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Douanne T, Stinchcombe JC, Griffiths GM. Teasing out function from morphology: Similarities between primary cilia and immune synapses. J Cell Biol 2021; 220:212075. [PMID: 33956049 PMCID: PMC8105739 DOI: 10.1083/jcb.202102089] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/19/2021] [Accepted: 04/19/2021] [Indexed: 12/12/2022] Open
Abstract
Immune synapses are formed between immune cells to facilitate communication and coordinate the immune response. The reorganization of receptors involved in recognition and signaling creates a transient area of plasma membrane specialized in signaling and polarized secretion. Studies on the formation of the immune synapse between cytotoxic T lymphocytes (CTLs) and their targets uncovered a critical role for centrosome polarization in CTL function and suggested a striking parallel between the synapse and primary cilium. Since these initial observations, a plethora of further morphological, functional, and molecular similarities have been identified between these two fascinating structures. In this review, we describe how advances in imaging and molecular techniques have revealed additional parallels as well as functionally significant differences and discuss how comparative studies continue to shed light on the molecular mechanisms underlying the functions of both the immune synapse and primary cilium.
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Affiliation(s)
- Tiphaine Douanne
- Cambridge Institute for Medical Research, Cambridge Biomedical Campus, University of Cambridge, Cambridge, England, UK
| | - Jane C Stinchcombe
- Cambridge Institute for Medical Research, Cambridge Biomedical Campus, University of Cambridge, Cambridge, England, UK
| | - Gillian M Griffiths
- Cambridge Institute for Medical Research, Cambridge Biomedical Campus, University of Cambridge, Cambridge, England, UK
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2
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Rubio-Ramos A, Labat-de-Hoz L, Correas I, Alonso MA. The MAL Protein, an Integral Component of Specialized Membranes, in Normal Cells and Cancer. Cells 2021; 10:1065. [PMID: 33946345 PMCID: PMC8145151 DOI: 10.3390/cells10051065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/12/2022] Open
Abstract
The MAL gene encodes a 17-kDa protein containing four putative transmembrane segments whose expression is restricted to human T cells, polarized epithelial cells and myelin-forming cells. The MAL protein has two unusual biochemical features. First, it has lipid-like properties that qualify it as a member of the group of proteolipid proteins. Second, it partitions selectively into detergent-insoluble membranes, which are known to be enriched in condensed cell membranes, consistent with MAL being distributed in highly ordered membranes in the cell. Since its original description more than thirty years ago, a large body of evidence has accumulated supporting a role of MAL in specialized membranes in all the cell types in which it is expressed. Here, we review the structure, expression and biochemical characteristics of MAL, and discuss the association of MAL with raft membranes and the function of MAL in polarized epithelial cells, T lymphocytes, and myelin-forming cells. The evidence that MAL is a putative receptor of the epsilon toxin of Clostridium perfringens, the expression of MAL in lymphomas, the hypermethylation of the MAL gene and subsequent loss of MAL expression in carcinomas are also presented. We propose a model of MAL as the organizer of specialized condensed membranes to make them functional, discuss the role of MAL as a tumor suppressor in carcinomas, consider its potential use as a cancer biomarker, and summarize the directions for future research.
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Affiliation(s)
- Armando Rubio-Ramos
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
| | - Leticia Labat-de-Hoz
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
| | - Isabel Correas
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
- Department of Molecular Biology, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Miguel A. Alonso
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
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3
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Tuna KM, Liu BC, Yue Q, Ghazi ZM, Ma HP, Eaton DC, Alli AA. Mal protein stabilizes luminal membrane PLC-β3 and negatively regulates ENaC in mouse cortical collecting duct cells. Am J Physiol Renal Physiol 2019; 317:F986-F995. [PMID: 31364376 PMCID: PMC6843038 DOI: 10.1152/ajprenal.00446.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 07/18/2019] [Accepted: 07/18/2019] [Indexed: 01/15/2023] Open
Abstract
Abnormally high epithelial Na+ channel (ENaC) activity in the aldosterone-sensitive distal nephron and collecting duct leads to hypertension. Myelin and lymphocyte (Mal) is a lipid raft-associated protein that has been previously shown to regulate Na+-K-2Cl- cotransporter and aquaporin-2 in the kidney, but it is not known whether it regulates renal ENaC. ENaC activity is positively regulated by the anionic phospholipid phosphate phosphatidylinositol 4,5-bisphosphate (PIP2). Members of the myristoylated alanine-rich C-kinase substrate (MARCKS) family increase PIP2 concentrations at the plasma membrane, whereas hydrolysis of PIP2 by phospholipase C (PLC) reduces PIP2 abundance. Our hypothesis was that Mal protein negatively regulates renal ENaC activity by stabilizing PLC protein expression at the luminal plasma membrane. We investigated the association between Mal, MARCKS-like protein, and ENaC. We showed Mal colocalizes with PLC-β3 in lipid rafts and positively regulates its protein expression, thereby reducing PIP2 availability at the plasma membrane. Kidneys of 129Sv mice injected with MAL shRNA lentivirus resulted in increased ENaC open probability in split-open renal tubules. Overexpression of Mal protein in mouse cortical collecting duct (mpkCCD) cells resulted in an increase in PLC-β3 protein expression at the plasma membrane. siRNA-mediated knockdown of MAL in mpkCCD cells resulted in a decrease in PLC-β3 protein expression and an increase in PIP2 abundance. Moreover, kidneys from salt-loaded mice showed less Mal membrane protein expression compared with non-salt-loaded mice. Taken together, Mal protein may play an essential role in the negative feedback of ENaC gating in principal cells of the collecting duct.
