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Banerjee B, Das D. Effects of bursty synthesis in organelle biogenesis. Math Biosci 2024; 370:109156. [PMID: 38346665 DOI: 10.1016/j.mbs.2024.109156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 01/31/2024] [Accepted: 02/03/2024] [Indexed: 02/16/2024]
Abstract
A fundamental question of cell biology is how cells control the number of organelles. The processes of organelle biogenesis, namely de novo synthesis, fission, fusion, and decay, are inherently stochastic, producing cell-to-cell variability in organelle abundance. In addition, experiments suggest that the synthesis of some organelles can be bursty. We thus ask how bursty synthesis impacts intracellular organelle number distribution. We develop an organelle biogenesis model with bursty de novo synthesis by considering geometrically distributed burst sizes. We analytically solve the model in biologically relevant limits and provide exact expressions for the steady-state organelle number distributions and their means and variances. We also present approximate solutions for the whole model, complementing with exact stochastic simulations. We show that bursts generally increase the noise in organelle numbers, producing distinct signatures in noise profiles depending on different mechanisms of organelle biogenesis. We also find different shapes of organelle number distributions, including bimodal distributions in some parameter regimes. Notably, bursty synthesis broadens the parameter regime of observing bimodality compared to the 'non-bursty' case. Together, our framework utilizes number fluctuations to elucidate the role of bursty synthesis in producing organelle number heterogeneity in cells.
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Affiliation(s)
- Binayak Banerjee
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia 741 246, West Bengal, India
| | - Dipjyoti Das
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia 741 246, West Bengal, India.
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2
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Abstract
Peroxisomes are highly dynamic, oxidative organelles with key metabolic functions in cellular lipid metabolism, such as the β-oxidation of fatty acids and the synthesis of myelin sheath lipids, as well as the regulation of cellular redox balance. Loss of peroxisomal functions causes severe metabolic disorders in humans. Furthermore, peroxisomes also fulfil protective roles in pathogen and viral defence and immunity, highlighting their wider significance in human health and disease. This has sparked increasing interest in peroxisome biology and their physiological functions. This review presents an update and a continuation of three previous review articles addressing the unsolved mysteries of this remarkable organelle. We continue to highlight recent discoveries, advancements, and trends in peroxisome research, and address novel findings on the metabolic functions of peroxisomes, their biogenesis, protein import, membrane dynamics and division, as well as on peroxisome-organelle membrane contact sites and organelle cooperation. Furthermore, recent insights into peroxisome organisation through super-resolution microscopy are discussed. Finally, we address new roles for peroxisomes in immune and defence mechanisms and in human disorders, and for peroxisomal functions in different cell/tissue types, in particular their contribution to organ-specific pathologies.
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Grants
- BB/W015420/1, BB/V018167/1, BB/T002255/1, BB/R016844/1 Biotechnology and Biological Sciences Research Council
- BB/W015420/1, BB/V018167/1, BB/T002255/1, BB/R016844/1 Biotechnology and Biological Sciences Research Council
- BB/W015420/1, BB/V018167/1, BB/T002255/1, BB/R016844/1 Biotechnology and Biological Sciences Research Council
- European Union’s Horizon 2020 research and innovation programme
- Deutsches Zentrum für Herz-Kreislaufforschung
- German Research Foundation
- Medical Faculty Mannheim, University of Heidelberg
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Affiliation(s)
- Rechal Kumar
- Faculty of Health and Life Sciences, Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK
| | - Markus Islinger
- Institute of Neuroanatomy, Medical Faculty Mannheim, Mannheim Centre for Translational Neuroscience, University of Heidelberg, 68167, Mannheim, Germany
| | - Harley Worthy
- Faculty of Health and Life Sciences, Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK
| | - Ruth Carmichael
- Faculty of Health and Life Sciences, Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
| | - Michael Schrader
- Faculty of Health and Life Sciences, Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
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3
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Kumari RM, Khatri A, Chaudhary R, Choudhary V. Concept of lipid droplet biogenesis. Eur J Cell Biol 2023; 102:151362. [PMID: 37742390 PMCID: PMC7615795 DOI: 10.1016/j.ejcb.2023.151362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/26/2023] Open
Abstract
Lipid droplets (LD) are functionally conserved fat storage organelles found in all cell types. LDs have a unique structure comprising of a hydrophobic core of neutral lipids (fat), triacylglycerol (TAG) and cholesterol esters (CE) surrounded by a phospholipid monolayer. LD surface is decorated by a multitude of proteins and enzymes rendering this compartment functional. Accumulating evidence suggests that LDs originate from discrete ER-subdomains, demarcated by the lipodystrophy protein seipin, however, the mechanisms of which are not well understood. LD biogenesis factors together with biophysical properties of the ER membrane orchestrate spatiotemporal regulation of LD nucleation and growth at specific ER subdomains in response to metabolic cues. Defects in LD formation manifests in several human pathologies, including obesity, lipodystrophy, ectopic fat accumulation, and insulin resistance. Here, we review recent advances in understanding the molecular events during initial stages of eukaryotic LD assembly and discuss the critical role of factors that ensure fidelity of this process.
