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Nozaki Y, Kobayashi M, Fukuoh T, Ishimatsu M, Narita T, Taki K, Hirao Y, Ayabe S, Yokoyama M, Otani Y, Mizunoe Y, Matsumoto M, Ohno N, Kaifu T, Okazaki S, Goitsuka R, Nakagawa Y, Shimano H, Iwakura Y, Higami Y. Mipep deficiency in adipocytes impairs mitochondrial protein maturation and leads to systemic inflammation and metabolic dysfunctions. Sci Rep 2025; 15:12839. [PMID: 40229443 PMCID: PMC11997187 DOI: 10.1038/s41598-025-97307-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2024] [Accepted: 04/03/2025] [Indexed: 04/16/2025] Open
Abstract
Most mitochondrial proteins encoded in the nuclear genome are synthesized in the cytoplasm. These proteins subsequently undergo maturation through the cleavage of a signal sequence at the N-terminus by one or two mitochondrial signal peptidases, which is essential for their function within mitochondria. The present study demonstrates that adipocyte-specific knockout of one mitochondrial signal peptidase, mitochondrial intermediate peptidase (MIPEP), resulted in disordered mitochondrial proteostasis of MIPEP substrate proteins and their defective maturation. MIPEP deficiency in white and brown adipocytes suppressed the expression of adipocyte differentiation, lipid metabolism, and mitochondrial biogenesis genes. These alterations led to lipoatrophy in white adipose tissue and the whitening of brown adipose tissue. Additionally, it induced an atypical mitochondrial unfolded protein response and local inflammation in white and brown adipose tissue. Furthermore, it induced fatty liver and splenomegaly and caused systemic impairments in glucose metabolism and inflammation. These findings indicate that maturation defects of certain mitochondrial proteins and subsequent proteostasis disorders in white and brown adipocytes cause chronic and systemic inflammatory and metabolic dysfunctions.
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Affiliation(s)
- Yuka Nozaki
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Masaki Kobayashi
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
- Department of Nutrition and Food Science, Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo, Japan
- Institute for Human Life Science, Ochanomizu University, Tokyo, Japan
| | - Tomoyoshi Fukuoh
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Mamiko Ishimatsu
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Takumi Narita
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Kanari Taki
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Yuto Hirao
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Shota Ayabe
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Miku Yokoyama
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Yuina Otani
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Yuhei Mizunoe
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Mami Matsumoto
- Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Developmental and Regenerative Neurobiology, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Nobuhiko Ohno
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
- Division of Ultrastructural Research, National Institute for Physiological Sciences, Okazaki, Japan
| | - Tomonori Kaifu
- Division of Immunology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Shogo Okazaki
- Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Japan
| | - Ryo Goitsuka
- Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Japan
| | - Yoshimi Nakagawa
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama, Japan
| | - Hitoshi Shimano
- Department of Endocrinology and Metabolism, Institute of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Yoichiro Iwakura
- Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Japan
| | - Yoshikazu Higami
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan.
- Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Japan.
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Samardak K, Bâcle J, Moriel-Carretero M. Behind the stoNE wall: A fervent activity for nuclear lipids. Biochimie 2024; 227:53-84. [PMID: 39111564 DOI: 10.1016/j.biochi.2024.08.002] [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: 04/09/2024] [Revised: 08/01/2024] [Accepted: 08/02/2024] [Indexed: 09/27/2024]
Abstract
The four main types of biomolecules are nucleic acids, proteins, carbohydrates and lipids. The knowledge about their respective interactions is as important as the individual understanding of each of them. However, while, for example, the interaction of proteins with the other three groups is extensively studied, that of nucleic acids and lipids is, in comparison, very poorly explored. An iconic paradigm of physical (and likely functional) proximity between DNA and lipids is the case of the genomic DNA in eukaryotes: enclosed within the nucleus by two concentric lipid bilayers, the wealth of implications of this interaction, for example in genome stability, remains underassessed. Nuclear lipid-related phenotypes have been observed for 50 years, yet in most cases kept as mere anecdotical descriptions. In this review, we will bring together the evidence connecting lipids with both the nuclear envelope and the nucleoplasm, and will make critical analyses of these descriptions. Our exploration establishes a scenario in which lipids irrefutably play a role in nuclear homeostasis.
