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Maruzs T, Feil-Börcsök D, Lakatos E, Juhász G, Blastyák A, Hargitai D, Jean S, Lőrincz P, Juhász G. Interaction of the sorting nexin 25 homologue Snazarus with Rab11 balances endocytic and secretory transport and maintains the ultrafiltration diaphragm in nephrocytes. Mol Biol Cell 2023; 34:ar87. [PMID: 37314856 PMCID: PMC10398886 DOI: 10.1091/mbc.e22-09-0421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 06/05/2023] [Accepted: 06/06/2023] [Indexed: 06/15/2023] Open
Abstract
Proper balance of exocytosis and endocytosis is important for the maintenance of plasma membrane lipid and protein homeostasis. This is especially critical in human podocytes and the podocyte-like Drosophila nephrocytes that both use a delicate diaphragm system with evolutionarily conserved components for ultrafiltration. Here, we show that the sorting nexin 25 homologue Snazarus (Snz) binds to Rab11 and localizes to Rab11-positive recycling endosomes in Drosophila nephrocytes, unlike in fat cells where it is present in plasma membrane/lipid droplet/endoplasmic reticulum contact sites. Loss of Snz leads to redistribution of Rab11 vesicles from the cell periphery and increases endocytic activity in nephrocytes. These changes are accompanied by defects in diaphragm protein distribution that resemble those seen in Rab11 gain-of-function cells. Of note, co-overexpression of Snz rescues diaphragm defects in Rab11 overexpressing cells, whereas snz knockdown in Rab11 overexpressing nephrocytes or simultaneous knockdown of snz and tbc1d8b encoding a Rab11 GTPase-activating protein (GAP) leads to massive expansion of the lacunar system that contains mislocalized diaphragm components: Sns and Pyd/ZO-1. We find that loss of Snz enhances while its overexpression impairs secretion, which, together with genetic epistasis analyses, suggest that Snz counteracts Rab11 to maintain the diaphragm via setting the proper balance of exocytosis and endocytosis.
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Affiliation(s)
- Tamás Maruzs
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
| | - Dalma Feil-Börcsök
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
- Doctoral School of Biology, University of Szeged, Szeged, H-6726 Hungary
| | - Enikő Lakatos
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
- Doctoral School of Biology, University of Szeged, Szeged, H-6726 Hungary
| | - Gábor Juhász
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
| | - András Blastyák
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
| | - Dávid Hargitai
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, H-1117 Hungary
| | - Steve Jean
- Department of Anatomy and Cell Biology, University of Sherbrooke, Sherbrooke, J1E 4K8 Canada
| | - Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, H-1117 Hungary
| | - Gábor Juhász
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, H-1117 Hungary
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2
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Ugrankar-Banerjee R, Tran S, Bowerman J, Kovalenko A, Paul B, Henne WM. The fat body cortical actin network regulates Drosophila inter-organ nutrient trafficking, signaling, and adipose cell size. eLife 2023; 12:e81170. [PMID: 37144872 PMCID: PMC10202455 DOI: 10.7554/elife.81170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 04/25/2023] [Indexed: 05/06/2023] Open
Abstract
Defective nutrient storage and adipocyte enlargement (hypertrophy) are emerging features of metabolic syndrome and type 2 diabetes. Within adipose tissues, how the cytoskeletal network contributes to adipose cell size, nutrient uptake, fat storage, and signaling remain poorly understood. Utilizing the Drosophila larval fat body (FB) as a model adipose tissue, we show that a specific actin isoform-Act5C-forms the cortical actin network necessary to expand adipocyte cell size for biomass storage in development. Additionally, we uncover a non-canonical role for the cortical actin cytoskeleton in inter-organ lipid trafficking. We find Act5C localizes to the FB cell surface and cell-cell boundaries, where it intimately contacts peripheral LDs (pLDs), forming a cortical actin network for cell architectural support. FB-specific loss of Act5C perturbs FB triglyceride (TG) storage and LD morphology, resulting in developmentally delayed larvae that fail to develop into flies. Utilizing temporal RNAi-depletion approaches, we reveal that Act5C is indispensable post-embryogenesis during larval feeding as FB cells expand and store fat. Act5C-deficient FBs fail to grow, leading to lipodystrophic larvae unable to accrue sufficient biomass for complete metamorphosis. In line with this, Act5C-deficient larvae display blunted insulin signaling and reduced feeding. Mechanistically, we also show this diminished signaling correlates with decreased lipophorin (Lpp) lipoprotein-mediated lipid trafficking, and find Act5C is required for Lpp secretion from the FB for lipid transport. Collectively, we propose that the Act5C-dependent cortical actin network of Drosophila adipose tissue is required for adipose tissue size-expansion and organismal energy homeostasis in development, and plays an essential role in inter-organ nutrient transport and signaling.
