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Ayyar VS, Song D. Mechanistic Pharmacokinetics and Pharmacodynamics of GalNAc-siRNA: Translational Model Involving Competitive Receptor-Mediated Disposition and RISC-Dependent Gene Silencing Applied to Givosiran. J Pharm Sci 2024; 113:176-190. [PMID: 37871778 DOI: 10.1016/j.xphs.2023.10.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/18/2023] [Accepted: 10/18/2023] [Indexed: 10/25/2023]
Abstract
Triantennary N-acetyl-D galactosamine (GalNAc)3-conjugated small interfering RNA (siRNA) have majorly advanced the development of RNA-based therapeutics. Chemically stabilized GalNAc-siRNAs exhibit extensive albeit capacity-limited (nonlinear) distribution into hepatocytes with additional complexities in intracellular liver disposition and pharmacology. A mechanism-based pharmacokinetic-pharmacodynamic (PK-PD) model of GalNAc-siRNA was developed to i) quantitate ASGPR-mediated disposition and downstream RNA-induced silencing complex (RISC)-dependent pharmacology following intravenous (IV) and subcutaneous (SC) dosing, ii) assess the kinetics of formed active metabolite, iii) leverage, as an example, published experimental data for givosiran, and iv) demonstrate PK translation across two preclinical species (rat and monkey) with subsequent prediction of human plasma PK. The structural model is based on competition between parent and formed active metabolite for occupancy and uptake via ASGPR into hepatocytes, intracellular sequestration and degradation, and downstream engagement of RNA-induced silencing complex (RISC) governing target mRNA degradation. The model jointly and accurately captured available concentration-time profiles of givosiran and/or AS(N-1)3' givosiran in rat and/or monkey plasma, liver, and/or kidney following givosiran administered both IV and SC. RISC-dependent gene silencing of ALAS1 mRNA was well-characterized. The model estimated an in vivo affinity (KD) value of 27.7 nM for GalNAc-ASGPR and weight-based allometric exponents of -0.27 and -0.24 for SC absorption and intracellular (endolysosomal) degradation rate constants. The model well-predicted reported givosiran plasma PK profiles in humans. PK simulations revealed net-shifts in liver-to-kidney distribution ratios with increasing IV and SC dose. Importantly, decreases in the relative liver uptake efficiency were demonstrated following IV and, to a lesser extent, following SC dosing explained by differential ASGPR occupancy profiles over time.
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Affiliation(s)
- Vivaswath S Ayyar
- Clinical Pharmacology & Pharmacometrics, Janssen Research and Development, Spring House, PA, USA.
| | - Dawei Song
- Clinical Pharmacology & Pharmacometrics, Janssen Research and Development, Spring House, PA, USA
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2
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Wang AF, Ayyar VS. Pharmacodynamic Models of Indirect Effects and Irreversible Inactivation with Turnover: Applicability to Mechanism-Based Modeling of Gene Silencing and Targeted Protein Degradation. J Pharm Sci 2024; 113:191-201. [PMID: 37884193 DOI: 10.1016/j.xphs.2023.10.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/18/2023] [Accepted: 10/18/2023] [Indexed: 10/28/2023]
Abstract
Indirect response (IDR) and turnover with inactivation (TI) comprise two arrays of mechanism-based pharmacodynamic (PD) models widely used to describe delayed drug effects. IDR Model-IV (stimulation of response loss) and TI (irreversible loss) have been described with discerning "signature" profiles; classical IDR-IV response-time profiles display slow declines where peak response shifts later with increasing dose, whereas TI profiles feature steep response declines with earlier-shifting nadirs. Herein, we demonstrate mathematical convergence of IDR-IV and TI models upon implementation with identical linear versus nonlinear pharmacologic effect terms. Time of peak response in IDR-IV can in fact shift earlier or later depending on PK or PD parameters (e.g., kel, Smax) and effect type. A generalized dynamic model linking mRNA and protein turnover is proposed. Applicability of IDR-IV and TI, with either linear or nonlinear terms acting on degradation/catabolism/loss of response, is demonstrated through model-fitting PK-PD effects of three proteolysis-targeting chimeras (PROTACs) and two ligand-conjugated small interfering RNAs (siRNA). This work clarifies mathematical properties, convergence, and expected responses of IDR-IV and TI, demonstrates their applicability for targeted gene-silencing and protein-degrading agents, and illustrates how well-designed in vivo studies covering broad dose ranges with richly sampled time-points can influence PK-PD model structure and parameter resolution.
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Affiliation(s)
- Angelia F Wang
- Clinical Pharmacology & Pharmacometrics, Janssen Research and Development, Spring House, PA, USA
| | - Vivaswath S Ayyar
- Clinical Pharmacology & Pharmacometrics, Janssen Research and Development, Spring House, PA, USA.
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3
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Pihl C, Lerche CM, Andersen F, Bjerring P, Haedersdal M. Improving the efficacy of photodynamic therapy for actinic keratosis: A comprehensive review of pharmacological pretreatment strategies. Photodiagnosis Photodyn Ther 2023; 43:103703. [PMID: 37429460 DOI: 10.1016/j.pdpdt.2023.103703] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/19/2023] [Accepted: 07/07/2023] [Indexed: 07/12/2023]
Abstract
BACKGROUND Photodynamic therapy (PDT) is approved for treatment of actinic keratoses (AKs) and field-cancerisation. Pretreatment with pharmacological compounds holds potential to improve PDT efficacy, through direct interaction with PpIX formation or through an independent response, both of which may improve PDT treatment. OBJECTIVE To present the currently available clinical evidence of pharmacological pretreatments prior to PDT and to associate potential clinical benefits with the pharmacological mechanisms of action of the individual compounds. METHODS A comprehensive search on the Embase, MEDLINE, and Web of Science databases was performed. RESULTS In total, 16 studies investigated 6 pretreatment compounds: 5-fluorouracil (5-FU), diclofenac, retinoids, salicylic acid, urea, and vitamin D. Two of these, 5-FU and vitamin D, robustly increased the efficacy of PDT across multiple studies, illustrated by mean increases in clearance rates of 21.88% and 12.4%, respectively. Regarding their mechanisms, 5-FU and vitamin D both increased PpIX accumulation, while 5-FU also induced a separate anticarcinogenic response. Pretreatment with diclofenac for four weeks improved the clearance rate in one study (24.9%), administration of retinoids had a significant effect in one of two studies (16.25%), while salicylic acid and urea did not lead to improved PDT efficacy. Diclofenac and retinoids demonstrated independent cytotoxic responses, whereas salicylic acid and urea acted as penetration enhancers to increase PpIX formation. CONCLUSION 5-FU and vitamin D are well-tested, promising candidates for pharmacological pretreatment prior to PDT. Both compounds affect the haem biosynthesis, providing a target for potential pretreatment candidates. KEY WORDS Photodynamic Therapy, Actinic Keratosis,Pre-tretment,Review,enhancement.
