in the heart, and there have been no gene expression profiling studies of ATF6-inducible genes, in vivo. We previously generated transgenic (TG) mice that express tamoxifen-activated ATF6, ATF6-MER, in the heart; ATF6-MER conferred tamoxifen-dependent ATF6 activation and protection from ischemic damage. To understand of the mechanism of ATF6-mediated cardioprotection, gene expression profiling of ATF6-MER TG mouse hearts was performed. Activated ATF6 changed expression levels of 1,162 genes in the heart; of the 775 ATF6-inducible genes, only 23 are known ERSR genes. One of the genes not expected to be induced by ATF6 is modulatory calcinuerin-interacting protein-1 (MCIP1). MCIP1 is induced in a calcineurin/NFAT-dependent manner during myocardial hypertrophy and it can feedback inhibit cardiomyocyte growth. We found that MCIP1 expression in cultured cardiomyocytes was increased by the prototypical ER stresser, tunicamycin (TM), or by simulated ischemia. Moreover, infecting cardiomyocytes with adenovirus encoding activated ATF6 induced MCIP1 expression and inhibited myocyte growth in response to the ï¡-adrenergic agonist, phenylephrine. These results suggest that MCIP1 can be induced in the heart by ER stresses, such as ischemia. Moreover, b integrating hypertrophy and ER stress, MCIP-modulated myocyte growth may help rejuvenate nascent ER protein folding, which could contribute to protection from ischemic damage. Experiment Overall Design: 12 mice were analyzed in this study. Four treatment groups were included in this study: transgenic ATF6-MER mice treated with tamoxifen, transgenic ATF6-MER mice treated with vehicle, nontransgenic littermates treated with tamoxifen, and nontransgenic littermates treated with vehicle. Each treatment group included 3 separate biological replicate samples. Each mouse sampled was male, C57/BL6, ~30 weeks old. Each mouse was treated, then the mouse was sacrificed, the heart was extracted, and left ventricle was isolated. Total RNA was isolated from the left ventricle, and used for hybridization onto an Affymetrix mus 430 2.0 full-genome chip. Each heart was hybridized onto its own chip.
2008-04-06 | E-GEOD-8322 | biostudies-arrayexpress
Project description:Activating transcription factor 6 alpha (ATF6⍺) is one of the three endoplasmic reticulum (ER) transmembrane stress sensors that mediate the unfolded protein response (UPR). Despite its significant involvement in long-term ER stress adaption, regulation of ATF6⍺ signalling is still poorly understood, possibly because its activation involves Golgi and nucleus trafficking. Here, we have generated a dual CHO-K1 ATF6⍺/IRE1⍺ reporter cell line to perform an unbiased genome-wide CRISPR/Cas9 mutagenesis screen, in the presence and absence of ER stress, to systematically profile genetic factors that specifically contribute to ATF6⍺ signalling. Anticipated and new candidate genes that regulate ATF6⍺ activation were discovered. Among these, calreticulin (CRT), a key ER luminal chaperone, emerged as a selective repressor molecule of ATF6⍺ signalling. Cells lacking CRT constitutively activated a BiP::sfGFP ATF6⍺-dependent reporter, had higher BiP levels and an increased rate of trafficking and processing of ATF6⍺. Purified CRT interacts with the luminal domain of ATF6⍺ in vitro and the two proteins co-immunoprecipitated from cell lysates. CRT depletion exposed a negative feedback loop implicating ATF6⍺ in repressing IRE1⍺ activity basally and overexpression of CRT reversed phenotype. Our data indicate that CRT, in addition to its known role as a chaperone, also serves as an ER repressor of ATF6⍺ to maintain selective regulation of the UPR.
2024-07-26 | GSE254745 | GEO