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Shomer N, Kadhim AZ, Grants JM, Cheng X, Alhusari D, Bhanshali F, Poon AFY, Lee MYY, Muhuri A, Park JI, Shih J, Lee D, Lee SJV, Lynn FC, Taubert S. Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans. PLoS Genet 2019; 15:e1008508. [PMID: 31815936 PMCID: PMC6922464 DOI: 10.1371/journal.pgen.1008508] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 12/19/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023] Open
Abstract
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.
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Affiliation(s)
- Naomi Shomer
- Graduate Program in Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Alexandre Zacharie Kadhim
- Graduate Program in Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Jennifer Margaret Grants
- Graduate Program in Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Xuanjin Cheng
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Deema Alhusari
- Graduate Program in Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Forum Bhanshali
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Amy Fong-Yuk Poon
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Michelle Ying Ya Lee
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Anik Muhuri
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Jung In Park
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - James Shih
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Dongyeop Lee
- Department of Life Sciences, School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, South Korea
| | - Seung-Jae V. Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-Gu, Daejeon, South Korea
| | - Francis Christopher Lynn
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Stefan Taubert
- Graduate Program in Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
- British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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