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Affiliation(s)
- Celina Pihl
- Department of Dermatology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark & Department of Pharmacy, University of Copenhagen, Nielsine Nielsens Vej 17, Entrance 9, 2nd floor, Copenhagen 2400, Denmark.
| | - Catharina M Lerche
- Department of Dermatology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark & Department of Pharmacy, University of Copenhagen, Nielsine Nielsens Vej 17, Entrance 9, 2nd floor, Copenhagen 2400, Denmark
| | - Flemming Andersen
- Private Hospital Molholm, Brummersvej 1, Vejle 7100, Denmark; Department of Dermatology, Aalborg University Hospital, Hobrovej 18-22, Aalborg 9100, Denmark
| | - Peter Bjerring
- Department of Dermatology, Aalborg University Hospital, Hobrovej 18-22, Aalborg 9100, Denmark
| | - Merete Haedersdal
- Department of Dermatology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark & Department of Clinical Medicine, University of Copenhagen, Nielsine Nielsens Vej 17, Entrance 9, 2nd floor, Copenhagen 2400, Denmark
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Abstract
An abundant metal in the human body, iron is essential for key biological pathways including oxygen transport, DNA metabolism, and mitochondrial function. Most iron is bound to heme but it can also be incorporated into iron-sulfur clusters or bind directly to proteins. Iron's capacity to cycle between Fe2+ and Fe3+ contributes to its biological utility but also renders it toxic in excess. Heme is an iron-containing tetrapyrrole essential for diverse biological functions including gas transport and sensing, oxidative metabolism, and xenobiotic detoxification. Like iron, heme is essential yet toxic in excess. As such, both iron and heme homeostasis are tightly regulated. Here we discuss molecular and physiologic aspects of iron and heme metabolism. We focus on dietary absorption; cellular import; utilization; and export, recycling, and elimination, emphasizing studies published in recent years. We end with a discussion on current challenges and needs in the field of iron and heme biology.
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Affiliation(s)
- Sohini Dutt
- Department of Animal and Avian Sciences and Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Iqbal Hamza
- Department of Animal and Avian Sciences and Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
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Maio N, Zhang DL, Ghosh MC, Jain A, SantaMaria AM, Rouault TA. Mechanisms of cellular iron sensing, regulation of erythropoiesis and mitochondrial iron utilization. Semin Hematol 2021; 58:161-174. [PMID: 34389108 DOI: 10.1053/j.seminhematol.2021.06.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 12/11/2022]
Abstract
To maintain an adequate iron supply for hemoglobin synthesis and essential metabolic functions while counteracting iron toxicity, humans and other vertebrates have evolved effective mechanisms to conserve and finely regulate iron concentration, storage, and distribution to tissues. At the systemic level, the iron-regulatory hormone hepcidin is secreted by the liver in response to serum iron levels and inflammation. Hepcidin regulates the expression of the sole known mammalian iron exporter, ferroportin, to control dietary absorption, storage and tissue distribution of iron. At the cellular level, iron regulatory proteins 1 and 2 (IRP1 and IRP2) register cytosolic iron concentrations and post-transcriptionally regulate the expression of iron metabolism genes to optimize iron availability for essential cellular processes, including heme biosynthesis and iron-sulfur cluster biogenesis. Genetic malfunctions affecting the iron sensing mechanisms or the main pathways that utilize iron in the cell cause a broad range of human diseases, some of which are characterized by mitochondrial iron accumulation. This review will discuss the mechanisms of systemic and cellular iron sensing with a focus on the main iron utilization pathways in the cell, and on human conditions that arise from compromised function of the regulatory axes that control iron homeostasis.
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Affiliation(s)
- Nunziata Maio
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - De-Liang Zhang
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Manik C Ghosh
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Anshika Jain
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Anna M SantaMaria
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Tracey A Rouault
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD.
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Fiorito V, Allocco AL, Petrillo S, Gazzano E, Torretta S, Marchi S, Destefanis F, Pacelli C, Audrito V, Provero P, Medico E, Chiabrando D, Porporato PE, Cancelliere C, Bardelli A, Trusolino L, Capitanio N, Deaglio S, Altruda F, Pinton P, Cardaci S, Riganti C, Tolosano E. The heme synthesis-export system regulates the tricarboxylic acid cycle flux and oxidative phosphorylation. Cell Rep 2021; 35:109252. [PMID: 34133926 DOI: 10.1016/j.celrep.2021.109252] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 12/21/2020] [Accepted: 05/25/2021] [Indexed: 12/14/2022] Open
Abstract
Heme is an iron-containing porphyrin of vital importance for cell energetic metabolism. High rates of heme synthesis are commonly observed in proliferating cells. Moreover, the cell-surface heme exporter feline leukemia virus subgroup C receptor 1a (FLVCR1a) is overexpressed in several tumor types. However, the reasons why heme synthesis and export are enhanced in highly proliferating cells remain unknown. Here, we illustrate a functional axis between heme synthesis and heme export: heme efflux through the plasma membrane sustains heme synthesis, and implementation of the two processes down-modulates the tricarboxylic acid (TCA) cycle flux and oxidative phosphorylation. Conversely, inhibition of heme export reduces heme synthesis and promotes the TCA cycle fueling and flux as well as oxidative phosphorylation. These data indicate that the heme synthesis-export system modulates the TCA cycle and oxidative metabolism and provide a mechanistic basis for the observation that both processes are enhanced in cells with high-energy demand.
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Affiliation(s)
- Veronica Fiorito
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Anna Lucia Allocco
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Sara Petrillo
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Elena Gazzano
- Department of Oncology, University of Torino, Torino, Italy
| | - Simone Torretta
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milano, Italy
| | - Saverio Marchi
- Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy
| | - Francesca Destefanis
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Consiglia Pacelli
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Valentina Audrito
- Immunogenetics Unit, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Paolo Provero
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy; Center for Omics Sciences, San Raffaele Scientific Institute IRCSS, Milano, Italy
| | - Enzo Medico
- Department of Oncology, University of Torino, Candiolo, TO, Italy; Candiolo Cancer Institute, FPO-IRCCS, Candiolo, TO, Italy
| | - Deborah Chiabrando
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Paolo Ettore Porporato
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | | | - Alberto Bardelli
- Department of Oncology, University of Torino, Candiolo, TO, Italy; Candiolo Cancer Institute, FPO-IRCCS, Candiolo, TO, Italy
| | - Livio Trusolino
- Department of Oncology, University of Torino, Candiolo, TO, Italy; Candiolo Cancer Institute, FPO-IRCCS, Candiolo, TO, Italy
| | - Nazzareno Capitanio
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Silvia Deaglio
- Immunogenetics Unit, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Fiorella Altruda
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Paolo Pinton
- Department of Medical Sciences and Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Simone Cardaci
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milano, Italy
| | - Chiara Riganti
- Department of Oncology, University of Torino, Torino, Italy
| | - Emanuela Tolosano
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
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7
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Maestro S, Córdoba KM, Olague C, Argemi J, Ávila MA, González-Aseguinolaza G, Smerdou C, Fontanellas A. Heme oxygenase-1 inducer hemin does not inhibit SARS-CoV-2 virus infection. Biomed Pharmacother 2021; 137:111384. [PMID: 33761605 PMCID: PMC7881701 DOI: 10.1016/j.biopha.2021.111384] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 02/01/2021] [Accepted: 02/08/2021] [Indexed: 01/24/2023] Open
Abstract
Antiviral agents with different mechanisms of action could induce synergistic effects against SARS-CoV-2 infection. Some reports suggest the therapeutic potential of the heme oxygenase-1 (HO-1) enzyme against virus infection. Given that hemin is a natural inducer of the HO-1 gene, the aim of this study was to develop an in vitro assay to analyze the antiviral potency of hemin against SARS-CoV-2 infection. A SARS-CoV-2 infectivity assay was conducted in Vero-E6 and Calu-3 epithelial cell lines. The antiviral effect of hemin, and chloroquine as a control, against SARS-CoV-2 virus infection was quantified by RT-qPCR using specific oligonucleotides for the N gene. Chloroquine induced a marked reduction of viral genome copies in kidney epithelial Vero-E6 cells but not in lung cancer Calu-3 cells. Hemin administration to the culture medium induced a high induction in the expression of the HO-1 gene that was stronger in Vero-E6 macaque-derived cells than in the human Calu-3 cell line. However, hemin treatment did not modify SARS-CoV-2 replication, as measured by viral genome quantification 48 h post-infection for Vero-E6 and 72 h post-infection for the Calu-3 lineages. In conclusion, although exposure to hemin induced strong HO-1 up-regulation, this effect was unable to inhibit or delay the progression of SARS-CoV-2 infection in two epithelial cell lines susceptible to infection.
