1
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Laczkó-Dobos H, Bhattacharjee A, Maddali AK, Kincses A, Abuammar H, Sebők-Nagy K, Páli T, Dér A, Hegedűs T, Csordás G, Juhász G. PtdIns4P is required for the autophagosomal recruitment of STX17 (syntaxin 17) to promote lysosomal fusion. Autophagy 2024; 20:1639-1650. [PMID: 38411137 PMCID: PMC11210929 DOI: 10.1080/15548627.2024.2322493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 02/20/2024] [Indexed: 02/28/2024] Open
Abstract
The autophagosomal SNARE STX17 (syntaxin 17) promotes lysosomal fusion and degradation, but its autophagosomal recruitment is incompletely understood. Notably, PtdIns4P is generated on autophagosomes and promotes fusion through an unknown mechanism. Here we show that soluble recombinant STX17 is spontaneously recruited to negatively charged liposomes and adding PtdIns4P to liposomes containing neutral lipids is sufficient for its recruitment. Consistently, STX17 colocalizes with PtdIns4P-positive autophagosomes in cells, and specific inhibition of PtdIns4P synthesis on autophagosomes prevents its loading. Molecular dynamics simulations indicate that C-terminal positively charged amino acids establish contact with membrane bilayers containing negatively charged PtdIns4P. Accordingly, Ala substitution of Lys and Arg residues in the C terminus of STX17 abolishes membrane binding and impairs its autophagosomal recruitment. Finally, only wild type but not Ala substituted STX17 expression rescues the autophagosome-lysosome fusion defect of STX17 loss-of-function cells. We thus identify a key step of autophagosome maturation that promotes lysosomal fusion.Abbreviations: Cardiolipin: 1',3'-bis[1-palmitoyl-2-oleoyl-sn-glycero-3-phospho]-glycerol; DMSO: dimethyl sulfoxide; GST: glutathione S-transferase; GUV: giant unilamellar vesicles; LAMP1: lysosomal associated membrane protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PA: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate; PC/POPC: 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine; PG: 1-palmitoyl-2-linoleoyl-sn-glycero-3-phospho-(1'-rac-glycerol); PI: L-α-phosphatidylinositol; PI4K2A: phosphatidylinositol 4-kinase type 2 alpha; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; POPE/PE: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine; PS: 1-stearoyl-2-linoleoyl-sn-glycero-3-phospho-L-serine; PtdIns(3,5)P2: 1,2-dioleoyl-sn-glycero-3-phospho-(1"-myo-inositol-3',5'-bisphosphate); PtdIns3P: 1,2- dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol-3'-phosphate); PtdIns4P: 1,2-dioleoyl-sn-glycero-3-phospho-(1"-myo-inositol-4'-phosphate); SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; STX17: syntaxin 17.
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Affiliation(s)
| | | | - Asha Kiran Maddali
- Institute of Genetics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
- Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - András Kincses
- Institute of Biophysics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
| | - Hussein Abuammar
- Institute of Genetics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
- Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - Krisztina Sebők-Nagy
- Institute of Biophysics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
| | - Tibor Páli
- Institute of Biophysics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
| | - András Dér
- Institute of Biophysics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
| | - Tamás Hegedűs
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- HUN-REN Biophysical Virology Research Group, Budapest, Hungary
| | - Gábor Csordás
- Institute of Genetics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
| | - Gábor Juhász
- Institute of Genetics, HUN-REN Biological Research Centre Szeged, Szeged, Hungary
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
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2
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Carrera P, Odenthal J, Risse KS, Jung Y, Kuerschner L, Bülow MH. The CD36 scavenger receptor Bez regulates lipid redistribution from fat body to ovaries in Drosophila. Development 2024; 151:dev202551. [PMID: 38713014 DOI: 10.1242/dev.202551] [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: 11/21/2023] [Accepted: 04/12/2024] [Indexed: 05/08/2024]
Abstract
Lipid distribution in an organism is mediated by the interplay between lipoprotein particles, lipoprotein receptors and class B scavenger receptors of the CD36 family. CD36 is a multifunctional protein mediating lipid uptake, mobilization and signaling at the plasma membrane and inside of the cell. The CD36 protein family has 14 members in Drosophila melanogaster, which allows for the differentiated analysis of their functions. Here, we unravel a role for the so far uncharacterized scavenger receptor Bez in lipid export from Drosophila adipocytes. Bez shares the lipid binding residue with CD36 and is expressed at the plasma membrane of the embryonic, larval and adult fat body. Bez loss of function lowers the organismal availability of storage lipids and blocks the maturation of egg chambers in ovaries. We demonstrate that Bez interacts with the APOB homolog Lipophorin at the plasma membrane of adipocytes and trace the Bez-dependent transfer of an alkyne-labeled fatty acid from adipocytes to Lipophorin. Our study demonstrates how lipids are distributed by scavenger receptor-lipoprotein interplay and contribute to the metabolic control of development.
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Affiliation(s)
- Pilar Carrera
- Life and Medical Sciences (LIMES), University of Bonn, Carl-Troll-Straße 31, 53115 Bonn, Germany
| | - Johanna Odenthal
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, 50931 Cologne, Germany
| | - Katharina S Risse
- Life and Medical Sciences (LIMES), University of Bonn, Carl-Troll-Straße 31, 53115 Bonn, Germany
| | - Yerin Jung
- Life and Medical Sciences (LIMES), University of Bonn, Carl-Troll-Straße 31, 53115 Bonn, Germany
| | - Lars Kuerschner
- Life and Medical Sciences (LIMES), University of Bonn, Carl-Troll-Straße 31, 53115 Bonn, Germany
| | - Margret H Bülow
- Life and Medical Sciences (LIMES), University of Bonn, Carl-Troll-Straße 31, 53115 Bonn, Germany
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3
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Majchrzak M, Stojanović O, Ajjaji D, Ben M'barek K, Omrane M, Thiam AR, Klemm RW. Perilipin membrane integration determines lipid droplet heterogeneity in differentiating adipocytes. Cell Rep 2024; 43:114093. [PMID: 38602875 DOI: 10.1016/j.celrep.2024.114093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 03/12/2024] [Accepted: 03/27/2024] [Indexed: 04/13/2024] Open
Abstract
The storage of fat within lipid droplets (LDs) of adipocytes is critical for whole-body health. Acute fatty acid (FA) uptake by differentiating adipocytes leads to the formation of at least two LD classes marked by distinct perilipins (PLINs). How this LD heterogeneity arises is an important yet unresolved cell biological problem. Here, we show that an unconventional integral membrane segment (iMS) targets the adipocyte specific LD surface factor PLIN1 to the endoplasmic reticulum (ER) and facilitates high-affinity binding to the first LD class. The other PLINs remain largely excluded from these LDs until FA influx recruits them to a second LD population. Preventing ER targeting turns PLIN1 into a soluble, cytoplasmic LD protein, reduces its LD affinity, and switches its LD class specificity. Conversely, moving the iMS to PLIN2 leads to ER insertion and formation of a separate LD class. Our results shed light on how differences in organelle targeting and disparities in lipid affinity of LD surface factors contribute to formation of LD heterogeneity.
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Affiliation(s)
- Mario Majchrzak
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Ozren Stojanović
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, UK
| | - Dalila Ajjaji
- Laboratoire de Physique de l'École Normale Supérieure (ENS), Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Kalthoum Ben M'barek
- Laboratoire de Physique de l'École Normale Supérieure (ENS), Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'École Normale Supérieure (ENS), Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure (ENS), Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Robin W Klemm
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, UK; Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.
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4
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Speer NO, Braun RJ, Reynolds EG, Brudnicka A, Swanson JM, Henne WM. Tld1 is a regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation. J Cell Biol 2024; 223:e202303026. [PMID: 37889293 PMCID: PMC10609110 DOI: 10.1083/jcb.202303026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 09/09/2023] [Accepted: 10/06/2023] [Indexed: 10/28/2023] Open
Abstract
Cells store lipids in the form of triglyceride (TG) and sterol ester (SE) in lipid droplets (LDs). Distinct pools of LDs exist, but a pervasive question is how proteins localize to and convey functions to LD subsets. Here, we show that the yeast protein YDR275W/Tld1 (for TG-associated LD protein 1) localizes to a subset of TG-containing LDs and reveal it negatively regulates lipolysis. Mechanistically, Tld1 LD targeting requires TG, and it is mediated by two distinct hydrophobic regions (HRs). Molecular dynamics simulations reveal that Tld1's HRs interact with TG on LDs and adopt specific conformations on TG-rich LDs versus SE-rich LDs in yeast and human cells. Tld1-deficient yeast display no defect in LD biogenesis but exhibit elevated TG lipolysis dependent on lipase Tgl3. Remarkably, overexpression of Tld1, but not LD protein Pln1/Pet10, promotes TG accumulation without altering SE pools. Finally, we find that Tld1-deficient cells display altered LD mobilization during extended yeast starvation. We propose that Tld1 senses TG-rich LDs and regulates lipolysis on LD subpopulations.
