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Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans
Zinc is essential for cellular functions as it is a catalytic and structural component of many proteins. In contrast, cadmium is not required in biological systems and is toxic. Zinc and cadmium levels are closely monitored and regulated as their excess causes cell stress. To maintain homeostasis, o...
Autores principales: | , , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6922464/ https://www.ncbi.nlm.nih.gov/pubmed/31815936 http://dx.doi.org/10.1371/journal.pgen.1008508 |
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author | Shomer, Naomi Kadhim, Alexandre Zacharie Grants, Jennifer Margaret Cheng, Xuanjin Alhusari, Deema Bhanshali, Forum Poon, Amy Fong-Yuk Lee, Michelle Ying Ya Muhuri, Anik Park, Jung In Shih, James Lee, Dongyeop Lee, Seung-Jae V. Lynn, Francis Christopher Taubert, Stefan |
author_facet | Shomer, Naomi Kadhim, Alexandre Zacharie Grants, Jennifer Margaret Cheng, Xuanjin Alhusari, Deema Bhanshali, Forum Poon, Amy Fong-Yuk Lee, Michelle Ying Ya Muhuri, Anik Park, Jung In Shih, James Lee, Dongyeop Lee, Seung-Jae V. Lynn, Francis Christopher Taubert, Stefan |
author_sort | Shomer, Naomi |
collection | PubMed |
description | Zinc is essential for cellular functions as it is a catalytic and structural component of many proteins. In contrast, cadmium is not required in biological systems and is toxic. Zinc and cadmium levels are closely monitored and regulated as their excess causes cell stress. To maintain homeostasis, organisms induce metal detoxification gene programs through stress responsive transcriptional regulatory complexes. In Caenorhabditis elegans, the MDT-15 subunit of the evolutionarily conserved Mediator transcriptional coregulator is required to induce genes upon exposure to excess zinc and cadmium. However, the regulatory partners of MDT-15 in this response, its role in cellular and physiological stress adaptation, and the putative role for mammalian MED15 in the metal stress responses remain unknown. Here, we show that MDT-15 interacts physically and functionally with the Nuclear Hormone Receptor HIZR-1 to promote molecular, cellular, and organismal adaptation to cadmium and excess zinc. Using gain- and loss-of-function mutants and qRT-PCR and reporter analysis, we find that mdt-15 and hizr-1 cooperate to induce zinc and cadmium responsive genes. Moreover, the two proteins interact physically in yeast-two-hybrid assays and this interaction is enhanced by the addition of zinc or cadmium, the former a known ligand of HIZR-1. Functionally, mdt-15 and hizr-1 mutants show defective storage of excess zinc in the gut and are hypersensitive to zinc-induced reductions in egg-laying. Furthermore, mdt-15 but not hizr-1 mutants are hypersensitive to cadmium-induced reductions in egg-laying, suggesting potential divergence of regulatory pathways. Lastly, mammalian MDT-15 orthologs bind genomic regulatory regions of metallothionein and zinc transporter genes in a cadmium and zinc-stimulated fashion, and human MED15 is required to induce a metallothionein gene in lung adenocarcinoma cells exposed to cadmium. Collectively, our data show that mdt-15 and hizr-1 cooperate to regulate cadmium detoxification and zinc storage and that this mechanism is at least partially conserved in mammals. |
format | Online Article Text |
id | pubmed-6922464 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-69224642020-01-07 Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans Shomer, Naomi Kadhim, Alexandre Zacharie Grants, Jennifer Margaret Cheng, Xuanjin Alhusari, Deema Bhanshali, Forum Poon, Amy Fong-Yuk Lee, Michelle Ying Ya Muhuri, Anik Park, Jung In Shih, James Lee, Dongyeop Lee, Seung-Jae V. Lynn, Francis Christopher Taubert, Stefan PLoS Genet Research Article Zinc is essential for cellular functions as it is a catalytic and structural component of many proteins. In contrast, cadmium is not required in biological systems and is toxic. Zinc and cadmium levels are closely monitored and regulated as their excess causes cell stress. To maintain homeostasis, organisms induce metal detoxification gene programs through stress responsive transcriptional regulatory complexes. In Caenorhabditis elegans, the MDT-15 subunit of the evolutionarily conserved Mediator transcriptional coregulator is required to induce genes upon exposure to excess zinc and cadmium. However, the regulatory partners of MDT-15 in this response, its role in cellular and physiological stress adaptation, and the putative role for mammalian MED15 in the metal stress responses remain unknown. Here, we show that MDT-15 interacts physically and functionally with the Nuclear Hormone Receptor HIZR-1 to promote molecular, cellular, and organismal adaptation to cadmium and excess zinc. Using gain- and loss-of-function mutants and qRT-PCR and reporter analysis, we find that mdt-15 and hizr-1 cooperate to induce zinc and cadmium responsive genes. Moreover, the two proteins interact physically in yeast-two-hybrid assays and this interaction is enhanced by the addition of zinc or cadmium, the former a known ligand of HIZR-1. Functionally, mdt-15 and hizr-1 mutants show defective storage of excess zinc in the gut and are hypersensitive to zinc-induced reductions in egg-laying. Furthermore, mdt-15 but not hizr-1 mutants are hypersensitive to cadmium-induced reductions in egg-laying, suggesting potential divergence of regulatory pathways. Lastly, mammalian MDT-15 orthologs bind genomic regulatory regions of metallothionein and zinc transporter genes in a cadmium and zinc-stimulated fashion, and human MED15 is required to induce a metallothionein gene in lung adenocarcinoma cells exposed to cadmium. Collectively, our data show that mdt-15 and hizr-1 cooperate to regulate cadmium detoxification and zinc storage and that this mechanism is at least partially conserved in mammals. Public Library of Science 2019-12-09 /pmc/articles/PMC6922464/ /pubmed/31815936 http://dx.doi.org/10.1371/journal.pgen.1008508 Text en © 2019 Shomer et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article Shomer, Naomi Kadhim, Alexandre Zacharie Grants, Jennifer Margaret Cheng, Xuanjin Alhusari, Deema Bhanshali, Forum Poon, Amy Fong-Yuk Lee, Michelle Ying Ya Muhuri, Anik Park, Jung In Shih, James Lee, Dongyeop Lee, Seung-Jae V. Lynn, Francis Christopher Taubert, Stefan Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans |
title | Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans |
title_full | Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans |
title_fullStr | Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans |
title_full_unstemmed | Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans |
title_short | Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans |
title_sort | mediator subunit mdt-15/med15 and nuclear receptor hizr-1/hnf4 cooperate to regulate toxic metal stress responses in caenorhabditis elegans |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6922464/ https://www.ncbi.nlm.nih.gov/pubmed/31815936 http://dx.doi.org/10.1371/journal.pgen.1008508 |
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