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Enkler L, Szentgyörgyi V, Pennauer M, Prescianotto-Baschong C, Riezman I, Wiesyk A, Avraham RE, Spiess M, Zalckvar E, Kucharczyk R, Riezman H, Spang A. Arf1 coordinates fatty acid metabolism and mitochondrial homeostasis. Nat Cell Biol 2023; 25:1157-1172. [PMID: 37400497 PMCID: PMC10415182 DOI: 10.1038/s41556-023-01180-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [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: 01/12/2022] [Accepted: 06/05/2023] [Indexed: 07/05/2023]
Abstract
Lipid mobilization through fatty acid β-oxidation is a central process essential for energy production during nutrient shortage. In yeast, this catabolic process starts in the peroxisome from where β-oxidation products enter mitochondria and fuel the tricarboxylic acid cycle. Little is known about the physical and metabolic cooperation between these organelles. Here we found that expression of fatty acid transporters and of the rate-limiting enzyme involved in β-oxidation is decreased in cells expressing a hyperactive mutant of the small GTPase Arf1, leading to an accumulation of fatty acids in lipid droplets. Consequently, mitochondria became fragmented and ATP synthesis decreased. Genetic and pharmacological depletion of fatty acids phenocopied the arf1 mutant mitochondrial phenotype. Although β-oxidation occurs in both mitochondria and peroxisomes in mammals, Arf1's role in fatty acid metabolism is conserved. Together, our results indicate that Arf1 integrates metabolism into energy production by regulating fatty acid storage and utilization, and presumably organelle contact sites.
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Affiliation(s)
| | | | | | | | - Isabelle Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Aneta Wiesyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Reut Ester Avraham
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Einat Zalckvar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Howard Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland.
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2
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Lismont C, Revenco I, Li H, Costa CF, Lenaerts L, Hussein MAF, De Bie J, Knoops B, Van Veldhoven PP, Derua R, Fransen M. Peroxisome-Derived Hydrogen Peroxide Modulates the Sulfenylation Profiles of Key Redox Signaling Proteins in Flp-In T-REx 293 Cells. Front Cell Dev Biol 2022; 10:888873. [PMID: 35557958 PMCID: PMC9086853 DOI: 10.3389/fcell.2022.888873] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 03/31/2022] [Indexed: 12/12/2022] Open
Abstract
The involvement of peroxisomes in cellular hydrogen peroxide (H2O2) metabolism has been a central theme since their first biochemical characterization by Christian de Duve in 1965. While the role of H2O2 substantially changed from an exclusively toxic molecule to a signaling messenger, the regulatory role of peroxisomes in these signaling events is still largely underappreciated. This is mainly because the number of known protein targets of peroxisome-derived H2O2 is rather limited and testing of specific targets is predominantly based on knowledge previously gathered in related fields of research. To gain a broader and more systematic insight into the role of peroxisomes in redox signaling, new approaches are urgently needed. In this study, we have combined a previously developed Flp-In T-REx 293 cell system in which peroxisomal H2O2 production can be modulated with a yeast AP-1-like-based sulfenome mining strategy to inventory protein thiol targets of peroxisome-derived H2O2 in different subcellular compartments. By using this approach, we identified more than 400 targets of peroxisome-derived H2O2 in peroxisomes, the cytosol, and mitochondria. We also observed that the sulfenylation kinetics profiles of key targets belonging to different protein families (e.g., peroxiredoxins, annexins, and tubulins) can vary considerably. In addition, we obtained compelling but indirect evidence that peroxisome-derived H2O2 may oxidize at least some of its targets (e.g., transcription factors) through a redox relay mechanism. In conclusion, given that sulfenic acids function as key intermediates in H2O2 signaling, the findings presented in this study provide valuable insight into how peroxisomes may be integrated into the cellular H2O2 signaling network.
