1
|
Waterham HR, Koster J, Ebberink MS, Ješina P, Zeman J, Nosková L, Kmoch S, Devic P, Cheillan D, Wanders RJA, Ferdinandusse S. Autosomal dominant Zellweger spectrum disorder caused by de novo variants in PEX14 gene. Genet Med 2023; 25:100944. [PMID: 37493040 DOI: 10.1016/j.gim.2023.100944] [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: 08/19/2022] [Revised: 07/19/2023] [Accepted: 07/19/2023] [Indexed: 07/27/2023] Open
Abstract
PURPOSE Zellweger spectrum disorders (ZSDs) are known as autosomal recessive disorders caused by defective peroxisome biogenesis due to bi-allelic pathogenic variants in any of at least 13 different PEX genes. Here, we report 2 unrelated patients who present with an autosomal dominant ZSD. METHODS We performed biochemical and genetic studies in blood and skin fibroblasts of the patients and demonstrated the pathogenicity of the identified PEX14 variants by functional cell studies. RESULTS We identified 2 different single heterozygous de novo variants in the PEX14 genes of 2 patients diagnosed with ZSD. Both variants cause messenger RNA mis-splicing, leading to stable expression of similar C-terminally truncated PEX14 proteins. Functional studies indicated that the truncated PEX14 proteins lost their function in peroxisomal matrix protein import and cause increased degradation of peroxisomes, ie, pexophagy, thus exerting a dominant-negative effect on peroxisome functioning. Inhibition of pexophagy by different autophagy inhibitors or genetic knockdown of the peroxisomal autophagy receptor NBR1 resulted in restoration of peroxisomal functions in the patients' fibroblasts. CONCLUSION Our finding of an autosomal dominant ZSD expands the genetic repertoire of ZSDs. Our study underscores that single heterozygous variants should not be ignored as possible genetic cause of diseases with an established autosomal recessive mode of inheritance.
Collapse
Affiliation(s)
- Hans R Waterham
- Amsterdam UMC - AMC, Department of Laboratory Medicine, Laboratory Genetic Metabolic Diseases, Amsterdam, The Netherlands; Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam, The Netherlands; Amsterdam Reproduction & Development, Amsterdam, The Netherlands; United for Metabolic Diseases, The Netherlands.
| | - Janet Koster
- Amsterdam UMC - AMC, Department of Laboratory Medicine, Laboratory Genetic Metabolic Diseases, Amsterdam, The Netherlands
| | - Merel S Ebberink
- Amsterdam UMC - AMC, Department of Laboratory Medicine, Laboratory Genetic Metabolic Diseases, Amsterdam, The Netherlands
| | - Pavel Ješina
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General Faculty Hospital, Prague 2, Czech Republic
| | - Jiri Zeman
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General Faculty Hospital, Prague 2, Czech Republic
| | - Lenka Nosková
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General Faculty Hospital, Prague 2, Czech Republic
| | - Stanislav Kmoch
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General Faculty Hospital, Prague 2, Czech Republic
| | - Perrine Devic
- Centre Hospitalier Universitaire de Lyon, CHU Lyon·U 301, Hopital Neurologique, Bron, France
| | - David Cheillan
- Service Biochimie et Biologie Moléculaire Grand Est, UM Pathologies Métaboliques, Erythrocytaires et Dépistage Périnatal, Centre de Biologie et de Pathologie Est, Groupement Hospitalier Est - Hospices Civils de Lyon, Bron Cedex, France
| | - Ronald J A Wanders
- Amsterdam UMC - AMC, Department of Laboratory Medicine, Laboratory Genetic Metabolic Diseases, Amsterdam, The Netherlands; Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam, The Netherlands; Amsterdam Reproduction & Development, Amsterdam, The Netherlands; United for Metabolic Diseases, The Netherlands
| | - Sacha Ferdinandusse
- Amsterdam UMC - AMC, Department of Laboratory Medicine, Laboratory Genetic Metabolic Diseases, Amsterdam, The Netherlands; Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam, The Netherlands
| |
Collapse
|
2
|
Characterization of Severity in Zellweger Spectrum Disorder by Clinical Findings: A Scoping Review, Meta-Analysis and Medical Chart Review. Cells 2022; 11:cells11121891. [PMID: 35741019 PMCID: PMC9221082 DOI: 10.3390/cells11121891] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/05/2022] [Accepted: 06/06/2022] [Indexed: 02/04/2023] Open
Abstract
Zellweger spectrum disorder (ZSD) is a rare, debilitating genetic disorder of peroxisome biogenesis that affects multiple organ systems and presents with broad clinical heterogeneity. Although severe, intermediate, and mild forms of ZSD have been described, these designations are often arbitrary, presenting difficulty in understanding individual prognosis and treatment effectiveness. The purpose of this study is to conduct a scoping review and meta-analysis of existing literature and a medical chart review to determine if characterization of clinical findings can predict severity in ZSD. Our PubMed search for articles describing severity, clinical findings, and survival in ZSD resulted in 107 studies (representing 307 patients) that were included in the review and meta-analysis. We also collected and analyzed these same parameters from medical records of 136 ZSD individuals from our natural history study. Common clinical findings that were significantly different across severity categories included seizures, hypotonia, reduced mobility, feeding difficulties, renal cysts, adrenal insufficiency, hearing and vision loss, and a shortened lifespan. Our primary data analysis also revealed significant differences across severity categories in failure to thrive, gastroesophageal reflux, bone fractures, global developmental delay, verbal communication difficulties, and cardiac abnormalities. Univariable multinomial logistic modeling analysis of clinical findings and very long chain fatty acid (VLCFA) hexacosanoic acid (C26:0) levels showed that the number of clinical findings present among seizures, abnormal EEG, renal cysts, and cardiac abnormalities, as well as plasma C26:0 fatty acid levels could differentiate severity categories. We report the largest characterization of clinical findings in relation to overall disease severity in ZSD. This information will be useful in determining appropriate outcomes for specific subjects in clinical trials for ZSD.