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Affiliation(s)
- Natalie Ortiz Speer
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - R. Jay Braun
- Department of Chemistry, University of Utah, Salt Lake City, UT, USA
| | - Emma Grace Reynolds
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alicja Brudnicka
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - W. Mike Henne
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
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5
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Pan H, Qin Y, Zhu J, Wang W, Liu Z, Huang X, Lam SM, Shui G, Wang Y, Jiang Y, Huang X. Centrins control chicken cone cell lipid droplet dynamics through lipid-droplet-localized SPDL1. Dev Cell 2023; 58:2528-2544.e8. [PMID: 37699389 DOI: 10.1016/j.devcel.2023.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 05/10/2023] [Accepted: 08/08/2023] [Indexed: 09/14/2023]
Abstract
As evolutionarily conserved organelles, lipid droplets (LDs) carry out numerous functions and have various subcellular localizations in different cell types and species. In avian cone cells, there is a single apically localized LD. We demonstrated that CIDEA (cell death inducing DFFA like effector a) and microtubules promote the formation of the single LD in chicken cone cells. Centrins, which are well-known centriole proteins, target to the cone cell LD via their C-terminal calcium-binding domains. Centrins localize on cone cell LDs with the help of SPDL1-L (spindle apparatus coiled-coil protein 1-L), a previously uncharacterized isoform of the kinetochore-associated dynein adaptor SPDL1. The loss of CETN3 or overexpression of a truncated CETN1 abrogates the apical localization of the cone cell LD. Simulation analysis showed that multiple LDs or a single mispositioned LD reduces the light sensitivity. Collectively, our findings identify a role of centrins in the regulation of cone cell LD localization, which is important for the light sensitivity of cone cells.
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Affiliation(s)
- Huimin Pan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yaqiang Qin
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinglin Zhu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhonghua Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiahe Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuqiang Jiang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Tianjian Laboratory of Advanced Biomedical Sciences, Zhengzhou 450001, China.
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6
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Sun X, Shen J, Perrimon N, Kong X, Wang D. The endoribonuclease Arlr is required to maintain lipid homeostasis by downregulating lipolytic genes during aging. Nat Commun 2023; 14:6254. [PMID: 37803019 PMCID: PMC10558556 DOI: 10.1038/s41467-023-42042-7] [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: 02/22/2023] [Accepted: 09/28/2023] [Indexed: 10/08/2023] Open
Abstract
While disorders in lipid metabolism have been associated with aging and age-related diseases, how lipid metabolism is regulated during aging is poorly understood. Here, we characterize the Drosophila endoribonuclease CG2145, an ortholog of mammalian EndoU that we named Age-related lipid regulator (Arlr), as a regulator of lipid homeostasis during aging. In adult adipose tissues, Arlr is necessary for maintenance of lipid storage in lipid droplets (LDs) as flies age, a phenotype that can be rescued by either high-fat or high-glucose diet. Interestingly, RNA-seq of arlr mutant adipose tissues and RIP-seq suggest that Arlr affects lipid metabolism through the degradation of the mRNAs of lipolysis genes - a model further supported by the observation that knockdown of Lsd-1, regucalcin, yip2 or CG5162, which encode genes involved in lipolysis, rescue the LD defects of arlr mutants. In addition, we characterize DendoU as a functional paralog of Arlr and show that human ENDOU can rescue arlr mutants. Altogether, our study reveals a role of ENDOU-like endonucleases as negative regulator of lipolysis.
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Affiliation(s)
- Xiaowei Sun
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
| | - Jie Shen
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Howard Hughes Medical Institute, Boston, MA, USA
| | - Xue Kong
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
| | - Dan Wang
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China.
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7
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Speer NO, Braun RJ, Reynolds E, Brudnicka A, Swanson J, Henne WM. Tld1 is a novel regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.07.531595. [PMID: 36945645 PMCID: PMC10028886 DOI: 10.1101/2023.03.07.531595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Cells store lipids in the form of triglyceride (TG) and sterol-ester (SE) in lipid droplets (LDs). Distinct pools of LDs exist, but a pervasive question is how proteins localize to and convey functions to LD subsets. Here, we show the yeast protein YDR275W/Tld1 (for TG-associated LD protein 1) localizes to a subset of TG-containing LDs, and reveal it negatively regulates lipolysis. Mechanistically, Tld1 LD targeting requires TG, and is mediated by two distinct hydrophobic regions (HRs). Molecular dynamics simulations reveal Tld1 HRs interact with TG on LDs and adopt specific conformations on TG-rich LDs versus SE-rich LDs in yeast and human cells. Tld1-deficient yeast display no defect in LD biogenesis, but exhibit elevated TG lipolysis dependent on lipase Tgl3. Remarkably, over-expression of Tld1, but not LD protein Pln1/Pet10, promotes TG accumulation without altering SE pools. Finally, we find Tld1-deficient cells display altered LD mobilization during extended yeast starvation. We propose Tld1 senses TG-rich LDs and regulates lipolysis on LD subpopulations.
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8
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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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9
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Henne WM. The (social) lives, deaths, and biophysical phases of lipid droplets. Curr Opin Cell Biol 2023; 82:102178. [PMID: 37295067 PMCID: PMC10782554 DOI: 10.1016/j.ceb.2023.102178] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023]
Abstract
Lipid droplets (LDs) are major lipid storage organelles, sequestering energy-rich triglycerides and serving as nutrient sinks for cellular homeostasis. Observed for over a century but generally ignored, LDs are now appreciated to play key roles in organismal physiology and disease. They also form numerous functional contacts with other organelles. Here, we highlight recent studies examining LDs from distinct perspectives of their life cycle: their biogenesis, "social" life as they interact with other organelles, and deaths via lipolysis or lipophagy. We also discuss recent work showing how changes in LD lipid content alter the biophysical phases of LD lipids, and how this may fine-tune the LD protein landscape and ultimately LD function.
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Affiliation(s)
- W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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10
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Bresgen N, Kovacs M, Lahnsteiner A, Felder TK, Rinnerthaler M. The Janus-Faced Role of Lipid Droplets in Aging: Insights from the Cellular Perspective. Biomolecules 2023; 13:912. [PMID: 37371492 DOI: 10.3390/biom13060912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/22/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
It is widely accepted that nine hallmarks-including mitochondrial dysfunction, epigenetic alterations, and loss of proteostasis-exist that describe the cellular aging process. Adding to this, a well-described cell organelle in the metabolic context, namely, lipid droplets, also accumulates with increasing age, which can be regarded as a further aging-associated process. Independently of their essential role as fat stores, lipid droplets are also able to control cell integrity by mitigating lipotoxic and proteotoxic insults. As we will show in this review, numerous longevity interventions (such as mTOR inhibition) also lead to strong accumulation of lipid droplets in Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and mammalian cells, just to name a few examples. In mammals, due to the variety of different cell types and tissues, the role of lipid droplets during the aging process is much more complex. Using selected diseases associated with aging, such as Alzheimer's disease, Parkinson's disease, type II diabetes, and cardiovascular disease, we show that lipid droplets are "Janus"-faced. In an early phase of the disease, lipid droplets mitigate the toxicity of lipid peroxidation and protein aggregates, but in a later phase of the disease, a strong accumulation of lipid droplets can cause problems for cells and tissues.
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Affiliation(s)
- Nikolaus Bresgen
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria
| | - Melanie Kovacs
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria
| | - Angelika Lahnsteiner
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria
| | - Thomas Klaus Felder
- Department of Laboratory Medicine, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Mark Rinnerthaler
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria
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11
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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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12
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Papsdorf K, Miklas JW, Hosseini A, Cabruja M, Morrow CS, Savini M, Yu Y, Silva-García CG, Haseley NR, Murphy LM, Yao P, de Launoit E, Dixon SJ, Snyder MP, Wang MC, Mair WB, Brunet A. Lipid droplets and peroxisomes are co-regulated to drive lifespan extension in response to mono-unsaturated fatty acids. Nat Cell Biol 2023; 25:672-684. [PMID: 37127715 PMCID: PMC10185472 DOI: 10.1038/s41556-023-01136-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/23/2023] [Indexed: 05/03/2023]
Abstract
Dietary mono-unsaturated fatty acids (MUFAs) are linked to longevity in several species. But the mechanisms by which MUFAs extend lifespan remain unclear. Here we show that an organelle network involving lipid droplets and peroxisomes is critical for MUFA-induced longevity in Caenorhabditis elegans. MUFAs upregulate the number of lipid droplets in fat storage tissues. Increased lipid droplet number is necessary for MUFA-induced longevity and predicts remaining lifespan. Lipidomics datasets reveal that MUFAs also modify the ratio of membrane lipids and ether lipids-a signature associated with decreased lipid oxidation. In agreement with this, MUFAs decrease lipid oxidation in middle-aged individuals. Intriguingly, MUFAs upregulate not only lipid droplet number but also peroxisome number. A targeted screen identifies genes involved in the co-regulation of lipid droplets and peroxisomes, and reveals that induction of both organelles is optimal for longevity. Our study uncovers an organelle network involved in lipid homeostasis and lifespan regulation, opening new avenues for interventions to delay aging.