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Affiliation(s)
- Celien Lismont
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Iulia Revenco
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Hongli Li
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Cláudio F Costa
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Lisa Lenaerts
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Mohamed A F Hussein
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Jonas De Bie
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Bernard Knoops
- Group of Animal Molecular and Cellular Biology, Institute of Biomolecular Science and Technology (LIBST), Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Paul P Van Veldhoven
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Rita Derua
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,SyBioMa, KU Leuven, Leuven, Belgium
| | - Marc Fransen
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
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3
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Garikapati V, Colasante C, Baumgart-Vogt E, Spengler B. Sequential lipidomic, metabolomic, and proteomic analyses of serum, liver, and heart tissue specimens from peroxisomal biogenesis factor 11α knockout mice. Anal Bioanal Chem 2022; 414:2235-2250. [PMID: 35083512 PMCID: PMC8821073 DOI: 10.1007/s00216-021-03860-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [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: 12/30/2020] [Revised: 11/25/2021] [Accepted: 12/20/2021] [Indexed: 12/16/2022]
Abstract
Peroxisomes are versatile single membrane-enclosed cytoplasmic organelles, involved in reactive oxygen species (ROS) and lipid metabolism and diverse other metabolic processes. Peroxisomal disorders result from mutations in Pex genes-encoded proteins named peroxins (PEX proteins) and single peroxisomal enzyme deficiencies. The PEX11 protein family (α, β, and γ isoforms) plays an important role in peroxisomal proliferation and fission. However, their specific functions and the metabolic impact caused by their deficiencies have not been precisely characterized. To understand the systemic molecular alterations caused by peroxisomal defects, here we utilized untreated peroxisomal biogenesis factor 11α knockout (Pex11α KO) mouse model and performed serial relative-quantitative lipidomic, metabolomic, and proteomic analyses of serum, liver, and heart tissue homogenates. We demonstrated significant specific changes in the abundances of multiple lipid species, polar metabolites, and proteins and dysregulated metabolic pathways in distinct biological specimens of the Pex11α KO adult mice in comparison to the wild type (WT) controls. Overall, the present study reports comprehensive semi-quantitative molecular omics information of the Pex11α KO mice, which might serve in the future as a reference for a better understanding of the roles of Pex11α and underlying pathophysiological mechanisms of peroxisomal biogenesis disorders.
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Affiliation(s)
- Vannuruswamy Garikapati
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, 35392, Giessen, Germany.,Institute for Anatomy and Cell Biology II, Division of Medical Cell Biology, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Claudia Colasante
- Institute for Anatomy and Cell Biology II, Division of Medical Cell Biology, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Eveline Baumgart-Vogt
- Institute for Anatomy and Cell Biology II, Division of Medical Cell Biology, Justus Liebig University Giessen, 35392, Giessen, Germany.
| | - Bernhard Spengler
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, 35392, Giessen, Germany.
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4
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Farré JC, Mahalingam SS, Proietto M, Subramani S. Peroxisome biogenesis, membrane contact sites, and quality control. EMBO Rep 2018; 20:embr.201846864. [PMID: 30530632 DOI: 10.15252/embr.201846864] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [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: 08/04/2018] [Revised: 10/08/2018] [Accepted: 11/16/2018] [Indexed: 12/19/2022] Open
Abstract
Peroxisomes are conserved organelles of eukaryotic cells with important roles in cellular metabolism, human health, redox homeostasis, as well as intracellular metabolite transfer and signaling. We review here the current status of the different co-existing modes of biogenesis of peroxisomal membrane proteins demonstrating the fascinating adaptability in their targeting and sorting pathways. While earlier studies focused on peroxisomes as autonomous organelles, the necessity of the ER and potentially even mitochondria as sources of peroxisomal membrane proteins and lipids has come to light in recent years. Additionally, the intimate physical juxtaposition of peroxisomes with other organelles has transitioned from being viewed as random encounters to a growing appreciation of the expanding roles of such inter-organellar membrane contact sites in metabolic and regulatory functions. Peroxisomal quality control mechanisms have also come of age with a variety of mechanisms operating both during biogenesis and in the cellular response to environmental cues.
