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Braulke T, Carette JE, Palm W. Lysosomal enzyme trafficking: from molecular mechanisms to human diseases. Trends Cell Biol 2024; 34:198-210. [PMID: 37474375 DOI: 10.1016/j.tcb.2023.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/16/2023] [Accepted: 06/19/2023] [Indexed: 07/22/2023]
Abstract
Lysosomes degrade and recycle macromolecules that are delivered through the biosynthetic, endocytic, and autophagic routes. Hydrolysis of the different classes of macromolecules is catalyzed by about 70 soluble enzymes that are transported from the Golgi apparatus to lysosomes in a mannose 6-phosphate (M6P)-dependent process. The molecular machinery that generates M6P tags for receptor-mediated targeting of lysosomal enzymes was thought to be understood in detail. However, recent studies on the M6P pathway have identified a previously uncharacterized core component, yielded structural insights in known components, and uncovered functions in various human diseases. Here we review molecular mechanisms of lysosomal enzyme trafficking and discuss its relevance for rare lysosomal disorders, cancer, and viral infection.
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Affiliation(s)
- Thomas Braulke
- Department of Osteology and Biomechanics, Cell Biology of Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jan E Carette
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Wilhelm Palm
- German Cancer Research Center (DKFZ), Heidelberg, Germany.
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2
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A Novel Splice Site Variant in the LDLRAP1 Gene Causes Familial Hypercholesterolemia. IRANIAN BIOMEDICAL JOURNAL 2021; 25:374-9. [PMID: 34425670 PMCID: PMC8487678 DOI: 10.52547/ibj.25.5.374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background: FH, a hereditary disorder, is caused by pathogenic variants in the LDLR, APOB, and PCSK9 genes. This study has assessed genetic variants in a family, clinically diagnosed with FH. Methods: A family was recruited from MASHAD study in Iran with possible FH based on the Simon Broom criteria. The DNA sample of an affected individual (proband) was analyzed using WES, followed by bioinformatics and segregation analyses. Results: A novel splice site variant (c.345-2A>G) was detected in the LDLRAP1 gene, which was segregated in all affected family members. Moreover, HMGCR rs3846662 g.23092A>G was found to be homozygous (G/G) in the proband, probably leading to reduced response to simvastatin and pravastatin. Conclusion: LDLRAP1 c.345-2A>G could alter the PTB, which acts as an important part of biological pathways related to lipid metabolism.
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3
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PCSK9 in cholesterol metabolism: from bench to bedside. Clin Sci (Lond) 2018; 132:1135-1153. [DOI: 10.1042/cs20180190] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/11/2018] [Accepted: 05/14/2018] [Indexed: 12/13/2022]
Abstract
Dyslipidemia, and specifically elevated low-density lipoprotein (LDL) cholesterol, is one of the most important cardiovascular risk factors. Statins are considered first line therapy for the primary and secondary prevention of cardiovascular disease. However, statins may not be adequate treatment for elevated circulating LDL levels and are ineffective in certain familial hypercholesterolemias. The discovery of proprotein convertase subtilisin/kexin type 9 (PCSK9), a regulatory protein that affects LDL receptors, offers a new alternative for these patients. Moreover, gain-of-function PCSK9 mutations were discovered to be the root cause of familial autosomal dominant hypercholesterolemia. Inhibition of PSCK9 reduces plasma LDL levels, even in patients for whom statins are ineffective or not tolerated. Alirocumab and evolocumab, human monoclonal antibodies that inhibit PCSK9, have been approved to lower LDL levels. While there are drawbacks to these treatments, including adverse events, administration by subcutaneous injection, and high cost, these drugs are indicated for the treatment of atherosclerotic cardiovascular disease and familial hypercholesterolemia as adjunct to diet and maximally tolerated statin therapy. PCSK9 inhibitors may work synergistically with statins to lower LDL. Novel approaches to PCSK9 inhibition are currently in development with the aim of providing safe and effective treatment options to decrease cardiovascular event burden, ideally at lower cost and with oral bioavailability.