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Affiliation(s)
| | - Jason W Miklas
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Amir Hosseini
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Matias Cabruja
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Christopher S Morrow
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Marzia Savini
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
| | - Yong Yu
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
| | - Carlos G Silva-García
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | | | | | - Pallas Yao
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | | | - Scott J Dixon
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | - Meng C Wang
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - William B Mair
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, Stanford, CA, USA.
- Glenn Laboratories for the Biology of Aging, Stanford University, Stanford, CA, USA.
- Wu Tsai Institute of Neurosciences, Stanford University, Stanford, CA, USA.
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13
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Kozan DW, Derrick JT, Ludington WB, Farber SA. From worms to humans: Understanding intestinal lipid metabolism via model organisms. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159290. [PMID: 36738984 PMCID: PMC9974936 DOI: 10.1016/j.bbalip.2023.159290] [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: 08/26/2022] [Revised: 01/10/2023] [Accepted: 01/19/2023] [Indexed: 02/05/2023]
Abstract
The intestine is responsible for efficient absorption and packaging of dietary lipids before they enter the circulatory system. This review provides a comprehensive overview of how intestinal enterocytes from diverse model organisms absorb dietary lipid and subsequently secrete the largest class of lipoproteins (chylomicrons) to meet the unique needs of each animal. We discuss the putative relationship between diet and metabolic disease progression, specifically Type 2 Diabetes Mellitus. Understanding the molecular response of intestinal cells to dietary lipid has the potential to undercover novel therapies to combat metabolic syndrome.
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Affiliation(s)
- Darby W Kozan
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States; Department of Embryology, Carnegie Institute for Science, Baltimore, MD, United States
| | - Joshua T Derrick
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States; Department of Embryology, Carnegie Institute for Science, Baltimore, MD, United States
| | - William B Ludington
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States; Department of Embryology, Carnegie Institute for Science, Baltimore, MD, United States
| | - Steven A Farber
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States; Department of Embryology, Carnegie Institute for Science, Baltimore, MD, United States.
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14
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Vernier CL, Leitner N, Zelle KM, Foltz M, Dutton S, Liang X, Halloran S, Millar JG, Ben-Shahar Y. A pleiotropic chemoreceptor facilitates the production and perception of mating pheromones. iScience 2022; 26:105882. [PMID: 36691619 PMCID: PMC9860498 DOI: 10.1016/j.isci.2022.105882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 11/17/2022] [Accepted: 12/21/2022] [Indexed: 12/31/2022] Open
Abstract
Optimal mating decisions depend on the robust coupling of signal production and perception because independent changes in either could carry a fitness cost. However, since the perception and production of mating signals are often mediated by different tissues and cell types, the mechanisms that drive and maintain their coupling remain unknown for most animal species. Here, we show that in Drosophila, behavioral responses to, and the production of, a putative inhibitory mating pheromone are co-regulated by Gr8a, a member of the Gustatory receptor gene family. Specifically, through behavioral and pheromonal data, we found that Gr8a independently regulates the behavioral responses of males and females to a putative inhibitory pheromone, as well as its production in the fat body and oenocytes of males. Overall, these findings provide a relatively simple molecular explanation for how pleiotropic receptors maintain robust mating signaling systems at the population and species levels.
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Affiliation(s)
- Cassondra L. Vernier
- Department of Biology, Washington University in Saint Louis, 1 Brookings Drive, Saint Louis, MO 63130, USA
| | - Nicole Leitner
- Department of Biology, Washington University in Saint Louis, 1 Brookings Drive, Saint Louis, MO 63130, USA
| | - Kathleen M. Zelle
- Department of Biology, Washington University in Saint Louis, 1 Brookings Drive, Saint Louis, MO 63130, USA
| | - Merrin Foltz
- Department of Biology, Washington University in Saint Louis, 1 Brookings Drive, Saint Louis, MO 63130, USA
| | - Sophia Dutton
- Department of Biology, Washington University in Saint Louis, 1 Brookings Drive, Saint Louis, MO 63130, USA
| | - Xitong Liang
- Department of Neuroscience, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Sean Halloran
- Department of Entomology, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA
| | - Jocelyn G. Millar
- Department of Entomology, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA
| | - Yehuda Ben-Shahar
- Department of Biology, Washington University in Saint Louis, 1 Brookings Drive, Saint Louis, MO 63130, USA,Corresponding author
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15
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Overduin M, Tran A, Eekels DM, Overduin F, Kervin TA. Transmembrane Membrane Readers form a Novel Class of Proteins That Include Peripheral Phosphoinositide Recognition Domains and Viral Spikes. MEMBRANES 2022; 12:1161. [PMID: 36422153 PMCID: PMC9692390 DOI: 10.3390/membranes12111161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Membrane proteins are broadly classified as transmembrane (TM) or peripheral, with functions that pertain to only a single bilayer at a given time. Here, we explicate a class of proteins that contain both transmembrane and peripheral domains, which we dub transmembrane membrane readers (TMMRs). Their transmembrane and peripheral elements anchor them to one bilayer and reversibly attach them to another section of bilayer, respectively, positioning them to tether and fuse membranes while recognizing signals such as phosphoinositides (PIs) and modifying lipid chemistries in proximity to their transmembrane domains. Here, we analyze full-length models from AlphaFold2 and Rosetta, as well as structures from nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, using the Membrane Optimal Docking Area (MODA) program to map their membrane-binding surfaces. Eukaryotic TMMRs include phospholipid-binding C1, C2, CRAL-TRIO, FYVE, GRAM, GTPase, MATH, PDZ, PH, PX, SMP, StART and WD domains within proteins including protrudin, sorting nexins and synaptotagmins. The spike proteins of SARS-CoV-2 as well as other viruses are also TMMRs, seeing as they are anchored into the viral membrane while mediating fusion with host cell membranes. As such, TMMRs have key roles in cell biology and membrane trafficking, and include drug targets for diseases such as COVID-19.
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Affiliation(s)
- Michael Overduin
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Anh Tran
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | | | - Finn Overduin
- Institute of Nutritional Science, University of Potsdam, 14476 Potsdam, Germany
| | - Troy A. Kervin
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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16
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Zhang Y, Chen R, Dong Y, Zhu J, Su K, Liu J, Xu J. Structural Studies Reveal Unique Non-canonical Regulators of G Protein Signaling Homology (RH) Domains in Sorting Nexins. J Mol Biol 2022; 434:167823. [PMID: 36103920 DOI: 10.1016/j.jmb.2022.167823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/30/2022] [Accepted: 09/06/2022] [Indexed: 11/24/2022]
Abstract
As a subgroup of sorting nexins (SNXs) that contain regulator of G protein signaling homology (RH) domain, SNX-RH proteins, including SNX13, SNX14 and SNX25, were proposed to play bifunctional roles in protein sorting and GPCR signaling regulation. However, mechanistic details of SNX-RH proteins functioning via RH domain remain to be illustrated. Here, we delineate crystal structures of the RH domains of SNX13 and SNX25, revealing a homodimer of SNX13 RH domain mediated by unique extended α4 and α5 helices, and a thiol modulated homodimer of SNX25-RH triggered by a unique cysteine on α6 helix. Further studies showed that RH domains of SNX-RH do not possess binding capacity toward Gα subunits, owing to the lack of critical residues for interaction. Thus, this study identifies a group of novel non-canonical RH domains that can act as a dimerization module in sorting nexins, which provides structural basis for mechanism studies on SNX-RH protein functions.
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Affiliation(s)
- Yulong Zhang
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rui Chen
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; School of Life Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Yan Dong
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Jiabin Zhu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Kai Su
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Jinsong Liu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China; Guangdong Provincial Key Laboratory of Biocomputing, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China.
| | - Jinxin Xu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China; Guangdong Provincial Key Laboratory of Biocomputing, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China.
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17
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Castro IG, Shortill SP, Dziurdzik SK, Cadou A, Ganesan S, Valenti R, David Y, Davey M, Mattes C, Thomas FB, Avraham RE, Meyer H, Fadel A, Fenech EJ, Ernst R, Zaremberg V, Levine TP, Stefan C, Conibear E, Schuldiner M. Systematic analysis of membrane contact sites in Saccharomyces cerevisiae uncovers modulators of cellular lipid distribution. eLife 2022; 11:74602. [DOI: 10.7554/elife.74602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Actively maintained close appositions between organelle membranes, also known as contact sites, enable the efficient transfer of biomolecules between cellular compartments. Several such sites have been described as well as their tethering machineries. Despite these advances we are still far from a comprehensive understanding of the function and regulation of most contact sites. To systematically characterize contact site proteomes, we established a high-throughput screening approach in Saccharomyces cerevisiae based on co-localization imaging. We imaged split fluorescence reporters for six different contact sites, several of which are poorly characterized, on the background of 1165 strains expressing a mCherry-tagged yeast protein that has a cellular punctate distribution (a hallmark of contact sites), under regulation of the strong TEF2 promoter. By scoring both co-localization events and effects on reporter size and abundance, we discovered over 100 new potential contact site residents and effectors in yeast. Focusing on several of the newly identified residents, we identified three homologs of Vps13 and Atg2 that are residents of multiple contact sites. These proteins share their lipid transport domain, thus expanding this family of lipid transporters. Analysis of another candidate, Ypr097w, which we now call Lec1 (Lipid-droplet Ergosterol Cortex 1), revealed that this previously uncharacterized protein dynamically shifts between lipid droplets and the cell cortex, and plays a role in regulation of ergosterol distribution in the cell. Overall, our analysis expands the universe of contact site residents and effectors and creates a rich database to mine for new functions, tethers, and regulators.