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Affiliation(s)
- Kseniya Samardak
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM) UMR5237, Université de Montpellier, Centre National de La Recherche Scientifique, 34293 Montpellier Cedex 5, France
| | - Janélie Bâcle
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM) UMR5237, Université de Montpellier, Centre National de La Recherche Scientifique, 34293 Montpellier Cedex 5, France
| | - María Moriel-Carretero
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM) UMR5237, Université de Montpellier, Centre National de La Recherche Scientifique, 34293 Montpellier Cedex 5, France.
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3
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Goblirsch BR, Wiener MC. Ste24: An Integral Membrane Protein Zinc Metalloprotease with Provocative Structure and Emergent Biology. J Mol Biol 2020; 432:5079-5090. [PMID: 32199981 PMCID: PMC7172729 DOI: 10.1016/j.jmb.2020.03.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 03/06/2020] [Accepted: 03/12/2020] [Indexed: 01/30/2023]
Abstract
Ste24, an integral membrane protein zinc metalloprotease, is found in every kingdom of eukaryotes. It was discovered approximately 20 years ago by yeast genetic screens identifying it as a factor responsible for processing the yeast mating a-factor pheromone. In animals, Ste24 processes prelamin A, a component of the nuclear lamina; mutations in the human ortholog of Ste24 diminish its activity, giving rise to genetic diseases of accelerated aging (progerias). Additionally, lipodystrophy, acquired from the standard highly active antiretroviral therapy used to treat AIDS patients, likely results from off-target interactions of HIV (aspartyl) protease inhibitor drugs with Ste24. Ste24 possesses a novel “α-barrel” structure, consisting of a ring of seven transmembrane α-helices enclosing a large (> 12,000 Å3) interior volume that contains the active-site and substrate-binding region; this “membrane-interior reaction chamber” is unprecedented in integral membrane protein structures. Additionally, the surface of the membrane-interior reaction chamber possesses a strikingly large negative electrostatic surface potential, adding additional “functional mystery.” Recent publications implicate Ste24 as a key factor in several endoplasmic reticulum processes, including the unfolded protein response, a cellular stress response of the endoplasmic reticulum, and removal of misfolded proteins from the translocon. Ste24, with its provocative structure, enigmatic mechanism, and recently emergent new biological roles including “translocon unclogger” and (non-enyzmatic) broad-spectrum viral restriction factor, presents far differently than before 2016, when it was viewed as a “CAAX protease” responsible for cleavage of prenylated (farnesylated or geranylgeranylated) substrates. The emphasis of this review is on Ste24 of the “Post-CAAX-Protease Era.” Ste24 is a eukaryotic integral membrane protein of novel structure. Ste24 is a gluzincin ZMP whose structure/function relationships are poorly explored. ZMP core, ZMP accessory, and “ɑ-barrel modules form the Ste24 tripartite architecture. Emergent biology of Ste24 includes roles as a translocon unclogger and a viral restriction factor.
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Affiliation(s)
- Brandon R Goblirsch
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Michael C Wiener
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
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Sangenito LS, Menna-Barreto RFS, d'Avila-Levy CM, Branquinha MH, Santos ALS. Repositioning of HIV Aspartyl Peptidase Inhibitors for Combating the Neglected Human Pathogen Trypanosoma cruzi. Curr Med Chem 2019; 26:6590-6613. [PMID: 31187704 DOI: 10.2174/0929867326666190610152934] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 08/11/2018] [Accepted: 08/23/2018] [Indexed: 12/11/2022]
Abstract
Chagas disease, caused by the flagellate parasite Trypanosoma cruzi, is a wellknown neglected tropical disease. This parasitic illness affects 6-7 million people and can lead to severe myocarditis and/or complications of the digestive tract. The changes in its epidemiology facilitate co-infection with the Human Immunodeficiency Virus (HIV), making even more difficult the diagnosis and prognosis. The parasitic infection is reactivated in T. cruzi/HIV co-infection, with the appearance of unusual manifestations in the chronic phase and the exacerbation of classical clinical signs. The therapeutic arsenal to treat Chagas disease, in all its clinical forms, is restricted basically to two drugs, benznidazole and nifurtimox. Both drugs are extremely toxic and the therapeutic efficacy is still unclear, making the clinical treatment a huge issue to be solved. Therefore, it seems obvious the necessity of new tangible approaches to combat this illness. In this sense, the repositioning of approved drugs appears as an interesting and viable strategy. The discovery of Human Immunodeficiency Virus Aspartyl Peptidase Inhibitors (HIV-PIs) represented a milestone in the treatment of Acquired Immune Deficiency Syndrome (AIDS) and, concomitantly, a marked reduction in both the incidence and prevalence of important bacterial, fungal and parasitic co-infections was clearly observed. Taking all these findings into consideration, the present review summarizes the promising and beneficial data concerning the effects of HIV-PIs on all the evolutionary forms of T. cruzi and in important steps of the parasite's life cycle, which highlight their possible application as alternative drugs to treat Chagas disease.