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Affiliation(s)
| | - Son Tran
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
| | - Jade Bowerman
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
| | | | - Blessy Paul
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
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3
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Abstract
SNX-RGS proteins are molecular tethers localized to multiple interorganelle contact sites that exhibit roles in cellular metabolism. Here, we highlight recent findings on these proteins and discuss their emerging roles in metabolism, human disease, and lipid trafficking.
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Affiliation(s)
- Hanaa Hariri
- Department of Biological Sciences, Wayne State University, Detroit, MI
| | - W. Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX
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4
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Lauzier A, Bossanyi MF, Larcher R, Nassari S, Ugrankar R, Henne WM, Jean S. Snazarus and its human ortholog SNX25 modulate autophagic flux. J Cell Sci 2022; 135:273525. [PMID: 34821359 DOI: 10.1242/jcs.258733] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 11/12/2021] [Indexed: 12/26/2022] Open
Abstract
Macroautophagy, the degradation and recycling of cytosolic components in the lysosome, is an important cellular mechanism. It is a membrane-mediated process that is linked to vesicular trafficking events. The sorting nexin (SNX) protein family controls the sorting of a large array of cargoes, and various SNXs impact autophagy. To improve our understanding of their functions in vivo, we screened all Drosophila SNXs using inducible RNA interference in the fat body. Significantly, depletion of Snazarus (Snz) led to decreased autophagic flux. Interestingly, we observed altered distribution of Vamp7-positive vesicles with Snz depletion, and the roles of Snz were conserved in human cells. SNX25, the closest human ortholog to Snz, regulates both VAMP8 endocytosis and lipid metabolism. Through knockout-rescue experiments, we demonstrate that these activities are dependent on specific SNX25 domains and that the autophagic defects seen upon SNX25 loss can be rescued by ethanolamine addition. We also demonstrate the presence of differentially spliced forms of SNX14 and SNX25 in cancer cells. This work identifies a conserved role for Snz/SNX25 as a regulator of autophagic flux and reveals differential isoform expression between paralogs.
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Affiliation(s)
- Annie Lauzier
- Faculté de Médecine et des Sciences de la Santé, Département d'immunologie et de biologie cellulaire, Université de Sherbrooke, 3201, Rue Jean Mignault, Sherbrooke, Québec, CanadaJ1E 4K8
| | - Marie-France Bossanyi
- Faculté de Médecine et des Sciences de la Santé, Département d'immunologie et de biologie cellulaire, Université de Sherbrooke, 3201, Rue Jean Mignault, Sherbrooke, Québec, CanadaJ1E 4K8
| | - Raphaëlle Larcher
- Faculté de Médecine et des Sciences de la Santé, Département d'immunologie et de biologie cellulaire, Université de Sherbrooke, 3201, Rue Jean Mignault, Sherbrooke, Québec, CanadaJ1E 4K8
| | - Sonya Nassari
- Faculté de Médecine et des Sciences de la Santé, Département d'immunologie et de biologie cellulaire, Université de Sherbrooke, 3201, Rue Jean Mignault, Sherbrooke, Québec, CanadaJ1E 4K8
| | - Rupali Ugrankar
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Hary Lines Boulevard, Dallas, TX 75390, USA
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Hary Lines Boulevard, Dallas, TX 75390, USA
| | - Steve Jean
- Faculté de Médecine et des Sciences de la Santé, Département d'immunologie et de biologie cellulaire, Université de Sherbrooke, 3201, Rue Jean Mignault, Sherbrooke, Québec, CanadaJ1E 4K8
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5
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Paul B, Weeratunga S, Tillu VA, Hariri H, Henne WM, Collins BM. Structural Predictions of the SNX-RGS Proteins Suggest They Belong to a New Class of Lipid Transfer Proteins. Front Cell Dev Biol 2022; 10:826688. [PMID: 35223850 PMCID: PMC8864675 DOI: 10.3389/fcell.2022.826688] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/13/2022] [Indexed: 12/12/2022] Open
Abstract
Recent advances in protein structure prediction using machine learning such as AlphaFold2 and RosettaFold presage a revolution in structural biology. Genome-wide predictions of protein structures are providing unprecedented insights into their architecture and intradomain interactions, and applications have already progressed towards assessing protein complex formation. Here we present detailed analyses of the sorting nexin proteins that contain regulator of G-protein signalling domains (SNX-RGS proteins), providing a key example of the ability of AlphaFold2 to reveal novel structures with previously unsuspected biological functions. These large proteins are conserved in most eukaryotes and are known to associate with lipid droplets (LDs) and sites of LD-membrane contacts, with key roles in regulating lipid metabolism. They