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Affiliation(s)
| | - Shawn P Shortill
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Samantha Katarzyna Dziurdzik
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Angela Cadou
- Laboratory for Molecular Cell Biology, University College London
| | | | - Rosario Valenti
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Yotam David
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | - Ffion B Thomas
- Laboratory for Molecular Cell Biology, University College London
| | | | - Hadar Meyer
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Amir Fadel
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Emma J Fenech
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | | | - Tim P Levine
- UCL Institute of Ophthalmology, University College London
| | | | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science
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18
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Scholz P, Chapman KD, Mullen RT, Ischebeck T. Finding new friends and revisiting old ones - how plant lipid droplets connect with other subcellular structures. THE NEW PHYTOLOGIST 2022; 236:833-838. [PMID: 35851478 DOI: 10.1111/nph.18390] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 07/03/2022] [Indexed: 06/15/2023]
Abstract
The number of described contact sites between different subcellular compartments and structures in eukaryotic cells has increased dramatically in recent years and, as such, has substantially reinforced the well-known premise that these kinds of connections are essential for overall cellular organization and the proper functioning of cellular metabolic and signaling pathways. Here, we discuss contact sites involving plant lipid droplets (LDs), including LD-endoplasmic reticulum (ER) connections that mediate the biogenesis of new LDs at the ER, LD-peroxisome connections, that facilitate the degradation of LD-stored triacylglycerols (TAGs), and the more recently discovered LD-plasma membrane connections, which involve at least three novel proteins, but have a yet unknown physiological function(s).
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Affiliation(s)
- Patricia Scholz
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, 37077, Göttingen, Germany
| | - Kent D Chapman
- Bio-Discovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX, 76203, USA
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Till Ischebeck
- Institute of Plant Biology and Biotechnology (IBBP), Green Biotechnology, University of Münster, 48143, Münster, Germany
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19
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Fundamental roles for inter-organelle communication in aging. Biochem Soc Trans 2022; 50:1389-1402. [PMID: 36305642 PMCID: PMC9704535 DOI: 10.1042/bst20220519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/27/2022] [Accepted: 10/17/2022] [Indexed: 11/17/2022]
Abstract
Advances in public health have nearly doubled life expectancy over the last century, but this demographic shift has also changed the landscape of human illness. Today, chronic and age-dependent diseases dominate the leading causes of morbidity and mortality worldwide. Targeting the underlying molecular, genetic and cell biological drivers of the aging process itself appears to be an increasingly viable strategy for developing therapeutics against these diseases of aging. Towards this end, one of the most exciting developments in cell biology over the last decade is the explosion of research into organelle contact sites and related mechanisms of inter-organelle communication. Identification of the molecular mediators of inter-organelle tethering and signaling is now allowing the field to investigate the consequences of aberrant organelle interactions, which frequently seem to correlate with age-onset pathophysiology. This review introduces the major cellular roles for inter-organelle interactions, including the regulation of organelle morphology, the transfer of ions, lipids and other metabolites, and the formation of hubs for nutrient and stress signaling. We explore how these interactions are disrupted in aging and present findings that modulation of inter-organelle communication is a promising avenue for promoting longevity. Through this review, we propose that the maintenance of inter-organelle interactions is a pillar of healthy aging. Learning how to target the cellular mechanisms for sensing and controlling inter-organelle communication is a key next hurdle for geroscience.
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20
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Linnemannstöns K, Karuna M P, Witte L, Choezom D, Honemann‐Capito M, Lagurin AS, Schmidt CV, Shrikhande S, Steinmetz L, Wiebke M, Lenz C, Gross JC. Microscopic and biochemical monitoring of endosomal trafficking and extracellular vesicle secretion in an endogenous in vivo model. J Extracell Vesicles 2022; 11:e12263. [PMID: 36103151 PMCID: PMC9473323 DOI: 10.1002/jev2.12263] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/17/2022] [Accepted: 05/22/2022] [Indexed: 11/10/2022] Open
Abstract
Extracellular vesicle (EV) secretion enables cell-cell communication in multicellular organisms. During development, EV secretion and the specific loading of signalling factors in EVs contributes to organ development and tissue differentiation. Here, we present an in vivo model to study EV secretion using the fat body and the haemolymph of the fruit fly, Drosophila melanogaster. The system makes use of tissue-specific EV labelling and is amenable to genetic modification by RNAi. This allows the unique combination of microscopic visualisation of EVs in different organs and quantitative biochemical purification to study how EVs are generated within the cells and which factors regulate their secretion in vivo. Characterisation of the system revealed that secretion of EVs from the fat body is mainly regulated by Rab11 and Rab35, highlighting the importance of recycling Rab GTPase family members for EV secretion. We furthermore discovered a so far unknown function of Rab14 along with the kinesin Klp98A in EV biogenesis and secretion.
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Affiliation(s)
- Karen Linnemannstöns
- Developmental BiochemistryUniversity Medical Center GoettingenGoettingenGermany
- Hematology and OncologyUniversity Medical Center GoettingenGoettingenGermany
- Molecular OncologyUniversity Medical Center GoettingenGoettingenGermany
| | - Pradhipa Karuna M
- Developmental BiochemistryUniversity Medical Center GoettingenGoettingenGermany
| | - Leonie Witte
- Developmental BiochemistryUniversity Medical Center GoettingenGoettingenGermany
| | - Dolma Choezom
- Developmental BiochemistryUniversity Medical Center GoettingenGoettingenGermany
| | | | - Alex Simon Lagurin
- Developmental BiochemistryUniversity Medical Center GoettingenGoettingenGermany
| | | | - Shreya Shrikhande
- Developmental BiochemistryUniversity Medical Center GoettingenGoettingenGermany
| | | | - Möbius Wiebke
- Electron Microscopy Core Unit, Department of NeurogeneticsMax Planck Institute of Experimental MedicineGöttingenGermany
| | - Christof Lenz
- Institute of Clinical ChemistryUniversity Medical Center GöttingenGöttingenGermany
- Bioanalytical Mass Spectrometry GroupMax Planck Institute for Biophysical ChemistryGöttingenGermany
| | - Julia Christina Gross
- Developmental BiochemistryUniversity Medical Center GoettingenGoettingenGermany
- Hematology and OncologyUniversity Medical Center GoettingenGoettingenGermany
- Department of MedicineHealth and Medical UniversityPotsdamGermany
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21
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Calderon D, Blecher-Gonen R, Huang X, Secchia S, Kentro J, Daza RM, Martin B, Dulja A, Schaub C, Trapnell C, Larschan E, O'Connor-Giles KM, Furlong EEM, Shendure J. The continuum of Drosophila embryonic development at single-cell resolution. Science 2022; 377:eabn5800. [PMID: 35926038 PMCID: PMC9371440 DOI: 10.1126/science.abn5800] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Drosophila melanogaster is a powerful, long-standing model for metazoan development and gene regulation. We profiled chromatin accessibility in almost 1 million and gene expression in half a million nuclei from overlapping windows spanning the entirety of embryogenesis. Leveraging developmental asynchronicity within embryo collections, we applied deep neural networks to infer the age of each nucleus, resulting in continuous, multimodal views of molecular and cellular transitions in absolute time. We identify cell lineages; infer their developmental relationships; and link dynamic changes in enhancer usage, transcription factor (TF) expression, and the accessibility of TFs' cognate motifs. With these data, the dynamics of enhancer usage and gene expression can be explored within and across lineages at the scale of minutes, including for precise transitions like zygotic genome activation.
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Affiliation(s)
- Diego Calderon
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Ronnie Blecher-Gonen
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.,The Crown Genomics Institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Xingfan Huang
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.,Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, WA 98195, USA
| | - Stefano Secchia
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - James Kentro
- Molecular Biology, Cell Biology, and Biochemistry Graduate Program, Brown University, Providence, RI 02912, USA
| | - Riza M Daza
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Beth Martin
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Alessandro Dulja
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Christoph Schaub
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.,Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA.,Allen Discovery Center for Cell Lineage Tracing, Seattle, WA 98195, USA
| | - Erica Larschan
- Molecular Biology, Cell Biology, and Biochemistry Graduate Program, Brown University, Providence, RI 02912, USA
| | - Kate M O'Connor-Giles
- Department of Neuroscience and Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Eileen E M Furlong
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.,Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA.,Allen Discovery Center for Cell Lineage Tracing, Seattle, WA 98195, USA.,Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
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22
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Sánchez-Álvarez M, Del Pozo MÁ, Bosch M, Pol A. Insights Into the Biogenesis and Emerging Functions of Lipid Droplets From Unbiased Molecular Profiling Approaches. Front Cell Dev Biol 2022; 10:901321. [PMID: 35756995 PMCID: PMC9213792 DOI: 10.3389/fcell.2022.901321] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/17/2022] [Indexed: 11/30/2022] Open
Abstract
Lipid droplets (LDs) are spherical, single sheet phospholipid-bound organelles that store neutral lipids in all eukaryotes and some prokaryotes. Initially conceived as relatively inert depots for energy and lipid precursors, these highly dynamic structures play active roles in homeostatic functions beyond metabolism, such as proteostasis and protein turnover, innate immunity and defense. A major share of the knowledge behind this paradigm shift has been enabled by the use of systematic molecular profiling approaches, capable of revealing and describing these non-intuitive systems-level relationships. Here, we discuss these advances and some of the challenges they entail, and highlight standing questions in the field.
