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Gruffaz C, Smirnov A. GTPase Era at the heart of ribosome assembly. Front Mol Biosci 2023; 10:1263433. [PMID: 37860580 PMCID: PMC10582724 DOI: 10.3389/fmolb.2023.1263433] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/21/2023] [Indexed: 10/21/2023] Open
Abstract
Ribosome biogenesis is a key process in all organisms. It relies on coordinated work of multiple proteins and RNAs, including an array of assembly factors. Among them, the GTPase Era stands out as an especially deeply conserved protein, critically required for the assembly of bacterial-type ribosomes from Escherichia coli to humans. In this review, we bring together and critically analyze a wealth of phylogenetic, biochemical, structural, genetic and physiological data about this extensively studied but still insufficiently understood factor. We do so using a comparative and, wherever possible, synthetic approach, by confronting observations from diverse groups of bacteria and eukaryotic organelles (mitochondria and chloroplasts). The emerging consensus posits that Era intervenes relatively early in the small subunit biogenesis and is essential for the proper shaping of the platform which, in its turn, is a prerequisite for efficient translation. The timing of Era action on the ribosome is defined by its interactions with guanosine nucleotides [GTP, GDP, (p)ppGpp], ribosomal RNA, and likely other factors that trigger or delay its GTPase activity. As a critical nexus of the small subunit biogenesis, Era is subject to sophisticated regulatory mechanisms at the transcriptional, post-transcriptional, and post-translational levels. Failure of these mechanisms or a deficiency in Era function entail dramatic generalized consequences for the protein synthesis and far-reaching, pleiotropic effects on the organism physiology, such as the Perrault syndrome in humans.
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Affiliation(s)
- Christelle Gruffaz
- UMR7156- Génétique Moléculaire, Génomique, Microbiologie (GMGM), University of Strasbourg, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
| | - Alexandre Smirnov
- UMR7156- Génétique Moléculaire, Génomique, Microbiologie (GMGM), University of Strasbourg, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
- University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France
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2
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The Bacterial ClpXP-ClpB Family Is Enriched with RNA-Binding Protein Complexes. Cells 2022; 11:cells11152370. [PMID: 35954215 PMCID: PMC9368063 DOI: 10.3390/cells11152370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/23/2022] [Accepted: 07/28/2022] [Indexed: 11/17/2022] Open
Abstract
In the matrix of bacteria/mitochondria/chloroplasts, Lon acts as the degradation machine for soluble proteins. In stress periods, however, proteostasis and survival depend on the strongly conserved Clp/Hsp100 family. Currently, the targets of ATP-powered unfoldases/disaggregases ClpB and ClpX and of peptidase ClpP heptameric rings are still unclear. Trapping experiments and proteome profiling in multiple organisms triggered confusion, so we analyzed the consistency of ClpP-trap targets in bacteria. We also provide meta-analyses of protein interactions in humans, to elucidate where Clp family members are enriched. Furthermore, meta-analyses of mouse complexomics are provided. Genotype–phenotype correlations confirmed our concept. Trapping, proteome, and complexome data retrieved consistent coaccumulation of CLPXP with GFM1 and TUFM orthologs. CLPX shows broad interaction selectivity encompassing mitochondrial translation elongation, RNA granules, and nucleoids. CLPB preferentially attaches to mitochondrial RNA granules and translation initiation components; CLPP is enriched with them all and associates with release/recycling factors. Mutations in CLPP cause Perrault syndrome, with phenotypes similar to defects in mtDNA/mtRNA. Thus, we propose that CLPB and CLPXP are crucial to counteract misfolded insoluble protein assemblies that contain nucleotides. This insight is relevant to improve ClpP-modulating drugs that block bacterial growth and for the treatment of human infertility, deafness, and neurodegeneration.