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Affiliation(s)
- Jean-Claude Farré
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
| | - Shanmuga S Mahalingam
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
| | - Marco Proietto
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
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5
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Yofe I, Soliman K, Chuartzman SG, Morgan B, Weill U, Yifrach E, Dick TP, Cooper SJ, Ejsing CS, Schuldiner M, Zalckvar E, Thoms S. Pex35 is a regulator of peroxisome abundance. J Cell Sci 2017; 130:791-804. [PMID: 28049721 DOI: 10.1242/jcs.187914] [Citation(s) in RCA: 21] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 11/24/2016] [Indexed: 12/12/2022] Open
Abstract
Peroxisomes are cellular organelles with vital functions in lipid, amino acid and redox metabolism. The cellular formation and dynamics of peroxisomes are governed by PEX genes; however, the regulation of peroxisome abundance is still poorly understood. Here, we use a high-content microscopy screen in Saccharomyces cerevisiae to identify new regulators of peroxisome size and abundance. Our screen led to the identification of a previously uncharacterized gene, which we term PEX35, which affects peroxisome abundance. PEX35 encodes a peroxisomal membrane protein, a remote homolog to several curvature-generating human proteins. We systematically characterized the genetic and physical interactome as well as the metabolome of mutants in PEX35, and we found that Pex35 functionally interacts with the vesicle-budding-inducer Arf1. Our results highlight the functional interaction between peroxisomes and the secretory pathway.
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Affiliation(s)
- Ido Yofe
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Kareem Soliman
- Department of Child and Adolescent Health, University Medical Center, Göttingen 37075, Germany
| | - Silvia G Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Bruce Morgan
- Department of Cellular Biochemistry, University of Kaiserslautern, Kaiserslautern 67653, Germany.,Division of Redox Regulation, ZMBH-DKFZ Alliance, German Cancer Research Center (DKFZ), Heidelberg 69121, Germany
| | - Uri Weill
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Eden Yifrach
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tobias P Dick
- Division of Redox Regulation, ZMBH-DKFZ Alliance, German Cancer Research Center (DKFZ), Heidelberg 69121, Germany
| | - Sara J Cooper
- HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Christer S Ejsing
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense 5230, Denmark
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Einat Zalckvar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sven Thoms
- Department of Child and Adolescent Health, University Medical Center, Göttingen 37075, Germany
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6
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Hua R, Kim PK. Multiple paths to peroxisomes: Mechanism of peroxisome maintenance in mammals. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2016; 1863:881-91. [DOI: 10.1016/j.bbamcr.2015.09.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 09/18/2015] [Accepted: 09/21/2015] [Indexed: 12/19/2022]
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7
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Just WW, Peränen J. Small GTPases in peroxisome dynamics. Biochim Biophys Acta 2016; 1863:1006-13. [PMID: 26775587 DOI: 10.1016/j.bbamcr.2016.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 01/05/2016] [Accepted: 01/07/2016] [Indexed: 12/12/2022]
Abstract
In this review article, we summarize current knowledge on peroxisome biogenesis/functions and the role that small GTPases may play in these processes. Precise intracellular distribution of cell organelles requires their regulated association to microtubules and the actin cytoskeleton. In this respect, RhoGDP/RhoGTP favor binding of peroxisomes to microtubules and actin filaments. In its GTP-bound form, RhoA activates a regulatory cascade involving Rho kinaseII and non-muscle myosinIIA. Such interactions frequently depend on phosphoinositides (PIs) of which PI4P, PI(4,5)P2, and PI(3,5)P2 were found to be present in the peroxisomal membrane. PIs are pivotal determinants of intracellular signaling and known to regulate a wide range of cellular functions. In many of these functions, small GTPases are implicated. The small GTPase ADP-ribosylation factor 1 (Arf1), for example, is known to stimulate synthesis of PI4P and PI(4,5)P2 on the Golgi to regulate protein and lipid sorting. In vitro binding assays localized Arf1 and the COPI complex to peroxisomes. In light of the recent discussion of pre-peroxisomal vesicle generation at the ER, peroxisomal Arf1-COPI vesicles may serve retrograde transport of ER-resident components. A mass spectrometric screen localized various Rab proteins to peroxisomes. Overexpression of these proteins in combination with laser-scanning fluorescence microscopy co-localized Rab6, Rab8, Rab10, Rab14, and Rab18 with peroxisomal structures. By analogy to the role these proteins play in other organelle dynamics, we may envisage what the function of these proteins may be in relation to the peroxisomal compartment.