Collapse
|
3
|
Label-Free Proteomics of the Fetal Pancreas Identifies Deficits in the Peroxisome in Rats with Intrauterine Growth Restriction. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:1520753. [PMID: 31781323 PMCID: PMC6874927 DOI: 10.1155/2019/1520753] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/31/2019] [Accepted: 09/09/2019] [Indexed: 12/11/2022]
Abstract
Aim The objective of the present study was to identify differentially expressed proteins (DEPs) in the pancreas of a fetus with intrauterine growth restriction (IUGR) and to investigate the molecular mechanisms leading to adulthood diabetes in IUGR. Methods The IUGR rat model was induced by maternal protein malnutrition. The fetal pancreas was collected at embryonic day 20 (E20). Protein was extracted, pooled, and subjected to label-free quantitative proteomic analysis. Bioinformatics analysis (GO and IPA) was performed to define the pathways and networks associated with DEPs. LC-MS results were confirmed by western blotting and/or quantitative PCR (q-PCR). The principal parameters of oxidative stress-superoxide dismutase (Sod) were determined in blood samples of fetal rats. Results A total of 57 DEPs (27 upregulated, 30 downregulated) were identified with a 1.5-fold change threshold and a p value ≤ 0.05 between the IUGR and the control pancreas. Bioinformatics analysis revealed that these proteins play important roles in peroxisome biogenesis and fission, fatty acid beta-oxidation (FAO), mitotic cell cycle, and histone modification. The peroxin Pex14 was downregulated in the IUGR pancreas as confirmed by western blotting and q-PCR. Pmp70, a peroxisomal membrane protein involved in the transport of fatty acids, was upregulated. Hsd17b4 and Acox1/2, which catalyze different steps of peroxisomal FAO, were dysregulated. Sod plasma concentrations in the IUGR fetus were higher than those in the control, suggesting partial compensation for oxidative stress. Multiple DEPs were related to the regulation of the cell cycle, including reduced Cdk1, Mcm2, and Brd4. The histone acetylation regulators Hdac1/2 were downregulated, whereas Sirt1/3 and acetylated H3K56 were increased in the IUGR fetal pancreas. Conclusion The present study identified DEPs in the fetal pancreas of IUGR rats by proteomic analysis. Downregulation of pancreas peroxins and dysregulation of enzymes involved in peroxisomal FAO may impair the biogenesis and function of the peroxisome and may underlie the development of T2 diabetes mellitus in adult IUGR rats. Disorders of cell cycle regulators may induce cell division arrest and lead to smaller islets. The present data provide new insight into the role of the peroxisome in the development of the pancreas and may be valuable in furthering our understanding of the pathogenesis of IUGR-induced diabetes.
Collapse
|
4
|
Lismont C, Nordgren M, Brees C, Knoops B, Van Veldhoven PP, Fransen M. Peroxisomes as Modulators of Cellular Protein Thiol Oxidation: A New Model System. Antioxid Redox Signal 2019; 30:22-39. [PMID: 28594286 DOI: 10.1089/ars.2017.6997] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
AIMS Peroxisomes are ubiquitous, single-membrane-bounded organelles that contain considerable amounts of enzymes involved in the production or breakdown of hydrogen peroxide (H2O2), a key signaling molecule in multiple biological processes and disease states. Despite this, the role of this organelle in cross-compartmental H2O2 signaling remains largely unclear, mainly because of the difficulty to modulate peroxisomal H2O2 production in a selective manner. This study aimed at establishing and validating a cellular model suitable to decipher the complex signaling processes associated with peroxisomal H2O2 release. RESULTS Here, we report the development of a human cell line that can be used to selectively generate H2O2 inside peroxisomes in a time- and dose-controlled manner. In addition, we provide evidence that peroxisome-derived H2O2 can oxidize redox-sensitive cysteine residues in multiple proteins within (e.g., peroxiredoxin-5 [PRDX5]) and outside (e.g., nuclear factor kappa B subunit 1 [NFKB1] and subunit RELA proto-oncogene [RELA], phosphatase and tensin homolog [PTEN], forkhead box O3 [FOXO3], and peroxin 5 [PEX5]) the peroxisomal compartment. Furthermore, we show that the extent of protein oxidation depends on the subcellular location of the target protein and is inversely correlated to catalase activity and cellular glutathione content. Finally, we demonstrate that excessive H2O2 production inside peroxisomes does not induce their selective degradation, at least not under the conditions examined. INNOVATION This study describes for the first time a powerful model system that can be used to examine the role of peroxisome-derived H2O2 in redox-regulated (patho)physiological processes, a research area in need of further investigation and innovative approaches. CONCLUSION Our results provide unambiguous evidence that peroxisomes can serve as regulatory hubs in thiol-based signaling networks.