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Affiliation(s)
- Sheila Maestro
- Gene Therapy and Regulation of Gene Expression Program, CIMA Universidad de Navarra, Pamplona, Spain; IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Karol M Córdoba
- IdiSNA, Navarra Institute for Health Research, Pamplona, Spain; Hepatology Program, CIMA Universidad de Navarra, Pamplona, Spain
| | - Cristina Olague
- Gene Therapy and Regulation of Gene Expression Program, CIMA Universidad de Navarra, Pamplona, Spain; IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Josepmaria Argemi
- IdiSNA, Navarra Institute for Health Research, Pamplona, Spain; Hepatology Program, CIMA Universidad de Navarra, Pamplona, Spain; National Institute for the Study of Liver and Gastrointestinal Diseases (CIBERehd, Carlos III Health Institute), Madrid, Spain
| | - Matías A Ávila
- IdiSNA, Navarra Institute for Health Research, Pamplona, Spain; Hepatology Program, CIMA Universidad de Navarra, Pamplona, Spain; National Institute for the Study of Liver and Gastrointestinal Diseases (CIBERehd, Carlos III Health Institute), Madrid, Spain
| | - Gloria González-Aseguinolaza
- Gene Therapy and Regulation of Gene Expression Program, CIMA Universidad de Navarra, Pamplona, Spain; IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Cristian Smerdou
- Gene Therapy and Regulation of Gene Expression Program, CIMA Universidad de Navarra, Pamplona, Spain; IdiSNA, Navarra Institute for Health Research, Pamplona, Spain.
| | - Antonio Fontanellas
- IdiSNA, Navarra Institute for Health Research, Pamplona, Spain; Hepatology Program, CIMA Universidad de Navarra, Pamplona, Spain; National Institute for the Study of Liver and Gastrointestinal Diseases (CIBERehd, Carlos III Health Institute), Madrid, Spain.
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8
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Liu G, Sil D, Maio N, Tong WH, Bollinger JM, Krebs C, Rouault TA. Heme biosynthesis depends on previously unrecognized acquisition of iron-sulfur cofactors in human amino-levulinic acid dehydratase. Nat Commun 2020; 11:6310. [PMID: 33298951 PMCID: PMC7725820 DOI: 10.1038/s41467-020-20145-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/06/2020] [Indexed: 12/18/2022] Open
Abstract
Heme biosynthesis and iron-sulfur cluster (ISC) biogenesis are two major mammalian metabolic pathways that require iron. It has long been known that these two pathways interconnect, but the previously described interactions do not fully explain why heme biosynthesis depends on intact ISC biogenesis. Herein we identify a previously unrecognized connection between these two pathways through our discovery that human aminolevulinic acid dehydratase (ALAD), which catalyzes the second step of heme biosynthesis, is an Fe-S protein. We find that several highly conserved cysteines and an Ala306-Phe307-Arg308 motif of human ALAD are important for [Fe4S4] cluster acquisition and coordination. The enzymatic activity of human ALAD is greatly reduced upon loss of its Fe-S cluster, which results in reduced heme biosynthesis in human cells. As ALAD provides an early Fe-S-dependent checkpoint in the heme biosynthetic pathway, our findings help explain why heme biosynthesis depends on intact ISC biogenesis. Heme biosynthesis depends on iron-sulfur (Fe-S) cluster biogenesis but the molecular connection between these pathways is not fully understood. Here, the authors show that the heme biosynthesis enzyme ALAD contains an Fe-S cluster, disruption of which reduces ALAD activity and heme production in human cells.
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Affiliation(s)
- Gang Liu
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Debangsu Sil
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nunziata Maio
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Wing-Hang Tong
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - J Martin Bollinger
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Carsten Krebs
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA. .,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
| | - Tracey Ann Rouault
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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RETRACTED ARTICLE: Role of aminolevulinic acid synthase 1 in doxorubicin-induced oxidative stress to the ardiomyocyte. Naunyn Schmiedebergs Arch Pharmacol 2020; 393:2231. [DOI: 10.1007/s00210-019-01799-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 12/19/2019] [Indexed: 10/25/2022]
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10
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Brewer CT, Kodali K, Wu J, Shaw TI, Peng J, Chen T. Toxicoproteomic Profiling of hPXR Transgenic Mice Treated with Rifampicin and Isoniazid. Cells 2020; 9:cells9071654. [PMID: 32660103 PMCID: PMC7407182 DOI: 10.3390/cells9071654] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/07/2020] [Accepted: 07/07/2020] [Indexed: 01/22/2023] Open
Abstract
Tuberculosis is a global health threat that affects millions of people every year, and treatment-limiting toxicity remains a considerable source of treatment failure. Recent reports have characterized the nature of hPXR-mediated hepatotoxicity and the systemic toxicity of antitubercular drugs. The antitubercular drug isoniazid plays a role in such pathologic states as acute intermittent porphyria, anemia, hepatotoxicity, hypercoagulable states (deep vein thrombosis, pulmonary embolism, or ischemic stroke), pellagra (vitamin B3 deficiency), peripheral neuropathy, and vitamin B6 deficiency. However, the mechanisms by which isoniazid administration leads to these states are unclear. To elucidate the mechanism of rifampicin- and isoniazid-induced liver and systemic injury, we performed tandem mass tag mass spectrometry-based proteomic screening of mPxr-/- and hPXR mice treated with combinations of rifampicin and isoniazid. Proteomic profiling analysis suggested that the hPXR liver proteome is affected by antitubercular therapy to disrupt [Fe-S] cluster assembly machinery, [2Fe-2S] cluster-containing proteins, cytochrome P450 enzymes, heme biosynthesis, homocysteine catabolism, oxidative stress responses, vitamin B3 metabolism, and vitamin B6 metabolism. These novel findings provide insight into the etiology of some of these processes and potential targets for subsequent investigations. Data are available via ProteomeXchange with identifier PXD019505.
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Affiliation(s)
- Christopher Trent Brewer
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (C.T.B.); (J.W.)
- College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
- Integrated Biomedical Sciences Program, College of Graduate Health Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Kiran Kodali
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (K.K.); (T.I.S.)
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (C.T.B.); (J.W.)
| | - Timothy I. Shaw
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (K.K.); (T.I.S.)
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Junmin Peng
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (K.K.); (T.I.S.)
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Correspondence: (J.P.); (T.C.); Tel.:+901-595-7499 (J.P.); +901-595-5937 (T.C.)
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (C.T.B.); (J.W.)
- Correspondence: (J.P.); (T.C.); Tel.:+901-595-7499 (J.P.); +901-595-5937 (T.C.)
