1
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Vo L, Schmidtke MW, Da Rosa-Junior NT, Ren M, Schlame M, Greenberg ML. Cardiolipin metabolism regulates expression of muscle transcription factor MyoD1 and muscle development. J Biol Chem 2023; 299:102978. [PMID: 36739949 PMCID: PMC9999232 DOI: 10.1016/j.jbc.2023.102978] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 01/27/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
The mitochondrial phospholipid cardiolipin (CL) is critical for numerous essential biological processes, including mitochondrial dynamics and energy metabolism. Mutations in the CL remodeling enzyme TAFAZZIN cause Barth syndrome, a life-threatening genetic disorder that results in severe physiological defects, including cardiomyopathy, skeletal myopathy, and neutropenia. To study the molecular mechanisms whereby CL deficiency leads to skeletal myopathy, we carried out transcriptomic analysis of the TAFAZZIN-knockout (TAZ-KO) mouse myoblast C2C12 cell line. Our data indicated that cardiac and muscle development pathways are highly decreased in TAZ-KO cells, consistent with a previous report of defective myogenesis in this cell line. Interestingly, the muscle transcription factor myoblast determination protein 1 (MyoD1) is significantly repressed in TAZ-KO cells and TAZ-KO mouse hearts. Exogenous expression of MyoD1 rescued the myogenesis defects previously observed in TAZ-KO cells. Our data suggest that MyoD1 repression is caused by upregulation of the MyoD1 negative regulator, homeobox protein Mohawk, and decreased Wnt signaling. Our findings reveal, for the first time, that CL metabolism regulates muscle differentiation through MyoD1 and identify the mechanism whereby MyoD1 is repressed in CL-deficient cells.
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Affiliation(s)
- Linh Vo
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Michael W Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | | | - Mindong Ren
- Department of Anesthesiology, Perioperative Care, and Pain Medicine at New York University Grossman School of Medicine, New York, New York, USA; Department of Cell Biology at New York University Grossman School of Medicine, New York, New York, USA
| | - Michael Schlame
- Department of Anesthesiology, Perioperative Care, and Pain Medicine at New York University Grossman School of Medicine, New York, New York, USA; Department of Cell Biology at New York University Grossman School of Medicine, New York, New York, USA
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA.
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2
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Abstract
Intercellular communication by Wnt proteins governs many essential processes during development, tissue homeostasis and disease in all metazoans. Many context-dependent effects are initiated in the Wnt-producing cells and depend on the export of lipidated Wnt proteins. Although much focus has been on understanding intracellular Wnt signal transduction, the cellular machinery responsible for Wnt secretion became better understood only recently. After lipid modification by the acyl-transferase Porcupine, Wnt proteins bind their dedicated cargo protein Evi/Wntless for transport and secretion. Evi/Wntless and Porcupine are conserved transmembrane proteins, and their 3D structures were recently determined. In this Review, we summarise studies and structural data highlighting how Wnts are transported from the ER to the plasma membrane, and the role of SNX3-retromer during the recycling of its cargo receptor Evi/Wntless. We also describe the regulation of Wnt export through a post-translational mechanism and review the importance of Wnt secretion for organ development and cancer, and as a future biomarker.
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Affiliation(s)
- Lucie Wolf
- German Cancer Research Center (DKFZ), Division of Signalling and Functional Genomics and Heidelberg University, BioQuant and Department of Cell and Molecular Biology, 69120 Heidelberg, Germany
| | - Michael Boutros
- German Cancer Research Center (DKFZ), Division of Signalling and Functional Genomics and Heidelberg University, BioQuant and Department of Cell and Molecular Biology, 69120 Heidelberg, Germany
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3
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Functional regulation of Wnt protein through post-translational modifications. Biochem Soc Trans 2022; 50:1797-1808. [DOI: 10.1042/bst20220735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/10/2022] [Accepted: 11/21/2022] [Indexed: 12/13/2022]
Abstract
Wnts are lipid-modified signaling glycoproteins present in all metazoans that play key roles in development and homeostasis. Post-translational modifications of Wnts regulate their function. Wnts have a unique post-translational modification, O-linked palmitoleation, that is absolutely required for their function. This Wnt-specific modification occurs during Wnt biosynthesis in the endoplasmic reticulum (ER), catalyzed by the O-acyltransferase Porcupine (PORCN). Palmitoleation is required for Wnt to bind to its transporter Wntless (WLS/Evi) as well as to its receptor Frizzled (FZD). Recent structural studies have illustrated how PORCN recognizes its substrates, and how drugs inhibit this. The abundance of WLS is tightly regulated by intracellular recycling and ubiquitylation-mediated degradation in the ER. The function of Wnt glycosylation is less well understood, and the sites and types of glycosylation are not largely conserved among different Wnts. In polarized tissues, the type of glycans can determine whether the route of trafficking is apical or basolateral. In addition, pairing of the 24 highly conserved cysteines in Wnts to form disulfide bonds is critical in maintaining proper structure and activities. Extracellularly, the amino terminus of a subset of Wnts can be cleaved by a dedicated glycosylphosphatidylinositol (GPI)-anchored metalloprotease TIKI, resulting in the inactivation of these Wnt proteins. Additionally, NOTUM is a secreted extracellular carboxylesterase that removes the palmitoleate moiety from Wnt, antagonizing its activity. In summary, Wnt signaling activity is controlled at multiple layers by post-translational modifications.