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Affiliation(s)
- Miguel Sánchez-Álvarez
- Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Miguel Ángel Del Pozo
- Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Marta Bosch
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
| | - Albert Pol
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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23
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Girik V, Feng S, Hariri H, Henne WM, Riezman H. Vacuole-Specific Lipid Release for Tracking Intracellular Lipid Metabolism and Transport in Saccharomyces cerevisiae. ACS Chem Biol 2022; 17:1485-1494. [PMID: 35667650 PMCID: PMC9207805 DOI: 10.1021/acschembio.2c00120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lipid metabolism is spatiotemporally regulated within cells, yet intervention into lipid functions at subcellular resolution remains difficult. Here, we report a method that enables site-specific release of sphingolipids and cholesterol inside the vacuole in Saccharomyces cerevisiae. Using this approach, we monitored real-time sphingolipid metabolic flux out of the vacuole by mass spectrometry and found that the endoplasmic reticulum-vacuole-tethering protein Mdm1 facilitated the metabolism of sphingoid bases into ceramides. In addition, we showed that cholesterol, once delivered into yeast using our method, could restore cell proliferation induced by ergosterol deprivation, overcoming the previously described sterol-uptake barrier under aerobic conditions. Together, these data define a new way to study intracellular lipid metabolism and transport from the vacuole in yeast.
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Affiliation(s)
- Vladimir Girik
- Department of Biochemistry, University of Geneva, Geneva 1205, Switzerland
| | - Suihan Feng
- Department of Biochemistry, University of Geneva, Geneva 1205, Switzerland.,National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva 1205, Switzerland
| | - Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390-9039 United States
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390-9039 United States
| | - Howard Riezman
- Department of Biochemistry, University of Geneva, Geneva 1205, Switzerland
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24
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Krawczyk HE, Sun S, Doner NM, Yan Q, Lim MSS, Scholz P, Niemeyer PW, Schmitt K, Valerius O, Pleskot R, Hillmer S, Braus GH, Wiermer M, Mullen RT, Ischebeck T. SEED LIPID DROPLET PROTEIN1, SEED LIPID DROPLET PROTEIN2, and LIPID DROPLET PLASMA MEMBRANE ADAPTOR mediate lipid droplet-plasma membrane tethering. THE PLANT CELL 2022; 34:2424-2448. [PMID: 35348751 PMCID: PMC9134073 DOI: 10.1093/plcell/koac095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/14/2022] [Indexed: 05/27/2023]
Abstract
Membrane contact sites (MCSs) are interorganellar connections that allow for the direct exchange of molecules, such as lipids or Ca2+ between organelles, but can also serve to tether organelles at specific locations within cells. Here, we identified and characterized three proteins of Arabidopsis thaliana that form a lipid droplet (LD)-plasma membrane (PM) tethering complex in plant cells, namely LD-localized SEED LD PROTEIN (SLDP) 1 and SLDP2 and PM-localized LD-PLASMA MEMBRANE ADAPTOR (LIPA). Using proteomics and different protein-protein interaction assays, we show that both SLDPs associate with LIPA. Disruption of either SLDP1 and SLDP2 expression, or that of LIPA, leads to an aberrant clustering of LDs in Arabidopsis seedlings. Ectopic co-expression of one of the SLDPs with LIPA is sufficient to reconstitute LD-PM tethering in Nicotiana tabacum pollen tubes, a cell type characterized by dynamically moving LDs in the cytosolic streaming. Furthermore, confocal laser scanning microscopy revealed both SLDP2.1 and LIPA to be enriched at LD-PM contact sites in seedlings. These and other results suggest that SLDP and LIPA interact to form a tethering complex that anchors a subset of LDs to the PM during post-germinative seedling growth in Arabidopsis.
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Affiliation(s)
- Hannah Elisa Krawczyk
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Siqi Sun
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Nathan M Doner
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Qiqi Yan
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
| | - Magdiel Sheng Satha Lim
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Patricia Scholz
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Philipp William Niemeyer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Kerstin Schmitt
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Oliver Valerius
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Roman Pleskot
- Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic
| | - Stefan Hillmer
- Electron Microscopy Core Facility, Heidelberg University, Heidelberg, Germany
| | - Gerhard H Braus
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Marcel Wiermer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
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25
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Wang L, Liu Y, Zhang X, Ye Y, Xiong X, Zhang S, Gu L, Jian Z, Wang H. Endoplasmic Reticulum Stress and the Unfolded Protein Response in Cerebral Ischemia/Reperfusion Injury. Front Cell Neurosci 2022; 16:864426. [PMID: 35602556 PMCID: PMC9114642 DOI: 10.3389/fncel.2022.864426] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/07/2022] [Indexed: 12/15/2022] Open
Abstract
Ischemic stroke is an acute cerebrovascular disease characterized by sudden interruption of blood flow in a certain part of the brain, leading to serious disability and death. At present, treatment methods for ischemic stroke are limited to thrombolysis or thrombus removal, but the treatment window is very narrow. However, recovery of cerebral blood circulation further causes cerebral ischemia/reperfusion injury (CIRI). The endoplasmic reticulum (ER) plays an important role in protein secretion, membrane protein folding, transportation, and maintenance of intracellular calcium homeostasis. Endoplasmic reticulum stress (ERS) plays a crucial role in cerebral ischemia pathophysiology. Mild ERS helps improve cell tolerance and restore cell homeostasis; however, excessive or long-term ERS causes apoptotic pathway activation. Specifically, the protein kinase R-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6), and inositol-requiring enzyme 1 (IRE1) pathways are significantly activated following initiation of the unfolded protein response (UPR). CIRI-induced apoptosis leads to nerve cell death, which ultimately aggravates neurological deficits in patients. Therefore, it is necessary and important to comprehensively explore the mechanism of ERS in CIRI to identify methods for preserving brain cells and neuronal function after ischemia.
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Affiliation(s)
- Lei Wang
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yan Liu
- Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xu Zhang
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yingze Ye
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xiaoxing Xiong
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Shudi Zhang
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Lijuan Gu
- Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, China
| | - Zhihong Jian
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
- Zhihong Jian,
| | - Hongfa Wang
- Rehabilitation Medicine Center, Department of Anesthesiology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
- *Correspondence: Hongfa Wang,
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26
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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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27
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Zhao X, Wang W, Yao Y, Li X, Huang X, Wang Y, Ding M, Huang X. An RDH‐Plin2 axis modulates lipid droplet size by antagonizing Bmm lipase. EMBO Rep 2022; 23:e52669. [PMID: 35132760 PMCID: PMC8892243 DOI: 10.15252/embr.202152669] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 12/04/2021] [Accepted: 12/21/2021] [Indexed: 12/18/2022] Open
Abstract
The size of lipid droplets varies greatly in vivo and is determined by both intrinsic and extrinsic factors. From an RNAi screen in Drosophila, we found that knocking down subunits of COP9 signalosome (CSN) results in enlarged lipid droplets under high‐fat, but not normal, conditions. We identified CG2064, a retinol dehydrogenase (RDH) homolog, as the proteasomal degradation target of CSN in regulating lipid droplet size. RDH/CG2064 interacts with the lipid droplet‐resident protein Plin2 and the RDH/CG2064‐Plin2 axis acts to reduce the overall level and lipid droplet localization of Bmm/ATGL lipase. This axis is important for larval survival under prolonged starvation. Thus, we discovered an RDH‐Plin2 axis modulates lipid droplet size.
