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Salzer U, Mairhofer M, De Franceschi L. Rainer Prohaska (1943-2022). Am J Hematol 2024; 99:144-145. [PMID: 37867398 DOI: 10.1002/ajh.27139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 10/07/2023] [Indexed: 10/24/2023]
Affiliation(s)
- Ulrich Salzer
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Vienna, Austria
- Center for Medical Biochemistry, Medical University of Vienna, Vienna, Austria
| | - Mario Mairhofer
- Medical Department of Hematology and Oncology, Johannes Kepler University, Linz, Austria
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2
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The Lipid Raft-Associated Protein Stomatin Is Required for Accumulation of Dectin-1 in the Phagosomal Membrane and for Full Activity of Macrophages against Aspergillus fumigatus. mSphere 2023; 8:e0052322. [PMID: 36719247 PMCID: PMC9942578 DOI: 10.1128/msphere.00523-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Alveolar macrophages belong to the first line of defense against inhaled conidia of the human-pathogenic fungus Aspergillus fumigatus. In lung alveoli, they contribute to phagocytosis and elimination of conidia. As a counterdefense, conidia have a gray-green pigment that enables them to survive in phagosomes of macrophages for some time. Previously, we showed that this conidial pigment interferes with the formation of flotillin-dependent lipid raft microdomains in the phagosomal membrane, thereby preventing the formation of functional phagolysosomes. Besides flotillins, stomatin is a major component of lipid rafts and can be targeted to the membrane. However, only limited information on stomatin is available, in particular on its role in defense against pathogens. To determine the function of this integral membrane protein, a stomatin-deficient macrophage line was generated by CRISPR/Cas9 gene editing. Immunofluorescence microscopy and flow cytometry revealed that stomatin contributes to the phagocytosis of conidia and is important for recruitment of the β-glucan receptor dectin-1 to both the cytoplasmic membrane and phagosomal membrane. In stomatin knockout cells, fusion of phagosomes and lysosomes, recruitment of the vATPase to phagosomes, and tumor necrosis factor alpha (TNF-α) levels were reduced when cells were infected with pigmentless conidia. Thus, our data suggest that stomatin is involved in maturation of phagosomes via fostering fusion of phagosomes with lysosomes. IMPORTANCE Stomatin is an integral membrane protein that contributes to the uptake of microbes, e.g., spores of the human-pathogenic fungus Aspergillus fumigatus. By generation of a stomatin-deficient macrophage line by advanced genetic engineering, we found that stomatin is involved in the recruitment of the β-glucan receptor dectin-1 to the phagosomal membrane of macrophages. Furthermore, stomatin is involved in maturation of phagosomes via fostering fusion of phagosomes with lysosomes. The data provide new insights on the important role of stomatin in the immune response against human-pathogenic fungi.
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3
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Komatsu T, Matsui I, Yokoyama H. Structural and mutational studies suggest key residues to determine whether stomatin SPFH domains form dimers or trimers. Biochem Biophys Rep 2022; 32:101384. [DOI: 10.1016/j.bbrep.2022.101384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/06/2022] [Indexed: 11/13/2022] Open
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4
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Donà F, Özbalci C, Paquola A, Ferrentino F, Terry SJ, Storck EM, Wang G, Eggert US. Removal of Stomatin, a Membrane-Associated Cell Division Protein, Results in Specific Cellular Lipid Changes. J Am Chem Soc 2022; 144:18069-18074. [PMID: 36136763 PMCID: PMC9545149 DOI: 10.1021/jacs.2c07907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Lipids are key constituents
of all cells, which express thousands
of different lipid species. In most cases, it is not known why cells
synthesize such diverse lipidomes, nor what regulates their metabolism.
Although it is known that dividing cells specifically regulate their
lipid content and that the correct lipid complement is required for
successful division, it is unclear how lipids connect with the cell
division machinery. Here, we report that the membrane protein stomatin
is involved in the cytokinesis step of cell division. Although it
is not a lipid biosynthetic enzyme, depletion of stomatin causes cells
to change their lipidomes. These changes include specific lipid species,
like ether lipids, and lipid families like phosphatidylcholines. Addition
of exogenous phosphatidylcholines rescues stomatin-induced defects.
These data suggest that stomatin interfaces with lipid metabolism.
Stomatin has multiple contacts with the plasma membrane and we identify
which sites are required for its role in cell division, as well as
associated lipid shifts. We also show that stomatin’s mobility
on the plasma membrane changes during division, further supporting
the requirement for a highly regulated physical interaction between
membrane lipids and this newly identified cell division protein.
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Affiliation(s)
- Federico Donà
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K
| | - Cagakan Özbalci
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K
| | - Andrea Paquola
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K.,Department of Chemistry, King's College London, London SE1 1DB, U.K
| | - Federica Ferrentino
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K.,Department of Chemistry, King's College London, London SE1 1DB, U.K
| | - Stephen J Terry
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K
| | - Elisabeth M Storck
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K
| | - Gaoge Wang
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K
| | - Ulrike S Eggert
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, U.K.,Department of Chemistry, King's College London, London SE1 1DB, U.K
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5
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Stomatin modulates adipogenesis through the ERK pathway and regulates fatty acid uptake and lipid droplet growth. Nat Commun 2022; 13:4174. [PMID: 35854007 PMCID: PMC9296665 DOI: 10.1038/s41467-022-31825-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 07/01/2022] [Indexed: 11/08/2022] Open
Abstract
Regulation of fatty acid uptake, lipid production and storage, and metabolism of lipid droplets (LDs), is closely related to lipid homeostasis, adipocyte hypertrophy and obesity. We report here that stomatin, a major constituent of lipid raft, participates in adipogenesis and adipocyte maturation by modulating related signaling pathways. In adipocyte-like cells, increased stomatin promotes LD growth or enlargements by facilitating LD-LD fusion. It also promotes fatty acid uptake from extracellular environment by recruiting effector molecules, such as FAT/CD36 translocase, to lipid rafts to promote internalization of fatty acids. Stomatin transgenic mice fed with high-fat diet exhibit obesity, insulin resistance and hepatic impairments; however, such phenotypes are not seen in transgenic animals fed with regular diet. Inhibitions of stomatin by gene knockdown or OB-1 inhibit adipogenic differentiation and LD growth through downregulation of PPARγ pathway. Effects of stomatin on PPARγ involves ERK signaling; however, an alternate pathway may also exist. Stomatin is a component of lipid rafts. Here, Wu et al. show that stomatin modulates the differentiation and functions of adipocytes by regulating adipogenesis signaling and fatty acid influx such that with excessive calorie intake, increased stomatin induces adiposity.