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4
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Doubravská L, Dostál V, Knop F, Libusová L, Macůrková M. Human myotubularin-related protein 9 regulates ER-to-Golgi trafficking and modulates WNT3A secretion. Exp Cell Res 2020; 386:111709. [PMID: 31704058 DOI: 10.1016/j.yexcr.2019.111709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 10/10/2019] [Accepted: 10/31/2019] [Indexed: 11/29/2022]
Abstract
Regulation of phosphatidylinositol phosphates plays a crucial role in signal transduction, membrane trafficking or autophagy. Members of the myotubularin family of lipid phosphatases contribute to phosphoinositide metabolism by counteracting the activity of phosphoinositide kinases. The mechanisms determining their subcellular localization and targeting to specific membrane compartments are still poorly understood. We show here that the inactive phosphatase MTMR9 localizes to the intermediate compartment and to the Golgi apparatus and is able to recruit its active phosphatase partners MTMR6 and MTMR8 to these locations. Furthermore, MTMR8 and MTMR9 co-localize with the small GTPase RAB1A and regulate its localization. Loss of MTMR9 expression compromises the integrity of the Golgi apparatus and results in altered distribution of RAB1A and actin nucleation-promoting factor WHAMM. Loss or overexpression of MTMR9 leads to decreased rate of protein secretion. We demonstrate that secretion of physiologically relevant cargo exemplified by the WNT3A protein is affected after perturbation of MTMR9 levels.
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Affiliation(s)
- Lenka Doubravská
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00, Prague 2, Czech Republic
| | - Vojtěch Dostál
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00, Prague 2, Czech Republic
| | - Filip Knop
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00, Prague 2, Czech Republic
| | - Lenka Libusová
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00, Prague 2, Czech Republic
| | - Marie Macůrková
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00, Prague 2, Czech Republic.
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5
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Henis-Korenblit S, Meléndez A. Methods to Determine the Role of Autophagy Proteins in C. elegans Aging. Methods Mol Biol 2019; 1880:561-586. [PMID: 30610723 DOI: 10.1007/978-1-4939-8873-0_37] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
This chapter describes methods for the analysis of autophagy proteins in C. elegans aging. We discuss the strains to be considered, the methods for the delivery of double-stranded RNA, and the methods to measure autophagy levels, autophagic flux, and degradation by autophagy.
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Affiliation(s)
- Sivan Henis-Korenblit
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
| | - Alicia Meléndez
- Department of Biology, Queens College, The City University of New York, Flushing, NY, USA.
- Biology and Biochemistry PhD Programs, The Graduate Center of the City University of New York, New York, NY, USA.
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6
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Kwon SH, Oh S, Nacke M, Mostov KE, Lipschutz JH. Adaptor Protein CD2AP and L-type Lectin LMAN2 Regulate Exosome Cargo Protein Trafficking through the Golgi Complex. J Biol Chem 2016; 291:25462-25475. [PMID: 27765817 DOI: 10.1074/jbc.m116.729202] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 09/27/2016] [Indexed: 01/30/2023] Open
Abstract
Exosomes, 40-150-nm extracellular vesicles, transport biological macromolecules that mediate intercellular communications. Although exosomes are known to originate from maturation of endosomes into multivesicular endosomes (also known as multivesicular bodies) with subsequent fusion of the multivesicular endosomes with the plasma membrane, it remains unclear how cargos are selected for exosomal release. Using an inducible expression system for the exosome cargo protein GPRC5B and following its trafficking trajectory, we show here that newly synthesized GPRC5B protein accumulates in the Golgi complex prior to its release into exosomes. The L-type lectin LMAN2 (also known as VIP36) appears to be specifically required for the accumulation of GPRC5B in the Golgi complex and restriction of GPRC5B transport along the exosomal pathway. This may occur due to interference with the adaptor protein GGA1-mediated trans Golgi network-to-endosome transport of GPRC5B. The adaptor protein CD2AP-mediated internalization following cell surface delivery appears to contribute to the Golgi accumulation of GPRC5B, possibly in parallel with biosynthetic/secretory trafficking from the endoplasmic reticulum. Our data thus reveal a Golgi-traversing pathway for exosomal release of the cargo protein GPRC5B in which CD2AP facilitates the entry and LMAN2 impedes the exit of the flux, respectively.
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Affiliation(s)
- Sang-Ho Kwon
- From the Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina 29425,
| | - Sekyung Oh
- the Department of Radiology, Stanford Cardiovascular Institute, and.,Department of Neurology and Neurological Sciences,Stanford University School of Medicine, Stanford, California 94305
| | - Marisa Nacke
- the Departments of Anatomy and Biochemistry/Biophysics, University of California, San Francisco, California 94143, and
| | - Keith E Mostov
- the Departments of Anatomy and Biochemistry/Biophysics, University of California, San Francisco, California 94143, and
| | - Joshua H Lipschutz
- From the Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina 29425.,the Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
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7
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Langton PF, Kakugawa S, Vincent JP. Making, Exporting, and Modulating Wnts. Trends Cell Biol 2016; 26:756-765. [PMID: 27325141 DOI: 10.1016/j.tcb.2016.05.011] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/15/2016] [Accepted: 05/20/2016] [Indexed: 10/21/2022]
Abstract
Wnt proteins activate a conserved signalling pathway that controls development and tissue homeostasis in all metazoans. The intensity of Wnt signalling must be tightly controlled to avoid diseases caused by excess or ectopic signalling. Over the years, many proteins dedicated to Wnt function have been identified, including Porcupine, which appends a palmitoleate moiety that is essential for signalling activity. This lipid inevitably affects subcellular trafficking and solubility, as well as providing a target for post-translational modulation. We review here the life history of Wnts, starting with progression through the secretory pathway, continuing with release and spread in the extracellular space, and finishing with the various proteins that dampen or inactivate Wnts in the extracellular space.
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Affiliation(s)
- Paul F Langton
- The Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Satoshi Kakugawa
- Hakuhodo Medical Inc., 6-1-20 Akasaka Minato-ku, Tokyo 107-0052, Japan
| | - Jean-Paul Vincent
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London NW7 1AA, UK.