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Affiliation(s)
- Leandro S Sangenito
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | - Rubem F S Menna-Barreto
- Laboratorio de Biologia Celular, Instituto Oswaldo Cruz (IOC), Fundacao Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Cláudia M d'Avila-Levy
- Laboratorio de Estudos Integrados em Protozoologia, Instituto Oswaldo Cruz (IOC), Fundacao Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Marta H Branquinha
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | - André L S Santos
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.,Programa de Pós-Graduação em Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
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5
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Goblirsch BR, Arachea BT, Councell DJ, Wiener MC. Phosphoramidon inhibits the integral membrane protein zinc metalloprotease ZMPSTE24. Acta Crystallogr D Struct Biol 2018; 74:739-747. [PMID: 30082509 PMCID: PMC6079626 DOI: 10.1107/s2059798318003431] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/27/2018] [Indexed: 11/10/2022] Open
Abstract
The integral membrane protein zinc metalloprotease ZMPSTE24 possesses a completely novel structure, comprising seven long kinked transmembrane helices that encircle a voluminous 14 000 Å3 cavity within the membrane. Functionally conserved soluble zinc metalloprotease residues are contained within this cavity. As part of an effort to understand the structural and functional relationships between ZMPSTE24 and soluble zinc metalloproteases, the inhibition of ZMPSTE24 by phosphoramidon [N-(α-rhamnopyranosyl-oxyhydroxyphosphinyl)-Leu-Trp], a transition-state analog and competitive inhibitor of multiple soluble zinc metalloproteases, especially gluzincins, has been characterized functionally and structurally. The functional results, the determination of preliminary IC50 values by the use of an intramolecular quenched-fluorescence fluorogenic peptide assay, indicate that phosphoramidon inhibits ZMPSTE24 in a manner consistent with competitive inhibition. The structural results, a 3.85 Å resolution X-ray crystal structure of a ZMPSTE24-phosphoramidon complex, indicate that the overall binding mode observed between phosphoramidon and soluble gluzincins is conserved. Based on the structural data, a significantly lower potency than that observed for soluble gluzincins such as thermolysin and neprilysin is predicted. These results strongly suggest a close relationship between soluble gluzincins and the integral membrane protein zinc metalloprotease ZMPSTE24.
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Affiliation(s)
- Brandon R. Goblirsch
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908-0886, USA
| | - Buenafe T. Arachea
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908-0886, USA
| | - Daniel J. Councell
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908-0886, USA
| | - Michael C. Wiener
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908-0886, USA
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6
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Drozdz MM, Jiang H, Pytowski L, Grovenor C, Vaux DJ. Formation of a nucleoplasmic reticulum requires de novo assembly of nascent phospholipids and shows preferential incorporation of nascent lamins. Sci Rep 2017; 7:7454. [PMID: 28785031 PMCID: PMC5547041 DOI: 10.1038/s41598-017-07614-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/29/2017] [Indexed: 01/29/2023] Open
Abstract
Structure of interphase cell nuclei remains dynamic and can undergo various changes of shape and organisation, in health and disease. The double-membraned envelope that separates nuclear genetic material from the rest of the cell frequently includes deep, branching tubular invaginations that form a dynamic nucleoplasmic reticulum (NR). This study addresses mechanisms by which NR can form in interphase nuclei. We present a combination of Nanoscale Secondary Ion Mass Spectrometry (NanoSIMS) approach and light microscopy techniques to follow formation of NR by using pulse-chase experiments to examine protein and lipid delivery to nascent NR in cultured cells. Lamina protein incorporation was assessed using precursor accumulation (for lamin A) or a MAPLE3 photoconvertible tag (for lamin B1) and membrane phospholipid incorporation using stable isotope labelling with deuterated precursors followed by high resolution NanoSIMS. In all three cases, nascent molecules were selectively incorporated into newly forming NR tubules; thus strongly suggesting that NR formation is a regulated process involving a focal assembly machine, rather than simple physical perturbation of a pre-existing nuclear envelope.