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11
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Gouya L, Ventura P, Balwani M, Bissell DM, Rees DC, Stölzel U, Phillips JD, Kauppinen R, Langendonk JG, Desnick RJ, Deybach J, Bonkovsky HL, Parker C, Naik H, Badminton M, Stein PE, Minder E, Windyga J, Bruha R, Cappellini MD, Sardh E, Harper P, Sandberg S, Aarsand AK, Andersen J, Alegre F, Ivanova A, Talbi N, Chan A, Querbes W, Ko J, Penz C, Liu S, Lin T, Simon A, Anderson KE. EXPLORE: A Prospective, Multinational, Natural History Study of Patients with Acute Hepatic Porphyria with Recurrent Attacks. Hepatology 2020; 71:1546-1558. [PMID: 31512765 PMCID: PMC7255459 DOI: 10.1002/hep.30936] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/04/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIMS Acute hepatic porphyria comprises a group of rare genetic diseases caused by mutations in genes involved in heme biosynthesis. Patients can experience acute neurovisceral attacks, debilitating chronic symptoms, and long-term complications. There is a lack of multinational, prospective data characterizing the disease and current treatment practices in severely affected patients. APPROACH AND RESULTS EXPLORE is a prospective, multinational, natural history study characterizing disease activity and clinical management in patients with acute hepatic porphyria who experience recurrent attacks. Eligible patients had a confirmed acute hepatic porphyria diagnosis and had experienced ≥3 attacks in the prior 12 months or were receiving prophylactic treatment. A total of 112 patients were enrolled and followed for at least 6 months. In the 12 months before the study, patients reported a median (range) of 6 (0-52) acute attacks, with 52 (46%) patients receiving hemin prophylaxis. Chronic symptoms were reported by 73 (65%) patients, with 52 (46%) patients experiencing these daily. During the study, 98 (88%) patients experienced a total of 483 attacks, 77% of which required treatment at a health care facility and/or hemin administration (median [range] annualized attack rate 2.0 [0.0-37.0]). Elevated levels of hepatic δ-aminolevulinic acid synthase 1 messenger ribonucleic acid levels, δ-aminolevulinic acid, and porphobilinogen compared with the upper limit of normal in healthy individuals were observed at baseline and increased further during attacks. Patients had impaired quality of life and increased health care utilization. CONCLUSIONS Patients experienced attacks often requiring treatment in a health care facility and/or with hemin, as well as chronic symptoms that adversely influenced day-to-day functioning. In this patient group, the high disease burden and diminished quality of life highlight the need for novel therapies.
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Affiliation(s)
- Laurent Gouya
- Centre de Référence Maladies Rares PorphyriesColombesFrance
- University of ParisParisFrance
- Laboratory of Excellence GR‐ExParisFrance
| | - Paolo Ventura
- Università degli Studi di Modena e Reggio EmiliaEmilia‐RomagnaItaly
| | | | | | - David C. Rees
- King’s College HospitalKing’s College LondonLondonUK
| | | | | | | | - Janneke G. Langendonk
- Porphyria CenterCenter for Lysosomal and Metabolic DiseaseDepartment of Internal MedicineErasmus MCUniversity Medical Center Rotterdamthe Netherlands
| | | | - Jean‐Charles Deybach
- Centre de Référence Maladies Rares PorphyriesColombesFrance
- University of ParisParisFrance
- Laboratory of Excellence GR‐ExParisFrance
| | - Herbert L. Bonkovsky
- Section on Gastroenterology & HepatologyWake Forest University/NC Baptist Medical CenterWinston‐SalemNC
| | | | | | | | | | | | - Jerzy Windyga
- Department of Hemostatic Disorders and Internal MedicineInstitute of Hematology and Transfusion MedicineWarsawPoland
| | - Radan Bruha
- 4th Internal ClinicGeneral University HospitalCharles UniversityPragueCzech Republic
| | | | - Eliane Sardh
- Porphyria Centre Sweden, Centre for Inherited Metabolic DiseasesKarolinska Institutet, Karolinska University HospitalStockholmSweden
| | - Pauline Harper
- Porphyria Centre Sweden, Centre for Inherited Metabolic DiseasesKarolinska Institutet, Karolinska University HospitalStockholmSweden
| | - Sverre Sandberg
- Norwegian Porphyria CentreHaukeland University HospitalBergenNorway
| | - Aasne K. Aarsand
- Norwegian Porphyria CentreHaukeland University HospitalBergenNorway
| | - Janice Andersen
- Norwegian Porphyria CentreHaukeland University HospitalBergenNorway
| | | | | | - Neila Talbi
- Centre de Référence Maladies Rares PorphyriesColombesFrance
- University of ParisParisFrance
- Laboratory of Excellence GR‐ExParisFrance
| | - Amy Chan
- Alnylam PharmaceuticalsCambridgeMA
| | | | - John Ko
- Alnylam PharmaceuticalsCambridgeMA
| | | | | | - Tim Lin
- Alnylam PharmaceuticalsCambridgeMA
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Brewer CT, Yang L, Edwards A, Lu Y, Low J, Wu J, Lee RE, Chen T. The Isoniazid Metabolites Hydrazine and Pyridoxal Isonicotinoyl Hydrazone Modulate Heme Biosynthesis. Toxicol Sci 2019; 168:209-224. [PMID: 30517741 PMCID: PMC6390808 DOI: 10.1093/toxsci/kfy294] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In a mouse model, rifampicin and isoniazid combination treatment results in cholestatic liver injury that is associated with an increase in protoporphyrin IX, the penultimate heme precursor. Both ferrochelatase (FECH/Fech) and aminolevulinic acid synthase 1 (ALAS1/Alas1) are crucial enzymes in regulating heme biosynthesis. Isoniazid has recently been reported to upregulate Alas1 but downregulate Fech protein levels in mice; however, the mechanism by which isoniazid mediates disruption of heme synthesis has been unclear. Two metabolites of isoniazid, pyridoxal isonicotinoyl hydrazone (PIH, the isoniazid-vitamin B6 conjugate) and hydrazine, have been detected in the urine of humans treated with isoniazid. Here we show that, in primary human hepatocytes and the human hepatocellular carcinoma cell line HepG2/C3A, (1) isoniazid treatment increases Alas1 protein levels but decreases Fech levels; (2) hydrazine treatment upregulates Alas1 protein and Alas1 mRNA levels; (3) PIH treatment decreases Fech protein levels, but not Fech mRNA levels; and (4) PIH is detected after isoniazid treatment, with levels increasing further when exogenous vitamin B6 analogs are coadministered. In addition, the PIH-mediated downregulation of human FECH is associated with iron chelation. Together, these data demonstrate that hydrazine upregulates ALAS1, whereas PIH downregulates FECH, suggesting that the metabolites of isoniazid mediate its disruption of heme biosynthesis by contributing to protoporphyrin IX accumulation.
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Affiliation(s)
- Christopher Trent Brewer
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
- Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Lei Yang
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
| | - Anne Edwards
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
| | - Yan Lu
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
| | - Jonathan Low
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
| | - Richard E Lee
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105
- Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, Tennessee 38163
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13
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Nakano T, Moriya K, Koike K, Horie T. Hepatitis C virus core protein triggers abnormal porphyrin metabolism in human hepatocellular carcinoma cells. PLoS One 2018; 13:e0198345. [PMID: 29856826 PMCID: PMC5983478 DOI: 10.1371/journal.pone.0198345] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/17/2018] [Indexed: 12/23/2022] Open
Abstract
Porphyria cutanea tarda (PCT), the most common of the human porphyrias, arises from a deficiency of uroporphyrinogen decarboxylase. Studies have shown a high prevalence of hepatitis C virus (HCV) infection in patients with PCT. While these observations implicate HCV infection as a risk factor for PCT pathogenesis, the mechanism of interaction between the virus and porphyrin metabolism is unknown. This study aimed to assess the effect of HCV core protein on intracellular porphyrin metabolism to elucidate the link between HCV infection and PCT. The accumulation and excretion of porphyrins after treatment with 5-aminolevulinic acid, a porphyrin precursor, were compared between cells stably expressing HCV core protein and controls. Cells expressing HCV core protein had lower amounts of intracellular protoporphyrin IX and heme and had higher amounts of excreted coproporphyrin III, the oxidized form of coproporphyrinogen III, compared with controls. These observations suggest that HCV core protein affects porphyrin metabolism and facilitates the export of excess coproporphyrinogen III and/or coproporphyrin III, possibly via porphyrin transporters. Real-time PCR analysis revealed that the presence of HCV core protein increased the mRNA expression of porphyrin exporters ABCG2 and FLVCR1. Western blot analysis showed a higher expression level of FLVCR1, but not ABCG2, as well as a higher expression level of mature ALAS1, which is the rate-limiting enzyme in the heme synthesis pathway, in HCV core protein-expressing cells compared with controls. The data indicate that HCV core protein induced abnormal intracellular porphyrin metabolism, with an over-excretion of coproporphyrin III. These findings may partially account for the susceptibility of HCV-infected individuals to PCT development.