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8
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Vergés M. Retromer in Polarized Protein Transport. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 323:129-79. [PMID: 26944621 DOI: 10.1016/bs.ircmb.2015.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Retromer is an evolutionary conserved protein complex required for endosome-to-Golgi retrieval of receptors for lysosomal hydrolases. It is constituted by a heterotrimer encoded by the vacuolar protein sorting (VPS) gene products Vps26, Vps35, and Vps29, which selects cargo, and a dimer of phosphoinositide-binding sorting nexins, which deforms the membrane. Recent progress in the mechanism of retromer assembly and functioning has strengthened the link between sorting at the endosome and cytoskeleton dynamics. Retromer is implicated in endosomal sorting of many cargos and plays an essential role in plant and animal development. Although it is best known for endosome sorting to the trans-Golgi network, it also intervenes in recycling to the plasma membrane. In polarized cells, such as epithelial cells and neurons, retromer may also be utilized for transcytosis and long-range transport. Considerable evidence implicates retromer in establishment and maintenance of cell polarity. That includes sorting of the apical polarity module Crumbs; regulation of retromer function by the basolateral polarity module Scribble; and retromer-dependent recycling of various cargoes to a certain surface domain, thus controlling polarized location and cell homeostasis. Importantly, altered retromer function has been linked to neurodegeneration, such as in Alzheimer's or Parkinson's disease. This review will underline how alterations in retromer localization and function may affect polarized protein transport and polarity establishment, thereby causing developmental defects and disease.
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Affiliation(s)
- Marcel Vergés
- Cardiovascular Genetics Group, Girona Biomedical Research Institute (IDIBGI), Girona, Spain; Medical Sciences Department, University of Girona, Girona, Spain.
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9
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PIP2Clustering: From model membranes to cells. Chem Phys Lipids 2015; 192:33-40. [DOI: 10.1016/j.chemphyslip.2015.07.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/26/2015] [Accepted: 07/27/2015] [Indexed: 11/23/2022]
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10
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Swarup S, Pradhan-Sundd T, Verheyen EM. Genome-wide identification of phospho-regulators of Wnt signaling in Drosophila. Development 2015; 142:1502-15. [DOI: 10.1242/dev.116715] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Evolutionarily conserved intercellular signaling pathways regulate embryonic development and adult tissue homeostasis in metazoans. The precise control of the state and amplitude of signaling pathways is achieved in part through the kinase- and phosphatase-mediated reversible phosphorylation of proteins. In this study, we performed a genome-wide in vivo RNAi screen for kinases and phosphatases that regulate the Wnt pathway under physiological conditions in the Drosophila wing disc. Our analyses have identified 54 high-confidence kinases and phosphatases capable of modulating the Wnt pathway, including 22 novel regulators. These candidates were also assayed for a role in the Notch pathway, and numerous phospho-regulators were identified. Additionally, each regulator of the Wnt pathway was evaluated in the wing disc for its ability to affect the mechanistically similar Hedgehog pathway. We identified 29 dual regulators that have the same effect on the Wnt and Hedgehog pathways. As proof of principle, we established that Cdc37 and Gilgamesh/CK1γ inhibit and promote signaling, respectively, by functioning at analogous levels of these pathways in both Drosophila and mammalian cells. The Wnt and Hedgehog pathways function in tandem in multiple developmental contexts, and the identification of several shared phospho-regulators serve as potential nodes of control under conditions of aberrant signaling and disease.
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Affiliation(s)
- Sharan Swarup
- Simon Fraser University, Department of Molecular Biology and Biochemistry, Burnaby V5A1S6, British Columbia, Canada
| | - Tirthadipa Pradhan-Sundd
- Simon Fraser University, Department of Molecular Biology and Biochemistry, Burnaby V5A1S6, British Columbia, Canada
| | - Esther M. Verheyen
- Simon Fraser University, Department of Molecular Biology and Biochemistry, Burnaby V5A1S6, British Columbia, Canada
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11
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Ericson VR, Spilker KA, Tugizova MS, Shen K. MTM-6, a phosphoinositide phosphatase, is required to promote synapse formation in Caenorhabditis elegans. PLoS One 2014; 9:e114501. [PMID: 25479419 PMCID: PMC4257696 DOI: 10.1371/journal.pone.0114501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 11/10/2014] [Indexed: 01/22/2023] Open
Abstract
Forming the proper number of synapses is crucial for normal neuronal development. We found that loss of function of the phosphoinositide phosphatase mtm-6 results in a reduction in the number of synaptic puncta. The reduction in synapses is partially the result of MTM-6 regulation of the secretion of the Wnt ligand EGL-20 from cells in the tail and partially the result of neuronal action. MTM-6 shows relative specificity for EGL-20 over the other Wnt ligands. We suggest that the ability of MTM-6 to regulate EGL-20 secretion is a function of its expression pattern. We conclude that regulation of secretion of different Wnt ligands can use different components. Additionally, we present a novel neuronal function for MTM-6.
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Affiliation(s)
- Vivian R. Ericson
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, California, United States of America
| | - Kerri A. Spilker
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, California, United States of America
| | - Madina S. Tugizova
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, California, United States of America
| | - Kang Shen
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, California, United States of America
- * E-mail:
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12
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Yu J, Virshup D. Updating the Wnt pathways. Biosci Rep 2014; 34:e00142. [PMID: 25208913 PMCID: PMC4201215 DOI: 10.1042/bsr20140119] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/05/2014] [Accepted: 09/11/2014] [Indexed: 12/12/2022] Open
Abstract
In the three decades since the discovery of the Wnt1 proto-oncogene in virus-induced mouse mammary tumours, our understanding of the signalling pathways that are regulated by the Wnt proteins has progressively expanded. Wnts are involved in an complex signalling network that governs multiple biological processes and cross-talk with multiple additional signalling cascades, including the Notch, FGF (fibroblast growth factor), SHH (Sonic hedgehog), EGF (epidermal growth factor) and Hippo pathways. The Wnt signalling pathway also illustrates the link between abnormal regulation of the developmental processes and disease manifestation. Here we provide an overview of Wnt-regulated signalling cascades and highlight recent advances. We focus on new findings regarding the dedicated Wnt production and secretion pathway with potential therapeutic targets that might be beneficial for patients with Wnt-related diseases.