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8
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Kohlwein SD, Veenhuis M, van der Klei IJ. Lipid droplets and peroxisomes: key players in cellular lipid homeostasis or a matter of fat--store 'em up or burn 'em down. Genetics 2013; 193:1-50. [PMID: 23275493 DOI: 10.1534/genetics.112.143362] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Lipid droplets (LDs) and peroxisomes are central players in cellular lipid homeostasis: some of their main functions are to control the metabolic flux and availability of fatty acids (LDs and peroxisomes) as well as of sterols (LDs). Both fatty acids and sterols serve multiple functions in the cell—as membrane stabilizers affecting membrane fluidity, as crucial structural elements of membrane-forming phospholipids and sphingolipids, as protein modifiers and signaling molecules, and last but not least, as a rich carbon and energy source. In addition, peroxisomes harbor enzymes of the malic acid shunt, which is indispensable to regenerate oxaloacetate for gluconeogenesis, thus allowing yeast cells to generate sugars from fatty acids or nonfermentable carbon sources. Therefore, failure of LD and peroxisome biogenesis and function are likely to lead to deregulated lipid fluxes and disrupted energy homeostasis with detrimental consequences for the cell. These pathological consequences of LD and peroxisome failure have indeed sparked great biomedical interest in understanding the biogenesis of these organelles, their functional roles in lipid homeostasis, interaction with cellular metabolism and other organelles, as well as their regulation, turnover, and inheritance. These questions are particularly burning in view of the pandemic development of lipid-associated disorders worldwide.
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Cui S, Fukao Y, Mano S, Yamada K, Hayashi M, Nishimura M. Proteomic analysis reveals that the Rab GTPase RabE1c is involved in the degradation of the peroxisomal protein receptor PEX7 (peroxin 7). J Biol Chem 2013; 288:6014-23. [PMID: 23297417 DOI: 10.1074/jbc.m112.438143] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biogenesis of peroxisomes is mediated by peroxins (PEXs). PEX7 is a cytosolic receptor that imports peroxisomal targeting signal type 2 (PTS2)-containing proteins. Although PEX7 is important for protein transport, the mechanisms that mediate its function are unknown. In this study, we performed proteomic analysis to identify PEX7-binding proteins using transgenic Arabidopsis expressing green fluorescent protein (GFP)-tagged PEX7. Our analysis identified RabE1c, a small GTPase, as a PEX7 binding partner. In vivo analysis revealed that GTP-bound RabE1c binds to PEX7 and that a subset of RabE1c localizes to peroxisomes and interacts with PEX7 on the peroxisome membrane. Unlike endogenous PEX7, which is predominantly localized to the cytosol, GFP-PEX7 accumulates abnormally on the peroxisomal membrane and induces degradation of endogenous PEX7, concomitant with a reduction in import of PTS2-containing proteins and decreased peroxisomal β-oxidation activity. Thus, GFP-PEX7 on the peroxisomal membrane exerts a dominant negative effect. Mutation of RabE1c restored endogenous PEX7 protein expression and import of PTS2-containing proteins as well as peroxisomal β-oxidation activity. Treatment with proteasome inhibitors also restored endogenous PEX7 protein levels in GFP-PEX7-expressing seedlings. Based on these findings, we conclude that RabE1c binds PEX7 and facilitates PEX7 degradation in the presence of immobile GFP-PEX7 accumulated at the membrane.