possess five domains, including an N-terminal transmembrane domain that anchors them to the endoplasmic reticulum, an RGS domain, a lipid interacting phox homology (PX) domain and two additional domains named the PXA and PXC domains of unknown structure and function. Here we report the crystal structure of the RGS domain of sorting nexin 25 (SNX25) and show that the AlphaFold2 prediction closely matches the experimental structure. Analysing the full-length SNX-RGS proteins across multiple homologues and species we find that the distant PXA and PXC domains in fact fold into a single unique structure that notably features a large and conserved hydrophobic pocket. The nature of this pocket strongly suggests a role in lipid or fatty acid binding, and we propose that these molecules represent a new class of conserved lipid transfer proteins.
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Affiliation(s)
- Blessy Paul
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Saroja Weeratunga
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Vikas A. Tillu
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Hanaa Hariri
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - W. Mike Henne
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Brett M. Collins
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
- *Correspondence: Brett M. Collins,
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6
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Tao X, Che Y, Li C, Ruan W, Xu J, Yu Y, Yang F, Wang J, Li H. Novel SNX13 Frameshift Variant in an Individual with Developmental Delay. Cytogenet Genome Res 2021; 161:514-519. [PMID: 34879376 DOI: 10.1159/000520296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/13/2021] [Indexed: 11/19/2022] Open
Abstract
Recently, an increasing number of genes have been associated with global developmental delay (GDD) and intellectual disability (ID). The sorting nexin (SNX) protein family plays multiple roles in protein trafficking and intracellular signaling. SNXs have been reported to be associated with several disorders, including Alzheimer disease and Down syndrome. Despite the growing evidence of an association of SNXs with neurodegeneration, SNX13 deficiency has not been associated with GDD or ID. In this study, we present the case of a 4-year-old boy with brain dysplasia and GDD, including language delay, cognitive delay, and dyskinesia. Exome sequencing revealed a 1-bp homozygous deletion in SNX13 (NM_015132.5: exon8: c.742_743del; p.Tyr248Leufs*20), which caused a frameshift and predicted early termination. Sanger sequencing confirmed that the variant was inherited from his parents respectively. Our findings associate SNX13 variation with GDD for the first time and provide a new GDD candidate gene.
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Affiliation(s)
- Xicheng Tao
- Department of Rehabilitation, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yueping Che
- Department of Rehabilitation, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Chenxi Li
- Department of Rehabilitation, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wencong Ruan
- Department of Rehabilitation, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jialu Xu
- Department of Rehabilitation, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yonglin Yu
- Department of Rehabilitation, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Fan Yang
- Cipher Gene, LLC, Beijing, China
| | - Jia Wang
- Cipher Gene, LLC, Beijing, China
| | - Haifeng Li
- Department of Rehabilitation, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
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7
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Renne MF, Hariri H. Lipid Droplet-Organelle Contact Sites as Hubs for Fatty Acid Metabolism, Trafficking, and Metabolic Channeling. Front Cell Dev Biol 2021; 9:726261. [PMID: 34595176 PMCID: PMC8477659 DOI: 10.3389/fcell.2021.726261] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/12/2021] [Indexed: 01/21/2023] Open
Abstract
Cells prepare for fluctuations in nutrient availability by storing energy in the form of neutral lipids in organelles called Lipid Droplets (LDs). Upon starvation, fatty acids (FAs) released from LDs are trafficked to different cellular compartments to be utilized for membrane biogenesis or as a source of energy. Despite the biochemical pathways being known in detail, the spatio-temporal regulation of FA synthesis, storage, release, and breakdown is not completely understood. Recent studies suggest that FA trafficking and metabolism are facilitated by inter-organelle contact sites that form between LDs and other cellular compartments such as the Endoplasmic Reticulum (ER), mitochondria, peroxisomes, and lysosomes. LD-LD contact sites are also sites where FAs are transferred in a directional manner to support LD growth and expansion. As the storage site of neutral lipids, LDs play a central role in FA homeostasis. In this mini review, we highlight the role of LD contact sites with other organelles in FA trafficking, channeling, and metabolism and discuss the implications for these pathways on cellular lipid and energy homeostasis.