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6
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Drummond HA. What Evolutionary Evidence Implies About the Identity of the Mechanoelectrical Couplers in Vascular Smooth Muscle Cells. Physiology (Bethesda) 2021; 36:292-306. [PMID: 34431420 DOI: 10.1152/physiol.00008.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Loss of pressure-induced vasoconstriction increases susceptibility to renal and cerebral vascular injury. Favored paradigms underlying initiation of the response include transient receptor potential channels coupled to G protein-coupled receptors or integrins as transducers. Degenerin channels may also mediate the response. This review addresses the 1) evolutionary role of these molecules in mechanosensing, 2) limitations to identifying mechanosensitive molecules, and 3) paradigm shifting molecular model for a VSMC mechanosensor.
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Affiliation(s)
- Heather A Drummond
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
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7
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A Role for STOML3 in Olfactory Sensory Transduction. eNeuro 2021; 8:ENEURO.0565-20.2021. [PMID: 33637538 PMCID: PMC7986538 DOI: 10.1523/eneuro.0565-20.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/25/2021] [Accepted: 02/08/2021] [Indexed: 11/24/2022] Open
Abstract
Stomatin-like protein-3 (STOML3) is an integral membrane protein expressed in the cilia of olfactory sensory neurons (OSNs), but its functional role in this cell type has never been addressed. STOML3 is also expressed in dorsal root ganglia neurons, where it has been shown to be required for normal touch sensation. Here, we extended previous results indicating that STOML3 is mainly expressed in the knob and proximal cilia of OSNs. We additionally showed that mice lacking STOML3 have a morphologically normal olfactory epithelium. Because of its presence in the cilia, together with known olfactory transduction components, we hypothesized that STOML3 could be involved in modulating odorant responses in OSNs. To investigate the functional role of STOML3, we performed loose patch recordings from wild-type (WT) and Stoml3 knock-out (KO) OSNs. We found that spontaneous mean firing activity was lower with additional shift in interspike intervals (ISIs) distributions in Stoml3 KOs compared with WT neurons. Moreover, the firing activity in response to stimuli was reduced both in spike number and duration in neurons lacking STOML3 compared with WT neurons. Control experiments suggested that the primary deficit in neurons lacking STOML3 was at the level of transduction and not at the level of action potential generation. We conclude that STOML3 has a physiological role in olfaction, being required for normal sensory encoding by OSNs.
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Skryabin GO, Komelkov AV, Galetsky SA, Bagrov DV, Evtushenko EG, Nikishin II, Zhordaniia KI, Savelyeva EE, Akselrod ME, Paianidi IG, Tchevkina EM. Stomatin is highly expressed in exosomes of different origin and is a promising candidate as an exosomal marker. J Cell Biochem 2020; 122:100-115. [PMID: 32951259 DOI: 10.1002/jcb.29834] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 04/13/2020] [Accepted: 06/30/2020] [Indexed: 01/05/2023]
Abstract
Proteins involved in the organizing of lipid rafts can be found in exosomes, as shown for caveolin-1, and they could contribute to exosomal cargo sorting, as shown for flotillins. Stomatin belongs to the same stomatin/prohibitin/flotillin/HflK/C family of lipid rafts proteins, but it has never been studied in exosomes except for extracellular vesicles (EVs) originating from blood cells. Here we first show the presence of stomatin in exosomes produced by epithelial cancer cells (non-small cell lung cancer, breast, and ovarian cancer cells) as well as in EVs from biological fluids, including blood plasma, ascitic fluids, and uterine flushings. A high abundance of stomatin in EVs of various origins and its enrichment in exosomes make stomatin a promising exosomal marker. Comparison with other lipid raft proteins and exosomal markers showed that the level of stomatin protein in exosomes from different sources corresponds well to that of CD9, while it differs essentially from flotillin-1 and flotillin-2 homologs, which in turn are present in exosomes in nearly equal proportions. In contrast, the level of vesicular caveolin-1 as well as its EV-to-cellular ratio vary drastically depending on cell type.
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Affiliation(s)
- Gleb O Skryabin
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
| | - Andrei V Komelkov
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
| | - Sergey A Galetsky
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
| | - Dmitry V Bagrov
- Department of Bioengineering, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Evgeniy G Evtushenko
- Department of Chemical Enzymology, Faculty of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | - Igor I Nikishin
- Department of Bioengineering, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Kirill I Zhordaniia
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
| | - Elizaveta E Savelyeva
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
| | - Maria E Akselrod
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
| | - Iulia G Paianidi
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
| | - Elena M Tchevkina
- Oncogene Regulation Department of Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
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9
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Yokoyama H, Suzuki K, Hara K, Matsui I, Hashimoto H. Inactive dimeric structure of the protease domain of stomatin operon partner protein. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2020; 76:515-520. [PMID: 32496213 DOI: 10.1107/s2059798320005021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 04/09/2020] [Indexed: 11/11/2022]
Abstract
The N-terminal region of the stomatin operon partner protein (STOPP) PH1510 (1510-N) from the hyperthermophilic archaeon Pyrococcus horikoshii is a serine protease with a catalytic Ser-Lys dyad (Ser97 and Lys138) and specifically cleaves the C-terminal hydrophobic region of the p-stomatin PH1511. In a form of human hemolytic anemia known as hereditary stomatocytosis, stomatin is deficient in the erythrocyte membrane owing to mis-trafficking. Stomatin is thought to act as an oligomeric scaffolding protein to support cell membranes. The cleavage of stomatin by STOPP might be involved in a regulatory system. Several crystal structures of 1510-N have previously been determined: the wild type, the K138A mutant and its complex with a substrate peptide. Here, the crystal structure of the S97A mutant of 1510-N (1510-N S97A) was determined at 2.25 Å resolution. The structure contained two 1510-N S97A molecules in the asymmetric unit. On the superposition of one monomer of the 1510-N S97A and wild-type dimers, the S97A Cα atom of the other monomer of 1510-N S97A deviated by 23 Å from that of the wild type. This result indicates that 1510-N can greatly change the form of its dimer. Because of crystallographic symmetry in space group P65, a sixfold helical structure is constructed using the 1510-N dimer as a basic unit. This helical structure may be common to STOPP structures.