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Finkielstein CV, Capelluto DGS. Disabled-2: A modular scaffold protein with multifaceted functions in signaling. Bioessays 2017; 38 Suppl 1:S45-55. [PMID: 27417122 DOI: 10.1002/bies.201670907] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/08/2015] [Accepted: 07/12/2015] [Indexed: 12/14/2022]
Abstract
Disabled-2 (Dab2) is a multimodular scaffold protein with signaling roles in the domains of cell growth, trafficking, differentiation, and homeostasis. Emerging evidences place Dab2 as a novel modulator of cell-cell interaction; however, its mode of action has remained largely elusive. In this review, we highlight the relevance of Dab2 function in cell signaling and development and provide the most recent and comprehensive analysis of Dab2's action as a mediator of homotypical and heterotypical interactions. Accordingly, Dab-2 controls the extent of platelet aggregation through various motifs within its N-terminus. Dab2 interacts with the cytosolic tail of the integrin receptor blocking inside-out signaling, whereas extracellular Dab2 competes with fibrinogen for integrin αIIb β3 receptor binding and, thus, modulates outside-in signaling. An additional level of regulation results from Dab2's association with cell surface lipids, an event that defines the extent of cell-cell interactions. As a multifaceted regulator, Dab2 acts as a mediator of endocytosis through its association with the [FY]xNPx[YF] motifs of internalized cell surface receptors, phosphoinositides, and clathrin. Other emerging roles of Dab2 include its participation in developmental mechanisms required for tissue formation and in modulation of immune responses. This review highlights the various novel mechanisms by which Dab2 mediates an array of signaling events with vast physiological consequences.
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Affiliation(s)
- Carla V Finkielstein
- Integrated Cellular Responses Laboratory, Department of Biological Sciences, Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, VA, USA
| | - Daniel G S Capelluto
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, VA, USA
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5
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Durst R, Ibe UK, Shpitzen S, Schurr D, Eliav O, Futema M, Whittall R, Szalat A, Meiner V, Knobler H, Gavish D, Henkin Y, Ellis A, Rubinstein A, Harats D, Bitzur R, Hershkovitz B, Humphries SE, Leitersdorf E. Molecular genetics of familial hypercholesterolemia in Israel–revisited. Atherosclerosis 2017; 257:55-63. [DOI: 10.1016/j.atherosclerosis.2016.12.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Revised: 12/10/2016] [Accepted: 12/16/2016] [Indexed: 10/20/2022]
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6
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Yan Y, Qiu S, Jin Z, Gong S, Bai Y, Lu J, Yu T. Detecting subnetwork-level dynamic correlations. Bioinformatics 2016; 33:256-265. [PMID: 27667792 DOI: 10.1093/bioinformatics/btw616] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 09/07/2016] [Accepted: 09/21/2016] [Indexed: 01/11/2023] Open
Abstract
MOTIVATION The biological regulatory system is highly dynamic. The correlations between many functionally related genes change over different biological conditions. Finding dynamic relations on the existing biological network may reveal important regulatory mechanisms. Currently no method is available to detect subnetwork-level dynamic correlations systematically on the genome-scale network. Two major issues hampered the development. The first is gene expression profiling data usually do not contain time course measurements to facilitate the analysis of dynamic relations, which can be partially addressed by using certain genes as indicators of biological conditions. Secondly, it is unclear how to effectively delineate subnetworks, and define dynamic relations between them. RESULTS Here we propose a new method named LANDD (Liquid Association for Network Dynamics Detection) to find subnetworks that show substantial dynamic correlations, as defined by subnetwork A is concentrated with Liquid Association scouting genes for subnetwork B. The method produces easily interpretable results because of its focus on subnetworks that tend to comprise functionally related genes. Also, the collective behaviour of genes in a subnetwork is a much more reliable indicator of underlying biological conditions compared to using single genes as indicators. We conducted extensive simulations to validate the method's ability to detect subnetwork-level dynamic correlations. Using a real gene expression dataset and the human protein-protein interaction network, we demonstrate the method links subnetworks of distinct biological processes, with both confirmed relations and plausible new functional implications. We also found signal transduction pathways tend to show extensive dynamic relations with other functional groups. AVAILABILITY AND IMPLEMENTATION The R package is available at https://cran.r-project.org/web/packages/LANDD CONTACTS: yunba@pcom.edu, jwlu33@hotmail.com or tianwei.yu@emory.eduSupplementary information: Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Yan Yan
- School of Software Engineering, Tongji University, Shanghai, China
| | - Shangzhao Qiu
- School of Software Engineering, Tongji University, Shanghai, China
| | - Zhuxuan Jin
- Department of Biostatistics and Bioinformatics, Emory University, Atlanta, GA, USA
| | - Sihong Gong
- School of Software Engineering, Tongji University, Shanghai, China
| | - Yun Bai
- Department of Pharmaceutical Sciences, School of Pharmacy, Philadelphia College of Osteopathic Medicine, Suwanee, GA, USA
| | - Jianwei Lu
- School of Software Engineering, Tongji University, Shanghai, China
- Institute of Advanced Translational Medicine, Tongji University, Shanghai, China
| | - Tianwei Yu
- Department of Biostatistics and Bioinformatics, Emory University, Atlanta, GA, USA
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7