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Affiliation(s)
- Kubra M Tuna
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida
| | - Bing-Chen Liu
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Qiang Yue
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Zinah M Ghazi
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - He-Ping Ma
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Abdel A Alli
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
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4
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Cassioli C, Baldari CT. A Ciliary View of the Immunological Synapse. Cells 2019; 8:E789. [PMID: 31362462 PMCID: PMC6721628 DOI: 10.3390/cells8080789] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/15/2019] [Accepted: 07/25/2019] [Indexed: 12/28/2022] Open
Abstract
The primary cilium has gone from being a vestigial organelle to a crucial signaling hub of growing interest given the association between a group of human disorders, collectively known as ciliopathies, and defects in its structure or function. In recent years many ciliogenesis proteins have been observed at extraciliary sites in cells and likely perform cilium-independent functions ranging from regulation of the cytoskeleton to vesicular trafficking. Perhaps the most striking example is the non-ciliated T lymphocyte, in which components of the ciliary machinery are repurposed for the assembly and function of the immunological synapse even in the absence of a primary cilium. Furthermore, the specialization traits described at the immunological synapse are similar to those seen in the primary cilium. Here, we review common regulators and features shared by the immunological synapse and the primary cilium that document the remarkable homology between these structures.
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Affiliation(s)
- Chiara Cassioli
- Department of Life Sciences, University of Siena, 53100 Siena, Italy
| | - Cosima T Baldari
- Department of Life Sciences, University of Siena, 53100 Siena, Italy.
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Takeuchi Y, Kito A, Itoh S, Naruse H, Fujikawa J, Sadek KM, Akiyama S, Yamashiro T, Wakisaka S, Abe M. Kruppel-Like Factor 4 represses osteoblast differentiation via ciliary Hedgehog signaling. Exp Cell Res 2018; 371:417-425. [PMID: 30193838 DOI: 10.1016/j.yexcr.2018.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/14/2018] [Accepted: 09/03/2018] [Indexed: 10/28/2022]
Abstract
Primary cilia are appendages observed in most types of cells, and serve as cellular antennae for sensing environmental signals. Evidence is accumulating that correct ciliogenesis and ciliary functions are indispensable for normal skeletal development by regulating signaling pathways important for bone development. However, whether ciliogenesis is regulated by bone-related factors in osteoblasts is largely unknown. Here we show that Kruppel-Like Factor 4 (KLF4), which is known to repress osteoblast differentiation, supports the formation and maintenance of cilia in cultured osteoblasts; however, the length of the cilia observed in KLF4-induced cells were significantly shorter compared to the control cells. Basal Hedgehog signaling was repressed by KLF4. Significantly, activating Hedgehog signaling using a Smoothened agonist significantly rescued osteoblast mineralization and osteoblastic gene expressions. Global gene expression analysis showed that KLF4 induced number of genes including the nuclear receptor, Pregnane X receptor (PXR), and PXR repressed calvarial osteoblast mineralization and repressed Gli1 expression similar as the effect observed by inducing KLF4. Our results implicate that KLF4 plays important roles for maintaining osteoblasts in an immature state by repressing basal activation of the Hedgehog signaling.
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Affiliation(s)
- Yuto Takeuchi
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan; Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Akiyoshi Kito
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan; Osaka University Dental Hospital Division of Special Care Dentistry, Osaka, Japan
| | - Shousaku Itoh
- Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Haruna Naruse
- Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Junji Fujikawa
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan; Osaka University Dental Hospital Division of Special Care Dentistry, Osaka, Japan
| | - Kadry Mahamed Sadek
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan; Department of Biochemistry, Faculty of Veterinary Medicine, Damnhour University, Egypt
| | - Shigehisa Akiyama
- Osaka University Dental Hospital Division of Special Care Dentistry, Osaka, Japan
| | - Takashi Yamashiro
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Satoshi Wakisaka
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Makoto Abe
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan.