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Affiliation(s)
- Hideshi Yokoyama
- Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Kana Suzuki
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Kodai Hara
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Ikuo Matsui
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Hiroshi Hashimoto
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
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10
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Appelman MD, Robin MJ, Vogels EW, Wolzak C, Vos WG, Vos HR, Van Es RM, Burgering BM, Van de Graaf SF. The Lipid Raft Component Stomatin Interacts with the Na + Taurocholate Cotransporting Polypeptide (NTCP) and Modulates Bile Salt Uptake. Cells 2020; 9:cells9040986. [PMID: 32316189 PMCID: PMC7226988 DOI: 10.3390/cells9040986] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 12/15/2022] Open
Abstract
The sodium taurocholate cotransporting polypeptide (NTCP) is expressed at the basolateral membrane of hepatocytes, where it mediates the uptake of conjugated bile acids and forms the hepatocyte entry receptor for the hepatitis B and D virus. Here, we aimed to identify novel protein–protein interactions that could play a role in the regulation of NTCP. To this end, NTCP was precipitated from HA-tagged hNTCP-expressing HepG2 cells, and chloride channel CLIC-like 1 (CLCC1) and stomatin were identified as interacting proteins by mass spectrometry. Interaction was confirmed by co-immunoprecipitation. NTCP, CLCC1 and stomatin were found at the plasma membrane in lipid rafts, as demonstrated by a combination of immunofluorescence, cell surface biotinylation and isolation of detergent-resistant membranes. Neither CLCC1 overexpression nor its knockdown had an effect on NTCP function. However, both stomatin overexpression and knockdown increased NTCP-mediated taurocholate uptake while NTCP abundance at the plasma membrane was only increased in stomatin depleted cells. These findings identify stomatin as an interactor of NTCP and show that the interaction modulates bile salt transport.
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Affiliation(s)
- Monique D. Appelman
- Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology, Endocrinology and Metabolism, 1105 BK Amsterdam, The Netherlands
| | - Marion J.D. Robin
- Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology, Endocrinology and Metabolism, 1105 BK Amsterdam, The Netherlands
| | - Esther W.M. Vogels
- Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology, Endocrinology and Metabolism, 1105 BK Amsterdam, The Netherlands
| | - Christie Wolzak
- Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology, Endocrinology and Metabolism, 1105 BK Amsterdam, The Netherlands
| | - Winnie G. Vos
- Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology, Endocrinology and Metabolism, 1105 BK Amsterdam, The Netherlands
| | - Harmjan R. Vos
- Center for Molecular Medicine, Molecular Cancer Research Section, University Medical Center, 3584 CX Utrecht, The Netherlands
| | - Robert M. Van Es
- Center for Molecular Medicine, Molecular Cancer Research Section, University Medical Center, 3584 CX Utrecht, The Netherlands
| | - Boudewijn M.T. Burgering
- Center for Molecular Medicine, Molecular Cancer Research Section, University Medical Center, 3584 CX Utrecht, The Netherlands
| | - Stan F.J. Van de Graaf
- Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology, Endocrinology and Metabolism, 1105 BK Amsterdam, The Netherlands
- Amsterdam UMC, Department of Gastroenterology and Hepatology, University of Amsterdam, Amsterdam Gastroenterology, Endocrinology and Metabolism, Amsterdam 1105 AZ, The Netherlands
- Correspondence:
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11
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Yokoyama H, Matsui I. The lipid raft markers stomatin, prohibitin, flotillin, and HflK/C (SPFH)-domain proteins form an operon with NfeD proteins and function with apolar polyisoprenoid lipids. Crit Rev Microbiol 2020; 46:38-48. [PMID: 31983249 DOI: 10.1080/1040841x.2020.1716682] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
SPFH-domain proteins are found in almost all organisms across three domains: archaea, bacteria, and eukaryotes. In eukaryotic organelles, their subfamilies exhibit overlapping distribution and functions; thus, the rationality of annotation to discriminate these subfamilies remains unclear. In this review, the binding ability of prokaryotic SPFH-domain proteins towards nonpolar polyisoprenoides such as squalene and lycopene, rather than cholesterol, is discussed. The hydrophobic region at the C-terminus of SPFH-domain proteins constitutes the main region that binds apolar polyisoprenoid lipids as well as cholesterol and substantively contributes towards lipid raft formation as these regions are self-assembled together with specific lipids. Because the scaffolding proteins caveolins show common topological properties with SPFH-domain proteins such as stomatin and flotillin, the α-helical segments of stomatin proteins can flexibly move along with the membrane surface, with such movement potentially leading to membrane bending via lipid raft clustering through the formation of high order homo-oligomeric complexes of SPFH-domain proteins. We also discuss the functional significance and ancient origin of SPFH-domain proteins and the NfeD protein (STOPP) operon, which can be traced back to the ancient living cells that diverged and evolved to archaea and bacteria. Based on the molecular mechanism whereby the STOPP-protease degrades the C-terminal hydrophobic clusters of SPFH-domain proteins, it is conceivable that STOPP-protease might control the physicochemical properties of lipid rafts.