Collapse
Affiliation(s)
- Celien Lismont
- 1 Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven-University of Leuven , Leuven, Belgium
| | - Marcus Nordgren
- 1 Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven-University of Leuven , Leuven, Belgium
| | - Chantal Brees
- 1 Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven-University of Leuven , Leuven, Belgium
| | - Bernard Knoops
- 2 Group of Animal Molecular and Cellular Biology, Institut des Sciences de la Vie (ISV), Université catholique de Louvain , Louvain-la-Neuve, Belgium
| | - Paul P Van Veldhoven
- 1 Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven-University of Leuven , Leuven, Belgium
| | - Marc Fransen
- 1 Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven-University of Leuven , Leuven, Belgium
| |
Collapse
|
5
|
Alshenaifi J, Ewida N, Anazi S, Shamseldin HE, Patel N, Maddirevula S, Al-Sheddi T, Alomar R, Alobeid E, Ibrahim N, Hashem M, Abdulwahab F, Jacob M, Alhashem A, Alzaidan HI, Seidahmed MZ, Alhashemi N, Rawashdeh R, Eyaid W, Al-Hassnan ZN, Rahbeeni Z, Alswaid A, Hadid A, Qari A, Mohammed DA, El Khashab HY, Alfadhel M, Abanemai M, Sunbul R, Al Tala S, Alkhalifi S, Alkharfi T, Abouelhoda M, Monies D, Al Tassan N, AlDubayan SH, Kurdi W, Al-Owain M, Dasouki MJ, Kentab AY, Atyani S, Makhseed N, Faqeih E, Shaheen R, Alkuraya FS. The many faces of peroxisomal disorders: Lessons from a large Arab cohort. Clin Genet 2018; 95:310-319. [PMID: 30561787 DOI: 10.1111/cge.13481] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 11/01/2018] [Accepted: 11/16/2018] [Indexed: 01/28/2023]
Abstract
Defects in the peroxisomes biogenesis and/or function result in peroxisomal disorders. In this study, we describe the largest Arab cohort to date (72 families) of clinically, biochemically and molecularly characterized patients with peroxisomal disorders. At the molecular level, we identified 43 disease-causing variants, half of which are novel. The founder nature of many of the variants allowed us to calculate the minimum disease burden for these disorders in our population ~1:30 000, which is much higher than previous estimates in other populations. Clinically, we found an interesting trend toward genotype/phenotype correlation in terms of long-term survival. Nearly half (40/75) of our peroxisomal disorders patients had documented survival beyond 1 year of age. Most unusual among the long-term survivors was a multiplex family in which the affected members presented as adults with non-specific intellectual disability and epilepsy. Other unusual presentations included the very recently described peroxisomal fatty acyl-CoA reductase 1 disorder as well as CRD, spastic paraparesis, white matter (CRSPW) syndrome. We conclude that peroxisomal disorders are highly heterogeneous in their clinical presentation. Our data also confirm the demonstration that milder forms of Zellweger spectrum disorders cannot be ruled out by the "gold standard" very long chain fatty acids assay, which highlights the value of a genomics-first approach in these cases.
Collapse
Affiliation(s)
- Jumanah Alshenaifi
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Nour Ewida
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Shams Anazi
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Hanan E Shamseldin
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Nisha Patel
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Sateesh Maddirevula
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Tarfa Al-Sheddi
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Rana Alomar
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Eman Alobeid
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Niema Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Mais Hashem
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Firdous Abdulwahab
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Minnie Jacob
- The Newborn Screening and Biochemical Genetics Laboratory, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Amal Alhashem
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.,Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Hamad I Alzaidan
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.,Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | | | | | - Rifaat Rawashdeh
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Wafaa Eyaid
- Medical Genetic Division, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Zuhair N Al-Hassnan
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.,Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Zuhair Rahbeeni
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Abdulrahman Alswaid
- Medical Genetic Division, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Adnan Hadid
- Department of Pediatrics College of Medicine and King Saud University Medical City, King Saud University, Riyadh, Saudi Arabia
| | - Alya Qari
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Dia A Mohammed
- Department of Pediatrics, Makkah Maternity and Children's Hospital, Makkah, Saudi Arabia
| | - Heba Y El Khashab
- Department of Pediatrics Dr. Sulimann AL Habib Medical Group, Riyadh, Saudi Arabia.,Department of Pediatrics, Division of Pediatric Neurology Children Hospital, Ain Shams University, Cairo, Egypt
| | - Majid Alfadhel
- Medical Genetic Division, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Mohammad Abanemai
- Pediatrics Department, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Rawda Sunbul
- Pediatrics Medical Genetic Unit (PMGU), Pediatrics Department, Qatif Central Hospital, Qatif, Saudi Arabia
| | - Saeed Al Tala
- Armed Forces Hospital Southern Region, Pediatric Directorate and Genetic Unit Khamis Mushayt, Khamis Mushait, Saudi Arabia
| | | | - Turki Alkharfi
- Department of Pediatrics, Sanad Hospital, Riyadh, Saudi Arabia
| | - Mohamed Abouelhoda
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| | - Dorota Monies
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| | - Nada Al Tassan