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Affiliation(s)
- R Mankamna Kumari
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Amit Khatri
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Ritika Chaudhary
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Vineet Choudhary
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India.
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Cheng CY, Romero DP, Zoltner M, Yao MC, Turkewitz AP. Structure and dynamics of the contractile vacuole complex in Tetrahymena thermophila. J Cell Sci 2023; 136:jcs261511. [PMID: 37902010 PMCID: PMC10729820 DOI: 10.1242/jcs.261511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/23/2023] [Indexed: 10/31/2023] Open
Abstract
The contractile vacuole complex (CVC) is a dynamic and morphologically complex membrane organelle, comprising a large vesicle (bladder) linked with a tubular reticulum (spongiome). CVCs provide key osmoregulatory roles across diverse eukaryotic lineages, but probing the mechanisms underlying their structure and function is hampered by the limited tools available for in vivo analysis. In the experimentally tractable ciliate Tetrahymena thermophila, we describe four proteins that, as endogenously tagged constructs, localize specifically to distinct CVC zones. The DOPEY homolog Dop1p and the CORVET subunit Vps8Dp localize both to the bladder and spongiome but with different local distributions that are sensitive to osmotic perturbation, whereas the lipid scramblase Scr7p colocalizes with Vps8Dp. The H+-ATPase subunit Vma4 is spongiome specific. The live imaging permitted by these probes revealed dynamics at multiple scales including rapid exchange of CVC-localized and soluble protein pools versus lateral diffusion in the spongiome, spongiome extension and branching, and CVC formation during mitosis. Although the association with DOP1 and VPS8D implicate the CVC in endosomal trafficking, both the bladder and spongiome might be isolated from bulk endocytic input.
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Affiliation(s)
- Chao-Yin Cheng
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Daniel P. Romero
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Martin Zoltner
- Biotechnology Biomedicine Centre of the Academy of Sciences, České Budějovice, 370 05, Czech Republic
| | - Meng-Chao Yao
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Aaron P. Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
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Aydogan MG, Hankins LE, Steinacker TL, Mofatteh M, Saurya S, Wainman A, Wong SS, Lu X, Zhou FY, Raff JW. Centriole distal-end proteins CP110 and Cep97 influence centriole cartwheel growth at the proximal-end. J Cell Sci 2022; 135:275722. [PMID: 35707992 PMCID: PMC9450887 DOI: 10.1242/jcs.260015] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/13/2022] [Indexed: 11/20/2022] Open
Abstract
Centrioles are composed of a central cartwheel tethered to nine-fold symmetric microtubule (MT) blades. The centriole cartwheel and MTs are thought to grow from opposite ends of these organelles, so it is unclear how they coordinate their assembly. We previously showed that in Drosophila embryos an oscillation of Polo-like kinase 4 (Plk4) helps to initiate and time the growth of the cartwheel at the proximal end. Here, in the same model, we show that CP110 and Cep97 form a complex close to the distal-end of the centriole MTs whose levels rise and fall as the new centriole MTs grow, in a manner that appears to be entrained by the core cyclin-dependent kinase (Cdk)–Cyclin oscillator that drives the nuclear divisions in these embryos. These CP110 and Cep97 dynamics, however, do not appear to time the period of centriole MT growth directly. Instead, we find that changing the levels of CP110 and Cep97 appears to alter the Plk4 oscillation and the growth of the cartwheel at the proximal end. These findings reveal an unexpected potential crosstalk between factors normally concentrated at opposite ends of the growing centrioles, which might help to coordinate centriole growth. This article has an associated First Person interview with the first authors of the paper. Summary: Cp110 and Cep97, proteins that are normally located at the distal-end of the centriole, appear able to influence the assembly of the centriole cartwheel at the proximal end.
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Affiliation(s)
- Mustafa G Aydogan
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.,Department of Biochemistry and Biophysics, University of California, San Francisco, USA
| | - Laura E Hankins
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | | | - Mohammad Mofatteh
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Saroj Saurya
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Alan Wainman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Siu-Shing Wong
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Xin Lu
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Felix Y Zhou
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Jordan W Raff
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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Ma CIJ, Brill JA. Quantitation of Secretory Granule Size in Drosophila Larval Salivary Glands. Bio Protoc 2021; 11:e4039. [PMID: 34250205 DOI: 10.21769/bioprotoc.4039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/14/2021] [Accepted: 03/24/2021] [Indexed: 11/02/2022] Open
Abstract
Maturation of secretory granules is a crucial process that ensures the bioactivity of cargo proteins undergoing regulated secretion. In Drosophila melanogaster, the larval salivary glands produce secretory granules that are up to four-fold larger in cross-sectional area after maturation. Therefore, we developed a live imaging microscopy approach to quantitate the size of secretory granules with a view to identifying genes involved in their maturation. Here, we describe the procedures of larval salivary gland dissection and sample preparation for live imaging with a fluorescence confocal microscope. Furthermore, we describe the workflow for measuring the size of secretory granules by cross-sectional surface area and statistical analysis. Our live imaging microscopy method provides a reliable read-out for the status of secretory granule maturation in Drosophila larval salivary glands.