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Affiliation(s)
- Takafumi Nakano
- Biopharmaceutics and Molecular Toxicology Unit, Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano-ku, Tokyo, Japan
- * E-mail:
| | - Kyoji Moriya
- Department of Internal Medicine, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kazuhiko Koike
- Department of Internal Medicine, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Toshiharu Horie
- Biopharmaceutics and Molecular Toxicology Unit, Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano-ku, Tokyo, Japan
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14
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Abstract
The physiological identity of every cell is maintained by highly specific transcriptional networks that establish a coherent molecular program that is in tune with nutritional conditions. The regulation of cell-specific transcriptional networks is accomplished by an epigenetic program via chromatin-modifying enzymes, whose activity is directly dependent on metabolites such as acetyl-coenzyme A, S-adenosylmethionine, and NAD+, among others. Therefore, these nuclear activities are directly influenced by the nutritional status of the cell. In addition to nutritional availability, this highly collaborative program between epigenetic dynamics and metabolism is further interconnected with other environmental cues provided by the day-night cycles imposed by circadian rhythms. Herein, we review molecular pathways and their metabolites associated with epigenetic adaptations modulated by histone- and DNA-modifying enzymes and their responsiveness to the environment in the context of health and disease.
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15
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Sachar M, Anderson KE, Ma X. Protoporphyrin IX: the Good, the Bad, and the Ugly. J Pharmacol Exp Ther 2015; 356:267-75. [PMID: 26588930 DOI: 10.1124/jpet.115.228130] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 11/20/2015] [Indexed: 01/10/2023] Open
Abstract
Protoporphyrin IX (PPIX) is ubiquitously present in all living cells in small amounts as a precursor of heme. PPIX has some biologic functions of its own, and PPIX-based strategies have been used for cancer diagnosis and treatment (the good). PPIX serves as the substrate for ferrochelatase, the final enzyme in heme biosynthesis, and its homeostasis is tightly regulated during heme synthesis. Accumulation of PPIX in human porphyrias can cause skin photosensitivity, biliary stones, hepatobiliary damage, and even liver failure (the bad and the ugly). In this work, we review the mechanisms that are associated with the broad aspects of PPIX. Because PPIX is a hydrophobic molecule, its disposition is by hepatic rather than renal excretion. Large amounts of PPIX are toxic to the liver and can cause cholestatic liver injury. Application of PPIX in cancer diagnosis and treatment is based on its photodynamic effects.
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Affiliation(s)
- Madhav Sachar
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania (M.S., X.M.); and Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston, Texas (K.E.A.)
| | - Karl E Anderson
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania (M.S., X.M.); and Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston, Texas (K.E.A.)
| | - Xiaochao Ma
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania (M.S., X.M.); and Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston, Texas (K.E.A.)
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16
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Abstract
As an essential element, iron plays a central role in many physiological processes, including redox balance, inflammation, energy metabolism, and environment sensing. Perturbations in iron homeostasis are associated with several conditions, including hyperglycemia and diabetes, both of which have been studied in patients and animal models. To clarify the pleiotropic role of iron homeostasis in diabetes development, the early studies on diseases with iron-overload, studies on clinical iron depletion therapies, associations between iron-related genetic polymorphisms and diabetes, and etiological mechanisms underlying iron perturbations-impaired insulin secretion and insulin sensitivity were carefully reviewed and discussed. Hereditary hemochromatosis, transfusion-dependent thalassemia, and excess heme iron intake can increase the risk of developing diabetes. Genetically modified mice and mice fed a high-iron diet present with discrepant phenotypes due to differences in tissue iron distribution. Moreover, several genetic polymorphisms related to iron homeostasis have been associated with the risk of developing diabetes. Tightly controlled iron metabolism is essential for insulin secretion and insulin sensitivity, and iron overload in pancreatic islets alters reactive oxygen species (ROS) generation, as well as hypoxia-inducible factor-1α (HIF-1α) stability and adenosine triphosphate (ATP) synthesis, thereby impairing the function and viability of β-cells. Decreased levels of adiponectin, macrophage-mediated inflammation, and ROS-mediated liver kinase B1 (LKB1)/adenosine monophosphate-activated protein kinase (AMPK) activation can contribute to iron overload-induced insulin resistance, whereas iron deficiency could also participate in obesity-related inflammation, hypoxia, and insulin resistance. Because iron homeostasis is closely correlated with many metabolic processes, future studies are needed in order to elucidate the finely tuned network among iron homeostasis, carbohydrate and lipid metabolism, inflammation, and hypoxia.
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Affiliation(s)
- Xinhui Wang
- Department of Nutrition, Research Center for Nutrition and Health, Institute of Nutrition and Food Safety, School of Public Health, School of Medicine, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, China
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17
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Abstract
Genetic variants in haem metabolism enzymes can be predisposition factors for adverse reactions in some individuals. New areas of haem biology may also be associated with idiosyncratic effects which are yet to be identified.
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Affiliation(s)
- Viktoria Vágány
- MRC Toxicology Unit
- Hodgkin Building
- University of Leicester
- Leicester LE1 9HN
- UK
| | - Andrew G. Smith
- MRC Toxicology Unit
- Hodgkin Building
- University of Leicester
- Leicester LE1 9HN
- UK
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18
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Besur S, Hou W, Schmeltzer P, Bonkovsky HL. Clinically important features of porphyrin and heme metabolism and the porphyrias. Metabolites 2014; 4:977-1006. [PMID: 25372274 PMCID: PMC4279155 DOI: 10.3390/metabo4040977] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 10/14/2014] [Accepted: 10/16/2014] [Indexed: 01/29/2023] Open
Abstract
Heme, like chlorophyll, is a primordial molecule and is one of the fundamental pigments of life. Disorders of normal heme synthesis may cause human diseases, including certain anemias (X-linked sideroblastic anemias) and porphyrias. Porphyrias are classified as hepatic and erythropoietic porphyrias based on the organ system in which heme precursors (5-aminolevulinic acid (ALA), porphobilinogen and porphyrins) are chiefly overproduced. The hepatic porphyrias are further subdivided into acute porphyrias and chronic hepatic porphyrias. The acute porphyrias include acute intermittent, hereditary copro-, variegate and ALA dehydratase deficiency porphyria. Chronic hepatic porphyrias include porphyria cutanea tarda and hepatoerythropoietic porphyria. The erythropoietic porphyrias include congenital erythropoietic porphyria (Gűnther’s disease) and erythropoietic protoporphyria. In this review, we summarize the key features of normal heme synthesis and its differing regulation in liver versus bone marrow. In both organs, principal regulation is exerted at the level of the first and rate-controlling enzyme, but by different molecules (heme in the liver and iron in the bone marrow). We also describe salient clinical, laboratory and genetic features of the eight types of porphyria.