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Affiliation(s)
- Marek M Drozdz
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
| | - Haibo Jiang
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Lior Pytowski
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
| | - Chris Grovenor
- Department of Materials, University of Oxford, Oxford, OX1 3PH, United Kingdom
| | - David J Vaux
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom.
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7
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Geisler CE, Renquist BJ. Hepatic lipid accumulation: cause and consequence of dysregulated glucoregulatory hormones. J Endocrinol 2017; 234:R1-R21. [PMID: 28428362 DOI: 10.1530/joe-16-0513] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 04/20/2017] [Indexed: 12/11/2022]
Abstract
Fatty liver can be diet, endocrine, drug, virus or genetically induced. Independent of cause, hepatic lipid accumulation promotes systemic metabolic dysfunction. By acting as peroxisome proliferator-activated receptor (PPAR) ligands, hepatic non-esterified fatty acids upregulate expression of gluconeogenic, beta-oxidative, lipogenic and ketogenic genes, promoting hyperglycemia, hyperlipidemia and ketosis. The typical hormonal environment in fatty liver disease consists of hyperinsulinemia, hyperglucagonemia, hypercortisolemia, growth hormone deficiency and elevated sympathetic tone. These endocrine and metabolic changes further encourage hepatic steatosis by regulating adipose tissue lipolysis, liver lipid uptake, de novo lipogenesis (DNL), beta-oxidation, ketogenesis and lipid export. Hepatic lipid accumulation may be induced by 4 separate mechanisms: (1) increased hepatic uptake of circulating fatty acids, (2) increased hepatic de novo fatty acid synthesis, (3) decreased hepatic beta-oxidation and (4) decreased hepatic lipid export. This review will discuss the hormonal regulation of each mechanism comparing multiple physiological models of hepatic lipid accumulation. Nonalcoholic fatty liver disease (NAFLD) is typified by increased hepatic lipid uptake, synthesis, oxidation and export. Chronic hepatic lipid signaling through PPARgamma results in gene expression changes that allow concurrent activity of DNL and beta-oxidation. The importance of hepatic steatosis in driving systemic metabolic dysfunction is highlighted by the common endocrine and metabolic disturbances across many conditions that result in fatty liver. Understanding the mechanisms underlying the metabolic dysfunction that develops as a consequence of hepatic lipid accumulation is critical to identifying points of intervention in this increasingly prevalent disease state.
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Affiliation(s)
- Caroline E Geisler
- School of Animal and Comparative Biomedical SciencesUniversity of Arizona, Tucson, Arizona, USA
| | - Benjamin J Renquist
- School of Animal and Comparative Biomedical SciencesUniversity of Arizona, Tucson, Arizona, USA
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8
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Arachea BT, Wiener MC. Acquisition of accurate data from intramolecular quenched fluorescence protease assays. Anal Biochem 2017; 522:30-36. [PMID: 28119065 DOI: 10.1016/j.ab.2017.01.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/19/2017] [Accepted: 01/20/2017] [Indexed: 10/20/2022]
Abstract
The Intramolecular Quenched Fluorescence (IQF) protease assay utilizes peptide substrates containing donor-quencher pairs that flank the scissile bond. Following protease cleavage, the dequenched donor emission of the product is subsequently measured. Inspection of the IQF literature indicates that rigorous treatment of systematic errors in observed fluorescence arising from inner-filter absorbance (IF) and non-specific intermolecular quenching (NSQ) is incompletely performed. As substrate and product concentrations vary during the time-course of enzyme activity, iterative solution of the kinetic rate equations is, generally, required to obtain the proper time-dependent correction to the initial velocity fluorescence data. Here, we demonstrate that, if the IQF assay is performed under conditions where IF and NSQ are approximately constant during the measurement of initial velocity for a given initial substrate concentration, then a simple correction as a function of initial substrate concentration can be derived and utilized to obtain accurate initial velocity data for analysis.