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Inactivity of Peptidase ClpP Causes Primary Accumulation of Mitochondrial Disaggregase ClpX with Its Interacting Nucleoid Proteins, and of mtDNA. Cells 2021; 10:cells10123354. [PMID: 34943861 PMCID: PMC8699119 DOI: 10.3390/cells10123354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/20/2021] [Accepted: 11/25/2021] [Indexed: 12/19/2022] Open
Abstract
Biallelic pathogenic variants in CLPP, encoding mitochondrial matrix peptidase ClpP, cause a rare autosomal recessive condition, Perrault syndrome type 3 (PRLTS3). It is characterized by primary ovarian insufficiency and early sensorineural hearing loss, often associated with progressive neurological deficits. Mouse models showed that accumulations of (i) its main protein interactor, the substrate-selecting AAA+ ATPase ClpX, (ii) mitoribosomes, and (iii) mtDNA nucleoids are the main cellular consequences of ClpP absence. However, the sequence of these events and their validity in human remain unclear. Here, we studied global proteome profiles to define ClpP substrates among mitochondrial ClpX interactors, which accumulated consistently in ClpP-null mouse embryonal fibroblasts and brains. Validation work included novel ClpP-mutant patient fibroblast proteomics. ClpX co-accumulated in mitochondria with the nucleoid component POLDIP2, the mitochondrial poly(A) mRNA granule element LRPPRC, and tRNA processing factor GFM1 (in mouse, also GRSF1). Only in mouse did accumulated ClpX, GFM1, and GRSF1 appear in nuclear fractions. Mitoribosomal accumulation was minor. Consistent accumulations in murine and human fibroblasts also affected multimerizing factors not known as ClpX interactors, namely, OAT, ASS1, ACADVL, STOM, PRDX3, PC, MUT, ALDH2, PMPCB, UQCRC2, and ACADSB, but the impact on downstream metabolites was marginal. Our data demonstrate the primary impact of ClpXP on the assembly of proteins with nucleic acids and show nucleoid enlargement in human as a key consequence.
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4
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Proteomic analysis demonstrates the role of the quality control protease LONP1 in mitochondrial protein aggregation. J Biol Chem 2021; 297:101134. [PMID: 34461102 PMCID: PMC8503632 DOI: 10.1016/j.jbc.2021.101134] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/23/2021] [Accepted: 08/26/2021] [Indexed: 11/20/2022] Open
Abstract
The mitochondrial matrix protease LONP1 is an essential part of the organellar protein quality control system. LONP1 has been shown to be involved in respiration control and apoptosis. Furthermore, a reduction in LONP1 level correlates with aging. Up to now, the effects of a LONP1 defect were mostly studied by utilizing transient, siRNA-mediated knockdown approaches. We generated a new cellular model system for studying the impact of LONP1 on mitochondrial protein homeostasis by a CRISPR/Cas-mediated genetic knockdown (gKD). These cells showed a stable reduction of LONP1 along with a mild phenotype characterized by absent morphological differences and only small negative effects on mitochondrial functions under normal culture conditions. To assess the consequences of a permanent LONP1 depletion on the mitochondrial proteome, we analyzed the alterations of protein levels by quantitative mass spectrometry, demonstrating small adaptive changes, in particular with respect to mitochondrial protein biogenesis. In an additional proteomic analysis, we determined the temperature-dependent aggregation behavior of mitochondrial proteins and its dependence on a reduction of LONP1 activity, demonstrating the important role of the protease for mitochondrial protein homeostasis in mammalian cells. We identified a significant number of mitochondrial proteins that are affected by a reduced LONP1 activity especially with respect to their stress-induced solubility. Taken together, our results suggest a very good applicability of the LONP1 gKD cell line as a model system for human aging processes.
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5
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Hilander T, Jackson CB, Robciuc M, Bashir T, Zhao H. The roles of assembly factors in mammalian mitoribosome biogenesis. Mitochondrion 2021; 60:70-84. [PMID: 34339868 DOI: 10.1016/j.mito.2021.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 02/08/2023]
Abstract
As ancient bacterial endosymbionts of eukaryotic cells, mitochondria have retained their own circular DNA as well as protein translation system including mitochondrial ribosomes (mitoribosomes). In recent years, methodological advancements in cryoelectron microscopy and mass spectrometry have revealed the extent of the evolutionary divergence of mitoribosomes from their bacterial ancestors and their adaptation to the synthesis of 13 mitochondrial DNA encoded oxidative phosphorylation complex subunits. In addition to the structural data, the first assembly pathway maps of mitoribosomes have started to emerge and concomitantly also the assembly factors involved in this process to achieve fully translational competent particles. These transiently associated factors assist in the intricate assembly process of mitoribosomes by enhancing protein incorporation, ribosomal RNA folding and modification, and by blocking premature or non-native protein binding, for example. This review focuses on summarizing the current understanding of the known mammalian mitoribosome assembly factors and discussing their possible roles in the assembly of small or large mitoribosomal subunits.
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Affiliation(s)
- Taru Hilander
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland.
| | - Christopher B Jackson
- Department of Biochemistry and Developmental Biology, Faculty of Medicine, University of Helsinki, Finland.
| | - Marius Robciuc
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Tanzeela Bashir
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Hongxia Zhao
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland; Key Laboratory of Stem Cell and Biopharmaceutical Technology, School of Life Sciences, Guangxi Normal University, Guangxi, China.