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Affiliation(s)
- Siddesh Besur
- Department of Medicine and Center for Liver Disease, Carolinas HealthCare System, Charlotte, NC 28204, USA.
| | - Wehong Hou
- Department of Research and the Liver, Digestive, and Metabolic Disorders Laboratory, Carolinas HealthCare System, Charlotte, NC 28203, USA.
| | - Paul Schmeltzer
- Department of Medicine and Center for Liver Disease, Carolinas HealthCare System, Charlotte, NC 28204, USA.
| | - Herbert L Bonkovsky
- Department of Medicine, Universities of CT, Farmington, CT 06030 and North Carolina, Chapel Hill, NC 27599, USA.
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19
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Jais A, Einwallner E, Sharif O, Gossens K, Lu TTH, Soyal SM, Medgyesi D, Neureiter D, Paier-Pourani J, Dalgaard K, Duvigneau JC, Lindroos-Christensen J, Zapf TC, Amann S, Saluzzo S, Jantscher F, Stiedl P, Todoric J, Martins R, Oberkofler H, Müller S, Hauser-Kronberger C, Kenner L, Casanova E, Sutterlüty-Fall H, Bilban M, Miller K, Kozlov AV, Krempler F, Knapp S, Lumeng CN, Patsch W, Wagner O, Pospisilik JA, Esterbauer H. Heme oxygenase-1 drives metaflammation and insulin resistance in mouse and man. Cell 2014; 158:25-40. [PMID: 24995976 DOI: 10.1016/j.cell.2014.04.043] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 03/03/2014] [Accepted: 04/18/2014] [Indexed: 02/07/2023]
Abstract
Obesity and diabetes affect more than half a billion individuals worldwide. Interestingly, the two conditions do not always coincide and the molecular determinants of "healthy" versus "unhealthy" obesity remain ill-defined. Chronic metabolic inflammation (metaflammation) is believed to be pivotal. Here, we tested a hypothesized anti-inflammatory role for heme oxygenase-1 (HO-1) in the development of metabolic disease. Surprisingly, in matched biopsies from "healthy" versus insulin-resistant obese subjects we find HO-1 to be among the strongest positive predictors of metabolic disease in humans. We find that hepatocyte and macrophage conditional HO-1 deletion in mice evokes resistance to diet-induced insulin resistance and inflammation, dramatically reducing secondary disease such as steatosis and liver toxicity. Intriguingly, cellular assays show that HO-1 defines prestimulation thresholds for inflammatory skewing and NF-κB amplification in macrophages and for insulin signaling in hepatocytes. These findings identify HO-1 inhibition as a potential therapeutic strategy for metabolic disease.
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Affiliation(s)
| | | | - Omar Sharif
- Medical University of Vienna, 1090 Vienna, Austria; CeMM, Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Klaus Gossens
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Tess Tsai-Hsiu Lu
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Selma M Soyal
- Paracelsus Medical University, 5020 Salzburg, Austria
| | - David Medgyesi
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; BIOSS Centre of Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | | | - Jamile Paier-Pourani
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, 1200 Vienna, Austria
| | - Kevin Dalgaard
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | | | | | | | - Sabine Amann
- Medical University of Vienna, 1090 Vienna, Austria
| | - Simona Saluzzo
- Medical University of Vienna, 1090 Vienna, Austria; CeMM, Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | | | - Patricia Stiedl
- Ludwig Boltzmann Institute for Cancer Research, 1090 Vienna, Austria
| | | | - Rui Martins
- Medical University of Vienna, 1090 Vienna, Austria; CeMM, Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | | | - Simone Müller
- University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | | | - Lukas Kenner
- Medical University of Vienna, 1090 Vienna, Austria; University of Veterinary Medicine Vienna, 1210 Vienna, Austria; Ludwig Boltzmann Institute for Cancer Research, 1090 Vienna, Austria
| | - Emilio Casanova
- Medical University of Vienna, 1090 Vienna, Austria; Ludwig Boltzmann Institute for Cancer Research, 1090 Vienna, Austria
| | | | | | - Karl Miller
- General Hospital Hallein, 5400 Hallein, Austria
| | - Andrey V Kozlov
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, 1200 Vienna, Austria
| | | | - Sylvia Knapp
- Medical University of Vienna, 1090 Vienna, Austria; CeMM, Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | | | | | | | - J Andrew Pospisilik
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany.
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20
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Vinchi F, Ingoglia G, Chiabrando D, Mercurio S, Turco E, Silengo L, Altruda F, Tolosano E. Heme exporter FLVCR1a regulates heme synthesis and degradation and controls activity of cytochromes P450. Gastroenterology 2014; 146:1325-38. [PMID: 24486949 PMCID: PMC4000440 DOI: 10.1053/j.gastro.2014.01.053] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 01/28/2014] [Accepted: 01/28/2014] [Indexed: 12/05/2022]
Abstract
BACKGROUND & AIMS The liver has one of the highest rates of heme synthesis of any organ. More than 50% of the heme synthesized in the liver is used for synthesis of P450 enzymes, which metabolize exogenous and endogenous compounds that include natural products, hormones, drugs, and carcinogens. Feline leukemia virus subgroup C cellular receptor 1a (FLVCR1a) is plasma membrane heme exporter that is ubiquitously expressed and controls intracellular heme content in hematopoietic lineages. We investigated the role of Flvcr1a in liver function in mice. METHODS We created mice with conditional disruption of Mfsd7b, which encodes Flvcr1a, in hepatocytes (Flvcr1a(fl/fl);alb-cre mice). Mice were analyzed under basal conditions, after phenylhydrazine-induced hemolysis, and after induction of cytochromes P450 synthesis. Livers were collected and analyzed by histologic, quantitative real-time polymerase chain reaction, and immunoblot analyses. Hepatic P450 enzymatic activities were measured. RESULTS Flvcr1a(fl/fl);alb-cre mice accumulated heme and iron in liver despite up-regulation of heme oxygenase 1, ferroportin, and ferritins. Hepatic heme export activity of Flvcr1a was closely associated with heme biosynthesis, which is required to sustain cytochrome induction. Upon cytochromes P450 stimulation, Flvcr1a(fl/fl);alb-cre mice had reduced cytochrome activity, associated with accumulation of heme in hepatocytes. The expansion of the cytosolic heme pool in these mice was likely responsible for the early inhibition of heme synthesis and increased degradation of heme, which reduced expression and activity of cytochromes P450. CONCLUSIONS In livers of mice, Flvcr1a maintains a free heme pool that regulates heme synthesis and degradation as well as cytochromes P450 expression and activity. These findings have important implications for drug metabolism.