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Affiliation(s)
- Buenafe T Arachea
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Michael C Wiener
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
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9
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Drozdz MM, Vaux DJ. Shared mechanisms in physiological and pathological nucleoplasmic reticulum formation. Nucleus 2017; 8:34-45. [PMID: 27797635 PMCID: PMC5287099 DOI: 10.1080/19491034.2016.1252893] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/13/2016] [Accepted: 10/19/2016] [Indexed: 12/14/2022] Open
Abstract
The mammalian nuclear envelope (NE) can develop complex dynamic membrane-bounded invaginations in response to both physiological and pathological stimuli. Since the formation of these nucleoplasmic reticulum (NR) structures can occur during interphase, without mitotic NE breakdown and reassembly, some other mechanism must drive their development. Here we consider models for deformation of the interphase NE, together with the evidence for their potential roles in NR formation.
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Affiliation(s)
| | - David John Vaux
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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10
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Abstract
Pulse-chase methods offer powerful tools for following the evolution of a biological system over time, but are usually limited to ensemble measurements of the average behavior of very large numbers of cells. Here we describe three methods ranging from a true pulse-chase, through selective regional photoactivation, to pharmacological induction of an altered protein state, which can be applied to time-dependent studies at the single-cell level. These methods are exemplified by experimental protocols to follow region-selective nuclear envelope targeting of nascent phospholipids, a nascent nuclear lamin protein (lamin B1), and an immature lamin precursor (prelamin A).
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11
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Abstract
Lipodystrophies are a genetically heterogeneous group of disorders characterized by loss of subcutaneous adipose tissue and metabolic dysfunction, including insulin resistance, increased levels of free fatty acids, abnormal adipocytokine secretion, and ectopic fat deposition, which are also observed in patients with visceral obesity and/or type 2 diabetes mellitus. Pathophysiological, biochemical, and genetic studies suggest that impairment in multiple adipose tissue functions, including adipocyte maturation, lipid storage, formation and/or maintenance of the lipid droplet, membrane composition, DNA repair efficiency, and insulin signaling, results in severe metabolic and endocrine consequences, ultimately leading to specific lipodystrophic phenotypes. In this review, recent evidences on the causes and metabolic processes of lipodystrophies will be presented, proposing a disease model that could be potentially informative for better understanding of common metabolic diseases in humans, including obesity, metabolic syndrome, and type 2 diabetes.
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Affiliation(s)
- Romina Ficarella
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare, n. 11, 70124, Bari, Italy,
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Hagen C, Werner S, Carregal-Romero S, N Malhas A, G Klupp B, Guttmann P, Rehbein S, Henzler K, C Mettenleiter T, J Vaux D, J Parak W, Schneider G, Grünewald K. Multimodal nanoparticles as alignment and correlation markers in fluorescence/soft X-ray cryo-microscopy/tomography of nucleoplasmic reticulum and apoptosis in mammalian cells. Ultramicroscopy 2014; 146:46-54. [PMID: 24973653 PMCID: PMC4181793 DOI: 10.1016/j.ultramic.2014.05.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/15/2014] [Accepted: 05/24/2014] [Indexed: 11/19/2022]
Abstract
Correlative fluorescence and soft X-ray cryo-microscopy/tomography on flat sample holders is perfectly suited to study the uncompromised physiological status of adherent cells at its best possible preservation by imaging after fast cryo-immobilization. To understand the mechanism by which herpesviruses induce nucleoplasmic reticulum, i.e. invaginations of the nuclear envelope, during their egress from the host cell nucleus, morphologically similar structures found in laminopathies and after chemical induction were investigated as a potentially more easily accessible model system. For example, anti-retroviral protease inhibitors like Saquinavir also induce invaginations of the nuclear membranes. With the help of newly designed multimodal nanoparticles as alignment and correlation markers, and by optimizing fluorescence cryo-microscopy data acquisition, an elaborate three-dimensional network of nucleoplasmic reticulum was demonstrated in nuclei of Saquinavir-treated rabbit kidney cells expressing a fluorescently labeled inner nuclear membrane protein. In part of the protease inhibitor-treated samples, nuclei exhibited dramatic ultrastructural changes indicative of programmed cell death/apoptosis. This unexpected observation highlights another unique feature of soft X-ray microscopy, i.e. high absorption contrast information not relying on labeled cellular components, at a 3D resolution of approximately 40 nm (half-pitch) and through a sample thickness of several micrometers. These properties make it a valuable part of the cell biology imaging toolbox to visualize the cellular ultrastructure in its completeness.