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Affiliation(s)
- Mike F. Renne
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Hanaa Hariri
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
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8
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Vieira N, Rito T, Correia-Neves M, Sousa N. Sorting Out Sorting Nexins Functions in the Nervous System in Health and Disease. Mol Neurobiol 2021; 58:4070-4106. [PMID: 33931804 PMCID: PMC8280035 DOI: 10.1007/s12035-021-02388-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/05/2021] [Indexed: 12/18/2022]
Abstract
Endocytosis is a fundamental process that controls protein/lipid composition of the plasma membrane, thereby shaping cellular metabolism, sensing, adhesion, signaling, and nutrient uptake. Endocytosis is essential for the cell to adapt to its surrounding environment, and a tight regulation of the endocytic mechanisms is required to maintain cell function and survival. This is particularly significant in the central nervous system (CNS), where composition of neuronal cell surface is crucial for synaptic functioning. In fact, distinct pathologies of the CNS are tightly linked to abnormal endolysosomal function, and several genome wide association analysis (GWAS) and biochemical studies have identified intracellular trafficking regulators as genetic risk factors for such pathologies. The sorting nexins (SNXs) are a family of proteins involved in protein trafficking regulation and signaling. SNXs dysregulation occurs in patients with Alzheimer’s disease (AD), Down’s syndrome (DS), schizophrenia, ataxia and epilepsy, among others, establishing clear roles for this protein family in pathology. Interestingly, restoration of SNXs levels has been shown to trigger synaptic plasticity recovery in a DS mouse model. This review encompasses an historical and evolutionary overview of SNXs protein family, focusing on its organization, phyla conservation, and evolution throughout the development of the nervous system during speciation. We will also survey SNXs molecular interactions and highlight how defects on SNXs underlie distinct pathologies of the CNS. Ultimately, we discuss possible strategies of intervention, surveying how our knowledge about the fundamental processes regulated by SNXs can be applied to the identification of novel therapeutic avenues for SNXs-related disorders.
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Affiliation(s)
- Neide Vieira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal. .,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Teresa Rito
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Margarida Correia-Neves
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
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9
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Seong KH, Matsumura T, Shimada-Niwa Y, Niwa R, Kang S. The Drosophila Individual Activity Monitoring and Detection System (DIAMonDS). eLife 2020; 9:e58630. [PMID: 33168136 PMCID: PMC7655107 DOI: 10.7554/elife.58630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 10/04/2020] [Indexed: 12/20/2022] Open
Abstract
Here, we have developed DIAMonDS (Drosophila Individual Activity Monitoring and Detection System) comprising time-lapse imaging by a charge-coupled device (CCD) flatbed scanner and Sapphire, a novel algorithm and web application. DIAMonDS automatically and sequentially identified the transition time points of multiple life cycle events such as pupariation, eclosion, and death in individual flies at high temporal resolution and on a large scale. DIAMonDS performed simultaneous multiple scans to measure individual deaths (≤1152 flies per scanner) and pupariation and eclosion timings (≤288 flies per scanner) under various chemical exposures, environmental conditions, and genetic backgrounds. DIAMonDS correctly identified 74-85% of the pupariation and eclosion events and ~ 92% of the death events within ± 10 scanning frames. This system is a powerful tool for studying the influences of genetic and environmental factors on fruit flies and efficient, high-throughput genetic and chemical screening in drug discovery.