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Affiliation(s)
- Hideshi Yokoyama
- Department of Medical and Life Sciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
| | - Ikuo Matsui
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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12
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Stráner P, Balogh E, Schay G, Arrondel C, Mikó Á, L'Auné G, Benmerah A, Perczel A, K Menyhárd D, Antignac C, Mollet G, Tory K. C-terminal oligomerization of podocin mediates interallelic interactions. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2448-2457. [PMID: 29660491 DOI: 10.1016/j.bbadis.2018.04.008] [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: 12/23/2017] [Revised: 03/22/2018] [Accepted: 04/11/2018] [Indexed: 01/01/2023]
Abstract
Interallelic interactions of membrane proteins are not taken into account while evaluating the pathogenicity of sequence variants in autosomal recessive disorders. Podocin, a membrane-anchored component of the slit diaphragm, is encoded by NPHS2, the major gene mutated in hereditary podocytopathies. We formerly showed that its R229Q variant is only pathogenic when trans-associated to specific 3' mutations and suggested the causal role of an abnormal C-terminal dimerization. Here we show by FRET analysis and size exclusion chromatography that podocin oligomerization occurs exclusively through the C-terminal tail (residues 283-382): principally through the first C-terminal helical region (H1, 283-313), which forms a coiled coil as shown by circular dichroism spectroscopy, and through the 332-348 region. We show the principal role of the oligomerization sites in mediating interallelic interactions: while the monomer-forming R286Tfs*17 podocin remains membranous irrespective of the coexpressed podocin variant identity, podocin variants with an intact H1 significantly influence each other's localization (r2 = 0.68, P = 9.2 × 10-32). The dominant negative effect resulting in intracellular retention of the pathogenic F344Lfs*4-R229Q heterooligomer occurs in parallel with a reduction in the FRET efficiency, suggesting the causal role of a conformational rearrangement. On the other hand, oligomerization can also promote the membrane localization: it can prevent the endocytosis of F344Lfs*4 or F344* podocin mutants induced by C-terminal truncation. In conclusion, C-terminal oligomerization of podocin can mediate both a dominant negative effect and interallelic complementation. Interallelic interactions of NPHS2 are not restricted to the R229Q variant and have to be considered in compound heterozygous individuals.
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Affiliation(s)
- Pál Stráner
- MTA-ELTE Protein Modeling Research Group and Laboratory of Structural Chemistry and Biology, Eötvös Loránd University, Budapest, Hungary
| | - Eszter Balogh
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
| | - Gusztáv Schay
- Semmelweis University, Department of Biophysics and Radiation Biology, Budapest, Hungary
| | - Christelle Arrondel
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Ágnes Mikó
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
| | - Gerda L'Auné
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
| | - Alexandre Benmerah
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - András Perczel
- MTA-ELTE Protein Modeling Research Group and Laboratory of Structural Chemistry and Biology, Eötvös Loránd University, Budapest, Hungary
| | - Dóra K Menyhárd
- MTA-ELTE Protein Modeling Research Group and Laboratory of Structural Chemistry and Biology, Eötvös Loránd University, Budapest, Hungary
| | - Corinne Antignac
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France; Assistance Publique - Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Département de Génétique, Paris, France
| | - Géraldine Mollet
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Kálmán Tory
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary; Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France.
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13
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Conrad KA, Rodriguez R, Salcedo EC, Rauceo JM. The Candida albicans stress response gene Stomatin-Like Protein 3 is implicated in ROS-induced apoptotic-like death of yeast phase cells. PLoS One 2018; 13:e0192250. [PMID: 29389961 PMCID: PMC5794166 DOI: 10.1371/journal.pone.0192250] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 01/18/2018] [Indexed: 11/19/2022] Open
Abstract
The ubiquitous presence of SPFH (Stomatin, Prohibitin, Flotillin, HflK/HflC) proteins in all domains of life suggests that their function would be conserved. However, SPFH functions are diverse with organism-specific attributes. SPFH proteins play critical roles in physiological processes such as mechanosensation and respiration. Here, we characterize the stomatin ORF19.7296/SLP3 in the opportunistic human pathogen Candida albicans. Consistent with the localization of stomatin proteins, a Slp3p-Yfp fusion protein formed visible puncta along the plasma membrane. We also visualized Slp3p within the vacuolar lumen. Slp3p primary sequence analyses identified four putative S-palmitoylation sites, which may facilitate membrane localization and are conserved features of stomatins. Plasma membrane insertion sequences are present in mammalian and nematode SPFH proteins, but are absent in Slp3p. Strikingly, Slp3p was present in yeast cells, but was absent in hyphal cells, thus categorizing it as a yeast-phase specific protein. Slp3p membrane fluorescence significantly increased in response to cellular stress caused by plasma membrane, cell wall, oxidative, or osmotic perturbants, implicating SLP3 as a general stress-response gene. A slp3Δ/Δ homozygous null mutant had no detected phenotype when slp3Δ/Δ mutants were grown in the presence of a variety of stress agents. Also, we did not observe a defect in ion accumulation, filamentation, endocytosis, vacuolar structure and function, cell wall structure, or cytoskeletal structure. However, SLP3 over-expression triggered apoptotic-like death following prolonged exposure to oxidative stress or when cells were induced to form hyphae. Our findings reveal the cellular localization of Slp3p, and for the first time associate Slp3p function with the oxidative stress response.