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Key Words
- adenomatous polyposis coli
- planar cell polarity (pcp)
- wnt
- apc, adenomatous polyposis coli
- bar, bin-amphiphysin-rvs
- cbp, creb (camp response element-binding)-binding protein
- cop, coat protein complex
- crd, cysteine-rich domain
- ctd, c-terminal domain
- ck1α, casein kinase 1 α
- er, endoplasmic reticulum fap, familial adenomatous polyposis
- fdh, focal dermal hypoplasia
- gsk3β, glycogen synthase kinase 3β
- lef, lymphoid enhancer-binding factor
- lrp, lipoprotein receptor-related protein
- ntd, n-terminal domain
- pcp, planar cell polarity
- porcn, protein porcupine
- ror2, receptor tyrosine kinase-like orphan receptor 2
- rspo, r-spondin
- sfrp, secreted frizzled-related protein
- snx-1, sorting nexin-1
- swim, wingless-interacting molecule
- tcf, t cell-specific factor
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Affiliation(s)
- Jia Yu
- *Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, 8 College Road, Singapore 169857, Singapore
| | - David M. Virshup
- *Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, 8 College Road, Singapore 169857, Singapore
- †Institute of Medical Biology, A*STAR, Singapore 138648, Singapore
- ‡Department of Biochemistry, National University of Singapore, Singapore 117597, Singapore
- §Department of Pediatrics, Duke University, Durham, NC 27710, U.S.A
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13
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Zhu H, Han M. Exploring developmental and physiological functions of fatty acid and lipid variants through worm and fly genetics. Annu Rev Genet 2014; 48:119-48. [PMID: 25195508 DOI: 10.1146/annurev-genet-041814-095928] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Lipids are more than biomolecules for energy storage and membrane structure. With ample structural variation, lipids critically participate in nearly all aspects of cellular function. Lipid homeostasis and metabolism are closely related to major human diseases and health problems. However, lipid functional studies have been significantly underdeveloped, partly because of the difficulty in applying genetics and common molecular approaches to tackle the complexity associated with lipid biosynthesis, metabolism, and function. In the past decade, a number of laboratories began to analyze the roles of lipid metabolism in development and other physiological functions using animal models and combining genetics, genomics, and biochemical approaches. These pioneering efforts have not only provided valuable insights regarding lipid functions in vivo but have also established feasible methodology for future studies. Here, we review a subset of these studies using Caenorhabditis elegans and Drosophila melanogaster.
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Affiliation(s)
- Huanhu Zhu
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309;
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14
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Wu Y, Cheng S, Zhao H, Zou W, Yoshina S, Mitani S, Zhang H, Wang X. PI3P phosphatase activity is required for autophagosome maturation and autolysosome formation. EMBO Rep 2014; 15:973-81. [PMID: 25124690 DOI: 10.15252/embr.201438618] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Autophagosome formation is promoted by the PI3 kinase complex and negatively regulated by myotubularin phosphatases, indicating that regulation of local phosphatidylinositol 3-phosphate (PtdIns3P) levels is important for this early phase of autophagy. Here, we show that the Caenorhabditis elegans myotubularin phosphatase MTM-3 catalyzes PtdIns3P turnover late in autophagy. MTM-3 acts downstream of the ATG-2/EPG-6 complex and upstream of EPG-5 to promote autophagosome maturation into autolysosomes. MTM-3 is recruited to autophagosomes by PtdIns3P, and loss of MTM-3 causes increased autophagic association of ATG-18 in a PtdIns3P-dependent manner. Our data reveal critical roles of PtdIns3P turnover in autophagosome maturation and/or autolysosome formation.
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Affiliation(s)
- Yanwei Wu
- College of Biological Sciences China Agriculture University, Beijing, China National Institute of Biological Sciences, Beijing, China
| | - Shiya Cheng
- National Institute of Biological Sciences, Beijing, China
| | - Hongyu Zhao
- State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Wei Zou
- National Institute of Biological Sciences, Beijing, China
| | - Sawako Yoshina
- Department of Physiology, School of Medicine and Institute for Integrated Medical Sciences Tokyo Women's Medical University, Shinjuku-ku Tokyo, Japan
| | - Shohei Mitani
- Department of Physiology, School of Medicine and Institute for Integrated Medical Sciences Tokyo Women's Medical University, Shinjuku-ku Tokyo, Japan
| | - Hong Zhang
- State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiaochen Wang
- National Institute of Biological Sciences, Beijing, China
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15
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Ackley BD. Wnt-signaling and planar cell polarity genes regulate axon guidance along the anteroposterior axis in C. elegans. Dev Neurobiol 2014; 74:781-96. [PMID: 24214205 PMCID: PMC4167394 DOI: 10.1002/dneu.22146] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 09/18/2013] [Accepted: 11/02/2013] [Indexed: 11/10/2022]
Abstract
During the development of the nervous system, neurons encounter signals that inform their outgrowth and polarization. Understanding how these signals combinatorially function to pattern the nervous system is of considerable interest to developmental neurobiologists. The Wnt ligands and their receptors have been well characterized in polarizing cells during asymmetric cell division. The planar cell polarity (PCP) pathway is also critical for cell polarization in the plane of an epithelium. The core set of PCP genes include members of the conserved Wnt-signaling pathway, such as Frizzled and Disheveled, but also the cadherin-domain protein Flamingo. In Drosophila, the Fat and Dachsous cadherins also function in PCP, but in parallel to the core PCP components. C. elegans also have two Fat-like and one Dachsous-like cadherins, at least one of which, cdh-4, contributes to neural development. In C. elegans Wnt ligands and the conserved PCP genes have been shown to regulate a number of different events, including embryonic cell polarity, vulval morphogenesis, and cell migration. As is also observed in vertebrates, the Wnt and PCP genes appear to function to primarily provide information about the anterior to posterior axis of development. Here, we review the recent work describing how mutations in the Wnt and core PCP genes affect axon guidance and synaptogenesis in C. elegans.