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Affiliation(s)
- Ki-Hyeon Seong
- RIKEN Cluster for Pioneering Research, RIKEN Tsukuba InstituteTsukubaJapan
- AMED-CREST, AMEDTokyoJapan
| | - Taishi Matsumura
- Graduate School of Science and Engineering, Yamagata University, JonanYonezawaJapan
| | - Yuko Shimada-Niwa
- AMED-CREST, AMEDTokyoJapan
- Life Science Center for Survival Dynamics, University of TsukubaTsukubaJapan
| | - Ryusuke Niwa
- AMED-CREST, AMEDTokyoJapan
- Life Science Center for Survival Dynamics, University of TsukubaTsukubaJapan
| | - Siu Kang
- AMED-CREST, AMEDTokyoJapan
- Graduate School of Science and Engineering, Yamagata University, JonanYonezawaJapan
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10
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Diverse species-specific phenotypic consequences of loss of function sorting nexin 14 mutations. Sci Rep 2020; 10:13763. [PMID: 32792680 PMCID: PMC7427099 DOI: 10.1038/s41598-020-70797-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 08/05/2020] [Indexed: 11/08/2022] Open
Abstract
Mutations in the SNX14 gene cause spinocerebellar ataxia, autosomal recessive 20 (SCAR20) in both humans and dogs. Studies implicating the phenotypic consequences of SNX14 mutations to be consequences of subcellular disruption to autophagy and lipid metabolism have been limited to in vitro investigation of patient-derived dermal fibroblasts, laboratory engineered cell lines and developmental analysis of zebrafish morphants. SNX14 homologues Snz (Drosophila) and Mdm1 (yeast) have also been conducted, demonstrated an important biochemical role during lipid biogenesis. In this study we report the effect of loss of SNX14 in mice, which resulted in embryonic lethality around mid-gestation due to placental pathology that involves severe disruption to syncytiotrophoblast cell differentiation. In contrast to other vertebrates, zebrafish carrying a homozygous, maternal zygotic snx14 genetic loss-of-function mutation were both viable and anatomically normal. Whilst no obvious behavioural effects were observed, elevated levels of neutral lipids and phospholipids resemble previously reported effects on lipid homeostasis in other species. The biochemical role of SNX14 therefore appears largely conserved through evolution while the consequences of loss of function varies between species. Mouse and zebrafish models therefore provide valuable insights into the functional importance of SNX14 with distinct opportunities for investigating its cellular and metabolic function in vivo.
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11
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Affiliation(s)
- Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster
- Cells-in-Motion Cluster of Excellence (EXC 1003—CiM), University of Münster
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12
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Hugenroth M, Bohnert M. Come a little bit closer! Lipid droplet-ER contact sites are getting crowded. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118603. [PMID: 31733263 DOI: 10.1016/j.bbamcr.2019.118603] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/26/2019] [Accepted: 10/29/2019] [Indexed: 12/12/2022]
Abstract
Not so long ago, contact sites between the endoplasmic reticulum (ER) and lipid droplets (LDs) were largely unexplored on a molecular level. In recent years however, numerous proteins have been identified that are enriched or exclusively located at the interfaces between LDs and the ER. These comprise members of protein classes typically found in diverse types of contacts, such as organelle tethers and lipid transfer proteins, but also proteins that have no similarities to known contact site machineries. This structurally heterogeneous group of contact site residents might be required to fulfill unique aspects of LD-ER contact biology, such as de novo LD biogenesis, and maintenance of lipidic connections between LDs and ER. Here, we summarize the current knowledge on the molecular components of this special organelle contact site, and discuss their features and functions.
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Affiliation(s)
- Marie Hugenroth
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Germany.
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13
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Ugrankar R, Bowerman J, Hariri H, Chandra M, Chen K, Bossanyi MF, Datta S, Rogers S, Eckert KM, Vale G, Victoria A, Fresquez J, McDonald JG, Jean S, Collins BM, Henne WM. Drosophila Snazarus Regulates a Lipid Droplet Population at Plasma Membrane-Droplet Contacts in Adipocytes. Dev Cell 2019; 50:557-572.e5. [PMID: 31422916 PMCID: PMC7446143 DOI: 10.1016/j.devcel.2019.07.021] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 04/22/2019] [Accepted: 07/17/2019] [Indexed: 01/22/2023]
Abstract
Adipocytes store nutrients as lipid droplets (LDs), but how they organize their LD stores to balance lipid uptake, storage, and mobilization remains poorly understood. Here, using Drosophila fat body (FB) adipocytes, we characterize spatially distinct LD populations that are maintained by different lipid pools. We identify peripheral LDs (pLDs) that make close contact with the plasma membrane (PM) and are maintained by lipophorin-dependent lipid trafficking. pLDs are distinct from larger cytoplasmic medial LDs (mLDs), which are maintained by FASN1-dependent de novo lipogenesis. We find that sorting nexin CG1514 or Snazarus (Snz) associates with pLDs and regulates LD homeostasis at ER-PM contact sites. Loss of SNZ perturbs pLD organization, whereas Snz over-expression drives LD expansion, triacylglyceride production, starvation resistance, and lifespan extension through a DESAT1-dependent pathway. We propose that Drosophila adipocytes maintain spatially distinct LD populations and identify Snz as a regulator of LD organization and inter-organelle crosstalk.