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Affiliation(s)
- Cheng-I J Ma
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Julie A Brill
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada
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Ma CIJ, Burgess J, Brill JA. Maturing secretory granules: Where secretory and endocytic pathways converge. Adv Biol Regul 2021; 80:100807. [PMID: 33866198 DOI: 10.1016/j.jbior.2021.100807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 10/21/2022]
Abstract
Secretory granules (SGs) are specialized organelles responsible for the storage and regulated release of various biologically active molecules from the endocrine and exocrine systems. Thus, proper SG biogenesis is critical to normal animal physiology. Biogenesis of SGs starts at the trans-Golgi network (TGN), where immature SGs (iSGs) bud off and undergo maturation before fusing with the plasma membrane (PM). How iSGs mature is unclear, but emerging studies have suggested an important role for the endocytic pathway. The requirement for endocytic machinery in SG maturation blurs the line between SGs and another class of secretory organelles called lysosome-related organelles (LROs). Therefore, it is important to re-evaluate the differences and similarities between SGs and LROs.
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Affiliation(s)
- Cheng-I Jonathan Ma
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Medical Sciences Building, Room 2374, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Jason Burgess
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, Medical Sciences Building, Room 4396, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Julie A Brill
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Medical Sciences Building, Room 2374, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Medical Sciences Building, Room 4396, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
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Cho YH, Ku CR, Choi YS, Lee HJ, Lee EJ. Danshen Extracts Prevents Obesity and Activates Mitochondrial Function in Brown Adipose Tissue. Endocrinol Metab (Seoul) 2021; 36:185-195. [PMID: 33677939 PMCID: PMC7937848 DOI: 10.3803/enm.2020.835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 12/31/2020] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Danshen has been widely used in oriental medicine to improve body function. The purpose of this study is to investigate the effect of water-soluble Danshen extract (DE) on weight loss and on activation proteins involved in mitochondrial biogenesis in brown adipose tissue (BAT) in obese mice. METHODS BAT was isolated from 7-week-old male Sprague-Dawley rats, and expression of proteins related to mitochondrial biogenesis was confirmed in both brown preadipocytes and mature brown adipocytes treated with DE. For the in vivo study, low-density lipoprotein receptor knock out mice were divided into three groups and treated for 17 weeks with: standard diet; high fat diet (HFD); HFD+DE. Body weight was measured every week, and oral glucose tolerance test was performed after DE treatment in streptozotocin-induced diabetic mice. To observe the changes in markers related to thermogenesis and adipogenesis in the BAT, white adipose tissue (WAT) and liver of experimental animals, tissues were removed and immediately frozen in liquid nitrogen. RESULTS DE increased the expression of uncoupling protein 1 and peroxisome proliferator-activated receptor gamma coactivator 1-alpha in brown preadipocytes, and also promoted the brown adipocyte differentiation and mitochondrial function in the mature brown adipocytes. Reactive oxygen species production in brown preadipocytes was increased depending on the concentration of DE. DE activates thermogenesis in BAT and normalizes increased body weight and adipogenesis in the liver due to HFD. Browning of WAT was increased in WAT of DE treatment group. CONCLUSION DE protects against obesity and activates mitochondrial function in BAT.
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Affiliation(s)
- Yoon Hee Cho
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Cheol Ryong Ku
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Young-Suk Choi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Hyeon Jeong Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Eun Jig Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
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Bahri H, Buratto J, Rojo M, Dompierre JP, Salin B, Blancard C, Cuvellier S, Rose M, Ben Ammar Elgaaied A, Tetaud E, di Rago JP, Devin A, Duvezin-Caubet S. TMEM70 forms oligomeric scaffolds within mitochondrial cristae promoting in situ assembly of mammalian ATP synthase proton channel. Biochim Biophys Acta Mol Cell Res 2020; 1868:118942. [PMID: 33359711 DOI: 10.1016/j.bbamcr.2020.118942] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/28/2020] [Accepted: 12/18/2020] [Indexed: 01/14/2023]
Abstract
Mitochondrial ATP-synthesis is catalyzed by a F1Fo-ATP synthase, an enzyme of dual genetic origin enriched at the edge of cristae where it plays a key role in their structure/stability. The enzyme's biogenesis remains poorly understood, both from a mechanistic and a compartmentalization point of view. The present study provides novel molecular insights into this process through investigations on a human protein called TMEM70 with an unclear role in the assembly of ATP synthase. A recent study has revealed the existence of physical interactions between TMEM70 and the subunit c (Su.c), a protein present in 8 identical copies forming a transmembrane oligomeric ring (c-ring) within the ATP synthase proton translocating domain (Fo). Herein we analyzed the ATP-synthase assembly in cells lacking TMEM70, mitochondrial DNA or F1 subunits and observe a direct correlation between TMEM70 and Su.c levels, regardless of the status of other ATP synthase subunits or of mitochondrial bioenergetics. Immunoprecipitation, two-dimensional blue-native/SDS-PAGE, and pulse-chase experiments reveal that TMEM70 forms large oligomers that interact with Su.c not yet incorporated into ATP synthase complexes. Moreover, discrete TMEM70-Su.c complexes with increasing Su.c contents can be detected, suggesting a role for TMEM70 oligomers in the gradual assembly of the c-ring. Furthermore, we demonstrate using expansion super-resolution microscopy the specific localization of TMEM70 at the inner cristae membrane, distinct from the MICOS component MIC60. Taken together, our results show that TMEM70 oligomers provide a scaffold for c-ring assembly and that mammalian ATP synthase is assembled within inner cristae membranes.