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Zhang W, Wu J, Ward MD, Yang S, Chuang YA, Xiao M, Li R, Leahy DJ, Worley PF. Structural basis of arc binding to synaptic proteins: implications for cognitive disease. Neuron 2015; 86:490-500. [PMID: 25864631 DOI: 10.1016/j.neuron.2015.03.030] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 03/07/2015] [Accepted: 03/07/2015] [Indexed: 11/16/2022]
Abstract
Arc is a cellular immediate-early gene (IEG) that functions at excitatory synapses and is required for learning and memory. We report crystal structures of Arc subdomains that form a bi-lobar architecture remarkably similar to the capsid domain of human immunodeficiency virus (HIV) gag protein. Analysis indicates Arc originated from the Ty3/Gypsy retrotransposon family and was "domesticated" in higher vertebrates for synaptic functions. The Arc N-terminal lobe evolved a unique hydrophobic pocket that mediates intermolecular binding with synaptic proteins as resolved in complexes with TARPγ2 (Stargazin) and CaMKII peptides and is essential for Arc's synaptic function. A consensus sequence for Arc binding identifies several additional partners that include genes implicated in schizophrenia. Arc N-lobe binding is inhibited by small chemicals suggesting Arc's synaptic action may be druggable. These studies reveal the remarkable evolutionary origin of Arc and provide a structural basis for understanding Arc's contribution to neural plasticity and disease.
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Affiliation(s)
- Wenchi Zhang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jing Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Matthew D Ward
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sunggu Yang
- Department of Nano-Bioengineering, Incheon National University, Incheon, 406-772, Korea
| | - Yang-An Chuang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Meifang Xiao
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ruojing Li
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Daniel J Leahy
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Paul F Worley
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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8
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9
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Li YI, Sanchez-Pulido L, Haerty W, Ponting CP. RBFOX and PTBP1 proteins regulate the alternative splicing of micro-exons in human brain transcripts. Genome Res 2015; 25:1-13. [PMID: 25524026 PMCID: PMC4317164 DOI: 10.1101/gr.181990.114] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 10/27/2014] [Indexed: 11/24/2022]
Abstract
Ninety-four percent of mammalian protein-coding exons exceed 51 nucleotides (nt) in length. The paucity of micro-exons (≤ 51 nt) suggests that their recognition and correct processing by the splicing machinery present greater challenges than for longer exons. Yet, because thousands of human genes harbor processed micro-exons, specialized mechanisms may be in place to promote their splicing. Here, we survey deep genomic data sets to define 13,085 micro-exons and to study their splicing mechanisms and molecular functions. More than 60% of annotated human micro-exons exhibit a high level of sequence conservation, an indicator of functionality. While most human micro-exons require splicing-enhancing genomic features to be processed, the splicing of hundreds of micro-exons is enhanced by the adjacent binding of splice factors in the introns of pre-messenger RNAs. Notably, splicing of a significant number of micro-exons was found to be facilitated by the binding of RBFOX proteins, which promote their inclusion in the brain, muscle, and heart. Our analyses suggest that accurate regulation of micro-exon inclusion by RBFOX proteins and PTBP1 plays an important role in the maintenance of tissue-specific protein-protein interactions.
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Affiliation(s)
- Yang I Li
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Luis Sanchez-Pulido
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Wilfried Haerty
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Chris P Ponting
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom;
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10
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Fisher OS, Liu W, Zhang R, Stiegler AL, Ghedia S, Weber JL, Boggon TJ. Structural basis for the disruption of the cerebral cavernous malformations 2 (CCM2) interaction with Krev interaction trapped 1 (KRIT1) by disease-associated mutations. J Biol Chem 2014; 290:2842-53. [PMID: 25525273 DOI: 10.1074/jbc.m114.616433] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Familial cerebral cavernous malformations (CCMs) are predominantly neurovascular lesions and are associated with mutations within the KRIT1, CCM2, and PDCD10 genes. The protein products of KRIT1 and CCM2 (Krev interaction trapped 1 (KRIT1) and cerebral cavernous malformations 2 (CCM2), respectively) directly interact with each other. Disease-associated mutations in KRIT1 and CCM2 mostly result in loss of their protein products, although rare missense point mutations can also occur. From gene sequencing of patients known or suspected to have one or more CCMs, we discover a series of missense point mutations in KRIT1 and CCM2 that result in missense mutations in the CCM2 and KRIT1 proteins. To place these mutations in the context of the molecular level interactions of CCM2 and KRIT1, we map the interaction of KRIT1 and CCM2 and find that the CCM2 phosphotyrosine binding (PTB) domain displays a preference toward the third of the three KRIT1 NPX(Y/F) motifs. We determine the 2.75 Å co-crystal structure of the CCM2 PTB domain with a peptide corresponding to KRIT1(NPX(Y/F)3), revealing a Dab-like PTB fold for CCM2 and its interaction with KRIT1(NPX(Y/F)3). We find that several disease-associated missense mutations in CCM2 have the potential to interrupt the KRIT1-CCM2 interaction by destabilizing the CCM2 PTB domain and that a KRIT1 mutation also disrupts this interaction. We therefore provide new insights into the architecture of CCM2 and how the CCM complex is disrupted in CCM disease.