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Affiliation(s)
| | | | | | | | | | | | | | - Emanuela Tolosano
- Molecular Biotechnology Center and Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
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21
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Chiabrando D, Vinchi F, Fiorito V, Mercurio S, Tolosano E. Heme in pathophysiology: a matter of scavenging, metabolism and trafficking across cell membranes. Front Pharmacol 2014; 5:61. [PMID: 24782769 PMCID: PMC3986552 DOI: 10.3389/fphar.2014.00061] [Citation(s) in RCA: 268] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/18/2014] [Indexed: 01/19/2023] Open
Abstract
Heme (iron-protoporphyrin IX) is an essential co-factor involved in multiple biological processes: oxygen transport and storage, electron transfer, drug and steroid metabolism, signal transduction, and micro RNA processing. However, excess free-heme is highly toxic due to its ability to promote oxidative stress and lipid peroxidation, thus leading to membrane injury and, ultimately, apoptosis. Thus, heme metabolism needs to be finely regulated. Intracellular heme amount is controlled at multiple levels: synthesis, utilization by hemoproteins, degradation and both intracellular and intercellular trafficking. This review focuses on recent findings highlighting the importance of controlling intracellular heme levels to counteract heme-induced oxidative stress. The contributions of heme scavenging from the extracellular environment, heme synthesis and incorporation into hemoproteins, heme catabolism and heme transport in maintaining adequate intracellular heme content are discussed. Particular attention is put on the recently described mechanisms of heme trafficking through the plasma membrane mediated by specific heme importers and exporters. Finally, the involvement of genes orchestrating heme metabolism in several pathological conditions is illustrated and new therapeutic approaches aimed at controlling heme metabolism are discussed.
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Affiliation(s)
- Deborah Chiabrando
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Francesca Vinchi
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Veronica Fiorito
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Sonia Mercurio
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Emanuela Tolosano
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
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22
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The alternative route to heme in the methanogenic archaeon Methanosarcina barkeri. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2014; 2014:327637. [PMID: 24669201 PMCID: PMC3942049 DOI: 10.1155/2014/327637] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 10/25/2013] [Indexed: 11/25/2022]
Abstract
In living organisms heme is formed from the common precursor uroporphyrinogen III by either one of two substantially different pathways. In contrast to eukaryotes and most bacteria which employ the so-called “classical” heme biosynthesis pathway, the archaea use an alternative route. In this pathway, heme is formed from uroporphyrinogen III via the intermediates precorrin-2, sirohydrochlorin, siroheme, 12,18-didecarboxysiroheme, and iron-coproporphyrin III. In this study the heme biosynthesis proteins AhbAB, AhbC, and AhbD from Methanosarcina barkeri were functionally characterized. Using an in vivo enzyme activity assay it was shown that AhbA and AhbB (Mbar_A1459 and Mbar_A1460) together catalyze the conversion of siroheme into 12,18-didecarboxysiroheme. The two proteins form a heterodimeric complex which might be subject to feedback regulation by the pathway end-product heme. Further, AhbC (Mbar_A1793) was shown to catalyze the formation of iron-coproporphyrin III in vivo. Finally, recombinant AhbD (Mbar_A1458) was produced in E. coli and purified indicating that this protein most likely contains two [4Fe-4S] clusters. Using an in vitro enzyme activity assay it was demonstrated that AhbD catalyzes the conversion of iron-coproporphyrin III into heme.
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Heme levels are increased in human failing hearts. J Am Coll Cardiol 2013; 61:1884-93. [PMID: 23500306 DOI: 10.1016/j.jacc.2013.02.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 01/15/2013] [Accepted: 02/05/2013] [Indexed: 11/24/2022]
Abstract
OBJECTIVES The goal of this study was to characterize the regulation of heme and non-heme iron in human failing hearts. BACKGROUND Iron is an essential molecule for cellular physiology, but in excess it facilitates oxidative stress. Mitochondria are the key regulators of iron homeostasis through heme and iron-sulfur cluster synthesis. Because mitochondrial function is depressed in failing hearts and iron accumulation can lead to oxidative stress, we hypothesized that iron regulation may also be impaired in heart failure (HF). METHODS We measured mitochondrial and cytosolic heme and non-heme iron levels in failing human hearts retrieved during cardiac transplantation surgery. In addition, we examined the expression of genes regulating cellular iron homeostasis, the heme biosynthetic pathway, and micro-RNAs that may potentially target iron regulatory networks. RESULTS Although cytosolic non-heme iron levels were reduced in HF, mitochondrial iron content was maintained. Moreover, we observed a significant increase in heme levels in failing hearts, with corresponding feedback inhibition of the heme synthetic enzymes and no change in heme degradation. The rate-limiting enzyme in heme synthesis, delta-aminolevulinic acid synthase 2 (ALAS2), was significantly upregulated in HF. Overexpression of ALAS2 in H9c2 cardiac myoblasts resulted in increased heme levels, and hypoxia and erythropoietin treatment increased heme production through upregulation of ALAS2. Finally, increased heme levels in cardiac myoblasts were associated with excess production of reactive oxygen species and cell death, suggesting a maladaptive role for increased heme in HF. CONCLUSIONS Despite global mitochondrial dysfunction, heme levels are maintained above baseline in human failing hearts.
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Manic G, Maurin-Marlin A, Galluzzi L, Subra F, Mouscadet JF, Bury-Moné S. 3' self-inactivating long terminal repeat inserts for the modulation of transgene expression from lentiviral vectors. Hum Gene Ther Methods 2012; 23:84-97. [PMID: 22456436 DOI: 10.1089/hgtb.2011.154] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Gene transfer for research or gene therapy requires the design of vectors that allow for adequate and safe transgene expression. Current methods to modulate the safety and expression profile of retroviral vectors can involve the insertion of insulators or scaffold/matrix-attachment regions in self-inactivating long terminal repeats (SIN-LTRs). Here, we generated a set of lentiviral vectors (with internal CMV or PGK promoter) in which we inserted (at the level of SIN-LTRs) sequences of avian (i.e., chicken hypersensitive site-4, cHS4), human (i.e., putative insulator and desert sequence), or bacterial origin. We characterized them with respect to viral titer, integration, transduction efficiency and transgene expression levels, in both integrase-proficient and -deficient contexts. We found that the cHS4 insulator enhanced transgene expression by a factor of 1.5 only when cloned in the antisense orientation. On the other hand, cHS4 in the sense orientation as well as all other inserts decreased transgene expression. This attenuation phenomenon persisted over long periods of time and did not correspond to extinction or variegation. Decreased transgene expression was associated with lower mRNA levels, yet RNA stability was not affected. Insertions within the SIN-LTRs may negatively affect transgene transcription in a direct fashion through topological rearrangements. The lentiviral vectors that we generated constitute valuable genetic tools for manipulating the level of transgene expression. Moreover, this study demonstrates that SIN-LTR inserts can decrease transgene expression, a phenomenon that might be overcome by modifying insert orientation, thereby highlighting the importance of careful vector design for gene therapy.
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Affiliation(s)
- Gwenola Manic
- Laboratoire de Biologie et de Pharmacologie Appliquée, UMR 8113 CNRS, Ecole Normale Supérieure de Cachan, FR-94230 Cachan, France
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Venkatesh S, Lee J, Singh K, Lee I, Suzuki CK. Multitasking in the mitochondrion by the ATP-dependent Lon protease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:56-66. [PMID: 22119779 DOI: 10.1016/j.bbamcr.2011.11.003] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 10/30/2011] [Accepted: 11/06/2011] [Indexed: 01/13/2023]
Abstract
The AAA(+) Lon protease is a soluble single-ringed homo-oligomer, which represents the most streamlined operational unit mediating ATP-dependent proteolysis. Despite its simplicity, the architecture of Lon proteases exhibits a species-specific diversity. Homology modeling provides insights into the structural features that distinguish bacterial and human Lon proteases as hexameric complexes from yeast Lon, which is uniquely heptameric. The best-understood functions of mitochondrial Lon are linked to maintaining proteostasis under normal metabolic conditions, and preventing proteotoxicity during environmental and cellular stress. An intriguing property of human Lon is its specific binding to G-quadruplex DNA, and its association with the mitochondrial genome in cultured cells. A fraction of Lon preferentially binds to the control region of mitochondrial DNA where transcription and replication are initiated. Here, we present an overview of the diverse functions of mitochondrial Lon, as well as speculative perspectives on its role in protein and mtDNA quality control.