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Affiliation(s)
- Hela Bahri
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France; Laboratoire de génétique, Immunologie et Pathologie Humaine, Faculté des sciences de Tunis, Université Tunis-El Manar FST, Tunis, Tunisie
| | - Jeremie Buratto
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France; Université Bordeaux, CNRS, IPB, CBMN (UMR 5248), Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, F-33600 Pessac, France
| | - Manuel Rojo
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Jim Paul Dompierre
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Bénédicte Salin
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Corinne Blancard
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Sylvain Cuvellier
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Marie Rose
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Amel Ben Ammar Elgaaied
- Laboratoire de génétique, Immunologie et Pathologie Humaine, Faculté des sciences de Tunis, Université Tunis-El Manar FST, Tunis, Tunisie
| | - Emmanuel Tetaud
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France; Laboratoire de Microbiologie Fondamentale et Pathogénicité UMR-CNRS 5234, 146 rue Léo Saignat, CEDEX F-33076 Bordeaux, France
| | - Jean-Paul di Rago
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Anne Devin
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Stéphane Duvezin-Caubet
- Université Bordeaux, IBGC, UMR 5095, F-33000 Bordeaux, France; CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France.
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Etoh K, Fukuda M. Rab10 regulates tubular endosome formation through KIF13A and KIF13B motors. J Cell Sci 2019; 132:jcs.226977. [PMID: 30700496 DOI: 10.1242/jcs.226977] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 01/17/2019] [Indexed: 01/02/2023] Open
Abstract
Recycling endosomes are stations that sort endocytic cargoes to their appropriate destinations. Tubular endosomes have been characterized as a recycling endosomal compartment for clathrin-independent cargoes. However, the molecular mechanism by which tubular endosome formation is regulated is poorly understood. In this study, we identified Rab10 as a novel protein localized at tubular endosomes by using a comprehensive localization screen of EGFP-tagged Rab small GTPases. Knockout of Rab10 completely abolished tubular endosomal structures in HeLaM cells. We also identified kinesin motors KIF13A and KIF13B as novel Rab10-interacting proteins by means of in silico screening. The results of this study demonstrated that both the Rab10-binding homology domain and the motor domain of KIF13A are required for Rab10-positive tubular endosome formation. Our findings provide insight into the mechanism by which the Rab10-KIF13A (or KIF13B) complex regulates tubular endosome formation. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Kan Etoh
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
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Abstract
Background The origin of cancer cells is the most fundamental yet unresolved problem in cancer research. Cancer cells are thought to be transformed from the normal cells. However, recent studies reveal that the primary cancer cells (PCCs) for cancer initiation and secondary cancer cells (SCCs) for cancer progression are formed in but not transformed from the senescent normal and cancer cells, respectively. Nevertheless, the cellular mechanism of PCCs/SCCs formation is unclear. Here, based on the evidences (1) the nascent PCCs/SCCs are small and organelle-less resembling bacteria; (2) our finding that the cyanobacterium TDX16 acquires its algal host DNA and turns into a new alga TDX16-DE by de novo organelle biogenesis, and (3) PCCs/SCCs formations share striking similarities with TDX16 development and transition, we propose the bacterial origin of cancer cells (BOCC). Presentation of the hypothesis The intracellular bacteria take up the DNAs of the senescent/necrotic normal cells/PCCs and then develop into PCCs/SCCs by hybridizing the acquired DNAs with their own ones and expressing the hybrid genomes. Testing the hypothesis BOCC can be confirmed by testing BOCC-based predictions, such as normal cells with no intracellular bacteria can not "transform" into cancer cells in any conditions. Implications of the hypothesis According to BOCC theory: (1) cancer cells are new single-celled eukaryotes, which is why the hallmarks of cancer are mostly the characteristics of protists; (2) genetic changes and instabilities are not the causes, but the consequences of cancer cell formation; and (3) the common role of carcinogens, infectious agents and relating factors is inducing or related to cellular senescence rather than mutations. Therefore, BOCC theory provides new rationale and direction for cancer research, prevention and therapy.