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Affiliation(s)
- Oriana S Fisher
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Weizhi Liu
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Rong Zhang
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Amy L Stiegler
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Sondhya Ghedia
- the Department of Clinical Genetics, Royal North Shore Hospital, Pacific Highway, St. Leonards, New South Wales 2065, Australia, and
| | | | - Titus J Boggon
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520,
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11
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Etxebarria A, Benito-Vicente A, Palacios L, Stef M, Cenarro A, Civeira F, Ostolaza H, Martin C. Functional Characterization and Classification of Frequent Low-Density Lipoprotein Receptor Variants. Hum Mutat 2014; 36:129-41. [DOI: 10.1002/humu.22721] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/24/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Aitor Etxebarria
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
| | - Asier Benito-Vicente
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
| | | | | | - Ana Cenarro
- Unidad de Lípidos and Laboratorio de Investigación Molecular; Hospital Universitario Miguel Servet; Instituto Aragonés de Ciencias de la Salud (IACS); Zaragoza Spain
| | - Fernando Civeira
- Unidad de Lípidos and Laboratorio de Investigación Molecular; Hospital Universitario Miguel Servet; Instituto Aragonés de Ciencias de la Salud (IACS); Zaragoza Spain
| | - Helena Ostolaza
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
| | - Cesar Martin
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
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12
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Kirchhausen T, Owen D, Harrison SC. Molecular structure, function, and dynamics of clathrin-mediated membrane traffic. Cold Spring Harb Perspect Biol 2014; 6:a016725. [PMID: 24789820 DOI: 10.1101/cshperspect.a016725] [Citation(s) in RCA: 303] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Clathrin is a molecular scaffold for vesicular uptake of cargo at the plasma membrane, where its assembly into cage-like lattices underlies the clathrin-coated pits of classical endocytosis. This review describes the structures of clathrin, major cargo adaptors, and other proteins that participate in forming a clathrin-coated pit, loading its contents, pinching off the membrane as a lattice-enclosed vesicle, and recycling the components. It integrates as much of the structural information as possible at the time of writing into a sketch of the principal steps in coated-pit and coated-vesicle formation.
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Affiliation(s)
- Tom Kirchhausen
- Department of Cell Biology, Harvard Medical School/PCMM, Boston, Massachusetts 02115
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13
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Traub LM, Bonifacino JS. Cargo recognition in clathrin-mediated endocytosis. Cold Spring Harb Perspect Biol 2013; 5:a016790. [PMID: 24186068 DOI: 10.1101/cshperspect.a016790] [Citation(s) in RCA: 217] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The endosomal system is expansive and complex, characterized by swift morphological transitions, dynamic remodeling of membrane constituents, and intracellular positioning changes. To properly navigate this ever-altering membrane labyrinth, transmembrane protein cargoes typically require specific sorting signals that are decoded by components of protein coats. The best-characterized sorting process within the endosomal system is the rapid internalization of select transmembrane proteins within clathrin-coated vesicles. Endocytic signals consist of linear motifs, conformational determinants, or covalent modifications in the cytosolic domains of transmembrane cargo. These signals are interpreted by a diverse set of clathrin-associated sorting proteins (CLASPs) that translocate from the cytosol to the inner face of the plasma membrane. Signal recognition by CLASPs is highly cooperative, involving additional interactions with phospholipids, Arf GTPases, other CLASPs, and clathrin, and is regulated by large conformational changes and covalent modifications. Related sorting events occur at other endosomal sorting stations.