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Affiliation(s)
- Brian D Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045
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16
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Abstract
The counterbalancing action of the endocytosis and secretory pathways maintains a dynamic equilibrium that regulates the composition of the plasma membrane, allowing it to maintain homeostasis and to change rapidly in response to alterations in the extracellular environment and/or intracellular metabolism. These pathways are intimately integrated with intercellular signaling systems and play critical roles in all cells. Studies in Caenorhabditis elegans have revealed diverse roles of membrane trafficking in physiology and development and have also provided molecular insight into the fundamental mechanisms that direct cargo sorting, vesicle budding, and membrane fisson and fusion. In this review, we summarize progress in understanding membrane trafficking mechanisms derived from work in C. elegans, focusing mainly on work done in non-neuronal cell-types, especially the germline, early embryo, coelomocytes, and intestine.
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Affiliation(s)
- Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan. ;
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17
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Inhibition of late endosomal maturation restores Wnt secretion in Caenorhabditis elegans vps-29 retromer mutants. Cell Signal 2014; 26:19-31. [DOI: 10.1016/j.cellsig.2013.09.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 09/05/2013] [Accepted: 09/13/2013] [Indexed: 01/01/2023]
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18
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Ward JD, Bojanala N, Bernal T, Ashrafi K, Asahina M, Yamamoto KR. Sumoylated NHR-25/NR5A regulates cell fate during C. elegans vulval development. PLoS Genet 2013; 9:e1003992. [PMID: 24348269 PMCID: PMC3861103 DOI: 10.1371/journal.pgen.1003992] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 10/16/2013] [Indexed: 11/19/2022] Open
Abstract
Individual metazoan transcription factors (TFs) regulate distinct sets of genes depending on cell type and developmental or physiological context. The precise mechanisms by which regulatory information from ligands, genomic sequence elements, co-factors, and post-translational modifications are integrated by TFs remain challenging questions. Here, we examine how a single regulatory input, sumoylation, differentially modulates the activity of a conserved C. elegans nuclear hormone receptor, NHR-25, in different cell types. Through a combination of yeast two-hybrid analysis and in vitro biochemistry we identified the single C. elegans SUMO (SMO-1) as an NHR-25 interacting protein, and showed that NHR-25 is sumoylated on at least four lysines. Some of the sumoylation acceptor sites are in common with those of the NHR-25 mammalian orthologs SF-1 and LRH-1, demonstrating that sumoylation has been strongly conserved within the NR5A family. We showed that NHR-25 bound canonical SF-1 binding sequences to regulate transcription, and that NHR-25 activity was enhanced in vivo upon loss of sumoylation. Knockdown of smo-1 mimicked NHR-25 overexpression with respect to maintenance of the 3° cell fate in vulval precursor cells (VPCs) during development. Importantly, however, overexpression of unsumoylatable alleles of NHR-25 revealed that NHR-25 sumoylation is critical for maintaining 3° cell fate. Moreover, SUMO also conferred formation of a developmental time-dependent NHR-25 concentration gradient across the VPCs. That is, accumulation of GFP-tagged NHR-25 was uniform across VPCs at the beginning of development, but as cells began dividing, a smo-1-dependent NHR-25 gradient formed with highest levels in 1° fated VPCs, intermediate levels in 2° fated VPCs, and low levels in 3° fated VPCs. We conclude that sumoylation operates at multiple levels to affect NHR-25 activity in a highly coordinated spatial and temporal manner.
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Affiliation(s)
- Jordan D. Ward
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
| | - Nagagireesh Bojanala
- Institute of Parasitology, Biology Centre ASCR, Ceske Budejovice, Czech Republic
- University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Teresita Bernal
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
| | - Kaveh Ashrafi
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
| | - Masako Asahina
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
- Institute of Parasitology, Biology Centre ASCR, Ceske Budejovice, Czech Republic
- University of South Bohemia, Ceske Budejovice, Czech Republic
- * E-mail: (MA); (KRY)
| | - Keith R. Yamamoto
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail: (MA); (KRY)
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19
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Kharitidi D, Manteghi S, Pause A. Pseudophosphatases: methods of analysis and physiological functions. Methods 2013; 65:207-18. [PMID: 24064037 DOI: 10.1016/j.ymeth.2013.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/20/2013] [Accepted: 09/11/2013] [Indexed: 01/27/2023] Open
Abstract
Protein tyrosine phosphatases (PTPs) are key enzymes in the regulation of cellular homeostasis and signaling pathways. Strikingly, not all PTPs bear enzymatic activity. A considerable fraction of PTPs are enzymatically inactive and are known as pseudophosphatases. Despite the lack of activity they execute pivotal roles in development, cell biology and human disease. The present review is focused on the methods used to identify pseudophosphatases, their targets, and physiological roles. We present a strategy for detailed enzymatic analysis of inactive PTPs, regulation of inactive PTP domains and identification of binding partners. Furthermore, we provide a detailed overview of human pseudophosphatases and discuss their regulation of cellular processes and functions in human pathologies.
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Affiliation(s)
- Dmitri Kharitidi
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, 3655, Promenade Sir William Osler, Montreal, QC H3G 1Y6, Canada.
| | - Sanaz Manteghi
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, 3655, Promenade Sir William Osler, Montreal, QC H3G 1Y6, Canada.
| | - Arnim Pause
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, 3655, Promenade Sir William Osler, Montreal, QC H3G 1Y6, Canada.
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20
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Yang PT, Anastas JN, Toroni RA, Shinohara MM, Goodson JM, Bosserhoff AK, Chien AJ, Moon RT. WLS inhibits melanoma cell proliferation through the β-catenin signalling pathway and induces spontaneous metastasis. EMBO Mol Med 2012; 4:1294-307. [PMID: 23129487 PMCID: PMC3531604 DOI: 10.1002/emmm.201201486] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 09/20/2012] [Accepted: 09/24/2012] [Indexed: 12/20/2022] Open
Abstract
Elevated levels of nuclear β-catenin are associated with higher rates of survival in patients with melanoma, raising questions as to how ß-catenin is regulated in this context. In the present study, we investigated the formal possibility that the secretion of WNT ligands that stabilize ß-catenin may be regulated in melanoma and thus contributes to differences in ß-catenin levels. We find that WLS, a conserved transmembrane protein necessary for WNT secretion, is decreased in both melanoma cell lines and in patient tumours relative to skin and to benign nevi. Unexpectedly, reducing endogenous WLS with shRNAs in human melanoma cell lines promotes spontaneous lung metastasis in xenografts in mice and promotes cell proliferation in vitro. Conversely, overexpression of WLS inhibits cell proliferation in vitro. Activating β-catenin downstream of WNT secretion blocks the increased cell migration and proliferation observed in the presence of WLS shRNAs, while inhibiting WNT signalling rescues the growth defects induced by excess WLS. These data suggest that WLS functions as a negative regulator of melanoma proliferation and spontaneous metastasis by activating WNT/β-catenin signalling.