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Affiliation(s)
- Karen A. Conrad
- Department of Sciences, John Jay College of the City University of New York, New York, New York, United States of America
| | - Ronald Rodriguez
- Department of Sciences, John Jay College of the City University of New York, New York, New York, United States of America
| | - Eugenia C. Salcedo
- Department of Sciences, John Jay College of the City University of New York, New York, New York, United States of America
| | - Jason M. Rauceo
- Department of Sciences, John Jay College of the City University of New York, New York, New York, United States of America
- * E-mail:
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Structure-function analysis of human stomatin: A mutation study. PLoS One 2017; 12:e0178646. [PMID: 28575093 PMCID: PMC5456319 DOI: 10.1371/journal.pone.0178646] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 05/16/2017] [Indexed: 12/27/2022] Open
Abstract
Stomatin is an ancient, widely expressed, oligomeric, monotopic membrane protein that is associated with cholesterol-rich membranes/lipid rafts. It is part of the SPFH superfamily including stomatin-like proteins, prohibitins, flotillin/reggie proteins, bacterial HflK/C proteins and erlins. Biochemical features such as palmitoylation, oligomerization, and hydrophobic “hairpin” structure show similarity to caveolins and other integral scaffolding proteins. Recent structure analyses of the conserved PHB/SPFH domain revealed amino acid residues and subdomains that appear essential for the structure and function of stomatin. To test the significance of these residues and domains, we exchanged or deleted them, expressed respective GFP-tagged mutants, and studied their subcellular localization, molecular dynamics and biochemical properties. We show that stomatin is a cholesterol binding protein and that at least two domains are important for the association with cholesterol-rich membranes. The conserved, prominent coiled-coil domain is necessary for oligomerization, while association with cholesterol-rich membranes is also involved in oligomer formation. FRAP analyses indicate that the C-terminus is the dominant entity for lateral mobility and binding site for the cortical actin cytoskeleton.
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15
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Lee JH, Hsieh CF, Liu HW, Chen CY, Wu SC, Chen TW, Hsu CS, Liao YH, Yang CY, Shyu JF, Fischer WB, Lin CH. Lipid raft-associated stomatin enhances cell fusion. FASEB J 2016; 31:47-59. [PMID: 27663861 DOI: 10.1096/fj.201600643r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/07/2016] [Indexed: 01/25/2023]
Abstract
Membrane fusions that occur during vesicle transport, virus infection, and tissue development, involve receptors that mediate membrane contact and initiate fusion and effectors that execute membrane reorganization and fusion pore formation. Some of these fusogenic receptors/effectors are preferentially recruited to lipid raft membrane microdomains. Therefore, major constituents of lipid rafts, such as stomatin, may be involved in the regulation of cell-cell fusion. Stomatin produced in cells can be released to the extracellular environment, either through protein refolding to pass across lipid bilayer or through exosome trafficking. We report that cells expressing more stomatin or exposed to exogenous stomatin are more prone to undergoing cell fusion. During osteoclastogenesis, depletion of stomatin inhibited cell fusion but had little effect on tartrate-resistant acid phosphatase production. Moreover, in stomatin transgenic mice, increased cell fusion leading to enhanced bone resorption and subsequent osteoporosis were observed. With its unique molecular topology, stomatin forms molecular assembly within lipid rafts or on the appositional plasma membranes, and promotes membrane fusion by modulating fusogenic protein engagement.-Lee, J.-H., Hsieh, C.-F., Liu, H.-W., Chen, C.-Y., Wu, S.-C., Chen, T.-W., Hsu, C.-S., Liao, Y.-H., Yang, C.-Y., Shyu, J.-F., Fischer, W. B., Lin, C.-H. Lipid raft-associated stomatin enhances cell fusion.
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Affiliation(s)
- Jui-Hao Lee
- Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan.,Institute of Microbiology and Immunology.,Institute of Biochemistry and Molecular Biology
| | | | - Hong-Wen Liu
- Institute of Microbiology and Immunology.,Chong Hin Loon Memorial Cancer and Biotherapy Research Center, and
| | - Chin-Yau Chen
- Institute of Microbiology and Immunology.,Department of Surgery, I-Lan, Taiwan
| | - Shao-Chin Wu
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Tung-Wei Chen
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | | | - Yu-Hsiu Liao
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Chih-Yung Yang
- Department of Education and Research, Taipei City Hospital, Taipei, Taiwan; and
| | - Jia-Fwu Shyu
- Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan
| | - Wolfgang B Fischer
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Chi-Hung Lin
- Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan; .,Institute of Microbiology and Immunology.,Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
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16
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Erythrocytes and their role as health indicator: Using structure in a patient-orientated precision medicine approach. Blood Rev 2016; 30:263-74. [DOI: 10.1016/j.blre.2016.01.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 01/13/2016] [Accepted: 01/26/2016] [Indexed: 12/15/2022]
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17
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Qi Y, Andolfi L, Frattini F, Mayer F, Lazzarino M, Hu J. Membrane stiffening by STOML3 facilitates mechanosensation in sensory neurons. Nat Commun 2015; 6:8512. [PMID: 26443885 PMCID: PMC4633829 DOI: 10.1038/ncomms9512] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 09/01/2015] [Indexed: 12/21/2022] Open
Abstract
Sensing force is crucial to maintain the viability of all living cells. Despite its fundamental importance, how force is sensed at the molecular level remains largely unknown. Here we show that stomatin-like protein-3 (STOML3) controls membrane mechanics by binding cholesterol and thus facilitates force transfer and tunes the sensitivity of mechano-gated channels, including Piezo channels. STOML3 is detected in cholesterol-rich lipid rafts. In mouse sensory neurons, depletion of cholesterol and deficiency of STOML3 similarly and interdependently attenuate mechanosensitivity while modulating membrane mechanics. In heterologous systems, intact STOML3 is required to maintain membrane mechanics to sensitize Piezo1 and Piezo2 channels. In C57BL/6N, but not STOML3−/− mice, tactile allodynia is attenuated by cholesterol depletion, suggesting that membrane stiffening by STOML3 is essential for mechanical sensitivity. Targeting the STOML3–cholesterol association might offer an alternative strategy for control of chronic pain. To maintain viability, cells must be able to sense and respond to mechanical stimuli. Here, Qi et al. show that the STOML3 protein acts in mechanosensation by binding cholesterol and regulating membrane stiffness which can in turn regulate ion flux through mechanosensitive channels.