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| | - Saud H AlDubayan
- Department of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts
| | - Wesam Kurdi
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.,Department of Obstetrics and Gynecology, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Mohammed Al-Owain
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.,Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Majed J Dasouki
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,The Newborn Screening and Biochemical Genetics Laboratory, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Amal Y Kentab
- Department of Pediatrics College of Medicine and King Saud University Medical City, King Saud University, Riyadh, Saudi Arabia
| | - Suha Atyani
- Department of Pediatrics, Mubarak Al-Kabeer Hospital, Kuwait, Kuwait
| | - Nawal Makhseed
- Pediatric Department, Al-Jahra Hospital, Ministry of Health, Kuwait, Kuwait
| | - Eissa Faqeih
- Department of Pediatric Subspecialties, Children's Hospital, Riyadh, Saudi Arabia
| | - Ranad Shaheen
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.,Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| |
Collapse
|
6
|
Cho DH, Kim YS, Jo DS, Choe SK, Jo EK. Pexophagy: Molecular Mechanisms and Implications for Health and Diseases. Mol Cells 2018; 41:55-64. [PMID: 29370694 PMCID: PMC5792714 DOI: 10.14348/molcells.2018.2245] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 12/28/2017] [Accepted: 12/29/2017] [Indexed: 02/06/2023] Open
Abstract
Autophagy is an intracellular degradation pathway for large protein aggregates and damaged organelles. Recent studies have indicated that autophagy targets cargoes through a selective degradation pathway called selective autophagy. Peroxisomes are dynamic organelles that are crucial for health and development. Pexophagy is selective autophagy that targets peroxisomes and is essential for the maintenance of homeostasis of peroxisomes, which is necessary in the prevention of various peroxisome-related disorders. However, the mechanisms by which pexophagy is regulated and the key players that induce and modulate pexophagy are largely unknown. In this review, we focus on our current understanding of how pexophagy is induced and regulated, and the selective adaptors involved in mediating pexophagy. Furthermore, we discuss current findings on the roles of pexophagy in physiological and pathological responses, which provide insight into the clinical relevance of pexophagy regulation. Understanding how pexophagy interacts with various biological functions will provide fundamental insights into the function of pexophagy and facilitate the development of novel therapeutics against peroxisomal dysfunction-related diseases.
Collapse
Affiliation(s)
- Dong-Hyung Cho
- Graduate School of East-West Medical Science, Kyung Hee University, Yongin 17104,
Korea
| | - Yi Sak Kim
- Department of Microbiology, Chungnam National University School of Medicine, Daejeon 35015,
Korea
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015,
Korea
- Infection Control Convergence Research Center, Chungnam National University School of Medicine, Daejeon 35015,
Korea
| | - Doo Sin Jo
- Graduate School of East-West Medical Science, Kyung Hee University, Yongin 17104,
Korea
| | - Seong-Kyu Choe
- Department of Microbiology and Center for Metabolic Function Regulation, Wonkwang University School of Medicine, Iksan 54538,
Korea
| | - Eun-Kyeong Jo
- Department of Microbiology, Chungnam National University School of Medicine, Daejeon 35015,
Korea
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015,
Korea
- Infection Control Convergence Research Center, Chungnam National University School of Medicine, Daejeon 35015,
Korea
| |
Collapse
|
7
|
Walton PA, Brees C, Lismont C, Apanasets O, Fransen M. The peroxisomal import receptor PEX5 functions as a stress sensor, retaining catalase in the cytosol in times of oxidative stress. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1833-1843. [PMID: 28760655 DOI: 10.1016/j.bbamcr.2017.07.013] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 07/03/2017] [Accepted: 07/27/2017] [Indexed: 02/08/2023]
Abstract
Accumulating evidence indicates that peroxisome functioning, catalase localization, and cellular oxidative balance are intimately interconnected. Nevertheless, it remains largely unclear why modest increases in the cellular redox state especially interfere with the subcellular localization of catalase, the most abundant peroxisomal antioxidant enzyme. This study aimed at gaining more insight into this phenomenon. Therefore, we first established a simple and powerful approach to study peroxisomal protein import and protein-protein interactions in living cells in response to changes in redox state. By employing this approach, we confirm and extend previous observations that Cys-11 of human PEX5, the shuttling import receptor for peroxisomal matrix proteins containing a C-terminal peroxisomal targeting signal (PTS1), functions as a redox switch that modulates the protein's activity in response to intracellular oxidative stress. In addition, we show that oxidative stress affects the import of catalase, a non-canonical PTS1-containing protein, more than the import of a reporter protein containing a canonical PTS1. Furthermore, we demonstrate that changes in the local redox state do not affect PEX5-substrate binding and that human PEX5 does not oligomerize in cellulo, not even when the cells are exposed to oxidative stress. Finally, we present evidence that catalase retained in the cytosol can protect against H2O2-mediated redox changes in a manner that peroxisomally targeted catalase does not. Together, these findings lend credit to the idea that inefficient catalase import, when coupled with the role of PEX5 as a redox-regulated import receptor, constitutes a cellular defense mechanism to combat oxidative insults of extra-peroxisomal origin.