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Affiliation(s)
- Pei-Tzu Yang
- Department of Pharmacology, Howard Hughes Medical Institute, Institute for Stem Cell and Regenerative Medicine, University of Washington School of MedicineSeattle, WA, USA
| | - Jamie N Anastas
- Department of Pharmacology, Howard Hughes Medical Institute, Institute for Stem Cell and Regenerative Medicine, University of Washington School of MedicineSeattle, WA, USA
| | - Rachel A Toroni
- Division of Dermatology, Department of Medicine, University of Washington School of MedicineSeattle, WA, USA
| | - Michi M Shinohara
- Division of Dermatology, Department of Medicine, University of Washington School of MedicineSeattle, WA, USA
| | - Jamie M Goodson
- Department of Biology, University of WashingtonSeattle, WA, USA
| | - Anja K Bosserhoff
- Department of Pathology, University of RegensburgRegensburg, Germany
| | - Andy J Chien
- Department of Pharmacology, Howard Hughes Medical Institute, Institute for Stem Cell and Regenerative Medicine, University of Washington School of MedicineSeattle, WA, USA
- Division of Dermatology, Department of Medicine, University of Washington School of MedicineSeattle, WA, USA
| | - Randall T Moon
- Department of Pharmacology, Howard Hughes Medical Institute, Institute for Stem Cell and Regenerative Medicine, University of Washington School of MedicineSeattle, WA, USA
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21
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Mochizuki Y, Ohashi R, Kawamura T, Iwanari H, Kodama T, Naito M, Hamakubo T. Phosphatidylinositol 3-phosphatase myotubularin-related protein 6 (MTMR6) is regulated by small GTPase Rab1B in the early secretory and autophagic pathways. J Biol Chem 2012. [PMID: 23188820 DOI: 10.1074/jbc.m112.395087] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A large family of myotubularin phosphatases dephosphorylates phosphatidylinositol 3-phosphate and phosphatidylinositol 3,5-bisphosphate, which are known to play important roles in vesicular trafficking and autophagy. The family is composed of 16 members, and understanding their regulatory mechanisms is important to understand their functions and related genetic diseases. We prepared anti-myotubularin-related protein 6 (MTMR6) monoclonal antibody and used it to study the regulatory mechanism of MTMR6. Endogenous MTMR6 was present in the cytoplasm and was condensed in the perinuclear region in a microtubule-dependent manner. MTMR6 preferentially interacted with GDP-bound Rab1B via the GRAM domain and partly overlapped with Rab1B in the pericentrosomal and peri-Golgi regions in normal rat kidney cells. Overexpression of GDP-bound Rab1B and the reduction of Rab1B disrupted the localization of MTMR6, suggesting that Rab1B regulates the localization of MTMR6. The reduction of MTMR6 accelerated the transport of vesicular stomatitis virus glycoprotein in which Rab1B is involved. Furthermore, reduction of MTMR6 or Rab1B inhibited the formation of the tubular omegasome that is induced by overexpression of DFCP1 in autophagy. Our results indicate that the cellular localization of MTMR6 is regulated by Rab1B in the early secretory and autophagic pathways. We propose a new regulatory mechanism of myotubularin phosphatase by the small GTPase Rab1B.
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Affiliation(s)
- Yasuhiro Mochizuki
- Department of Molecular Biology and Medicine, The University of Tokyo, Tokyo 153-8904, Japan.
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22
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Abstract
The retromer complex is a vital element of the endosomal protein sorting machinery that is conserved across all eukaryotes. Retromer is most closely associated with the endosome-to-Golgi retrieval pathway and is necessary to maintain an active pool of hydrolase receptors in the trans-Golgi network. Recent progress in studies of retromer have identified new retromer-interacting proteins, including the WASH complex and cargo such as the Wntless/MIG-14 protein, which now extends the role of retromer beyond the endosome-to-Golgi pathway and has revealed that retromer is required for aspects of endosome-to-plasma membrane sorting and regulation of signalling events. The interactions between the retromer complex and other macromolecular protein complexes now show how endosomal protein sorting is coordinated with actin assembly and movement along microtubules, and place retromer squarely at the centre of a complex set of protein machinery that governs endosomal protein sorting. Dysregulation of retromer-mediated endosomal protein sorting leads to various pathologies, including neurodegenerative diseases such as Alzheimer disease and spastic paraplegia and the mechanisms underlying these pathologies are starting to be understood. In this Commentary, I will highlight recent advances in the understanding of retromer-mediated endosomal protein sorting and discuss how retromer contributes to a diverse set of physiological processes.
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Abstract
Wnt proteins comprise a major family of signaling molecules that orchestrate and influence a myriad of cell biological and developmental processes. Although our understanding of the role of Wnt signaling in regulating development and affecting disease, such as cancer, has been ever increasing, the study of the Wnt proteins themselves has been painstaking and slow moving. Despite advances in the biochemical characterization of Wnt proteins, many mysteries remain unsolved. In contrast to other developmental signaling molecules, such as fibroblast growth factors (FGF), transforming growth factors (TGFβ), and Sonic hedgehog (Shh), Wnt proteins have not conformed to many standard methods of protein production, such as bacterial overexpression, and analysis, such as ligand-receptor binding assays. The reasons for their recalcitrant nature are likely a consequence of the complex set of posttranslational modifications involving several highly specialized and poorly characterized processing enzymes. With the recent description of the first Wnt protein structure, the time is ripe to uncover and possibly resolve many of the remaining issues surrounding Wnt proteins and their interactions. Here we describe the process of maturation of Wnt from its initial translation to its eventual release from a cell and interactions in the extracellular environment.