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Affiliation(s)
- Rupali Ugrankar
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jade Bowerman
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Mintu Chandra
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia, QLD 4072, Australia
| | - Kevin Chen
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia, QLD 4072, Australia
| | - Marie-France Bossanyi
- Department of Anatomy and Cell Biology, University of Sherbrooke, 2500 Boulevard de l'Universite, Sherbrooke, QC J1K 2R1, Canada
| | - Sanchari Datta
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Sean Rogers
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Kaitlyn M Eckert
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gonçalo Vale
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Alexia Victoria
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | | | - Jeffrey G McDonald
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Molecular Genetics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Steve Jean
- Department of Anatomy and Cell Biology, University of Sherbrooke, 2500 Boulevard de l'Universite, Sherbrooke, QC J1K 2R1, Canada
| | - Brett M Collins
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia, QLD 4072, Australia
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA.
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14
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Bryant D, Liu Y, Datta S, Hariri H, Seda M, Anderson G, Peskett E, Demetriou C, Sousa S, Jenkins D, Clayton P, Bitner-Glindzicz M, Moore GE, Henne WM, Stanier P. SNX14 mutations affect endoplasmic reticulum-associated neutral lipid metabolism in autosomal recessive spinocerebellar ataxia 20. Hum Mol Genet 2019; 27:1927-1940. [PMID: 29635513 DOI: 10.1093/hmg/ddy101] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/15/2018] [Indexed: 12/12/2022] Open
Abstract
Mutations in SNX14 cause the autosomal recessive cerebellar ataxia 20 (SCAR20). Mutations generally result in loss of protein although several coding region deletions have also been reported. Patient-derived fibroblasts show disrupted autophagy, but the precise function of SNX14 is unknown. The yeast homolog, Mdm1, functions in endoplasmic reticulum (ER)-lysosome/vacuole inter-organelle tethering, but functional conservation in mammals is still required. Here, we show that loss of SNX14 alters but does not block autophagic flux. In addition, we find that SNX14 is an ER-associated protein that functions in neutral lipid homeostasis and inter-organelle crosstalk. SNX14 requires its N-terminal transmembrane helices for ER localization, while the Phox homology (PX) domain is dispensable for subcellular localization. Both SNX14-mutant fibroblasts and SNX14KO HEK293 cells accumulate aberrant cytoplasmic vacuoles, suggesting defects in endolysosomal homeostasis. However, ER-late endosome/lysosome contact sites are maintained in SNX14KO cells, indicating that it is not a prerequisite for ER-endolysosomal tethering. Further investigation of SNX14- deficiency indicates general defects in neutral lipid metabolism. SNX14KO cells display distinct perinuclear accumulation of filipin in LAMP1-positive lysosomal structures indicating cholesterol accumulation. Consistent with this, SNX14KO cells display a slight but detectable decrease in cholesterol ester levels, which is exacerbated with U18666A. Finally, SNX14 associates with ER-derived lipid droplets (LD) following oleate treatment, indicating a role in ER-LD crosstalk. We therefore identify an important role for SNX14 in neutral lipid homeostasis between the ER, lysosomes and LDs that may provide an early intervention target to alleviate the clinical symptoms of SCAR20.
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Affiliation(s)
- Dale Bryant
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Yang Liu
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sanchari Datta
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marian Seda
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Glenn Anderson
- Histopathology Department, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Emma Peskett
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Charalambos Demetriou
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Sergio Sousa
- Serviço de Genética Medica, Hospital Pediatrico, Centro Hospitalar e Universitário de Coimbra, 3000-602 Coimbra, Portugal
| | - Dagan Jenkins
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Peter Clayton
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Maria Bitner-Glindzicz
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Gudrun E Moore
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Philip Stanier
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
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15
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Henne WM. Discovery and Roles of ER-Endolysosomal Contact Sites in Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 997:135-147. [PMID: 28815527 DOI: 10.1007/978-981-10-4567-7_10] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Inter-organelle membrane contact sites (MCSs) serve as unique microenvironments for the sensing and exchange of cellular metabolites and lipids. Though poorly defined, ER-endolysosomal contact sites are quickly becoming recognized as centers for inter-organelle lipid exchange and metabolic decision-making. Here, we review the discovery and current state of knowledge of ER-endolysosomal MCSs with particular focus on the molecular players that establish and/or utilize these contact sites in metabolism. We also discuss associations of ER-endolysosomal MCS-associated proteins in human disease, as well as the therapeutic promise these contact sites hold in modulating cellular physiology.