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Bernabé-Rubio M, Alonso MA. Routes and machinery of primary cilium biogenesis. Cell Mol Life Sci 2017; 74:4077-4095. [PMID: 28624967 PMCID: PMC11107551 DOI: 10.1007/s00018-017-2570-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/01/2017] [Accepted: 06/13/2017] [Indexed: 02/06/2023]
Abstract
Primary cilia are solitary, microtubule-based protrusions of the cell surface that play fundamental roles as photosensors, mechanosensors and biochemical sensors. Primary cilia dysfunction results in a long list of developmental and degenerative disorders that combine to give rise to a large spectrum of human diseases affecting almost any major body organ. Depending on the cell type, primary ciliogenesis is initiated intracellularly, as in fibroblasts, or at the cell surface, as in renal polarized epithelial cells. In this review, we have focused on the routes of primary ciliogenesis placing particular emphasis on the recently described pathway in renal polarized epithelial cells by which the midbody remnant resulting from a previous cell division event enables the centrosome for initiation of primary cilium assembly. The protein machinery implicated in primary cilium formation in epithelial cells, including the machinery best known for its involvement in establishing cell polarity and polarized membrane trafficking, is also discussed.
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Affiliation(s)
- Miguel Bernabé-Rubio
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - Miguel A Alonso
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain.
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Reales E, Bernabé-Rubio M, Casares-Arias J, Rentero C, Fernández-Barrera J, Rangel L, Correas I, Enrich C, Andrés G, Alonso MA. The MAL protein is crucial for proper membrane condensation at the ciliary base, which is required for primary cilium elongation. J Cell Sci 2015; 128:2261-70. [DOI: 10.1242/jcs.164970] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/30/2015] [Indexed: 01/11/2023] Open
Abstract
ABSTRACT
The base of the primary cilium contains a zone of condensed membranes whose importance is not known. Here, we have studied the involvement of MAL, a tetraspanning protein that exclusively partitions into condensed membrane fractions, in the condensation of membranes at the ciliary base and investigated the importance of these membranes in primary cilium formation. We show that MAL accumulates at the ciliary base of epithelial MDCK cells. Knockdown of MAL expression resulted in a drastic reduction in the condensation of membranes at the ciliary base, the percentage of ciliated cells and the length of the cilia, but did not affect the docking of the centrosome to the plasma membrane or produce missorting of proteins to the pericentriolar zone or to the membrane of the remaining cilia. Rab8 (for which there are two isoforms, Rab8A and Rab8b), IFT88 and IFT20, which are important components of the machinery of ciliary growth, were recruited normally to the ciliary base of MAL-knockdown cells but were unable to elongate the primary cilium correctly. MAL, therefore, is crucial for the proper condensation of membranes at the ciliary base, which is required for efficient primary cilium extension.
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Affiliation(s)
- Elena Reales
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Miguel Bernabé-Rubio
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Javier Casares-Arias
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Carles Rentero
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Barcelona 08036, Spain
| | - Jaime Fernández-Barrera
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Laura Rangel
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Isabel Correas
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Carlos Enrich
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Barcelona 08036, Spain
| | - Germán Andrés
- Electron Microscopy Unit, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Miguel A. Alonso
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
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Finetti F, Onnis A, Baldari CT. Regulation of vesicular traffic at the T cell immune synapse: lessons from the primary cilium. Traffic 2015; 16:241-9. [PMID: 25393976 DOI: 10.1111/tra.12241] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 10/29/2014] [Accepted: 11/11/2014] [Indexed: 01/05/2023]
Abstract
The signals that orchestrate the process of T cell activation are coordinated at the specialized interface that forms upon contact with an antigen presenting cell displaying a specific MHC-associated peptide ligand, known as the immune synapse. The central role of vesicular traffic in the assembly of the immune synapse has emerged only in recent years with the finding that sustained T-cell receptor (TCR) signaling involves delivery of TCR/CD3 complexes from an intracellular pool associated with recycling endosomes. A number of receptors as well as membrane-associated signaling mediators have since been demonstrated to exploit this process to localize to the immune synapse. Here, we will review our current understanding of the mechanisms responsible for TCR recycling, with a focus on the intraflagellar transport system, a multimolecular complex that is responsible for the assembly and function of the primary cilium which we have recently implicated in polarized endosome recycling to the immune synapse.
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Affiliation(s)
- Francesca Finetti
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy
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