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Affiliation(s)
- Sundararajan Venkatesh
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, 185 South Orange Avenue, MSB E-633, Newark, New Jersey 07103 USA
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The REV-ERBs and RORs: molecular links between circadian rhythms and lipid homeostasis. Future Med Chem 2011; 3:623-38. [PMID: 21526899 DOI: 10.4155/fmc.11.9] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Research efforts spanning the past two decades have established a clear link between nuclear receptor function, regulation of the circadian clock and lipid homeostasis. As such, this family of receptors represents an important area of research. Recent advances in the field have identified two nuclear receptor subfamilies, the REV-ERBs and the 'retinoic acid receptor-related orphan receptors' (RORs), as critical regulators of the circadian clock with significant roles in lipid homeostasis. In this review, the latest information garnered from cutting-edge research on these two nuclear receptor subfamilies will be discussed. Through direct targeting of the REV-ERBs and RORs with synthetic ligands, generation of novel tools aimed at characterizing their function in vivo have been developed, which may lead to novel therapeutics for the treatment of metabolic disorders.
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Tian Q, Li T, Hou W, Zheng J, Schrum LW, Bonkovsky HL. Lon peptidase 1 (LONP1)-dependent breakdown of mitochondrial 5-aminolevulinic acid synthase protein by heme in human liver cells. J Biol Chem 2011; 286:26424-30. [PMID: 21659532 DOI: 10.1074/jbc.m110.215772] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
5-Aminolevulinic acid synthase (ALAS-1) is the first rate controlling enzyme that controls cellular heme biosynthesis. Negative feedback regulation of ALAS-1 by the end product heme is well documented and provides the foundation for heme treatment of acute porphyrias, a group of diseases caused by genetic defects in the heme biosynthesis pathway and exacerbated by controlled up-regulation of ALAS-1. Heme is known to affect ALAS-1 activity by repressing gene transcription, accelerating mRNA degradation, and impeding pre-ALAS-1 mitochondrial translocation. In the current study, we examined the effect of heme on the rate of mature ALAS-1 protein turnover in human cells and tissues and explored the mediator involved in this new regulatory mechanism. We found that heme and other metalloporphyrins such as CoPP and CrPP decreased mitochondrial ALAS-1 protein through proteolysis. This degradative effect cannot be emulated by iron or free protoporphyrin, two major chemical components of the heme ring, and is independent of oxidative stress. Down-regulating the activity of mitochondrial LONP1, an ATP-dependent protease that controls the selective turnover of mitochondrial matrix proteins, with potent inhibitors and specific siRNA diminished the negative effect of heme on mitochondrial ALAS-1. Therefore, our data support the existence of a conserved heme feedback regulatory mechanism that functions on the mature form of ALAS-1 protein through the activity of a mitochondrial proteolytic system.
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Affiliation(s)
- Qing Tian
- Liver, Digestive, and Metabolic Disorders Laboratory, Carolinas Medical Center, Charlotte, North Carolina 28203, USA
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Chernova T, Steinert JR, Richards P, Mistry R, Challiss RAJ, Jukes-Jones R, Cain K, Smith AG, Forsythe ID. Early failure of N-methyl-D-aspartate receptors and deficient spine formation induced by reduction of regulatory heme in neurons. Mol Pharmacol 2011; 79:844-54. [PMID: 21325018 DOI: 10.1124/mol.110.069831] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
An initial stage of many neurodegenerative processes is associated with compromised synaptic function and precedes synapse loss, neurite fragmentation, and neuronal death. We showed previously that deficiency of heme, regulating many proteins of pharmacological importance, causes neurodegeneration of primary cortical neurons via N-methyl-d-aspartate receptor (NMDAR)-dependent suppression of the extracellular signal-regulated kinase 1/2 pathway. Here, we asked whether the reduction of heme causes synaptic perturbation before neurite fragmentation in neuronal cultures and investigated molecular mechanisms of synaptic dysfunction in these cells. We showed the change in the NR2B subunit phosphorylation that correlates with compromised NMDAR function after the reduction of regulatory heme and a rapid rescue of NR2B phosphorylation and NMDAR function by exogenous heme. Electrophysiological recordings demonstrated diminished NMDAR currents and NMDAR-mediated calcium influx after 24 h of inhibition of heme synthesis. These effects were reversed by treatment with heme; however, inhibition of the Src family kinases abolished the rescue effect of heme on NMDA-evoked currents. Diminished NMDAR current and Ca(2+) influx resulted in suppressed cGMP production and impairment of spine formation. Exogenous heme exerted rescue effects on NR2B tyrosine phosphorylation and NMDA-evoked currents within minutes, suggesting direct interactions within the NMDAR complex. These synaptic changes after inhibition of heme synthesis occurred at this stage without apparent dysfunction of major hemoproteins. We conclude that regulatory heme is necessary in maintaining NR2B phosphorylation and NMDAR function. NMDAR failure occurs before neurite fragmentation and may be a causal factor in neurodegeneration; this could suggest a route for an early pharmacological intervention.
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Affiliation(s)
- Tatyana Chernova
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom.
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Correia MA, Sinclair PR, De Matteis F. Cytochrome P450 regulation: the interplay between its heme and apoprotein moieties in synthesis, assembly, repair, and disposal. Drug Metab Rev 2010; 43:1-26. [PMID: 20860521 DOI: 10.3109/03602532.2010.515222] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Heme is vital to our aerobic universe. Heme cellular content is finely tuned through an exquisite control of synthesis and degradation. Heme deficiency is deleterious to cells, whereas excess heme is toxic. Most of the cellular heme serves as the prosthetic moiety of functionally diverse hemoproteins, including cytochromes P450 (P450s). In the liver, P450s are its major consumers, with >50% of hepatic heme committed to their synthesis. Prosthetic heme is the sine qua non of P450 catalytic biotransformation of both endo- and xenobiotics. This well-recognized functional role notwithstanding, heme also regulates P450 protein synthesis, assembly, repair, and disposal. These less well-appreciated aspects are reviewed herein.
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Affiliation(s)
- Maria Almira Correia
- Department of Cellular and Molecular Pharmacology, The Liver Center, University of California, San Francisco, 94158, USA.
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PGC-1alpha negatively regulates hepatic FGF21 expression by modulating the heme/Rev-Erb(alpha) axis. Proc Natl Acad Sci U S A 2009; 106:22510-5. [PMID: 20018698 DOI: 10.1073/pnas.0912533106] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
FGF21 is a hormone produced in liver and fat that dramatically improves peripheral insulin sensitivity and lipid metabolism. We show here that obese mice with genetically reduced levels of a key hepatic transcriptional coactivator, PGC-1alpha, have improved whole-body insulin sensitivity with increased levels of hepatic and circulating FGF21. Gain- and loss-of-function studies in primary mouse hepatocytes show that hepatic FGF21 levels are regulated by the expression of PGC-1alpha. Importantly, PGC-1alpha-mediated reduction of FGF21 expression is dependent on Rev-Erbalpha and the expression of ALAS-1. ALAS-1 is a PGC-1alpha target gene and the rate-limiting enzyme in the synthesis of heme, a ligand for Rev-Erbalpha. Modulation of intracellular heme levels mimics the effect of PGC-1alpha on FGF21 expression, and inhibition of heme biosynthesis completely abrogates the down-regulation of FGF21 in response to PGC-1alpha. Thus, PGC-1alpha can impact hepatic and systemic metabolism by regulating the levels of a nuclear receptor ligand.
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