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6
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A model of the aged lung epithelium in idiopathic pulmonary fibrosis. Aging (Albany NY) 2021; 13:16922-16937. [PMID: 34238764 PMCID: PMC8312437 DOI: 10.18632/aging.203291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/19/2021] [Indexed: 01/19/2023]
Abstract
Idiopathic pulmonary fibrosis (IPF) is an age-related disorder that carries a universally poor prognosis and is thought to arise from repetitive micro injuries to the alveolar epithelium. To date, a major factor limiting our understanding of IPF is a deficiency of disease models, particularly in vitro models that can recapitulate the full complement of molecular attributes in the human condition. In this study, we aimed to develop a model that more closely resembles the aberrant IPF lung epithelium. By exposing mouse alveolar epithelial cells to repeated, low doses of bleomycin, instead of usual one-time exposures, we uncovered changes strikingly similar to those in the IPF lung epithelium. This included the acquisition of multiple phenotypic and functional characteristics of senescent cells and the adoption of previously described changes in mitochondrial homeostasis, including alterations in redox balance, energy production and activity of the mitochondrial unfolded protein response. We also uncovered dramatic changes in cellular metabolism and detected a profound loss of proteostasis, as characterized by the accumulation of cytoplasmic protein aggregates, dysregulated expression of chaperone proteins and decreased activity of the ubiquitin proteasome system. In summary, we describe an in vitro model that closely resembles the aberrant lung epithelium in IPF. We propose that this simple yet powerful tool could help uncover new biological mechanisms and assist in developing new pharmacological tools to treat the disease.
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7
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Kingsley LJ, He X, McNeill M, Nelson J, Nikulin V, Ma Z, Lu W, Zhou VW, Manuia M, Kreusch A, Gao MY, Witmer D, Vaillancourt MT, Lu M, Greenblatt S, Lee C, Vashisht A, Bender S, Spraggon G, Michellys PY, Jia Y, Haling JR, Lelais G. Structure-Based Design of Selective LONP1 Inhibitors for Probing In Vitro Biology. J Med Chem 2021; 64:4857-4869. [PMID: 33821636 DOI: 10.1021/acs.jmedchem.0c02152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
LONP1 is an AAA+ protease that maintains mitochondrial homeostasis by removing damaged or misfolded proteins. Elevated activity and expression of LONP1 promotes cancer cell proliferation and resistance to apoptosis-inducing reagents. Despite the importance of LONP1 in human biology and disease, very few LONP1 inhibitors have been described in the literature. Herein, we report the development of selective boronic acid-based LONP1 inhibitors using structure-based drug design as well as the first structures of human LONP1 bound to various inhibitors. Our efforts led to several nanomolar LONP1 inhibitors with little to no activity against the 20S proteasome that serve as tool compounds to investigate LONP1 biology.
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Affiliation(s)
- Laura J Kingsley
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Xiaohui He
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Matthew McNeill
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - John Nelson
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Victor Nikulin
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Zhiwei Ma
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Wenshuo Lu
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Vicki W Zhou
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Mari Manuia
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Andreas Kreusch
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Mu-Yun Gao
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Darbi Witmer
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Mei-Ting Vaillancourt
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Min Lu
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Sarah Greenblatt
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Christian Lee
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Ajay Vashisht
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Steven Bender
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Glen Spraggon
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Pierre-Yves Michellys
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Yong Jia
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Jacob R Haling
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
| | - Gérald Lelais
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Dr., San Diego, California 92121, United States
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Torres-Odio S, Lei Y, Gispert S, Maletzko A, Key J, Menissy SS, Wittig I, Auburger G, West AP. Loss of Mitochondrial Protease CLPP Activates Type I IFN Responses through the Mitochondrial DNA-cGAS-STING Signaling Axis. THE JOURNAL OF IMMUNOLOGY 2021; 206:1890-1900. [PMID: 33731338 DOI: 10.4049/jimmunol.2001016] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 02/01/2021] [Indexed: 12/12/2022]
Abstract
Caseinolytic mitochondrial matrix peptidase proteolytic subunit (CLPP) is a serine protease that degrades damaged or misfolded mitochondrial proteins. CLPP-null mice exhibit growth retardation, deafness, and sterility, resembling human Perrault syndrome, but also display immune system alterations. However, the molecular mechanisms and signaling pathways underlying immunological changes in CLPP-null mice remain unclear. In this study, we report the steady-state activation of type I IFN signaling and antiviral gene expression in CLPP-deficient cells and tissues, resulting in marked resistance to RNA and DNA virus infection. Depletion of the cyclic GMP-AMP (cGAS)-stimulator of IFN genes (STING) DNA sensing pathway reduces steady-state IFN-I signaling and abrogates the broad antiviral phenotype of CLPP-null cells. Moreover, we report that CLPP deficiency leads to mitochondrial DNA (mtDNA) instability and packaging alterations. Pharmacological and genetic approaches to deplete mtDNA or inhibit cytosolic release markedly reduce antiviral gene expression, implicating mtDNA stress as the driver of IFN-I signaling in CLPP-null mice. Our work places the cGAS-STING-IFN-I innate immune pathway downstream of CLPP and may have implications for understanding Perrault syndrome and other human diseases involving CLPP dysregulation.