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Affiliation(s)
- Qing-Lin Dong
- Department of Bioengineering, Hebei University of Technology, Tianjin, 300130 China
| | - Xiang-Ying Xing
- Department of Bioengineering, Hebei University of Technology, Tianjin, 300130 China
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Abstract
Peroxisomes are key metabolic organelles, which contribute to cellular lipid metabolism, e.g. the β-oxidation of fatty acids and the synthesis of myelin sheath lipids, as well as cellular redox balance. Peroxisomal dysfunction has been linked to severe metabolic disorders in man, but peroxisomes are now also recognized as protective organelles with a wider significance in human health and potential impact on a large number of globally important human diseases such as neurodegeneration, obesity, cancer, and age-related disorders. Therefore, the interest in peroxisomes and their physiological functions has significantly increased in recent years. In this review, we intend to highlight recent discoveries, advancements and trends in peroxisome research, and present an update as well as a continuation of two former review articles addressing the unsolved mysteries of this astonishing organelle. We summarize novel findings on the biological functions of peroxisomes, their biogenesis, formation, membrane dynamics and division, as well as on peroxisome-organelle contacts and cooperation. Furthermore, novel peroxisomal proteins and machineries at the peroxisomal membrane are discussed. Finally, we address recent findings on the role of peroxisomes in the brain, in neurological disorders, and in the development of cancer.
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Affiliation(s)
- Markus Islinger
- Institute of Neuroanatomy, Center for Biomedicine and Medical Technology Mannheim, Medical Faculty Manheim, University of Heidelberg, 68167, Mannheim, Germany
| | - Alfred Voelkl
- Institute for Anatomy and Cell Biology, University of Heidelberg, 69120, Heidelberg, Germany
| | - H Dariush Fahimi
- Institute for Anatomy and Cell Biology, University of Heidelberg, 69120, Heidelberg, Germany
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13
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Liebers M, Chevalier F, Blanvillain R, Pfannschmidt T. PAP genes are tissue- and cell-specific markers of chloroplast development. Planta 2018; 248:629-646. [PMID: 29855700 DOI: 10.1007/s00425-018-2924-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/21/2018] [Indexed: 05/03/2023]
Abstract
Expression of PAP genes is strongly coordinated and represents a highly selective cell-specific marker associated with the development of chloroplasts in photosynthetically active organs of Arabidopsis seedlings and adult plants. Transcription in plastids of plants depends on the activity of phage-type single-subunit nuclear-encoded RNA polymerases (NEP) and a prokaryotic multi-subunit plastid-encoded RNA polymerase (PEP). PEP is comprised of the core subunits α, β, β' and β″ encoded by rpoA, rpoB/C1/C2 genes located on the plastome. This core enzyme needs to interact with nuclear-encoded sigma factors for proper promoter recognition. In chloroplasts, the core enzyme is surrounded by additional 12 nuclear-encoded subunits, all of eukaryotic origin. These PEP-associated proteins (PAPs) were found to be essential for chloroplast biogenesis as Arabidopsis inactivation mutants for each of them revealed albino or pale-green phenotypes. In silico analysis of transcriptomic data suggests that PAP genes represent a tightly controlled regulon, whereas wetlab data are sparse and correspond to the expression of individual genes mostly studied at the seedling stage. Using RT-PCR, transient, and stable expression assays of PAP promoter-GUS-constructs, we do provide, in this study, a comprehensive expression catalogue for PAP genes throughout the life cycle of Arabidopsis. We demonstrate a selective impact of light on PAP gene expression and uncover a high tissue specificity that is coupled to developmental progression especially during the transition from skotomorphogenesis to photomorphogenesis. Our data imply that PAP gene expression precedes the formation of chloroplasts rendering PAP genes a tissue- and cell-specific marker of chloroplast biogenesis.
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Affiliation(s)
- Monique Liebers
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000, Grenoble, France
| | - Fabien Chevalier
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000, Grenoble, France
| | - Robert Blanvillain
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000, Grenoble, France.
| | - Thomas Pfannschmidt
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000, Grenoble, France.
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14
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Abstract
Long considered inert fat storage depots, it has become clear that lipid droplets (LDs) are bona fide organelles. Like other organelles, they have a characteristic complement of proteins and lipids, and undergo a life cycle that includes biogenesis, maturation, interactions with other organelles, and turnover. I will discuss recent insights into mechanisms governing the life cycle of LDs, and compare and contrast the LD life cycle with that of other metabolic organelles such as mitochondria, peroxisomes, and autophagosomes, highlighting open questions in the field.
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Affiliation(s)
- Sarah Cohen
- University of North Carolina, Chapel Hill, NC, United States.
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15
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Abstract
The vascular environment can rapidly alter, and the speed with which responses to both physiological and pathological changes are required necessitates the existence of a highly responsive system. The endothelium can quickly deliver bioactive molecules by regulated exocytosis of its secretory granules, the Weibel-Palade bodies (WPBs). WPBs include proteins that initiate both haemostasis and inflammation, as well those that modulate blood pressure and angiogenesis. WPB formation is driven by von Willebrand factor, their most abundant protein, which controls both shape and size of WPBs. WPB are generated in a range of sizes, with the largest granules over ten times the size of the smallest. In this Cell Science at a Glance and the accompanying poster, we discuss the emerging mechanisms by which WPB size is controlled and how this affects the ability of this organelle to modulate haemostasis. We will also outline the different modes of exocytosis and their polarity that are currently being explored, and illustrate that these large secretory organelles provide a model for how elements of secretory granule biogenesis and exocytosis cooperate to support a complex and diverse set of functions.