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Affiliation(s)
- Linton M Traub
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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14
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Shah M, Baterina OY, Taupin V, Farquhar MG. ARH directs megalin to the endocytic recycling compartment to regulate its proteolysis and gene expression. ACTA ACUST UNITED AC 2013; 202:113-27. [PMID: 23836931 PMCID: PMC3704979 DOI: 10.1083/jcb.201211110] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
ARH is required for the trafficking of megalin from early endosomes to the endocytic recycling compartment, where megalin undergoes intramembrane proteolysis, releasing a tail fragment that represses megalin transcription. Receptors internalized by endocytosis can return to the plasma membrane (PM) directly from early endosomes (EE; fast recycling) or they can traffic from EE to the endocytic recycling compartment (ERC) and recycle from there (slow recycling). How receptors are sorted for trafficking along these two pathways remains unclear. Here we show that autosomal recessive hypercholesterolemia (ARH) is required for trafficking of megalin, a member of the LDL receptor family, from EE to the ERC by coupling it to dynein; in the absence of ARH, megalin returns directly to the PM from EE via the connecdenn2/Rab35 fast recycling pathway. Binding of ARH to the endocytic adaptor AP-2 prevents fast recycling of megalin. ARH-mediated trafficking of megalin to the ERC is necessary for γ-secretase mediated cleavage of megalin and release of a tail fragment that mediates transcriptional repression. These results identify a novel mechanism for sorting receptors for trafficking to the ERC and link ERC trafficking to regulated intramembrane proteolysis (RIP) and expression of megalin.
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Affiliation(s)
- Mehul Shah
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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15
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Zhao Z, Pompey S, Dong H, Weng J, Garuti R, Michaely P. S-nitrosylation of ARH is required for LDL uptake by the LDL receptor. J Lipid Res 2013; 54:1550-1559. [PMID: 23564733 DOI: 10.1194/jlr.m033167] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The LDL receptor (LDLR) relies upon endocytic adaptor proteins for internalization of lipoproteins. The results of this study show that the LDLR adaptor autosomal recessive hypercholesterolemia protein (ARH) requires nitric oxide to support LDL uptake. Nitric oxide nitrosylates ARH at C199 and C286, and these posttranslational modifications are necessary for association of ARH with the adaptor protein 2 (AP-2) component of clathrin-coated pits. In the absence of nitrosylation, ARH is unable to target LDL-LDLR complexes to coated pits, resulting in poor LDL uptake. The role of nitric oxide on LDLR function is specific for ARH because inhibition of nitric oxide synthase activity impairs ARH-supported LDL uptake but has no effect on other LDLR-dependent lipoprotein uptake processes, including VLDL remnant uptake and dab2-supported LDL uptake. These findings suggest that cells that depend upon ARH for LDL uptake can control which lipoproteins are internalized by their LDLRs through changes in nitric oxide.
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Affiliation(s)
- Zhenze Zhao
- Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Shanica Pompey
- Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Hongyun Dong
- Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Jian Weng
- Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Rita Garuti
- Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Peter Michaely
- Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX.
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16
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Ghai R, Bugarcic A, Liu H, Norwood SJ, Skeldal S, Coulson EJ, Li SSC, Teasdale RD, Collins BM. Structural basis for endosomal trafficking of diverse transmembrane cargos by PX-FERM proteins. Proc Natl Acad Sci U S A 2013; 110:E643-52. [PMID: 23382219 PMCID: PMC3581954 DOI: 10.1073/pnas.1216229110] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transit of proteins through the endosomal organelle following endocytosis is critical for regulating the homeostasis of cell-surface proteins and controlling signal transduction pathways. However, the mechanisms that control these membrane-transport processes are poorly understood. The Phox-homology (PX) domain-containing proteins sorting nexin (SNX) 17, SNX27, and SNX31 have emerged recently as key regulators of endosomal recycling and bind conserved Asn-Pro-Xaa-Tyr-sorting signals in transmembrane cargos via an atypical band, 4.1/ezrin/radixin/moesin (FERM) domain. Here we present the crystal structure of the SNX17 FERM domain bound to the sorting motif of the P-selectin adhesion protein, revealing both the architecture of the atypical FERM domain and the molecular basis for recognition of these essential sorting sequences. We further show that the PX-FERM proteins share a promiscuous ability to bind a wide array of putative cargo molecules, including receptor tyrosine kinases, and propose a model for their coordinated molecular interactions with membrane, cargo, and regulatory proteins.
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Affiliation(s)
| | | | - Huadong Liu
- Department of Biochemistry and
- Siebens Drake Medical Research Institute, University of Western Ontario, London, ON, Canada N6A 5C1
| | | | - Sune Skeldal
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia; and
| | - Elizabeth J. Coulson
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia; and
| | - Shawn Shun-Cheng Li
- Department of Biochemistry and
- Siebens Drake Medical Research Institute, University of Western Ontario, London, ON, Canada N6A 5C1
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