Collapse
Affiliation(s)
- Paul A Walton
- Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven - University of Leuven, Herestraat 49, Box 601, B-3000 Leuven, Belgium; Department of Anatomy and Cell Biology, University of Western Ontario, 474 Medical Sciences Building, London, Ontario ON N6A 3K7, Canada
| | - Chantal Brees
- Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven - University of Leuven, Herestraat 49, Box 601, B-3000 Leuven, Belgium
| | - Celien Lismont
- Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven - University of Leuven, Herestraat 49, Box 601, B-3000 Leuven, Belgium
| | - Oksana Apanasets
- Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven - University of Leuven, Herestraat 49, Box 601, B-3000 Leuven, Belgium
| | - Marc Fransen
- Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, KU Leuven - University of Leuven, Herestraat 49, Box 601, B-3000 Leuven, Belgium.
| |
Collapse
|
8
|
Allosteric modulation of peroxisomal membrane protein recognition by farnesylation of the peroxisomal import receptor PEX19. Nat Commun 2017; 8:14635. [PMID: 28281558 PMCID: PMC5353646 DOI: 10.1038/ncomms14635] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 01/19/2017] [Indexed: 01/13/2023] Open
Abstract
The transport of peroxisomal membrane proteins (PMPs) requires the soluble PEX19 protein as chaperone and import receptor. Recognition of cargo PMPs by the C-terminal domain (CTD) of PEX19 is required for peroxisome biogenesis in vivo. Farnesylation at a C-terminal CaaX motif in PEX19 enhances the PMP interaction, but the underlying molecular mechanisms are unknown. Here, we report the NMR-derived structure of the farnesylated human PEX19 CTD, which reveals that the farnesyl moiety is buried in an internal hydrophobic cavity. This induces substantial conformational changes that allosterically reshape the PEX19 surface to form two hydrophobic pockets for the recognition of conserved aromatic/aliphatic side chains in PMPs. Mutations of PEX19 residues that either mediate farnesyl contacts or are directly involved in PMP recognition abolish cargo binding and cannot complement a ΔPEX19 phenotype in human Zellweger patient fibroblasts. Our results demonstrate an allosteric mechanism for the modulation of protein function by farnesylation. PEX19 is a chaperone and import receptor for peroxisomal membrane proteins (PMPs). Here the authors present the structure of the farnesylated C-terminal domain of PEX19, and its interaction with PMPs reveals how the farnesyl moiety allosterically reshapes the PMP binding surface and modulates PEX19 function.
Collapse
|
9
|
Madsen MB, Kogelman LJA, Kadarmideen HN, Rasmussen HB. Systems genetics analysis of pharmacogenomics variation during antidepressant treatment. THE PHARMACOGENOMICS JOURNAL 2016; 18:144-152. [PMID: 27752142 DOI: 10.1038/tpj.2016.68] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 06/17/2016] [Accepted: 08/25/2016] [Indexed: 12/24/2022]
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are the most widely used antidepressants, but the efficacy of the treatment varies significantly among individuals. It is believed that complex genetic mechanisms play a part in this variation. We have used a network based approach to unravel the involved genetic components. Moreover, we investigated the potential difference in the genetic interaction networks underlying SSRI treatment response over time. We found four hub genes (ASCC3, PPARGC1B, SCHIP1 and TMTC2) with different connectivity in the initial SSRI treatment period (baseline to week 4) compared with the subsequent period (4-8 weeks after initiation), suggesting that different genetic networks are important at different times during SSRI treatment. The strongest interactions in the initial SSRI treatment period involved genes encoding transcriptional factors, and in the subsequent period genes involved in calcium homeostasis. In conclusion, we suggest a difference in genetic interaction networks between initial and subsequent SSRI response.
Collapse
Affiliation(s)
- M B Madsen
- Institute of Biological Psychiatry, Mental Health Centre Sct. Hans, Capital Region of Denmark, Roskilde, Denmark.,iPSYCH, The Lundbeck Foundation Initiative for Integrative Psychiatric Research, Denmark
| | - L J A Kogelman
- Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - H N Kadarmideen
- Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - H B Rasmussen
- Institute of Biological Psychiatry, Mental Health Centre Sct. Hans, Capital Region of Denmark, Roskilde, Denmark.,iPSYCH, The Lundbeck Foundation Initiative for Integrative Psychiatric Research, Denmark
| |
Collapse
|
10
|
Nordgren M, Francisco T, Lismont C, Hennebel L, Brees C, Wang B, Van Veldhoven PP, Azevedo JE, Fransen M. Export-deficient monoubiquitinated PEX5 triggers peroxisome removal in SV40 large T antigen-transformed mouse embryonic fibroblasts. Autophagy 2016; 11:1326-40. [PMID: 26086376 DOI: 10.1080/15548627.2015.1061846] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Peroxisomes are ubiquitous cell organelles essential for human health. To maintain a healthy cellular environment, dysfunctional and superfluous peroxisomes need to be selectively removed. Although emerging evidence suggests that peroxisomes are mainly degraded by pexophagy, little is known about the triggers and molecular mechanisms underlying this process in mammalian cells. In this study, we show that PEX5 proteins fused to a bulky C-terminal tag trigger peroxisome degradation in SV40 large T antigen-transformed mouse embryonic fibroblasts. In addition, we provide evidence that this process is autophagy-dependent and requires monoubiquitination of the N-terminal cysteine residue that marks PEX5 for recycling. As our findings also demonstrate that the addition of a bulky tag to the C terminus of PEX5 does not interfere with PEX5 monoubiquitination but strongly inhibits its export from the peroxisomal membrane, we hypothesize that such a tag mimics a cargo protein that cannot be released from PEX5, thus keeping monoubiquitinated PEX5 at the membrane for a sufficiently long time to be recognized by the autophagic machinery. This in turn suggests that monoubiquitination of the N-terminal cysteine of peroxisome-associated PEX5 not only functions to recycle the peroxin back to the cytosol, but also serves as a quality control mechanism to eliminate peroxisomes with a defective protein import machinery.