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Affiliation(s)
- Sylvia Torres-Odio
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807
| | - Yuanjiu Lei
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807
| | - Suzana Gispert
- Experimental Neurology, Goethe University, 60590 Frankfurt am Main, Germany; and
| | - Antonia Maletzko
- Experimental Neurology, Goethe University, 60590 Frankfurt am Main, Germany; and
| | - Jana Key
- Experimental Neurology, Goethe University, 60590 Frankfurt am Main, Germany; and
| | - Saeed S Menissy
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807
| | - Ilka Wittig
- Functional Proteomics, Faculty of Medicine, Goethe University, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Goethe University, 60590 Frankfurt am Main, Germany; and
| | - A Phillip West
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807;
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Key J, Harter PN, Sen NE, Gradhand E, Auburger G, Gispert S. Mid-Gestation lethality of Atxn2l-Ablated Mice. Int J Mol Sci 2020; 21:E5124. [PMID: 32698485 PMCID: PMC7404131 DOI: 10.3390/ijms21145124] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/10/2020] [Accepted: 07/16/2020] [Indexed: 12/11/2022] Open
Abstract
Depletion of yeast/fly Ataxin-2 rescues TDP-43 overexpression toxicity. In mouse models of Amyotrophic Lateral Sclerosis via TDP-43 overexpression, depletion of its ortholog ATXN2 mitigated motor neuron degeneration and extended lifespan from 25 days to >300 days. There is another ortholog in mammals, named ATXN2L (Ataxin-2-like), which is almost uncharacterized but also functions in RNA surveillance at stress granules. We generated mice with Crispr/Cas9-mediated deletion of Atxn2l exons 5-8, studying homozygotes prenatally and heterozygotes during aging. Our novel findings indicate that ATXN2L absence triggers mid-gestational embryonic lethality, affecting female animals more strongly. Weight and development stages of homozygous mutants were reduced. Placenta phenotypes were not apparent, but brain histology showed lamination defects and apoptosis. Aged heterozygotes showed no locomotor deficits or weight loss over 12 months. Null mutants in vivo displayed compensatory efforts to maximize Atxn2l expression, which were prevented upon nutrient abundance in vitro. Mouse embryonal fibroblast cells revealed more multinucleated giant cells upon ATXN2L deficiency. In addition, in human neural cells, transcript levels of ATXN2L were induced upon starvation and glucose and amino acids exposure, but this induction was partially prevented by serum or low cholesterol administration. Neither ATXN2L depletion triggered dysregulation of ATXN2, nor a converse effect was observed. Overall, this essential role of ATXN2L for embryogenesis raises questions about its role in neurodegenerative diseases and neuroprotective therapies.
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Affiliation(s)
- Jana Key
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
- Faculty of Biosciences, Goethe-University, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
| | - Patrick N. Harter
- Institute of Neurology (Edinger-Institute), University Hospital Frankfurt, Goethe University, Heinrich-Hoffmann-Strasse 7, 60528 Frankfurt am Main, Germany;
| | - Nesli-Ece Sen
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
- Faculty of Biosciences, Goethe-University, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
| | - Elise Gradhand
- Dr. Senckenberg Institute for Pathology, University Hospital, Goethe University, Theodor-Stern-Kai-7, 60590 Frankfurt am Main, Germany;
| | - Georg Auburger
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
| | - Suzana Gispert
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
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10
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De Gaetano A, Gibellini L, Bianchini E, Borella R, De Biasi S, Nasi M, Boraldi F, Cossarizza A, Pinti M. Impaired Mitochondrial Morphology and Functionality in Lonp1wt/- Mice. J Clin Med 2020; 9:jcm9061783. [PMID: 32521756 PMCID: PMC7355737 DOI: 10.3390/jcm9061783] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 05/31/2020] [Accepted: 06/04/2020] [Indexed: 01/11/2023] Open
Abstract
LONP1 is a nuclear-encoded mitochondrial protease crucial for organelle homeostasis; mutations of LONP1 have been associated with Cerebral, Ocular, Dental, Auricular, and Skeletal anomalies (CODAS) syndrome. To clarify the role of LONP1 in vivo, we generated a mouse model in which Lonp1 was ablated. The homozygous Lonp−/− mouse was not vital, while the heterozygous Lonp1wt/− showed similar growth rate, weight, length, life-span and histologic features as wild type. Conversely, ultrastructural analysis of heterozygous enterocytes evidenced profound morphological alterations of mitochondria, which appeared increased in number, swollen and larger, with a lower complexity. Embryonic fibroblasts (MEFs) from Lonp1wt/− mice showed a reduced expression of Lonp1 and Tfam, whose expression is regulated by LONP1. Mitochondrial DNA was also reduced, and mitochondria were swollen and larger, albeit at a lesser extent than enterocytes, with a perinuclear distribution. From the functional point of view, mitochondria from heterozygous MEF showed a lower oxygen consumption rate in basal conditions, either in the presence of glucose or galactose, and a reduced expression of mitochondrial complexes than wild type. In conclusion, the presence of one functional copy of the Lonp1 gene leads to impairment of mitochondrial ultrastructure and functions in vivo.