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Affiliation(s)
- Xuefan Zhao
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Wei Wang
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
| | - Yan Yao
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
| | - Xia Li
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
| | - Xiahe Huang
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
| | - Mei Ding
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Innovation Academy for Seed Design Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
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28
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Basu I, Bar S, Prasad M, Datta R. Adipose deficiency and aberrant autophagy in a Drosophila model of MPS VII is corrected by pharmacological stimulators of mTOR. Biochim Biophys Acta Mol Basis Dis 2022; 1868:166399. [DOI: 10.1016/j.bbadis.2022.166399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 10/18/2022]
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29
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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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30
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Lu A, Hsieh F, Sharma BR, Vaughn SR, Enrich C, Pfeffer SR. CRISPR screens for lipid regulators reveal a role for ER-bound SNX13 in lysosomal cholesterol export. J Cell Biol 2022; 221:212937. [PMID: 34936700 PMCID: PMC8704955 DOI: 10.1083/jcb.202105060] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 11/02/2021] [Accepted: 11/29/2021] [Indexed: 11/22/2022] Open
Abstract
We report here two genome-wide CRISPR screens performed to identify genes that, when knocked out, alter levels of lysosomal cholesterol or bis(monoacylglycero)phosphate. In addition, these screens were also performed under conditions of NPC1 inhibition to identify modifiers of NPC1 function in lysosomal cholesterol export. The screens confirm tight coregulation of cholesterol and bis(monoacylglycero)phosphate in cells and reveal an unexpected role for the ER-localized SNX13 protein as a negative regulator of lysosomal cholesterol export and contributor to ER–lysosome membrane contact sites. In the absence of NPC1 function, SNX13 knockdown redistributes lysosomal cholesterol and is accompanied by triacylglycerol-rich lipid droplet accumulation and increased lysosomal bis(monoacylglycero)phosphate. These experiments provide unexpected insight into the regulation of lysosomal lipids and modification of these processes by novel gene products.
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Affiliation(s)
- Albert Lu
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA.,Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
| | | | - Bikal R Sharma
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA
| | - Sydney R Vaughn
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA
| | - Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
| | - Suzanne R Pfeffer
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA
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31
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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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32
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Parra-Peralbo E, Talamillo A, Barrio R. Origin and Development of the Adipose Tissue, a Key Organ in Physiology and Disease. Front Cell Dev Biol 2022; 9:786129. [PMID: 34993199 PMCID: PMC8724577 DOI: 10.3389/fcell.2021.786129] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/01/2021] [Indexed: 12/17/2022] Open
Abstract
Adipose tissue is a dynamic organ, well known for its function in energy storage and mobilization according to nutrient availability and body needs, in charge of keeping the energetic balance of the organism. During the last decades, adipose tissue has emerged as the largest endocrine organ in the human body, being able to secrete hormones as well as inflammatory molecules and having an important impact in multiple processes such as adipogenesis, metabolism and chronic inflammation. However, the cellular progenitors, development, homeostasis and metabolism of the different types of adipose tissue are not fully known. During the last decade, Drosophila melanogaster has demonstrated to be an excellent model to tackle some of the open questions in the field of metabolism and development of endocrine/metabolic organs. Discoveries ranged from new hormones regulating obesity to subcellular mechanisms that regulate lipogenesis and lipolysis. Here, we review the available evidences on the development, types and functions of adipose tissue in Drosophila and identify some gaps for future research. This may help to understand the cellular and molecular mechanism underlying the pathophysiology of this fascinating key tissue, contributing to establish this organ as a therapeutic target.
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Affiliation(s)
| | - Ana Talamillo
- Center for Cooperative Research in Biosciences (CIC BioGUNE), Basque Research and Technology Alliance (BRTA), Derio, Spain
| | - Rosa Barrio
- Center for Cooperative Research in Biosciences (CIC BioGUNE), Basque Research and Technology Alliance (BRTA), Derio, Spain
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33
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Lu A. Sorting (Nexin-13) out Novel Insights into Endolysosomal Cholesterol Export. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2022; 5:25152564221114513. [PMID: 37366510 PMCID: PMC10243570 DOI: 10.1177/25152564221114513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/28/2022] [Accepted: 07/21/2022] [Indexed: 06/28/2023]
Abstract
Transport in and out of the endolysosomal compartment represents a key step in the regulation of cellular cholesterol homeostasis. Despite important recent advances, how LDL-derived, free cholesterol is exported from the lumen of endolysosomes to other organelles is still a matter of debate. We recently devised a CRISPR/Cas9 genome-scale strategy to uncover genes involved in the regulation of endolysosomal cholesterol homeostasis and the functionally linked phospholipid, bis(monoacylglycerol)-phosphate. This approach confirmed known genes and pathways involved in this process, and more importantly revealed previously unrecognized roles for new players, such as Sorting Nexin-13 (SNX13). Here we discuss the unexpected regulatory role of SNX13 in endolysosomal cholesterol export.
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Affiliation(s)
- Albert Lu
- Departament de Biomedicina, Unitat de Biologia Cel·lular,
Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut
d’Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
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34
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Olarte MJ, Swanson JMJ, Walther TC, Farese RV. The CYTOLD and ERTOLD pathways for lipid droplet-protein targeting. Trends Biochem Sci 2022; 47:39-51. [PMID: 34583871 PMCID: PMC8688270 DOI: 10.1016/j.tibs.2021.08.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 01/03/2023]
Abstract
Lipid droplets (LDs) are the main organelles for lipid storage, and their surfaces contain unique proteins with diverse functions, including those that facilitate the deposition and mobilization of LD lipids. Among organelles, LDs have an unusual structure with an organic, hydrophobic oil phase covered by a phospholipid monolayer. The unique properties of LD monolayer surfaces require proteins to localize to LDs by distinct mechanisms. Here we review the two pathways known to mediate direct LD protein localization: the CYTOLD pathway mediates protein targeting from the cytosol toLDs, and the ERTOLD pathway functions in protein targeting from the endoplasmic reticulum toLDs. We describe the emerging principles for each targeting pathway in animal cells and highlight open questions in the field.
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Affiliation(s)
- Maria-Jesus Olarte
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Tobias C Walther
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
| | - Robert V Farese
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
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Drosophila Keap1 xenobiotic response factor regulates developmental transcription through binding to chromatin. Dev Biol 2022; 481:139-147. [PMID: 34662537 PMCID: PMC9502878 DOI: 10.1016/j.ydbio.2021.10.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 10/01/2021] [Accepted: 10/08/2021] [Indexed: 01/03/2023]
Abstract
The Keap1-Nrf2 complex is a central regulator that mediates transcriptional responses to xenobiotic stimuli and is highly related with multiple human diseases. The molecular mechanisms and biological functions of Keap1 and Nrf2 are not fully understood. The Drosophila Keap1 homolog (dKeap1) is conserved with mammalian Keap1 except that dKeap1 contains a 156 aa C-terminal tail (CTD). A dKeap1 truncation with the CTD removed (dKeap1-ΔCTD) shows abolished nuclear localization and chromatin-binding. Expression of dKeap1-ΔCTD in the dKeap1 null background significantly rescues this mutant to the adult stage, but the files showed partial lethality, sterility and defects in adipose tissue. In the rescued flies, expression levels of ecdysone-response genes, ecdysone-synthetic genes and adipogenesis genes were down-regulated in specific tissues, indicating that the chromatin-binding of dKeap1 mediates the activation of these developmental genes. At the same time, dKeap1-ΔCTD can still suppress the basal expression of detoxifying genes and mediate the activation of these genes in response to xenobiotic stimuli, suggesting that the chromatin-binding of dKeap1 is not required for the regulation of detoxifying genes. These results support a model in which dKeap1 on one hand functions as an inhibitor for the Nrf2-mediated transcription in the xenobiotic response pathway and on the other hand functions as a chromatin-binding transcription activator in the developmental pathway. Our study reveals a novel mechanism whereby Keap1-Nrf2 xenobiotic response signaling regulates development using a mechanism independent of redox signaling.
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Xu M, Ding L, Liang J, Yang X, Liu Y, Wang Y, Ding M, Huang X. NAD kinase sustains lipogenesis and mitochondrial metabolismthrough fatty acid synthesis. Cell Rep 2021; 37:110157. [PMID: 34965438 DOI: 10.1016/j.celrep.2021.110157] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/27/2021] [Accepted: 12/02/2021] [Indexed: 10/19/2022] Open
Abstract
Lipid storage in fat tissue is important for energy homeostasis and cellular functions. Through RNAi screening in Drosophila fat body, we found that knockdown of a Drosophila NAD kinase (NADK), which phosphorylates NAD to synthesize NADP de novo, causes lipid storage defects. NADK sustains lipogenesis by maintaining the pool of NADPH. Promoting NADPH production rescues the lipid storage defect in the fat body of NADK RNAi animals. Furthermore, NADK and fatty acid synthase 1 (FASN1) regulate mitochondrial mass and function by altering the levels of acetyl-CoA and fatty acids. Reducing the level of acetyl-CoA or increasing the synthesis of cardiolipin (CL), a mitochondrion-specific phospholipid, partially rescues the mitochondrial defects of NADK RNAi. Therefore, NADK- and FASN1-mediated fatty acid synthesis coordinates lipid storage and mitochondrial function.