Collapse
Affiliation(s)
- Marcus Nordgren
- a Laboratory of Lipid Biochemistry and Protein Interactions; Department of Cellular and Molecular Medicine; University of Leuven - KU Leuven ; Leuven , Belgium
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Komatsuzaki S, Ogawa E, Shimozawa N, Sakamoto O, Haginoya K, Uematsu M, Hasegawa Y, Matsubara Y, Ohura T. First Japanese case of Zellweger syndrome with a mutation in PEX14. Pediatr Int 2015; 57:1189-92. [PMID: 26627464 DOI: 10.1111/ped.12713] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 04/21/2015] [Indexed: 11/28/2022]
Abstract
Zellweger syndrome, one of the peroxisome biogenesis disorders, is an autosomal recessive disease caused by mutations in PEX genes. It is characterized by severe hypotonia, failure to thrive, psychomotor retardation, liver dysfunction, and sensorineural hearing impairment. Most of the patients with this disease die before the age of 1 year. PEX14 is the 13th PEX gene responsible for peroxisome biogenesis disorders. Thus far, only two patients with PEX14 deficiency have been reported. Here, we report the first case of a Japanese patient with a PEX14 mutation who showed severe hypotonia, psychomotor retardation, demyelination, and developed rickets at the age of 5 months. An increased excretion of 3,6-epoxydicarboxylic acids leads to the diagnosis of Zellweger syndrome and a mutation analysis of PEX14 revealed a homozygous mutation of c.538C>T (p.Q180X). The patient survived for a prolonged period of time but died of liver failure at the age of 46 months.
Collapse
Affiliation(s)
- Shoko Komatsuzaki
- Department of Medical Genetics.,Department of Pediatrics, Tohoku University School of Medicine, Sendai.,Division of Inborn Metabolic Diseases, University Children's Hospital Heidelberg, Heidelberg, Germany
| | - Eishin Ogawa
- Department of Pediatrics, Tohoku University School of Medicine, Sendai
| | - Nobuyuki Shimozawa
- Division of Genomics Research, Life Science Research Center, Gifu University, Gifu
| | - Osamu Sakamoto
- Department of Pediatrics, Tohoku University School of Medicine, Sendai
| | - Kazuhiro Haginoya
- Department of Pediatrics, Tohoku University School of Medicine, Sendai
| | - Mitsugu Uematsu
- Department of Pediatrics, Tohoku University School of Medicine, Sendai
| | - Yuki Hasegawa
- Department of Pediatrics, Shimane University School of Medicine, Izumo, Japan
| | | | - Toshihiro Ohura
- Department of Pediatrics, Tohoku University School of Medicine, Sendai
| |
Collapse
|
12
|
Malinescu B, Martius E, Pelin AM. Violent death in a rare peroxisomal disease--Zellweger syndrome. Forensic Sci Int 2015; 255:89-95. [PMID: 26235911 DOI: 10.1016/j.forsciint.2015.07.009] [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: 12/26/2014] [Revised: 05/10/2015] [Accepted: 07/01/2015] [Indexed: 11/17/2022]
Abstract
Peroxisomal diseases are rare (1:50,000), genetically determined disorders (autosomal recessive), systemic, multiorgan illnesses with prominent involvement of the nervous system, caused either by the failure to form or to maintain the peroxisome, or by a defect in the function of a single or multiple peroxisomal enzymes. Peroxisomes contain approximately 50 enzymes which are responsible for many metabolic reactions, and play an important role in the oxidation of saturated very-long-chain fatty acids (VLCFA). The authors present the case of a Romanian boy, who died at the age of 1.6 of one of the peroxisomal diseases-Zellweger syndrome. Newborn infants with Zellweger syndrome have a typical dysmorphic facies, neonatal seizures, profound hypotonia, and eye abnormalities. Major abnormalities are present in the liver (fibrotic), kidney (cortical cysts), and brain (lipid-laden macrophages and histiocytes in cortical and periventricular areas, demyelination, centrosylvian polymicrogyria and pachygyria)-cerebro-hepato-renal syndrome (CHRS) (Zellweger). Infants with Zellweger syndrome rarely live more than a few months, but in this case the survival was longer, and the cause of death was not directly the peroxisomal disease but a violent cause of death-mechanical asphyxia with tracheo-bronchial food aspiration. The authors present the results of investigations carried out during the child's life, but also data collected at the autopsy and hystopathological postnecroptic investigations. By presenting this case, the authors wish to bring to your attention a rare pathology in forensic practice by the paradox of finding a common violent cause of death, asphyxia with food aspiration, in a rare metabolic-genetic disease, which is usually fatal by itself.
Collapse
Affiliation(s)
- Bogdan Malinescu
- Ilfov Medico-Legal Service, Sos Vitan Barzesti 9, Sector 4, 042122 Bucharest, Romania.
| | - Eliza Martius
- National Institute of Legal Medicine "Mina Minovici", Department of Pathology, Sos Vitan Barzesti 9, Sector 4, 042122 Bucharest, Romania.
| | - Ana Maria Pelin
- "Dunarea De Jos" University, Faculty of Medicine and Pharmacy, Department of Pharmaceutical Sciences, Str. Al. I. Cuza Nr. 35, 800216 Galati, Romania.