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Affiliation(s)
- Yanmei Qi
- Sensory Mechanotransduction, Centre for Integrative Neuroscience, Otfried-Mueller-Strasse 25, 72076 Tuebingen, Germany
| | - Laura Andolfi
- Istituto Officina dei Materiali Consiglio Nazionale delle Ricerche, Laboratorio TASC, 34149 Basovizza, Trieste, Italy
| | - Flavia Frattini
- Sensory Mechanotransduction, Centre for Integrative Neuroscience, Otfried-Mueller-Strasse 25, 72076 Tuebingen, Germany
| | - Florian Mayer
- Sensory Mechanotransduction, Centre for Integrative Neuroscience, Otfried-Mueller-Strasse 25, 72076 Tuebingen, Germany
| | - Marco Lazzarino
- Istituto Officina dei Materiali Consiglio Nazionale delle Ricerche, Laboratorio TASC, 34149 Basovizza, Trieste, Italy
| | - Jing Hu
- Sensory Mechanotransduction, Centre for Integrative Neuroscience, Otfried-Mueller-Strasse 25, 72076 Tuebingen, Germany
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Mulcahy MJ, Blattman SB, Barrantes FJ, Lukas RJ, Hawrot E. Resistance to Inhibitors of Cholinesterase 3 (Ric-3) Expression Promotes Selective Protein Associations with the Human α7-Nicotinic Acetylcholine Receptor Interactome. PLoS One 2015; 10:e0134409. [PMID: 26258666 PMCID: PMC4530945 DOI: 10.1371/journal.pone.0134409] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 07/08/2015] [Indexed: 11/19/2022] Open
Abstract
The α7-nicotinic acetylcholine receptor (α7-nAChR) is a ligand-gated ion channel widely expressed in vertebrates and is associated with numerous physiological functions. As transmembrane ion channels, α7-nAChRs need to be expressed on the surface of the plasma membrane to function. The receptor has been reported to associate with proteins involved with receptor biogenesis, modulation of receptor properties, as well as intracellular signaling cascades and some of these associated proteins may affect surface expression of α7-nAChRs. The putative chaperone resistance to inhibitors of cholinesterase 3 (Ric-3) has been reported to interact with, and enhance the surface expression of, α7-nAChRs. In this study, we identified proteins that associate with α7-nAChRs when Ric-3 is expressed. Using α-bungarotoxin (α-bgtx), we isolated and compared α7-nAChR-associated proteins from two stably transfected, human tumor-derived cell lines: SH-EP1-hα7 expressing human α7-nAChRs and the same cell line further transfected to express Ric-3, SH-EP1-hα7-Ric-3. Mass spectrometric analysis of peptides identified thirty-nine proteins that are associated with α7-nAChRs only when Ric-3 was expressed. Significantly, and consistent with reports of Ric-3 function in the literature, several of the identified proteins are involved in biological processes that may affect nAChR surface expression such as post-translational processing of proteins, protein trafficking, and protein transport. Additionally, proteins affecting the cell cycle, the cytoskeleton, stress responses, as well as cyclic AMP- and inositol triphosphate-dependent signaling cascades were identified. These results illuminate how α-bgtx may be used to isolate and identify α7-nAChRs as well as how the expression of chaperones such as Ric-3 can influence proteins associating with α7-nAChRs. These associating proteins may alter activities of α7-nAChRs to expand their functionally-relevant repertoire as well as to affect biogenesis and membrane trafficking of α7-nAChRs.
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Affiliation(s)
- Matthew J. Mulcahy
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island, United States of America
| | - Sydney B. Blattman
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island, United States of America
| | - Francisco J. Barrantes
- Laboratory of Molecular Neurobiology, Institute of Biomedical Research, UCA-CONICET, Buenos Aires, Argentina
| | - Ronald J. Lukas
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
| | - Edward Hawrot
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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19
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Membrane rafts in the erythrocyte membrane: a novel role of MPP1p55. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 842:61-78. [PMID: 25408337 DOI: 10.1007/978-3-319-11280-0_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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20
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Guillier C, Cacas JL, Recorbet G, Deprêtre N, Mounier A, Mongrand S, Simon-Plas F, Wipf D, Dumas-Gaudot E. Direct purification of detergent-insoluble membranes from Medicago truncatula root microsomes: comparison between floatation and sedimentation. BMC PLANT BIOLOGY 2014; 14:255. [PMID: 25267185 PMCID: PMC4193990 DOI: 10.1186/s12870-014-0255-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 09/20/2014] [Indexed: 05/05/2023]
Abstract
BACKGROUND Membrane microdomains are defined as highly dynamic, sterol- and sphingolipid-enriched domains that resist to solubilization by non-ionic detergents. In plants, these so-called Detergent Insoluble Membrane (DIM) fractions have been isolated from plasma membrane by using conventional ultracentrifugation on density gradient (G). In animals, a rapid (R) protocol, based on sedimentation at low speed, which avoids the time-consuming sucrose gradient, has also been developed to recover DIMs from microsomes as starting material. In the current study, we sought to compare the ability of the Rapid protocol versus the Gradient one for isolating DIMs directly from microsomes of M. truncatula roots. For that purpose, Triton X-100 detergent-insoluble fractions recovered with the two methods were analyzed and compared for their sterol/sphingolipid content and proteome profiles. RESULTS Inferred from sterol enrichment, presence of typical sphingolipid long-chain bases from plants and canonical DIM protein markers, the possibility to prepare DIMs from M. truncatula root microsomes was confirmed both for the Rapid and Gradient protocols. Contrary to sphingolipids, the sterol and protein profiles of DIMs were found to depend on the method used. Namely, DIM fractions were differentially enriched in spinasterol and only shared 39% of common proteins as assessed by GeLC-MS/MS profiling. Quantitative analysis of protein indicated that each purification procedure generated a specific subset of DIM-enriched proteins from Medicago root microsomes. Remarkably, these two proteomes were found to display specific cellular localizations and biological functions. In silico analysis of membrane-associative features within R- and G-enriched proteins, relative to microsomes, showed that the most noticeable difference between the two proteomes corresponded to an increase in the proportion of predicted signal peptide-containing proteins after sedimentation (R) compared to its decrease after floatation (G), suggesting that secreted proteins likely contribute to the specificity of the R-DIM proteome. CONCLUSIONS Even though microsomes were used as initial material, we showed that the protein composition of the G-DIM fraction still mostly mirrored that of plasmalemma-originating DIMs conventionally retrieved by floatation. In parallel, the possibility to isolate by low speed sedimentation DIM fractions that seem to target the late secretory pathway supports the existence of plant microdomains in other organelles.