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Affiliation(s)
- Karl Willert
- Department of Cellular and Molecular Medicine, University of California, San Diego, California 92093, USA.
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24
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Jean S, Cox S, Schmidt EJ, Robinson FL, Kiger A. Sbf/MTMR13 coordinates PI(3)P and Rab21 regulation in endocytic control of cellular remodeling. Mol Biol Cell 2012; 23:2723-40. [PMID: 22648168 PMCID: PMC3395661 DOI: 10.1091/mbc.e12-05-0375] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The MTM phosphatases include poorly defined, catalytically inactive members. Drosophila Sbf, an MTM pseudophosphatase, physically and functionally interacts with class II PI3-kinase, Mtm PI3-phosphatase, and Rab21, each required for macrophage remodeling. Sbf plays dual roles in Mtm PI(3)P turnover and as a Rab21 GEF to coordinate endosomal dynamics. Cells rely on the coordinated regulation of lipid phosphoinositides and Rab GTPases to define membrane compartment fates along distinct trafficking routes. The family of disease-related myotubularin (MTM) phosphoinositide phosphatases includes catalytically inactive members, or pseudophosphatases, with poorly understood functions. We found that Drosophila MTM pseudophosphatase Sbf coordinates both phosphatidylinositol 3-phosphate (PI(3)P) turnover and Rab21 GTPase activation in an endosomal pathway that controls macrophage remodeling. Sbf dynamically interacts with class II phosphatidylinositol 3-kinase and stably recruits Mtm to promote turnover of a PI(3)P subpool essential for endosomal trafficking. Sbf also functions as a guanine nucleotide exchange factor that promotes Rab21 GTPase activation associated with PI(3)P endosomes. Of importance, Sbf, Mtm, and Rab21 function together, along with Rab11-mediated endosomal trafficking, to control macrophage protrusion formation. This identifies Sbf as a critical coordinator of PI(3)P and Rab21 regulation, which specifies an endosomal pathway and cortical control.
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Affiliation(s)
- Steve Jean
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0380, USA
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25
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Abstract
Proteins involved in membrane remodeling play an essential role in a plethora of cell functions including endocytosis and intracellular transport. Defects in several of them lead to human diseases. Myotubularins, amphiphysins, and dynamins are all proteins implicated in membrane trafficking and/or remodeling. Mutations in myotubularin, amphiphysin 2 (BIN1), and dynamin 2 lead to different forms of centronuclear myopathy, while mutations in myotubularin-related proteins cause Charcot-Marie-Tooth neuropathies. In addition to centronuclear myopathy, dynamin 2 is also mutated in a dominant form of Charcot-Marie-Tooth neuropathy. While several proteins from these different families are implicated in similar diseases, mutations in close homologues or in the same protein in the case of dynamin 2 lead to diseases affecting different tissues. This suggests (1) a common molecular pathway underlying these different neuromuscular diseases, and (2) tissue-specific regulation of these proteins. This review discusses the pathophysiology of the related neuromuscular diseases on the basis of animal models developed for proteins of the myotubularin, amphiphysin, and dynamin families. A better understanding of the common mechanisms between these neuromuscular disorders will lead to more specific health care and therapeutic approaches.
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26
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Tronchère H, Bolino A, Laporte J, Payrastre B. Myotubularins and associated neuromuscular diseases. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/clp.12.7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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27
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Abstract
Throughout the animal kingdom, Wnt-triggered signal transduction pathways play fundamental roles in embryonic development and tissue homeostasis. Wnt proteins are modified as glycolipoproteins and are secreted into the extracellular environment as morphogens. Recent studies on the intracellular trafficking of Wnt proteins demonstrate multiple layers of regulation along its secretory pathway. These findings have propelled a great deal of interest among researchers to further investigate the molecular mechanisms that control the release of Wnts and hence the level of Wnt signaling. This review is dedicated to Wntless, a putative G-protein coupled receptor that transports Wnts intracellularly for secretion. Here, we highlight the conclusions drawn from the most recent cellular, molecular and genetic studies that affirm the role of Wntless in the secretion of Wnt proteins.
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28
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Harterink M, Korswagen HC. Dissecting the Wnt secretion pathway: key questions on the modification and intracellular trafficking of Wnt proteins. Acta Physiol (Oxf) 2012; 204:8-16. [PMID: 21439025 DOI: 10.1111/j.1748-1716.2011.02287.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Wnt family of signalling proteins has essential functions in development and adult tissue homoeostasis throughout the animal kingdom. Although signalling cascades triggered by Wnt proteins have been extensively studied, much remains to be learned about how Wnts are produced and secreted. Over the past few years, it has become clear that the secretion of Wnt proteins requires a specialized trafficking pathway. As this pathway has been discussed in two recent reviews (Lorenowicz & Korswagen 2009, Port & Basler 2010), we will focus our discussion on the key questions that need to be addressed to gain a more complete understanding of the mechanism and regulation of this essential secretion pathway.
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Affiliation(s)
- M Harterink
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, The Netherlands
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29
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Davies EM, Sheffield DA, Tibarewal P, Fedele CG, Mitchell CA, Leslie NR. The PTEN and Myotubularin phosphoinositide 3-phosphatases: linking lipid signalling to human disease. Subcell Biochem 2012; 58:281-336. [PMID: 22403079 DOI: 10.1007/978-94-007-3012-0_8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Two classes of lipid phosphatases selectively dephosphorylate the 3 position of the inositol ring of phosphoinositide signaling molecules: the PTEN and the Myotubularin families. PTEN dephosphorylates PtdIns(3,4,5)P(3), acting in direct opposition to the Class I PI3K enzymes in the regulation of cell growth, proliferation and polarity and is an important tumor suppressor. Although there are several PTEN-related proteins encoded by the human genome, none of these appear to fulfill the same functions. In contrast, the Myotubularins dephosphorylate both PtdIns(3)P and PtdIns(3,5)P(2), making them antagonists of the Class II and Class III PI 3-kinases and regulators of membrane traffic. Both phosphatase groups were originally identified through their causal mutation in human disease. Mutations in specific myotubularins result in myotubular myopathy and Charcot-Marie-Tooth peripheral neuropathy; and loss of PTEN function through mutation and other mechanisms is evident in as many as a third of all human tumors. This chapter will discuss these two classes of phosphatases, covering what is known about their biochemistry, their functions at the cellular and whole body level and their influence on human health.