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Affiliation(s)
- William Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, 75013, USA.
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16
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Organelle remodeling at membrane contact sites. J Struct Biol 2016; 196:15-19. [PMID: 27181417 DOI: 10.1016/j.jsb.2016.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 01/17/2023]
Abstract
Cellular organelles must execute sophisticated biological processes to persist, and often communicate with one another to exchange metabolites and information. Recent studies suggest inter-organelle membrane contact sites (MCSs) are hubs for this cellular cross-talk. MCSs also govern membrane remodeling, thus controlling aspects of organelle shape, identity, and function. Here, we summarize three emerging phenomena that MCSs appear to govern: 1) organelle identity via the non-vesicular exchange of lipids, 2) mitochondrial shape and division, and 3) endosomal migration in response to sterol trafficking. We also discuss the role for ER-endolysosomal contact sites in cholesterol metabolism, and the potential biomedical importance this holds. Indeed, the emerging field inter-organellar cross-talk promises substantial advances in the fields of lipid metabolism and cell signaling.
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17
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Hariri H, Ugrankar R, Liu Y, Henne WM. Inter-organelle ER-endolysosomal contact sites in metabolism and disease across evolution. Commun Integr Biol 2016; 9:e1156278. [PMID: 27489577 PMCID: PMC4951168 DOI: 10.1080/19420889.2016.1156278] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/13/2016] [Indexed: 12/29/2022] Open
Abstract
Since their initial observation, contact sites formed between different organelles have transitioned from ignored curiosities to recognized centers for the exchange of metabolites and lipids. Contact formed between the ER and endomembrane system (eg. the plasma membrane, endosomes, and lysosomes) is of particular biomedical interest, as it governs aspects of lipid metabolism, organelle identity, and cell signaling. Here, we review the field of ER-endolysosomal communication from the perspective of three model systems: budding yeast, the fruit fly D. melanogaster, and mammals. From this broad perspective, inter-organelle communication displays a consistent role in metabolic regulation that was differentially tuned during the development of complex metazoan life. We also examine the current state of understanding of lipid exchange between organelles, and discuss molecular mechanisms by which this occurs.
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Affiliation(s)
- Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
| | - Rupali Ugrankar
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
| | - Yang Liu
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
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18
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Mas C, Norwood SJ, Bugarcic A, Kinna G, Leneva N, Kovtun O, Ghai R, Ona Yanez LE, Davis JL, Teasdale RD, Collins BM. Structural basis for different phosphoinositide specificities of the PX domains of sorting nexins regulating G-protein signaling. J Biol Chem 2014; 289:28554-68. [PMID: 25148684 DOI: 10.1074/jbc.m114.595959] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sorting nexins (SNXs) or phox homology (PX) domain containing proteins are central regulators of cell trafficking and signaling. A subfamily of PX domain proteins possesses two unique PX-associated domains, as well as a regulator of G protein-coupled receptor signaling (RGS) domain that attenuates Gαs-coupled G protein-coupled receptor signaling. Here we delineate the structural organization of these RGS-PX proteins, revealing a protein family with a modular architecture that is conserved in all eukaryotes. The one exception to this is mammalian SNX19, which lacks the typical RGS structure but preserves all other domains. The PX domain is a sensor of membrane phosphoinositide lipids and we find that specific sequence alterations in the PX domains of the mammalian RGS-PX proteins, SNX13, SNX14, SNX19, and SNX25, confer differential phosphoinositide binding preferences. Although SNX13 and SNX19 PX domains bind the early endosomal lipid phosphatidylinositol 3-phosphate, SNX14 shows no membrane binding at all. Crystal structures of the SNX19 and SNX14 PX domains reveal key differences, with alterations in SNX14 leading to closure of the binding pocket to prevent phosphoinositide association. Our findings suggest a role for alternative membrane interactions in spatial control of RGS-PX proteins in cell signaling and trafficking.