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Affiliation(s)
- Christelle Guillier
- />UMR1347 INRA/Agrosup/Université de Bourgogne Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, 17 Rue Sully, BP 86510, F-21065 Dijon Cedex, France
| | - Jean-Luc Cacas
- />UMR1347 INRA/Agrosup/Université de Bourgogne Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, 17 Rue Sully, BP 86510, F-21065 Dijon Cedex, France
- />CNRS, Laboratoire de Biogenèse Membranaire (LBM), Université Bordeaux UMR 5200, F-33000 Villenave d’Ornon, France
| | - Ghislaine Recorbet
- />UMR1347 INRA/Agrosup/Université de Bourgogne Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, 17 Rue Sully, BP 86510, F-21065 Dijon Cedex, France
| | - Nicolas Deprêtre
- />UMR CSGA: Centre des Sciences du Goût et de l’alimentation, UMR 6265 CNRS, 1324 INRA-uB, Dijon, France
| | - Arnaud Mounier
- />UMR1347 INRA/Agrosup/Université de Bourgogne Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, 17 Rue Sully, BP 86510, F-21065 Dijon Cedex, France
| | - Sébastien Mongrand
- />CNRS, Laboratoire de Biogenèse Membranaire (LBM), Université Bordeaux UMR 5200, F-33000 Villenave d’Ornon, France
| | - Françoise Simon-Plas
- />UMR1347 INRA/Agrosup/Université de Bourgogne Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, 17 Rue Sully, BP 86510, F-21065 Dijon Cedex, France
| | - Daniel Wipf
- />UMR1347 INRA/Agrosup/Université de Bourgogne Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, 17 Rue Sully, BP 86510, F-21065 Dijon Cedex, France
| | - Eliane Dumas-Gaudot
- />UMR1347 INRA/Agrosup/Université de Bourgogne Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, 17 Rue Sully, BP 86510, F-21065 Dijon Cedex, France
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Yokoyama H, Matsui I. Crystal structure of the stomatin operon partner protein from Pyrococcus horikoshii indicates the formation of a multimeric assembly. FEBS Open Bio 2014; 4:804-12. [PMID: 25349784 PMCID: PMC4208085 DOI: 10.1016/j.fob.2014.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/09/2014] [Accepted: 09/09/2014] [Indexed: 01/21/2023] Open
Abstract
The structure of C-terminal domain of stomatin operon partner protein PH1510 was determined. C-terminal domain of PH1510 (1510-C) forms a five-stranded β-barrel known as an OB-fold. 1510-C could assemble into multimers based on a dimer as a basic unit. 1510-C functions as a scaffold protein to form a multimeric assembly with stomatin.
Stomatin, prohibitin, flotillin, and HflK/C (SPFH) domain proteins are found in the lipid raft microdomains of various cellular membranes. Stomatin/STOPP (stomatin operon partner protein) gene pairs are present in both archaeal and bacterial species, and their protein products may be involved in the quality control of membrane proteins. In the present study, the crystal structure of the C-terminal soluble domain of STOPP PH1510 (1510-C) from the hyperthermophilic archaeon Pyrococcus horikoshii was determined at 2.4 Å resolution. The structure of 1510-C had a compact five-stranded β-barrel fold known as an oligosaccharide/oligonucleotide-binding fold (OB-fold). According to crystal packing, 1510-C could assemble into multimers based on a dimer as a basic unit. 1510-C also formed a large cylinder-like structure composed of 24 subunits or a large triangular prism-like structure composed of 12 subunits. These results indicate that 1510-C functions as a scaffold protein to form the multimeric assembly of STOPP and stomatin.
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Affiliation(s)
- Hideshi Yokoyama
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Ikuo Matsui
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
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22
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Lapatsina L, Jira JA, Smith ESJ, Poole K, Kozlenkov A, Bilbao D, Lewin GR, Heppenstall PA. Regulation of ASIC channels by a stomatin/STOML3 complex located in a mobile vesicle pool in sensory neurons. Open Biol 2013; 2:120096. [PMID: 22773952 PMCID: PMC3390797 DOI: 10.1098/rsob.120096] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 06/01/2012] [Indexed: 01/21/2023] Open
Abstract
A complex of stomatin-family proteins and acid-sensing (proton-gated) ion channel (ASIC) family members participate in sensory transduction in invertebrates and vertebrates. Here, we have examined the role of the stomatin-family protein stomatin-like protein-3 (STOML3) in this process. We demonstrate that STOML3 interacts with stomatin and ASIC subunits and that this occurs in a highly mobile vesicle pool in dorsal root ganglia (DRG) neurons and Chinese hamster ovary cells. We identify a hydrophobic region in the N-terminus of STOML3 that is required for vesicular localization of STOML3 and regulates physical and functional interaction with ASICs. We further characterize STOML3-containing vesicles in DRG neurons and show that they are Rab11-positive, but not part of the early-endosomal, lysosomal or Rab14-dependent biosynthetic compartment. Moreover, uncoupling of vesicles from microtubules leads to incorporation of STOML3 into the plasma membrane and increased acid-gated currents. Thus, STOML3 defines a vesicle pool in which it associates with molecules that have critical roles in sensory transduction. We suggest that the molecular features of this vesicular pool may be characteristic of a ‘transducosome’ in sensory neurons.