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Affiliation(s)
- Christoph Hagen
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
| | - Stephan Werner
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, 12489 Berlin, Germany.
| | | | - Ashraf N Malhas
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
| | - Barbara G Klupp
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany.
| | - Peter Guttmann
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, 12489 Berlin, Germany.
| | - Stefan Rehbein
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, 12489 Berlin, Germany.
| | - Katja Henzler
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, 12489 Berlin, Germany.
| | - Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany.
| | - David J Vaux
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
| | - Wolfgang J Parak
- Fachbereich Physik, Philipps Universität Marburg, Marburg 35043, Germany.
| | - Gerd Schneider
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, 12489 Berlin, Germany.
| | - Kay Grünewald
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
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13
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Nuclear envelope-related lipodystrophies. Semin Cell Dev Biol 2014; 29:148-57. [DOI: 10.1016/j.semcdb.2013.12.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/06/2013] [Accepted: 12/20/2013] [Indexed: 12/12/2022]
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14
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Dam DHM, Lee JH, Sisco PN, Co DT, Zhang M, Wasielewski MR, Odom TW. Direct observation of nanoparticle-cancer cell nucleus interactions. ACS NANO 2012; 6:3318-26. [PMID: 22424173 PMCID: PMC3337354 DOI: 10.1021/nn300296p] [Citation(s) in RCA: 204] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultrafast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy.
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Affiliation(s)
| | - Jung Heon Lee
- Department of Chemistry, Northwestern University, Evanston, IL, 60208
- School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, South Korea, 400-746
| | - Patrick N. Sisco
- Department of Chemistry, Northwestern University, Evanston, IL, 60208
| | - Dick T. Co
- Department of Chemistry, Northwestern University, Evanston, IL, 60208
| | - Ming Zhang
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, IL, 60611
| | | | - Teri W. Odom
- Department of Chemistry, Northwestern University, Evanston, IL, 60208
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208
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15
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Goulbourne CN, Malhas AN, Vaux DJ. The induction of a nucleoplasmic reticulum by prelamin A accumulation requires CTP:phosphocholine cytidylyltransferase-α. J Cell Sci 2011; 124:4253-66. [PMID: 22223883 PMCID: PMC3258109 DOI: 10.1242/jcs.091009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2011] [Indexed: 12/24/2022] Open
Abstract
Farnesylated prelamin A accumulates when the final endoproteolytic maturation of the protein fails to occur and causes a dysmorphic nuclear phenotype; however, the morphology and mechanisms of biogenesis of these changes remain unclear. We show here that acute prelamin A accumulation after reduction in the activity of the ZMPSTE24 endoprotease by short interfering RNA knockdown, results in the generation of a complex nucleoplasmic reticulum that depends for its formation on the enzyme CTP:phosphocholine-cytidylyltransferase-α (CCT-α, also known as choline-phosphate cytidylyltransferase A). This structure can form during interphase, confirming that it is independent of mitosis and therefore not a consequence of disordered nuclear envelope assembly. Serial-section dual-axis electron tomography reveals that these invaginations can take two forms: one in which the inner nuclear membrane infolds alone with an inter membrane space interior, and the other in which an invagination of both nuclear membranes occurs, enclosing a cytoplasmic core. Both types of invagination can co-exist in one nucleus and both are frequently studded with nuclear pore complexes (NPC), which reduces NPC abundance on the nuclear surface.
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Affiliation(s)
- Chris N. Goulbourne
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Ashraf N. Malhas
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - David J. Vaux
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
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16
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Abstract
Hutchinson-Gilford Progeria Syndrome (HGPS) is a severe premature aging syndrome that affects children. These children display characteristics associated with normal aging and die young usually from cardiovascular problems or stroke. Classical HGPS is caused by mutations in the gene encoding the nuclear structural protein lamin A. This mutation leads to a novel version of lamin A that retains a farnesyl group from its processing. This protein is called Progerin and is toxic to cellular function. Pre-lamin A is an immature version of lamin A and also has a farnesylation modification, which is cleaved in the maturation process to create lamin A.
