Unknown,Transcriptomics,Genomics,Proteomics

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Zinc sensing by metal-responsive transcription factor 1 (MTF1) controls metallothionein and ZnT1 expression to buffer the sensitivity of the transcriptome response to zinc

ABSTRACT: Only a small number of genes are known direct targets of the zinc-responsive transcription factor MTF1; therefore, the aim of this study was to gain a more complete understanding of the MTF-1 regulated zinc-responsive component of the transcriptome. A targeted siRNA was used to deplete MTF1 expression in the human intestinal cell line Caco-2. We predicted that the response to zinc of direct MTF1 target genes would be abrogated by MTF1 knockdown. Surprisingly, a greater number of genes were regulated by zinc following MFT1 knockdown, and most genes that responded to zinc under both control and MTF1-depleted conditions had an augmented response in the latter condition. Exceptions were the zinc effluxer ZnT1 and a suite of metallothionein genes, suggesting that responses of other genes to zinc are usually buffered by increases in these proteins. We propose that MTF1 heads a hierarchy of zinc sensors, and through controlling the expression of a raft of metallothioneins and other key proteins involved in controlling intracellular zinc levels (e.g. ZnT1) alters zinc buffering capacity and total cellular zinc content. We tested and validated this model by overexpressing metallothionein and observing the predicted curtailment in response of the zinc-repressed SLC30A5 (ZnT5) promoter. The model provides the framework for an integrated understanding of cellular zinc homeostasis. Because MTs can bind metals other than zinc, this framework links with overall cellular metal homeostasis. Gene expression profiling by Illumina BeadArray of the effects of ZNF658 gene knockdown by siRNA. 2 different siRNAs were used, with appropriate non-targetting controls. All experiments were carried out in triplicate.

ORGANISM(S): Homo sapiens

SUBMITTER: Simon Cockell

PROVIDER: E-GEOD-76510 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Zinc sensing by metal-responsive transcription factor 1 (MTF1) controls metallothionein and ZnT1 expression to buffer the sensitivity of the transcriptome response to zinc.

Hardyman J E J JE Tyson J J Jackson K A KA Aldridge C C Cockell S J SJ Wakeling L A LA Valentine R A RA Ford D D

Metallomics : integrated biometal science 20160301 3

Only a small number of genes are known direct targets of the zinc-responsive transcription factor MTF1; therefore, the aim of this study was to gain a more complete understanding of the MTF-1 regulated zinc-responsive component of the transcriptome. A targeted siRNA was used to deplete MTF1 expression in the human intestinal cell line Caco-2. We predicted that the response to zinc of direct MTF1 target genes would be abrogated by MTF1 knockdown. Surprisingly, a greater number of genes were regul ...[more]

PMID: 26824222

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Project description:MTF1 is a highly conserved metal-binding transcription factor in eukaryotes. MTF1 binds to DNA sequence motifs, termed metal response elements (MREs) to induce the expression of genes involved in metal and oxidative stress homeostasis. MTF1 is responsive to both metal excess and deprivation, and can also protect cells from oxidative and hypoxic stresses. Disruption of metal homeostasis leads to the development of several pathological states. Despite its roles in these processes , MTF1 has been shown to be required for developmental processes such as embryonic liver formation. In this study, we used multiple strategies to understand the mechanism by which MTF1 functions in skeletal muscle differentiation and to determine the role cellular copper (Cu) status plays in this process. We provide the functional relationships between MTF1, Cu, myogenic gene promoters, and MyoD, an specific component of the myogenic transcriptional machinery in differentiating primary myoblasts derived from mouse satellite cells. We found that MTF1 is induced and translocated to the nucleus upon initiation of myogenesis. Consistent with previous studies from our laboratory , addition of non-toxic concentrations of Cu promote myogenesis and enhanced MTF1 expression. CRISPR/Cas9-mediated depletion of MTF1 demonstrated that MTF1 is essential for proper development of skeletal muscle, as partial Mtf1 knockdown leads to apoptosis to differentiating myoblasts. MTF1 was also found to bind Cu at a carboxy-terminal tetra-cysteine cluster, which may contribute to the mobilization of Cu to the nucleus during myogenesis. ChIP-seq and ChIP-qPCR analyses showed that MTF1 binds at the promoter regions of myogenic genes as part of a complex with MyoD, the master transcriptional regulator of the myogenic lineage. These results have the potential to initiate a new area of research in MTF1 function and in the regulation of myogenesis. Furthermore, these studies set the basis to understand the role of Cu at the transcriptional level, affects growth and development and will contribute to the largely unexplored are of muscular phenotypes observed in human pathologies associated to Cu misbalance, such as Menkes’ and Wilson’s diseases.

Project description:This a model from the article: The dynamic balance of import and export of zinc in Escherichia coli suggests a heterogeneous population response to stress Takahashi H, Oshima T, Doherty N, Clayton SR, Iqbal M, Hill PJ, Hobman JL, Tobe T, Ogasawara N, Kanaya S and Stekel DJ journal year id, Abstract: Zinc is essential for life, but toxic in excess. Thus all cells must control their internal zinc concentration. We used a systems approach, alternating rounds of experiments and models, to further elucidate the zinc control systems in Escherichia coli. We measured the response to zinc of the main specific zinc import and export systems in the wild type, and a series of deletion mutant strains. We interpreted these data with a detailed mathematical model and Bayesian model fitting routines. There are three key findings: First, that alternate, non-inducible importers and exporters are important. Second, that an internal zinc reservoir is essential for maintaining the internal zinc concentration. Third, our data fitting led us to propose that the cells mount a heterogeneous response to zinc: some respond effectively, while others die or stop growing. In a further round of experiments we demonstrated lower viable cell counts in the mutant strain tested exposed to excess zinc, consistent with this hypothesis. A stochastic model simulation demonstrated considerable fluctuations in the cellular levels of the ZntA exporter protein, reinforcing this proposal. We hypothesise that maintaining population heterogeneity could be a bet-hedging response allowing a population of cells to survive in varied and fluctuating environments. This model originates from BioModels Database: A Database of Annotated Published Models (http://www.ebi.ac.uk/biomodels/). It is copyright (c) 2005-2011 The BioModels.net Team. For more information see the terms of use. To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le NovÃ¨re N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.

Dataset Information

Zinc sensing by metal-responsive transcription factor 1 (MTF1) controls metallothionein and ZnT1 expression to buffer the sensitivity of the transcriptome response to zinc

Publications

Zinc sensing by metal-responsive transcription factor 1 (MTF1) controls metallothionein and ZnT1 expression to buffer the sensitivity of the transcriptome response to zinc.

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