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Affiliation(s)
- Jessica J McCormack
- MRC Laboratory of Molecular Cell Biology, University College London, Gower Street, London, WC1E6BT, UK
| | - Mafalda Lopes da Silva
- MRC Laboratory of Molecular Cell Biology, University College London, Gower Street, London, WC1E6BT, UK
| | - Francesco Ferraro
- MRC Laboratory of Molecular Cell Biology, University College London, Gower Street, London, WC1E6BT, UK
| | - Francesca Patella
- MRC Laboratory of Molecular Cell Biology, University College London, Gower Street, London, WC1E6BT, UK
| | - Daniel F Cutler
- MRC Laboratory of Molecular Cell Biology, University College London, Gower Street, London, WC1E6BT, UK
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16
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Banerjee H, Rachubinski RA. Involvement of SNARE protein Ykt6 in glycosome biogenesis in Trypanosoma brucei. Mol Biochem Parasitol 2017; 218:28-37. [PMID: 29107734 DOI: 10.1016/j.molbiopara.2017.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 10/02/2017] [Accepted: 10/21/2017] [Indexed: 11/30/2022]
Abstract
The kinetoplastid parasites Trypanosoma and Leishmania are etiologic agents of diseases like African sleeping sickness, Chagas and leishmaniasis that inflict many tropical and subtropical parts of the world. These parasites are distinctive in that they compartmentalize most of the usually cytosolic enzymes of the glycolytic pathway within a peroxisome-like organelle called the glycosome. Functional glycosomes are essential in both the procyclic and bloodstream forms of trypanosomatid parasites, and mislocalization of glycosomal enzymes to the cytosol is fatal for the parasite. The life cycle of these parasites is intimately linked to their efficient protein and vesicular trafficking machinery that helps them in immune evasion, host-pathogen interaction and organelle biogenesis and integrity. Soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) proteins play important roles in vesicular trafficking and mediate a wide range of protein-protein interactions in eukaryotes. We show here that the SNARE protein Ykt6 is necessary for glycosome biogenesis and function in Trypanosoma brucei. RNAi-mediated depletion of Ykt6 in both the procyclic and bloodstream forms of T. brucei leads to mislocalization of glycosomal matrix proteins to the cytosol, pronounced reduction in glycosome number, and cell death. GFP-tagged Ykt6 appears as punctate structures in the T. brucei cell and colocalizes in part to glycosomes. Our results constitute the first demonstration of a role for SNARE proteins in the biogenesis of peroxisomal organelles.
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Affiliation(s)
- Hiren Banerjee
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Richard A Rachubinski
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
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17
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Lutfullahoğlu-Bal G, Keskin A, Seferoğlu AB, Dunn CD. Bacterial tail anchors can target to the mitochondrial outer membrane. Biol Direct 2017; 12:16. [PMID: 28738827 PMCID: PMC5525287 DOI: 10.1186/s13062-017-0187-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 07/10/2017] [Indexed: 01/15/2023] Open
Abstract
Background During the generation and evolution of the eukaryotic cell, a proteobacterial endosymbiont was re-fashioned into the mitochondrion, an organelle that appears to have been present in the ancestor of all present-day eukaryotes. Mitochondria harbor proteomes derived from coding information located both inside and outside the organelle, and the rate-limiting step toward the formation of eukaryotic cells may have been development of an import apparatus allowing protein entry to mitochondria. Currently, a widely conserved translocon allows proteins to pass from the cytosol into mitochondria, but how proteins encoded outside of mitochondria were first directed to these organelles at the dawn of eukaryogenesis is not clear. Because several proteins targeted by a carboxyl-terminal tail anchor (TA) appear to have the ability to insert spontaneously into the mitochondrial outer membrane (OM), it is possible that self-inserting, tail-anchored polypeptides obtained from bacteria might have formed the first gate allowing proteins to access mitochondria from the cytosol. Results Here, we tested whether bacterial TAs are capable of targeting to mitochondria. In a survey of proteins encoded by the proteobacterium Escherichia coli, predicted TA sequences were directed to specific subcellular locations within the yeast Saccharomyces cerevisiae. Importantly, TAs obtained from DUF883 family members ElaB and YqjD were abundantly localized to and inserted at the mitochondrial OM. Conclusions Our results support the notion that eukaryotic cells are able to utilize membrane-targeting signals present in bacterial proteins obtained by lateral gene transfer, and our findings make plausible a model in which mitochondrial protein translocation was first driven by tail-anchored proteins. Reviewers This article was reviewed by Michael Ryan and Thomas Simmen. Electronic supplementary material The online version of this article (doi:10.1186/s13062-017-0187-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Abdurrahman Keskin
- Department of Molecular Biology and Genetics, Koç University, 34450 Sarıyer, İstanbul, Turkey.,Present Address: Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Ayşe Bengisu Seferoğlu
- Department of Molecular Biology and Genetics, Koç University, 34450 Sarıyer, İstanbul, Turkey
| | - Cory D Dunn
- Department of Molecular Biology and Genetics, Koç University, 34450 Sarıyer, İstanbul, Turkey. .,Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland.