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Affiliation(s)
- Anna De Gaetano
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (A.D.G.); (F.B.)
| | - Lara Gibellini
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, 41125 Modena, Italy; (L.G.); (R.B.); (S.D.B.); (A.C.)
| | - Elena Bianchini
- Department of Surgery, Medicine, Dentistry and Morphological Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (E.B.); (M.N.)
| | - Rebecca Borella
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, 41125 Modena, Italy; (L.G.); (R.B.); (S.D.B.); (A.C.)
| | - Sara De Biasi
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, 41125 Modena, Italy; (L.G.); (R.B.); (S.D.B.); (A.C.)
| | - Milena Nasi
- Department of Surgery, Medicine, Dentistry and Morphological Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (E.B.); (M.N.)
| | - Federica Boraldi
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (A.D.G.); (F.B.)
| | - Andrea Cossarizza
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, 41125 Modena, Italy; (L.G.); (R.B.); (S.D.B.); (A.C.)
| | - Marcello Pinti
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (A.D.G.); (F.B.)
- Correspondence: ; Tel.: +39-059-205-5386; Fax: +39-059-205-5426
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11
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Gibellini L, De Gaetano A, Mandrioli M, Van Tongeren E, Bortolotti CA, Cossarizza A, Pinti M. The biology of Lonp1: More than a mitochondrial protease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 354:1-61. [PMID: 32475470 DOI: 10.1016/bs.ircmb.2020.02.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Initially discovered as a protease responsible for degradation of misfolded or damaged proteins, the mitochondrial Lon protease (Lonp1) turned out to be a multifaceted enzyme, that displays at least three different functions (proteolysis, chaperone activity, binding of mtDNA) and that finely regulates several cellular processes, within and without mitochondria. Indeed, LONP1 in humans is ubiquitously expressed, and is involved in regulation of response to oxidative stress and, heat shock, in the maintenance of mtDNA, in the regulation of mitophagy. Furthermore, its proteolytic activity can regulate several biochemical pathways occurring totally or partially within mitochondria, such as TCA cycle, oxidative phosphorylation, steroid and heme biosynthesis and glutamine production. Because of these multiple activities, Lon protease is highly conserved throughout evolution, and mutations occurring in its gene determines severe diseases in humans, including a rare syndrome characterized by Cerebral, Ocular, Dental, Auricular and Skeletal anomalies (CODAS). Finally, alterations of LONP1 regulation in humans can favor tumor progression and aggressiveness, further highlighting the crucial role of this enzyme in mitochondrial and cellular homeostasis.
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Affiliation(s)
- Lara Gibellini
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, Modena, Italy
| | - Anna De Gaetano
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Mauro Mandrioli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Elia Van Tongeren
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Andrea Cossarizza
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, Modena, Italy
| | - Marcello Pinti
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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12
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The Mitochondrial Lon Protease: Novel Functions off the Beaten Track? Biomolecules 2020; 10:biom10020253. [PMID: 32046155 PMCID: PMC7072132 DOI: 10.3390/biom10020253] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 12/11/2022] Open
Abstract
To maintain organellar function, mitochondria contain an elaborate endogenous protein quality control system. As one of the two soluble energy-dependent proteolytic enzymes in the matrix compartment, the protease Lon is a major component of this system, responsible for the degradation of misfolded proteins, in particular under oxidative stress conditions. Lon defects have been shown to negatively affect energy production by oxidative phosphorylation but also mitochondrial gene expression. In this review, recent studies on the role of Lon in mammalian cells, in particular on its protective action under diverse stress conditions and its relationship to important human diseases are summarized and commented.
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