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Affiliation(s)
- Joanna M Bridger
- Centre of Cell & Chromosome Biology, Brunel Institute of Ageing Studies, Brunel University, London, UK.
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17
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Malhas A, Goulbourne C, Vaux DJ. The nucleoplasmic reticulum: form and function. Trends Cell Biol 2011; 21:362-73. [PMID: 21514163 DOI: 10.1016/j.tcb.2011.03.008] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/17/2011] [Accepted: 03/23/2011] [Indexed: 11/29/2022]
Abstract
The nuclear envelope (NE) physically separates nucleoplasm and cytoplasm, contributes to nuclear structural integrity, controls selective bidirectional transport of ions and macromolecular cargo, regulates gene expression, and acts as a mechanotransducer and a platform for signalling. It is noteworthy however that the NE is not simply a smooth-surfaced outer boundary but is interrupted by invaginations that reach deep within the nucleoplasm and could even traverse the nucleus completely. The existence of such a complex branched network of invaginations forming a nucleoplasmic reticulum (NR) provides sites that are capable of carrying out the 'conventional' NE functions deep within the nucleus in regions that would otherwise be remote from the nuclear periphery. In this review, we describe the structural features of NR in normal and pathological states and discuss the current understanding of their functional and possible pathological roles.
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Affiliation(s)
- Ashraf Malhas
- Sir William Dunn School of Pathology, Oxford OX1 3RE, UK
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18
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Abstract
Identification and characterization of the molecular mechanisms contributing to the high incidence of insulin resistance in HIV infected patients treated with combined antiretroviral therapy remains a critically important goal in the quest to improve the safety of antiretroviral treatment regimens. The use of in vitro model systems together with the investigation of drug-mediated effects on glucose homeostasis in animals and healthy human volunteers has provided important insight into the contribution of individual drugs to insulin resistance and affected cellular pathways. HIV protease inhibitor mediated blockade of glucose transport and nucleoside reverse transcriptase inhibitor mediated mitochondrial toxicity have been well characterized. Together with growing understanding of mediators of insulin resistance in non-HIV metabolic syndrome, additional cellular effects including the induction of endoplasmic reticulum and oxidative stress, altered adipocytokine secretion, and lipotoxicity have been integrated into this developing picture. Further elucidation of these mechanisms provides potential for the continued development of safer antiviral drugs and targeted treatment of insulin resistance in affected patients.
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Affiliation(s)
- Paul W Hruz
- Department of Pediatrics, Washington University School of Medicine, St Louis, MO 63110, USA.
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19
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Abstract
The nuclear envelope has long been a focus of basic research for a highly specialized group of cell biologists. More recently, an expanding group of scientists and physicians have developed a keen interest in the nuclear envelope since mutations in the genes encoding lamins and associated proteins have been shown to cause a diverse range of human diseases often called laminopathies or nuclear envelopathies. Most of these diseases have tissue-selective phenotypes, suggesting that the nuclear envelope must function in cell-type- and developmental-stage-specific processes such as chromatin organization, regulation of gene expression, controlled nucleocytoplasmic transport and response to stress in metazoans. On 22-23 April 2009, Professor Christopher Hutchison organized the 4th British Nuclear Envelope Disease and Chromatin Organization meeting at the College of St Hild and St Bede at Durham University, sponsored by the Biochemical Society. In attendance were investigators with one common interest, the nuclear envelope, but with diverse expertise and training in animal and plant cell biology, genetics, developmental biology and medicine. We were each honoured to be keynote speakers. This issue of Biochemical Society Transactions contains papers written by some of the presenters at this scientifically exciting meeting, held in a bucolic setting where the food was tasty and the wine flowed freely. Perhaps at the end of this excellent meeting more questions were raised than answered, which will stimulate future research. However, what became clear is that the nuclear envelope is a cellular structure with critical functions in addition to its traditional role as a barrier separating the nuclear and cytoplasmic compartments in interphase eukaryotic cells.
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