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18
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Abstract
Lipid droplets are the universal cellular organelles for the transient or long-term storage of lipids. The number, size and composition of lipid droplets vary greatly within cells in a homogenous population as well as in different cell types. The variability of intracellular lipid-storage organelles reflects the diversification of lipid droplet composition and function. Lipid droplet diversification results, for example, in two cellular lipid droplet populations that are prone to diminish and grow, respectively. The aberrant accumulation or depletion of lipids are hallmarks or causes of various human pathologies. Thus, a better understanding of the origins of lipid droplet diversification is not only a fascinating cell biology question but also potentially serves to improve comprehension of pathologies that entail the accumulation of lipids. This Commentary covers the lipid droplet life cycle and highlights the early steps during lipid droplet biogenesis, which we propose to be the potential driving forces of lipid droplet diversification.
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Affiliation(s)
- Abdou Rachid Thiam
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University; Université Paris Diderot Sorbonne Paris-Cité; Sorbonne Universités UPMC Univ Paris 06; CNRS; 24 rue Lhomond, Paris 75005, France
| | - Mathias Beller
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University, Universitätsstr. 1, Düsseldorf 40225, Germany .,Systems Biology of Lipid Metabolism, Heinrich Heine University, Universitätsstr. 1, Düsseldorf 40225, Germany
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19
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Rhiel E. On the biogenesis and degradation of ejectisomes in Pyramimonas grossii (Prasinophyceae). Protoplasma 2016; 253:1101-1110. [PMID: 26255174 DOI: 10.1007/s00709-015-0868-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/01/2015] [Indexed: 06/04/2023]
Abstract
The biogenesis, assembly, and degradation of ejectisomes of Pyramimonas grossii were investigated by conventional transmission electron microscopy. Premature ejectisomes were mainly found beneath the cell envelope, often in close proximity to the nucleus, and as vesicles with diameters of 100 to 400 nm. Ejectisomes in the early stages of development contained only a few (2-4) turns of the ejectisome tapes. In the course of the ejectisome development, the number of turns and the widths of the coiled tapes increased. It is likely that vesicles, which were up to 650 nm in diameter, with granule- and plate-like structures inside, delivered additional preassembled ejectisome polypeptides to these premature stages. Both types of vesicles, those containing early stages of ejectisomes and those delivering additional ejectisome material, are believed to originate directly from the endoplasmic reticulum. Mature ejectisomes were mainly registered at the apical periphery of the cells. Up to 11 ejectisomes were found within a single cell. Ejectisomes that were most likely being in the process of degradation were registered within the cytoplasm and within vesicles, often together with material which resembled body scales. Mature ejectisomes which were still furled or which were arrested in the process of discharge were also found outside the cells in the medium.
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Affiliation(s)
- Erhard Rhiel
- Planktologie, ICBM, Carl-von-Ossietzky-Universität Oldenburg, P.O.B. 2503, D-26129, Oldenburg, Germany.
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20
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Abstract
Macro-autophagy (autophagy) is a conserved catabolic pathway for the degradation of cytoplasmic material in the lysosomal system. This is achieved by the sequestration of the cytoplasmic cargo material within double membrane-bound vesicles that fuse with lysosomes, wherein the vesicle’s inner membrane and the cargo are degraded. Autophagosomes form in a de novo manner and their precursors are initially detected as small membrane structures that are referred to as isolation membranes. The isolation membranes gradually expand and subsequently close to give rise to autophagosomes. Many proteins required to form autophagosomes have been identified but how they act mechanistically is still enigmatic. Here we critically review reconstitution approaches employed to decipher the inner working of the fascinating autophagy machinery.
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Affiliation(s)
- Eleonora Turco
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
| | - Sascha Martens
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
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21
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Aroso M, Agricola B, Hacker C, Schrader M. Proteoglycans support proper granule formation in pancreatic acinar cells. Histochem Cell Biol 2015; 144:331-46. [PMID: 26105026 DOI: 10.1007/s00418-015-1339-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2015] [Indexed: 12/31/2022]
Abstract
Zymogen granules (ZG) are specialized organelles in the exocrine pancreas which allow digestive enzyme storage and regulated secretion. The molecular mechanisms of their biogenesis and the sorting of zymogens are still incompletely understood. Here, we investigated the role of proteoglycans in granule formation and secretion of zymogens in pancreatic AR42J cells, an acinar model system. Cupromeronic Blue cytochemistry and biochemical studies revealed an association of proteoglycans primarily with the granule membrane. Removal of proteoglycans by carbonate treatment led to a loss of membrane curvature indicating a supportive role in the maintenance of membrane shape and stability. Chemical inhibition of proteoglycan synthesis impaired the formation of normal electron-dense granules in AR42J cells and resulted in the formation of unusually small granule structures. These structures still contained the zymogen carboxypeptidase, a cargo molecule of secretory granules, but migrated to lighter fractions after density gradient centrifugation. Furthermore, the basal secretion of amylase was increased in AR42J cells after inhibitor treatment. In addition, irregular-shaped granules appeared in pancreatic lobules. We conclude that the assembly of a proteoglycan scaffold at the ZG membrane is supporting efficient packaging of zymogens and the proper formation of stimulus-competent storage granules in acinar cells of the pancreas.