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Affiliation(s)
- Mengyao Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Long Ding
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jingjing Liang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiao Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; School of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, TaiAn 271016, China
| | - Yuan Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mei Ding
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Hello from the other side: Membrane contact of lipid droplets with other organelles and subsequent functional implications. Prog Lipid Res 2021; 85:101141. [PMID: 34793861 DOI: 10.1016/j.plipres.2021.101141] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/10/2021] [Accepted: 11/10/2021] [Indexed: 02/06/2023]
Abstract
Lipid droplets (LDs) are ubiquitous organelles that play crucial roles in response to physiological and environmental cues. The identification of several neutral lipid synthesizing and regulatory protein complexes have propelled significant advance on the mechanisms of LD biogenesis in the endoplasmic reticulum (ER). Increasing evidence suggests that distinct proteins and regulatory factors, which localize to membrane contact sites (MCS), are involved not only in interorganellar lipid exchange and transport, but also function in other important cellular processes, including autophagy, mitochondrial dynamics and inheritance, ion signaling and inter-regulation of these MCS. More and more tethers and molecular determinants are associated to MCS and to a diversity of cellular and pathophysiological processes, demonstrating the dynamics and importance of these junctions in health and disease. The conjugation of lipids with proteins in supramolecular complexes is known to be paramount for many biological processes, namely membrane biosynthesis, cell homeostasis, regulation of organelle division and biogenesis, and cell growth. Ultimately, this physical organization allows the contact sites to function as crucial metabolic hubs that control the occurrence of chemical reactions. This leads to biochemical and metabolite compartmentalization for the purposes of energetic efficiency and cellular homeostasis. In this review, we will focus on the structural and functional aspects of LD-organelle interactions and how they ensure signaling exchange and metabolites transfer between organelles.
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Zhang H, Hong Y, Yang W, Wang R, Yao T, Wang J, Liu K, Yuan H, Xu C, Zhou Y, Li G, Zhang L, Luo H, Zhang X, Du D, Sun H, Zheng Q, Zhang YW, Zhao Y, Zhou Y, Xu H, Wang X. SNX14 deficiency-induced defective axonal mitochondrial transport in Purkinje cells underlies cerebellar ataxia and can be reversed by valproate. Natl Sci Rev 2021; 8:nwab024. [PMID: 34691693 PMCID: PMC8310771 DOI: 10.1093/nsr/nwab024] [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: 07/12/2020] [Revised: 01/18/2021] [Accepted: 02/05/2021] [Indexed: 12/11/2022] Open
Abstract
Loss-of-function mutations in sorting nexin 14 (SNX14) cause autosomal recessive spinocerebellar ataxia 20, which is a form of early-onset cerebellar ataxia that lacks molecular mechanisms and mouse models. We generated Snx14-deficient mouse models and observed severe motor deficits and cell-autonomous Purkinje cell degeneration. SNX14 deficiency disrupted microtubule organization and mitochondrial transport in axons by destabilizing the microtubule-severing enzyme spastin, which is implicated in dominant hereditary spastic paraplegia with cerebellar ataxia, and compromised axonal integrity and mitochondrial function. Axonal transport disruption and mitochondrial dysfunction further led to degeneration of high-energy-demanding Purkinje cells, which resulted in the pathogenesis of cerebellar ataxia. The antiepileptic drug valproate ameliorated motor deficits and cerebellar degeneration in Snx14-deficient mice via the restoration of mitochondrial transport and function in Purkinje cells. Our study revealed an unprecedented role for SNX14-dependent axonal transport in cerebellar ataxia, demonstrated the convergence of SNX14 and spastin in mitochondrial dysfunction, and suggested valproate as a potential therapeutic agent.
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Affiliation(s)
- Hongfeng Zhang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Yujuan Hong
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Weijie Yang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Ruimin Wang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Ting Yao
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Jian Wang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Ke Liu
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Huilong Yuan
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Chaoqun Xu
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Yuanyuan Zhou
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Guanxian Li
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Lishan Zhang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Hong Luo
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Xian Zhang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Dan Du
- Cancer Research Center, Department of Stomatology, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Hao Sun
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Qiuyang Zheng
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Yun-Wu Zhang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Yingjun Zhao
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Ying Zhou
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Huaxi Xu
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
| | - Xin Wang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, China
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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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40
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Saric A, Freeman SA, Williamson CD, Jarnik M, Guardia CM, Fernandopulle MS, Gershlick DC, Bonifacino JS. SNX19 restricts endolysosome motility through contacts with the endoplasmic reticulum. Nat Commun 2021; 12:4552. [PMID: 34315878 PMCID: PMC8316374 DOI: 10.1038/s41467-021-24709-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 06/24/2021] [Indexed: 12/12/2022] Open
Abstract
The ability of endolysosomal organelles to move within the cytoplasm is essential for the performance of their functions. Long-range movement involves coupling of the endolysosomes to motor proteins that carry them along microtubule tracks. This movement is influenced by interactions with other organelles, but the mechanisms involved are incompletely understood. Herein we show that the sorting nexin SNX19 tethers endolysosomes to the endoplasmic reticulum (ER), decreasing their motility and contributing to their concentration in the perinuclear area of the cell. Tethering depends on two N-terminal transmembrane domains that anchor SNX19 to the ER, and a PX domain that binds to phosphatidylinositol 3-phosphate on the endolysosomal membrane. Two other domains named PXA and PXC negatively regulate the interaction of SNX19 with endolysosomes. These studies thus identify a mechanism for controlling the motility and positioning of endolysosomes that involves tethering to the ER by a sorting nexin.
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Affiliation(s)
- Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Chad D Williamson
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Michal Jarnik
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Carlos M Guardia
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Michael S Fernandopulle
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - David C Gershlick
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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41
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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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Heier C, Klishch S, Stilbytska O, Semaniuk U, Lushchak O. The Drosophila model to interrogate triacylglycerol biology. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158924. [PMID: 33716135 DOI: 10.1016/j.bbalip.2021.158924] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 02/24/2021] [Accepted: 03/05/2021] [Indexed: 12/21/2022]
Abstract
The deposition of storage fat in the form of triacylglycerol (TAG) is an evolutionarily conserved strategy to cope with fluctuations in energy availability and metabolic stress. Organismal TAG storage in specialized adipose tissues provides animals a metabolic reserve that sustains survival during development and starvation. On the other hand, excessive accumulation of adipose TAG, defined as obesity, is associated with an increasing prevalence of human metabolic diseases. During the past decade, the fruit fly Drosophila melanogaster, traditionally used in genetics and developmental biology, has been established as a versatile model system to study TAG metabolism and the etiology of lipid-associated metabolic diseases. Similar to humans, Drosophila TAG homeostasis relies on the interplay of organ systems specialized in lipid uptake, synthesis, and processing, which are integrated by an endocrine network of hormones and messenger molecules. Enzymatic formation of TAG from sugar or dietary lipid, its storage in lipid droplets, and its mobilization by lipolysis occur via mechanisms largely conserved between Drosophila and humans. Notably, dysfunctional Drosophila TAG homeostasis occurs in the context of aging, overnutrition, or defective gene function, and entails tissue-specific and organismal pathologies that resemble human disease. In this review, we summarize the physiology and biochemistry of TAG in Drosophila and outline the potential of this organism as a model system to understand the genetic and dietary basis of TAG storage and TAG-related metabolic disorders.
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Affiliation(s)
- Christoph Heier
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, Humboldtstrasse 50, A-8010 Graz, Austria; BioTechMed-Graz, Graz, Austria.
| | - Svitlana Klishch
- Department of Biochemistry and Biotechnology, Department Biochemistry 1, Faculty of Natural Sciences, Vasyl Stefanyk Precarpathian National University, 57 Shevchenka str, Ivano-Frankivsk 76018, Ukraine
| | - Olha Stilbytska
- Department of Biochemistry and Biotechnology, Department Biochemistry 1, Faculty of Natural Sciences, Vasyl Stefanyk Precarpathian National University, 57 Shevchenka str, Ivano-Frankivsk 76018, Ukraine
| | - Uliana Semaniuk
- Department of Biochemistry and Biotechnology, Department Biochemistry 1, Faculty of Natural Sciences, Vasyl Stefanyk Precarpathian National University, 57 Shevchenka str, Ivano-Frankivsk 76018, Ukraine
| | - Oleh Lushchak
- Department of Biochemistry and Biotechnology, Department Biochemistry 1, Faculty of Natural Sciences, Vasyl Stefanyk Precarpathian National University, 57 Shevchenka str, Ivano-Frankivsk 76018, Ukraine.
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Amatya B, Lee H, Asico LD, Konkalmatt P, Armando I, Felder RA, Jose PA. SNX-PXA-RGS-PXC Subfamily of SNXs in the Regulation of Receptor-Mediated Signaling and Membrane Trafficking. Int J Mol Sci 2021; 22:ijms22052319. [PMID: 33652569 PMCID: PMC7956473 DOI: 10.3390/ijms22052319] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/13/2021] [Accepted: 02/22/2021] [Indexed: 12/26/2022] Open
Abstract
The SNX-PXA-RGS-PXC subfamily of sorting nexins (SNXs) belongs to the superfamily of SNX proteins. SNXs are characterized by the presence of a common phox-homology (PX) domain, along with other functional domains that play versatile roles in cellular signaling and membrane trafficking. In addition to the PX domain, the SNX-PXA-RGS-PXC subfamily, except for SNX19, contains a unique RGS (regulators of G protein signaling) domain that serves as GTPase activating proteins (GAPs), which accelerates GTP hydrolysis on the G protein α subunit, resulting in termination of G protein-coupled receptor (GPCR) signaling. Moreover, the PX domain selectively interacts with phosphatidylinositol-3-phosphate and other phosphoinositides found in endosomal membranes, while also associating with various intracellular proteins. Although SNX19 lacks an RGS domain, all members of the SNX-PXA-RGS-PXC subfamily serve as dual regulators of receptor cargo signaling and endosomal trafficking. This review discusses the known and proposed functions of the SNX-PXA-RGS-PXC subfamily and how it participates in receptor signaling (both GPCR and non-GPCR) and endosomal-based membrane trafficking. Furthermore, we discuss the difference of this subfamily of SNXs from other subfamilies, such as SNX-BAR nexins (Bin-Amphiphysin-Rvs) that are associated with retromer or other retrieval complexes for the regulation of receptor signaling and membrane trafficking. Emerging evidence has shown that the dysregulation and malfunction of this subfamily of sorting nexins lead to various pathophysiological processes and disorders, including hypertension.