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Affiliation(s)
- Caroline Mas
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Suzanne J Norwood
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Andrea Bugarcic
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Genevieve Kinna
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Natalya Leneva
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Oleksiy Kovtun
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Rajesh Ghai
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Lorena E Ona Yanez
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Jasmine L Davis
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Rohan D Teasdale
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Brett M Collins
- From the Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
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19
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Abstract
Adipose tissue is formed at stereotypic times and locations in a diverse array of organisms. Once formed, the tissue is dynamic, responding to homeostatic and external cues and capable of a 15-fold expansion. The formation and maintenance of adipose tissue is essential to many biological processes and when perturbed leads to significant diseases. Despite this basic and clinical significance, understanding of the developmental biology of adipose tissue has languished. In this Review, we highlight recent efforts to unveil adipose developmental cues, adipose stem cell biology and the regulators of adipose tissue homeostasis and dynamism.
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Affiliation(s)
- Daniel C Berry
- Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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20
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Stenesen D, Suh JM, Seo J, Yu K, Lee KS, Kim JS, Min KJ, Graff JM. Adenosine nucleotide biosynthesis and AMPK regulate adult life span and mediate the longevity benefit of caloric restriction in flies. Cell Metab 2013; 17:101-12. [PMID: 23312286 PMCID: PMC3614013 DOI: 10.1016/j.cmet.2012.12.006] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 08/08/2012] [Accepted: 12/11/2012] [Indexed: 12/31/2022]
Abstract
A common thread among conserved life span regulators lies within intertwined roles in metabolism and energy homeostasis. We show that heterozygous mutations of AMP biosynthetic enzymes extend Drosophila life span. The life span benefit of these mutations depends upon increased AMP:ATP and ADP:ATP ratios and adenosine monophosphate-activated protein kinase (AMPK). Transgenic expression of AMPK in adult fat body or adult muscle, key metabolic tissues, extended life span, while AMPK RNAi reduced life span. Supplementing adenine, a substrate for AMP biosynthesis, to the diet of long-lived AMP biosynthesis mutants reversed life span extension. Remarkably, this simple change in diet also blocked the prolongevity effects of dietary restriction. These data establish AMP biosynthesis, adenosine nucleotide ratios, and AMPK as determinants of adult life span; provide a mechanistic link between cellular anabolism and energy sensing pathways; and indicate that dietary adenine manipulations might alter metabolism to influence animal life span.
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Affiliation(s)
- Drew Stenesen
- Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Jae Myoung Suh
- Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Gene Expression Laboratory, Salk Institute, La Jolla, CA 92037, USA
| | - Jin Seo
- Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Kweon Yu
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 305-806, Korea
| | - Kyu-Sun Lee
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 305-806, Korea
| | - Jong-Seok Kim
- Department of Biological Sciences, Inha University, Incheon, 402-751, Korea
| | - Kyung-Jin Min
- Department of Biological Sciences, Inha University, Incheon, 402-751, Korea
| | - Jonathan M. Graff
- Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- To whom correspondence should be addressed: NB5.118, 6000 Harry Hines Blvd., Dallas, TX 75390-9133. Tel: 214-648-1481; Fax: 214-648-1960;
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21
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Insights into the PX (phox-homology) domain and SNX (sorting nexin) protein families: structures, functions and roles in disease. Biochem J 2011; 441:39-59. [DOI: 10.1042/bj20111226] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mammalian genome encodes 49 proteins that possess a PX (phox-homology) domain, responsible for membrane attachment to organelles of the secretory and endocytic system via binding of phosphoinositide lipids. The PX domain proteins, most of which are classified as SNXs (sorting nexins), constitute an extremely diverse family of molecules that play varied roles in membrane trafficking, cell signalling, membrane remodelling and organelle motility. In the present review, we present an overview of the family, incorporating recent functional and structural insights, and propose an updated classification of the proteins into distinct subfamilies on the basis of these insights. Almost all PX domain proteins bind PtdIns3P and are recruited to early endosomal membranes. Although other specificities and localizations have been reported for a select few family members, the molecular basis for binding to other lipids is still not clear. The PX domain is also emerging as an important protein–protein interaction domain, binding endocytic and exocytic machinery, transmembrane proteins and many other molecules. A comprehensive survey of the molecular interactions governed by PX proteins highlights the functional diversity of the family as trafficking cargo adaptors and membrane-associated scaffolds regulating cell signalling. Finally, we examine the mounting evidence linking PX proteins to different disorders, in particular focusing on their emerging importance in both pathogen invasion and amyloid production in Alzheimer's disease.
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