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Affiliation(s)
- Miguel Aroso
- Centre for Cell Biology and Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - Brigitte Agricola
- Department of Cell Biology and Cell Pathology, University of Marburg, 35037, Marburg, Germany
| | - Christian Hacker
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK
| | - Michael Schrader
- Centre for Cell Biology and Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal. .,College of Life and Environmental Sciences, Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
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22
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Chang J, Klute MJ, Tower RJ, Mast FD, Dacks JB, Rachubinski RA. An ancestral role in peroxisome assembly is retained by the divisional peroxin Pex11 in the yeast Yarrowia lipolytica. J Cell Sci 2015; 128:1327-40. [PMID: 25663700 DOI: 10.1242/jcs.157743] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The peroxin Pex11 has a recognized role in peroxisome division. Pex11p remodels and elongates peroxisomal membranes prior to the recruitment of dynamin-related GTPases that act in membrane scission to divide peroxisomes. We performed a comprehensive comparative genomics survey to understand the significance of the evolution of the Pex11 protein family in yeast and other eukaryotes. Pex11p is highly conserved and ancestral, and has undergone numerous lineage-specific duplications, whereas other Pex11 protein family members are fungal-specific innovations. Functional characterization of the in-silico-predicted Pex11 protein family members of the yeast Yarrowia lipolytica, i.e. Pex11p, Pex11Cp and Pex11/25p, demonstrated that Pex11Cp and Pex11/25p have a role in the regulation of peroxisome size and number characteristic of Pex11 protein family members. Unexpectedly, deletion of PEX11 in Y. lipolytica produces cells that lack morphologically identifiable peroxisomes, mislocalize peroxisomal matrix proteins and preferentially degrade peroxisomal membrane proteins, i.e. they exhibit the classical pex mutant phenotype, which has not been observed previously in cells deleted for the PEX11 gene. Our results are consistent with an unprecedented role for Pex11p in de novo peroxisome assembly.
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Affiliation(s)
- Jinlan Chang
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Mary J Klute
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Robert J Tower
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Fred D Mast
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Joel B Dacks
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
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23
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Abstract
The endoplasmic reticulum (ER) is required for the de novo biogenesis of peroxisomes in mammalian cells. However, its role in peroxisome maintenance is unclear. To explore ER involvement in the maintenance of peroxisomes, we redirect a peroxisomal membrane protein (PMP), PEX3, to directly target to the ER using the N-terminal ER signal sequence from preprolactin. Using biochemical techniques and fluorescent imaging, we find that ER-targeting PEX3 (ssPEX3) is continuously imported into pre-existing peroxisomes. This suggests that the ER constitutively provides membrane proteins and associated lipids to pre-existing peroxisomes. Using quantitative time-lapse live-cell fluorescence microscopy applied to cells that were either depleted of or exogenously expressing PEX16, we find that PEX16 mediates the peroxisomal trafficking of two distinct peroxisomal membrane proteins, PEX3 and PMP34, via the ER. These results not only provide insight into peroxisome maintenance and PMP trafficking in mammalian cells but also highlight important similarities and differences in the mechanisms of PMP import between the mammalian and yeast systems.
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Affiliation(s)
- Alexander Aranovich
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Rong Hua
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Andrew D Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 1Z9, Canada
| | - Peter K Kim
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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24
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Chang J, Tower RJ, Lancaster DL, Rachubinski RA. Dynein light chain interaction with the peroxisomal import docking complex modulates peroxisome biogenesis in yeast. J Cell Sci 2013; 126:4698-706. [PMID: 23943868 DOI: 10.1242/jcs.129056] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dynein is a large macromolecular motor complex that moves cargo along microtubules. A motor-independent role for the light chain of dynein, Dyn2p, in peroxisome biology in Saccharomyces cerevisiae was suggested from its interaction with Pex14p, a component of the peroxisomal matrix protein import docking complex. Here we show that cells of the yeast Yarrowia lipolytica deleted for the gene encoding the homologue of Dyn2p are impaired in peroxisome function and biogenesis. These cells exhibit compromised growth on medium containing oleic acid as the carbon source, the metabolism of which requires functional peroxisomes. Their peroxisomes have abnormal morphology, atypical matrix protein localization, and an absence of proteolytic processing of the matrix enzyme thiolase, which normally occurs upon its import into the peroxisome. We also show physical and genetic interactions between Dyn2p and members of the docking complex, particularly Pex17p. Together, our results demonstrate a role for Dyn2p in the assembly of functional peroxisomes and provide evidence that Dyn2p acts in cooperation with the peroxisomal matrix protein import docking complex to effect optimal matrix protein import.
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Affiliation(s)
- Jinlan Chang
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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25
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Abstract
In this chapter, we summarize recent theoretical efforts to address a variety of issues in Golgi morphogenesis: de novo biogenesis of compartments with precise chemical identity, the transport of proteins through the Golgi, the maintenance of chemical identity, and the morphology of Golgi compartments, from the perspective of nonequilibrium physics.
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Affiliation(s)
- Pierre Sens
- Laboratoire Gulliver, CNRS-ESPCI, UMR 7083, 75231 Paris, France
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