| |
Collapse
|
13
|
Neuhaus A, Kooshapur H, Wolf J, Meyer NH, Madl T, Saidowsky J, Hambruch E, Lazam A, Jung M, Sattler M, Schliebs W, Erdmann R. A novel Pex14 protein-interacting site of human Pex5 is critical for matrix protein import into peroxisomes. J Biol Chem 2013; 289:437-48. [PMID: 24235149 DOI: 10.1074/jbc.m113.499707] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein import into peroxisomes relies on the import receptor Pex5, which recognizes proteins with a peroxisomal targeting signal 1 (PTS1) in the cytosol and directs them to a docking complex at the peroxisomal membrane. Receptor-cargo docking occurs at the membrane-associated protein Pex14. In human cells, this interaction is mediated by seven conserved diaromatic penta-peptide motifs (WXXX(F/Y) motifs) in the N-terminal half of Pex5 and the N-terminal domain of Pex14. A systematic screening of a Pex5 peptide library by ligand blot analysis revealed a novel Pex5-Pex14 interaction site of Pex5. The novel motif composes the sequence LVAEF with the evolutionarily conserved consensus sequence LVXEF. Replacement of the amino acid LVAEF sequence by alanines strongly affects matrix protein import into peroxisomes in vivo. The NMR structure of a complex of Pex5-(57-71) with the Pex14-N-terminal domain showed that the novel motif binds in a similar α-helical orientation as the WXXX(F/Y) motif but that the tryptophan pocket is now occupied by a leucine residue. Surface plasmon resonance analyses revealed 33 times faster dissociation rates for the LVXEF ligand when compared with a WXXX(F/Y) motif. Surprisingly, substitution of the novel motif with the higher affinity WXXX(F/Y) motif impairs protein import into peroxisomes. These data indicate that the distinct kinetic properties of the novel Pex14-binding site in Pex5 are important for processing of the peroxisomal targeting signal 1 receptor at the peroxisomal membrane. The novel Pex14-binding site may represent the initial tethering site of Pex5 from which the cargo-loaded receptor is further processed in a sequential manner.
Collapse
Affiliation(s)
- Alexander Neuhaus
- From the Institut für Physiologische Chemie, Abteilung Systembiochemie, Ruhr-Universität Bochum, D-44780 Bochum
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Ebberink MS, Mooijer PAW, Gootjes J, Koster J, Wanders RJA, Waterham HR. Genetic classification and mutational spectrum of more than 600 patients with a Zellweger syndrome spectrum disorder. Hum Mutat 2011; 32:59-69. [PMID: 21031596 DOI: 10.1002/humu.21388] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The autosomal recessive Zellweger syndrome spectrum (ZSS) disorders comprise a main subgroup of the peroxisome biogenesis disorders and can be caused by mutations in any of 12 different currently identified PEX genes resulting in severe multisystemic disorders. To get insight into the spectrum of PEX gene defects among ZSS disorders and to investigate if additional human PEX genes are required for functional peroxisome biogenesis, we assigned over 600 ZSS fibroblast cell lines to different genetic complementation groups. These fibroblast cell lines were subjected to a complementation assay involving fusion by means of polyethylene glycol or a PEX cDNA transfection assay specifically developed for this purpose. In a majority of the cell lines we subsequently determined the underlying mutations by sequence analysis of the implicated PEX genes. The PEX cDNA transfection assay allows for the rapid identification of PEX genes defective in ZSS patients. The assignment of over 600 fibroblast cell lines to different genetic complementation groups provides the most comprehensive and representative overview of the frequency distribution of the different PEX gene defects. We did not identify any novel genetic complementation group, suggesting that all PEX gene defects resulting in peroxisome deficiency are currently known.
Collapse
Affiliation(s)
- Merel S Ebberink
- Academic Medical Centre at the University of Amsterdam, The Netherlands
| | | | | | | | | | | |
Collapse
|
15
|
Monroe-Augustus M, Ramón NM, Ratzel SE, Lingard MJ, Christensen SE, Murali C, Bartel B. Matrix proteins are inefficiently imported into Arabidopsis peroxisomes lacking the receptor-docking peroxin PEX14. PLANT MOLECULAR BIOLOGY 2011; 77:1-15. [PMID: 21553312 PMCID: PMC3529590 DOI: 10.1007/s11103-011-9782-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 04/24/2011] [Indexed: 05/24/2023]
Abstract
Mutations in peroxisome biogenesis proteins (peroxins) can lead to developmental deficiencies in various eukaryotes. PEX14 and PEX13 are peroxins involved in docking cargo-receptor complexes at the peroxisomal membrane, thus aiding in the transport of the cargo into the peroxisomal matrix. Genetic screens have revealed numerous Arabidopsis thaliana peroxins acting in peroxisomal matrix protein import; the viable alleles isolated through these screens are generally partial loss-of-function alleles, whereas null mutations that disrupt delivery of matrix proteins to peroxisomes can confer embryonic lethality. In this study, we used forward and reverse genetics in Arabidopsis to isolate four pex14 alleles. We found that all four alleles conferred reduced PEX14 mRNA levels and displayed physiological and molecular defects suggesting reduced but not abolished peroxisomal matrix protein import. The least severe pex14 allele, pex14-3, accumulated low levels of a C-terminally truncated PEX14 product that retained partial function. Surprisingly, even the severe pex14-2 allele, which lacked detectable PEX14 mRNA and PEX14 protein, was viable, fertile, and displayed residual peroxisome matrix protein import. As pex14 plants matured, import improved. Together, our data indicate that PEX14 facilitates, but is not essential for peroxisomal matrix protein import in plants.