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Affiliation(s)
- Bibhas Amatya
- The George Washington University, Washington, DC 20052, USA;
| | - Hewang Lee
- Department of Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA; (H.L.); (L.D.A.); (P.K.); (I.A.)
| | - Laureano D. Asico
- Department of Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA; (H.L.); (L.D.A.); (P.K.); (I.A.)
| | - Prasad Konkalmatt
- Department of Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA; (H.L.); (L.D.A.); (P.K.); (I.A.)
| | - Ines Armando
- Department of Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA; (H.L.); (L.D.A.); (P.K.); (I.A.)
| | - Robin A. Felder
- Department of Pathology, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA;
| | - Pedro A. Jose
- Department of Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA; (H.L.); (L.D.A.); (P.K.); (I.A.)
- Department of Pathology, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA;
- Department of Pharmacology/Physiology, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA
- Correspondence:
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Klemm RW, Carvalho P. Principles of organelle spatial organization and interactions. Mol Biol Cell 2021; 31:401-402. [PMID: 32163349 PMCID: PMC8734309 DOI: 10.1091/mbc.e20-01-0007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Affiliation(s)
- Robin W Klemm
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, OX1 3RE Oxford, UK
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Snx14 proximity labeling reveals a role in saturated fatty acid metabolism and ER homeostasis defective in SCAR20 disease. Proc Natl Acad Sci U S A 2020; 117:33282-33294. [PMID: 33310904 DOI: 10.1073/pnas.2011124117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Fatty acids (FAs) are central cellular metabolites that contribute to lipid synthesis, and can be stored or harvested for metabolic energy. Dysregulation in FA processing and storage causes toxic FA accumulation or altered membrane compositions and contributes to metabolic and neurological disorders. Saturated lipids are particularly detrimental to cells, but how lipid saturation levels are maintained remains poorly understood. Here, we identify the cerebellar ataxia spinocerebellar ataxia, autosomal recessive 20 (SCAR20)-associated protein Snx14, an endoplasmic reticulum (ER)-lipid droplet (LD) tethering protein, as a factor required to maintain the lipid saturation balance of cell membranes. We show that following saturated FA (SFA) treatment, the ER integrity of SNX14 KO cells is compromised, and both SNX14 KO cells and SCAR20 disease patient-derived cells are hypersensitive to SFA-mediated lipotoxic cell death. Using APEX2-based proximity labeling, we reveal the protein composition of Snx14-associated ER-LD contacts and define a functional interaction between Snx14 and Δ-9 FA desaturase SCD1. Lipidomic profiling reveals that SNX14 KO cells increase membrane lipid saturation following exposure to palmitate, phenocopying cells with perturbed SCD1 activity. In line with this, SNX14 KO cells manifest delayed FA processing and lipotoxicity, which can be rescued by SCD1 overexpression. Altogether, these mechanistic insights reveal a role for Snx14 in FA and ER homeostasis, defects in which may underlie the neuropathology of SCAR20.
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Almeida C, Amaral MD. A central role of the endoplasmic reticulum in the cell emerges from its functional contact sites with multiple organelles. Cell Mol Life Sci 2020; 77:4729-4745. [PMID: 32313974 PMCID: PMC11104799 DOI: 10.1007/s00018-020-03523-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/30/2020] [Accepted: 04/06/2020] [Indexed: 02/08/2023]
Abstract
Early eukaryotic cells emerged from the compartmentalization of metabolic processes into specific organelles through the development of an endomembrane system (ES), a precursor of the endoplasmic reticulum (ER), which was essential for their survival. Recently, substantial evidence emerged on how organelles communicate among themselves and with the plasma membrane (PM) through contact sites (CSs). From these studies, the ER-the largest single structure in eukaryotic cells-emerges as a central player communicating with all organelles to coordinate cell functions and respond to external stimuli to maintain cellular homeostasis. Herein we review the functional insights into the ER-CSs with other organelles in a physiological perspective. We hypothesize that, in addition to the primitive role by the ES in the appearance of proto-eukaryotes, its successor-the ER-emerges as the key coordinator of inter-organelle/PM communication. The ER thus appears to be the 'maestro' driving eukaryotic cell evolution by incorporating new functions/organelles, while remaining the real coordinator overarching cellular functions and orchestrating them with the external milieu.
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Affiliation(s)
- Celso Almeida
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, University of Lisboa, Campo Grande, C8 bdg, 1749-016, Lisbon, Portugal.
| | - Margarida D Amaral
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, University of Lisboa, Campo Grande, C8 bdg, 1749-016, Lisbon, Portugal.
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Cao Z, Wang X, Huang X, Mak HY. Are endoplasmic reticulum subdomains shaped by asymmetric distribution of phospholipids? Evidence from a C. elegans model system. Bioessays 2020; 43:e2000199. [PMID: 33169432 DOI: 10.1002/bies.202000199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/13/2020] [Accepted: 09/18/2020] [Indexed: 12/19/2022]
Abstract
Physical contact between organelles are widespread, in part to facilitate the shuttling of protein and lipid cargoes for cellular homeostasis. How do protein-protein and protein-lipid interactions shape organelle subdomains that constitute contact sites? The endoplasmic reticulum (ER) forms extensive contacts with multiple organelles, including lipid droplets (LDs) that are central to cellular fat storage and mobilization. Here, we focus on ER-LD contacts that are highlighted by the conserved protein seipin, which promotes LD biogenesis and expansion. Seipin is enriched in ER tubules that form cage-like structures around a subset of LDs. Such enrichment is strongly dependent on polyunsaturated and cyclopropane fatty acids. Based on these findings, we speculate on molecular events that lead to the formation of seipin-positive peri-LD cages in which protein movement is restricted. We hypothesize that asymmetric distribution of specific phospholipids distinguishes cage membrane tubules from the bulk ER.
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Affiliation(s)
- Zhe Cao
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Xiaowei Wang
- Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Xuhui Huang
- Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Ho Yi Mak
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
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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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Bohnert M. Tether Me, Tether Me Not—Dynamic Organelle Contact Sites in Metabolic Rewiring. Dev Cell 2020; 54:212-225. [DOI: 10.1016/j.devcel.2020.06.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/17/2020] [Accepted: 06/20/2020] [Indexed: 02/04/2023]
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50
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Chen Y, Cai GH, Xia B, Wang X, Zhang CC, Xie BC, Shi XC, Liu H, Lu JF, Zhang RX, Zhu MQ, Liu M, Yang SZ, Yang Zhang D, Chu XY, Khan R, Wang YL, Wu JW. Mitochondrial aconitase controls adipogenesis through mediation of cellular ATP production. FASEB J 2020; 34:6688-6702. [PMID: 32212192 DOI: 10.1096/fj.201903224rr] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 11/11/2022]
Abstract
Mitochondrial aconitase (Aco2) catalyzes the conversion of citrate to isocitrate in the TCA cycle, which produces NADH and FADH2, driving synthesis of ATP through OXPHOS. In this study, to explore the relationship between adipogenesis and mitochondrial energy metabolism, we hypothesize that Aco2 may play a key role in the lipid synthesis. Here, we show that overexpression of Aco2 in 3T3-L1 cells significantly increased lipogenesis and adipogenesis, accompanied by elevated mitochondrial biogenesis and ATP production. However, when ATP is depleted by rotenone, an inhibitor of the respiratory chain, the promotive role of Aco2 in adipogenesis is abolished. In contrast to Aco2 overexpression, deficiency of Aco2 markedly reduced lipogenesis and adipogenesis, along with the decreased mitochondrial biogenesis and ATP production. Supplementation of isocitrate efficiently rescued the inhibitory effect of Aco2 deficiency. Similarly, the restorative effect of isocitrate was abolished in the presence of rotenone. Together, these results show that Aco2 sustains normal adipogenesis through mediating ATP production, revealing a potential mechanistic link between TCA cycle enzyme and lipid synthesis. Our work suggest that regulation of adipose tissue mitochondria function may be a potential way for combating abnormal adipogenesis related diseases such as obesity and lipodystrophy.
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Affiliation(s)
- Yan Chen
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Guo He Cai
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Bo Xia
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Xin Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Cong Cong Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Bao Cai Xie
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Xiao Chen Shi
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Huan Liu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Jun Feng Lu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Rui Xin Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Meng Qing Zhu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Min Liu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Shi Zhen Yang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Dan Yang Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Xin Yi Chu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Rajwali Khan
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Yong Liang Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Jiang Wei Wu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
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