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Affiliation(s)
- Elizabeth M Davies
- Division of Cell Signalling and Immunology, Wellcome Trust Biocentre, College of Life Sciences, University of Dundee, Dow Street, DD1 5EH, Dundee, Scotland, United Kingdom,
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30
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Cullen PJ, Korswagen HC. Sorting nexins provide diversity for retromer-dependent trafficking events. Nat Cell Biol 2011; 14:29-37. [PMID: 22193161 PMCID: PMC3613977 DOI: 10.1038/ncb2374] [Citation(s) in RCA: 265] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Sorting nexins are a large family of evolutionarily conserved phosphoinositide-binding proteins that have fundamental roles in orchestrating cargo sorting through the membranous maze that is the endosomal network. One ancient group of complexes that contain sorting nexins is the retromer. Here we discuss how retromer complexes regulate endosomal sorting, and describe how this is generating exciting new insight into the central role played by endosomal sorting in development and homeostasis of normal tissues.
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Affiliation(s)
- Peter J. Cullen
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, U.K
| | - Hendrik C. Korswagen
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
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31
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Shilo BZ, Schejter ED. Regulation of developmental intercellular signalling by intracellular trafficking. EMBO J 2011; 30:3516-26. [PMID: 21878993 DOI: 10.1038/emboj.2011.269] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 07/01/2011] [Indexed: 11/09/2022] Open
Abstract
Universal trafficking components within the cell can be recruited to coordinate and regulate the developmental signalling cascades. We will present ways in which the intracellular trafficking machinery is used to affect and modulate the outcome of signal transduction in developmental contexts, thus regulating multicellular development. Each of the signalling components must reach its proper intracellular destination, in a form that is properly folded and modified. In many instances, the ability to bring components together or segregate them into distinct compartments within the cell actually provides the switch mechanism to turn developmental signalling pathways on or off. The review will begin with a focus on the signal-sending cells, and the ways in which ligand trafficking can impinge on the signalling outcome, via processing, endocytosis and recycling. We will then turn to the signal-receiving cell, and discuss mechanisms by which endocytosis can affect the spatial features of the signal, and the compartmentalization of components downstream to the receptor.
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Affiliation(s)
- Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
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32
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33
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Abstract
The endosomal network is an organized array of intracellular, membranous compartments that function as sorting sites for endosomal and biosynthetic cargo. The fate of endocytic cargo is reliant upon interactions with a number of molecularly distinct sorting complexes, which tightly control the relationship between sorting of their respective cargo and the physical process of membrane re-scuplturing required for the formation of transport carries. One such complex, retromer, mediates retrograde transport from endosomes to the trans-Golgi network (TGN). Disregulation of retromer has been implicated in a host of disease states including late-onset Alzheimer's. Rather than give a broad overview of retromer biology, here we aim to outline the recent advances in understanding this complex, focussing on the involvement of both clathrin and the cytoskeleton in retromer function.
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Affiliation(s)
- Ian J McGough
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
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34
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Valkenburg KC, Graveel CR, Zylstra-Diegel CR, Zhong Z, Williams BO. Wnt/β-catenin Signaling in Normal and Cancer Stem Cells. Cancers (Basel) 2011; 3:2050-79. [PMID: 24212796 PMCID: PMC3757404 DOI: 10.3390/cancers3022050] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/12/2011] [Accepted: 04/13/2011] [Indexed: 12/23/2022] Open
Abstract
The ability of Wnt ligands to initiate a signaling cascade that results in cytoplasmic stabilization of, and nuclear localization of, β-catenin underlies their ability to regulate progenitor cell differentiation. In this review, we will summarize the current knowledge of the mechanisms underlying Wnt/β-catenin signaling and how the pathway regulates normal differentiation of stem cells in the intestine, mammary gland, and prostate. We will also discuss how dysregulation of the pathway is associated with putative cancer stem cells and the potential therapeutic implications of regulating Wnt signaling.
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Affiliation(s)
- Kenneth C Valkenburg
- Van Andel Research Institute, 333 Bostwick Ave. N.E., Grand Rapids, MI 49503, USA.
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35
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Abstract
Wnt signaling is one of the most important developmental signaling pathways that controls cell fate decisions and tissue patterning during early embryonic and later development. It is activated by highly conserved Wnt proteins that are secreted as palmitoylated glycoproteins and act as morphogens to form a concentration gradient across a developing tissue. Wnt proteins regulate transcriptional and posttranscriptional processes depending on the distance of their origin and activate distinct intracellular cascades, commonly referred to as canonical (β-catenin-dependent) and noncanonical (β-catenin-independent) pathways. Therefore, the secretion and the diffusion of Wnt proteins needs to be tightly regulated to induce short- and long-range downstream signaling. Even though the Wnt signaling cascade has been studied intensively, key aspects and principle mechanisms, such as transport of Wnt growth factors or regulation of signaling specificity between different Wnt pathways, remain unresolved. Here, we introduce basic principles of Wnt/Wg signal transduction and highlight recent discoveries, such as the involvement of vacuolar ATPases and vesicular acidification in Wnt signaling. We also discuss recent findings regarding posttranslational modifications of Wnts, trafficking through the secretory pathway and developmental consequences of impaired Wnt secretion. Understanding the detailed mechanism and regulation of Wnt protein secretion will provide valuable insights into many human diseases based on overactivated Wnt signaling.
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Affiliation(s)
- Tina Buechling
- German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics, Department of Cell and Molecular Biology, University of Heidelberg
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