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Affiliation(s)
- Songkui Cui
- Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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10
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Amaral A, Castillo J, Estanyol JM, Ballescà JL, Ramalho-Santos J, Oliva R. Human sperm tail proteome suggests new endogenous metabolic pathways. Mol Cell Proteomics 2012; 12:330-42. [PMID: 23161514 DOI: 10.1074/mcp.m112.020552] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Proteomic studies are contributing greatly to our understanding of the sperm cell, and more detailed descriptions are expected to clarify additional cellular and molecular sperm attributes. The aim of this study was to characterize the subcellular proteome of the human sperm tail and, hopefully, identify less concentrated proteins (not found in whole cell proteome studies). Specifically, we were interested in characterizing the sperm metabolic proteome and gaining new insights into the sperm metabolism issue. Sperm were isolated from normozoospermic semen samples and depleted of any contaminating leukocytes. Tail fractions were obtained by means of sonication followed by sucrose-gradient ultracentrifugation, and their purity was confirmed via various techniques. Liquid chromatography and tandem mass spectrometry of isolated sperm tail peptides resulted in the identification of 1049 proteins, more than half of which had not been previously described in human sperm. The categorization of proteins according to their function revealed two main groups: proteins related to metabolism and energy production (26%), and proteins related to sperm tail structure and motility (11%). Interestingly, a great proportion of the metabolic proteome (24%) comprised enzymes involved in lipid metabolism, including enzymes for mitochondrial beta-oxidation. Unexpectedly, we also identified various peroxisomal proteins, some of which are known to be involved in the oxidation of very long chain fatty acids. Analysis of our data using Reactome suggests that both mitochondrial and peroxisomal pathways might indeed be active in sperm, and that the use of fatty acids as fuel might be more preponderant than previously thought. In addition, incubation of sperm with the fatty acid oxidation inhibitor etomoxir resulted in a significant decrease in sperm motility. Contradicting a common concept in the literature, we suggest that the male gamete might have the capacity to obtain energy from endogenous pools, and thus to adapt to putative exogenous fluctuations.
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Affiliation(s)
- Alexandra Amaral
- Human Genetics Research Group, IDIBAPS, Faculty of Medicine, University of Barcelona, Casanova 143, 08036 Barcelona, Spain
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11
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Lynes EM, Simmen T. Urban planning of the endoplasmic reticulum (ER): how diverse mechanisms segregate the many functions of the ER. Biochim Biophys Acta 2011; 1813:1893-905. [PMID: 21756943 PMCID: PMC7172674 DOI: 10.1016/j.bbamcr.2011.06.011] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/22/2011] [Accepted: 06/23/2011] [Indexed: 12/21/2022]
Abstract
The endoplasmic reticulum (ER) is the biggest organelle in most cell types, but its characterization as an organelle with a continuous membrane belies the fact that the ER is actually an assembly of several, distinct membrane domains that execute diverse functions. Almost 20 years ago, an essay by Sitia and Meldolesi first listed what was known at the time about domain formation within the ER. In the time that has passed since, additional ER domains have been discovered and characterized. These include the mitochondria-associated membrane (MAM), the ER quality control compartment (ERQC), where ER-associated degradation (ERAD) occurs, and the plasma membrane-associated membrane (PAM). Insight has been gained into the separation of nuclear envelope proteins from the remainder of the ER. Research has also shown that the biogenesis of peroxisomes and lipid droplets occurs on specialized membranes of the ER. Several studies have shown the existence of specific marker proteins found on all these domains and how they are targeted there. Moreover, a first set of cytosolic ER-associated sorting proteins, including phosphofurin acidic cluster sorting protein 2 (PACS-2) and Rab32 have been identified. Intra-ER targeting mechanisms appear to be superimposed onto ER retention mechanisms and rely on transmembrane and cytosolic sequences. The crucial roles of ER domain formation for cell physiology are highlighted with the specific targeting of the tumor metastasis regulator gp78 to ERAD-mediating membranes or of the promyelocytic leukemia protein to the MAM.
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Affiliation(s)
- Emily M Lynes
- Department of Cell Biology, University of Alberta, Alberta, Canada
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12
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Opaliński Ł, Veenhuis M, van der Klei IJ. Peroxisomes: Membrane events accompanying peroxisome proliferation. Int J Biochem Cell Biol 2011; 43:847-51. [DOI: 10.1016/j.biocel.2011.03.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 03/03/2011] [Accepted: 03/07/2011] [Indexed: 10/18/2022]
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