Collapse
Affiliation(s)
- Melanie Monroe-Augustus
- Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA
| | - Naxhiely Martínez Ramón
- Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA
| | - Sarah E. Ratzel
- Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA
| | - Matthew J. Lingard
- Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA. 700 Chesterfield Parkway, Chesterfield, MO 63017, USA
| | - Sarah E. Christensen
- Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA
| | - Chaya Murali
- Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA
| | - Bonnie Bartel
- Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA
| |
Collapse
|
16
|
Anthonio EA, Brees C, Baumgart-Vogt E, Hongu T, Huybrechts SJ, Van Dijck P, Mannaerts GP, Kanaho Y, Van Veldhoven PP, Fransen M. Small G proteins in peroxisome biogenesis: the potential involvement of ADP-ribosylation factor 6. BMC Cell Biol 2009; 10:58. [PMID: 19686593 PMCID: PMC3224584 DOI: 10.1186/1471-2121-10-58] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Accepted: 08/17/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Peroxisomes execute diverse and vital functions in virtually every eukaryote. New peroxisomes form by budding from pre-existing organelles or de novo by vesiculation of the ER. It has been suggested that ADP-ribosylation factors and COPI coatomer complexes are involved in these processes. RESULTS Here we show that all viable Saccharomyces cerevisiae strains deficient in one of the small GTPases which have an important role in the regulation of vesicular transport contain functional peroxisomes, and that the number of these organelles in oleate-grown cells is significantly upregulated in the arf1 and arf3 null strains compared to the wild-type strain. In addition, we provide evidence that a portion of endogenous Arf6, the mammalian orthologue of yeast Arf3, is associated with the cytoplasmic face of rat liver peroxisomes. Despite this, ablation of Arf6 did neither influence the regulation of peroxisome abundance nor affect the localization of peroxisomal proteins in cultured fetal hepatocytes. However, co-overexpression of wild-type, GTP hydrolysis-defective or (dominant-negative) GTP binding-defective forms of Arf1 and Arf6 caused mislocalization of newly-synthesized peroxisomal proteins and resulted in an alteration of peroxisome morphology. CONCLUSION These observations suggest that Arf6 is a key player in mammalian peroxisome biogenesis. In addition, they also lend strong support to and extend the concept that specific Arf isoform pairs may act in tandem to regulate exclusive trafficking pathways.
Collapse
Affiliation(s)
- Erin A Anthonio
- Department of Molecular Cell Biology, Catholic University of Leuven, Leuven, Belgium.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Huybrechts SJ, Van Veldhoven PP, Brees C, Mannaerts GP, Los GV, Fransen M. Peroxisome dynamics in cultured mammalian cells. Traffic 2009; 10:1722-33. [PMID: 19719477 DOI: 10.1111/j.1600-0854.2009.00970.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Despite the identification and characterization of various proteins that are essential for peroxisome biogenesis, the origin and the turnover of peroxisomes are still unresolved critical issues. In this study, we used the HaloTag technology as a new approach to examine peroxisome dynamics in cultured mammalian cells. This technology is based on the formation of a covalent bond between the HaloTag protein--a mutated bacterial dehalogenase which is fused to the protein of interest--and a synthetic haloalkane ligand that contains a fluorophore or affinity tag. By using cell-permeable ligands of distinct fluorescence, it is possible to image distinct pools of newly synthesized proteins, generated from a single genetic HaloTag-containing construct, at different wavelengths. Here, we show that peroxisomes display an age-related heterogeneity with respect to their capacity to incorporate newly synthesized proteins. We also demonstrate that these organelles do not exchange their protein content. In addition, we present evidence that the matrix protein content of pre-existing peroxisomes is not evenly distributed over new organelles. Finally, we show that peroxisomes in cultured mammalian cells, under basal growth conditions, have a half-life of approximately 2 days and are mainly degraded by an autophagy-related mechanism. The implications of these findings are discussed.
Collapse
Affiliation(s)
- Sofie J Huybrechts
- Katholieke Universiteit Leuven, Faculteit Geneeskunde, Departement Moleculaire Celbiologie, LIPIT, Campus Gasthuisberg (O&N 1), Leuven, Belgium
| | | | | | | | | | | |
Collapse
|
18
|
Grou CP, Carvalho AF, Pinto MP, Huybrechts SJ, Sá-Miranda C, Fransen M, Azevedo JE. Properties of the ubiquitin-pex5p thiol ester conjugate. J Biol Chem 2009; 284:10504-13. [PMID: 19208625 DOI: 10.1074/jbc.m808978200] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Pex5p, the peroxisomal protein cycling receptor, binds newly synthesized peroxisomal matrix proteins in the cytosol and promotes their translocation across the organelle membrane. During its transient passage through the membrane, Pex5p is monoubiquitinated at a conserved cysteine residue, a requisite for its subsequent ATP-dependent export back into the cytosol. Here we describe the properties of the soluble and membrane-bound monoubiquitinated Pex5p species (Ub-Pex5p). Our data suggest that 1) Ub-Pex5p is deubiquitinated by a combination of context-dependent enzymatic and nonenzymatic mechanisms; 2) soluble Ub-Pex5p retains the capacity to interact with the peroxisomal import machinery in a cargo-dependent manner; and 3) substitution of the conserved cysteine residue of Pex5p by a lysine results in a quite functional protein both in vitro and in vivo. Additionally, we show that MG132, a proteasome inhibitor, blocks the import of a peroxisomal reporter protein in vivo.
Collapse
Affiliation(s)
- Cláudia P Grou
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal
| | | | | | | | | | | | | |
Collapse
|