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Prajapati M, Zhang JZ, Chiu L, Chong GS, Mercadante CJ, Kowalski HL, Delaney B, Anderson JA, Guo S, Aghajan M, Bartnikas TB. Hepatic HIF2 is a key determinant of manganese excess and polycythemia in SLC30A10 deficiency. JCI Insight 2024; 9:e169738. [PMID: 38652538 DOI: 10.1172/jci.insight.169738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/10/2024] [Indexed: 04/25/2024] Open
Abstract
Manganese is an essential yet potentially toxic metal. Initially reported in 2012, mutations in SLC30A10 are the first known inherited cause of manganese excess. SLC30A10 is an apical membrane protein that exports manganese from hepatocytes into bile and from enterocytes into the lumen of the gastrointestinal tract. SLC30A10 deficiency results in impaired gastrointestinal manganese excretion, leading to manganese excess, neurologic deficits, liver cirrhosis, polycythemia, and erythropoietin excess. Neurologic and liver disease are attributed to manganese toxicity. Polycythemia is attributed to erythropoietin excess. The goal of this study was to determine the basis of erythropoietin excess in SLC30A10 deficiency. Here, we demonstrate that transcription factors hypoxia-inducible factor 1a (Hif1a) and 2a (Hif2a), key mediators of the cellular response to hypoxia, are both upregulated in livers of Slc30a10-deficient mice. Hepatic Hif2a deficiency corrected erythropoietin expression and polycythemia and attenuated aberrant hepatic gene expression in Slc30a10-deficient mice, while hepatic Hif1a deficiency had no discernible impact. Hepatic Hif2a deficiency also attenuated manganese excess, though the underlying cause of this is not clear at this time. Overall, our results indicate that hepatic HIF2 is a key determinant of pathophysiology in SLC30A10 deficiency and expand our understanding of the contribution of HIFs to human disease.
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Affiliation(s)
- Milankumar Prajapati
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Jared Z Zhang
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Lauren Chiu
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Grace S Chong
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Courtney J Mercadante
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Heather L Kowalski
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Bradley Delaney
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Jessica A Anderson
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Shuling Guo
- Ionis Pharmaceuticals, Inc., Carlsbad, California, USA
| | | | - Thomas B Bartnikas
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
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Smithwick ER, Bhagi-Damodaran A, Damodaran AR. Equilibrium dialysis with HPLC detection to measure substrate binding affinity of a non-heme iron halogenase. bioRxiv 2024:2024.04.03.588023. [PMID: 38617253 PMCID: PMC11014511 DOI: 10.1101/2024.04.03.588023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Determination of substrate binding affinity (Kd) is critical to understanding enzyme function. An extensive number of methods have been developed and employed to study ligand/substrate binding, but the best approach depends greatly on the substrate and the enzyme in question. Below we describe how to measure the Kd of BesD, a non-heme iron halogenase, for its native substrate lysine using equilibrium dialysis with subsequent detection with High Performance Liquid Chromatography (HPLC). This method can be performed in anaerobic glove bag settings, requires readily available HPLC instrumentation for subsequent detection, and is adaptable to meet the needs of a variety of substrate affinity measurements.
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Affiliation(s)
- Elizabeth R. Smithwick
- Department of Chemistry, University of Minnesota -Twin Cities, 207 Pleasant St. SE. Minneapolis, MN 55455
| | - Ambika Bhagi-Damodaran
- Department of Chemistry, University of Minnesota -Twin Cities, 207 Pleasant St. SE. Minneapolis, MN 55455
| | - Anoop Rama Damodaran
- Department of Chemistry, University of Minnesota -Twin Cities, 207 Pleasant St. SE. Minneapolis, MN 55455
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Martin CB, Taabazuing CY, Knapp MJ. Dynamic Domain Links Substrate Binding and Catalysis in the Factor-Inhibiting-HIF-1. Biochemistry 2023; 62:2442-2449. [PMID: 37526986 DOI: 10.1021/acs.biochem.3c00231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
The interplay between active-site chemistry and functionally relevant enzyme motions can provide useful insights into selective enzyme modulation. Modulation of the hypoxia-sensing function of factor-inhibiting-HIF-1 (FIH) enzyme is a potential therapeutic strategy in disease states such as ischemia and cancer. The hypoxia-sensing function of FIH relies in major part on the tight coupling of the first half of the catalytic mechanism which involves O2 activation and eventual succinate production to the second half which involves HIF-1α/CTAD substrate hydroxylation. In this study, we demonstrate the role of a loop hinge domain in FIH (FIH102-118) called the 100s loop in maintaining this particular tight coupling. Molecular dynamics patterns from Gaussian Network Model (iGNM) database analysis of FIH identified the 100s loop as one dynamic domain containing a hinge residue (Tyr102) with a potential substrate positioning role. Enzymological and biophysical studies of the 100s loop point mutants revealed altered enzyme kinetics with the exception of the conservative FIH mutant Y102F, which suggests a sterics-related role for this residue. Removal of the bulk of Tyr102 (Y102A) resulted in succinate production, autohydroxylation, and an O2 binding environment comparable to wild-type FIH. However, the HIF-1α/CTAD substrate hydroxylation of this mutant was significantly reduced which implies that (1) the FIH loop hinge residue Tyr102 does not affect O2 activation, (2) the stacking steric interaction of Tyr102 is important in substrate positioning for productive hydroxylation, and (3) Tyr102 is important for the synchronization of O2 activation and substrate hydroxylation.
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Affiliation(s)
- Cristina B Martin
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Cornelius Y Taabazuing
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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Ding F, Peng W, Peng YK, Liu BQ. Estimating the potential toxicity of chiral diclofop-methyl: Mechanistic insight into the enantioselective behavior. Toxicology 2020; 438:152446. [DOI: 10.1016/j.tox.2020.152446] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/26/2020] [Accepted: 03/25/2020] [Indexed: 02/06/2023]
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