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Affiliation(s)
- Liudmila Lapatsina
- Department of Neuroscience, Max-Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13092 Berlin-Buch, Germany
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Clustering of OB-fold domains of the partner protease complexed with trimeric stomatin from Thermococcales. Biochimie 2013; 95:1494-501. [PMID: 23587725 DOI: 10.1016/j.biochi.2013.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Accepted: 04/04/2013] [Indexed: 11/22/2022]
Abstract
The C-terminal soluble domain of stomatin operon partner protein (STOPP) of the hyperthermophilic archaeon Pyrococcus horikoshii has an oligonucleotide binding-fold (OB-fold). STOPP lacks the conserved surface residues necessary for binding to DNA/RNA. A tryptophan (W) residue is conserved instead at the molecular surface. Solvent-accessible W residues are often found at interfaces of protein-protein complexes, which suggested the possibility of self-assembling of STOPP. Protein-protein interactions among the C-terminal soluble domains of STOPP PH1510 (1510-C) were then analyzed by chemical linking and blue native polyacrylamide gel electrophoresis (BN-PAGE) methods. These results suggest that the soluble domains of STOPP could assemble into homo-oligomers. Since hexameric subcomplex I from archaeal proteasome consists of coiled-coil segments and OB-fold domains, molecular modeling of 1510-C was performed using hexameric subcomplex I as a template. Although 1510-C is a comparatively small polypeptide consisting of approximately 60 residues, numerous salt bridges and hydrophobic interactions were observed in the predicted hexamer of 1510-C, suggesting the stability of the homo-oligomeric structure. This oligomeric property of STOPP may be favorable for triplicate proteolysis of the trimer of prokaryotic stomatin.
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Abstract
How mechanical forces are sensed remains largely mysterious. The forces that gate prokaryotic and several eukaryotic channels were found to come from the lipid membrane. Our survey of animal cells found that membrane force foci all have cholesterol-gathering proteins and are reinforced with cholesterol. This result is evident in overt force sensors at the tips of stereocilia for vertebrate hearing and the touch receptor of Caenorhabditis elegans and mammalian neurons. For less specialized cells, cadherins sustain the force between neighboring cells and integrins between cells and matrix. These tension bearers also pass through and bind to a cholesterol-enriched platform before anchoring to cytoskeleton through other proteins. Cholesterol, in alliance with sphingomyelin and specialized proteins, enforces a more ordered structure in the bilayer. Such a stiffened platform can suppress mechanical noise, redirect, rescale, and confine force. We speculate that such platforms may be dynamic. The applied force may allow disordered-phase lipids to enter the platform-staging channel opening in the thinner mobile neighborhood. The platform may also contain specialized protein/lipid subdomains enclosing mechanosensitive channels to open with localized tension. Such a dynamic stage can mechanically operate structurally disparate channels or enzymes without having to tie them directly to cadherin, integrin, or other protein tethers.
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A novel domain regulating degradation of the glomerular slit diaphragm protein podocin in cell culture systems. PLoS One 2013; 8:e57078. [PMID: 23437316 PMCID: PMC3577791 DOI: 10.1371/journal.pone.0057078] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Accepted: 01/17/2013] [Indexed: 11/19/2022] Open
Abstract
Mutations in the gene NPHS2 are the most common cause of hereditary steroid-resistant nephrotic syndrome. Its gene product, the stomatin family member protein podocin represents a core component of the slit diaphragm, a unique structure that bridges the space between adjacent podocyte foot processes in the kidney glomerulus. Dislocation and misexpression of slit diaphragm components have been described in the pathogenesis of acquired and hereditary nephrotic syndrome. However, little is known about mechanisms regulating cellular trafficking and turnover of podocin. Here, we discover a three amino acids-comprising motif regulating intracellular localization of podocin in cell culture systems. Mutations of this motif led to markedly reduced degradation of podocin. These findings give novel insight into the molecular biology of the slit diaphragm protein podocin, enabling future research to establish the biological relevance of podocin turnover and localization.
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Identification, localization, and functional implications of the microdomain-forming stomatin family in the ciliated protozoan Paramecium tetraurelia. EUKARYOTIC CELL 2013; 12:529-44. [PMID: 23376944 DOI: 10.1128/ec.00324-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The SPFH protein superfamily is assumed to occur universally in eukaryotes, but information from protozoa is scarce. In the Paramecium genome, we found only Stomatins, 20 paralogs grouped in 8 families, STO1 to STO8. According to cDNA analysis, all are expressed, and molecular modeling shows the typical SPFH domain structure for all subgroups. For further analysis we used family-specific sequences for fluorescence and immunogold labeling, gene silencing, and functional tests. With all family members tested, we found a patchy localization at/near the cell surface and on vesicles. The Sto1p and Sto4p families are also associated with the contractile vacuole complex. Sto4p also makes puncta on some food vacuoles and is abundant on vesicles recycling from the release site of spent food vacuoles to the site of nascent food vacuole formation. Silencing of the STO1 family reduces mechanosensitivity (ciliary reversal upon touching an obstacle), thus suggesting relevance for positioning of mechanosensitive channels in the plasmalemma. Silencing of STO4 members increases pulsation frequency of the contractile vacuole complex and reduces phagocytotic activity of Paramecium cells. In summary, Sto1p and Sto4p members seem to be involved in positioning specific superficial and intracellular microdomain-based membrane components whose functions may depend on mechanosensation (extracellular stimuli and internal osmotic pressure).
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Stomatin interacts with GLUT1/SLC2A1, band 3/SLC4A1, and aquaporin-1 in human erythrocyte membrane domains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:956-66. [PMID: 23219802 PMCID: PMC3790964 DOI: 10.1016/j.bbamem.2012.11.030] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 10/20/2012] [Accepted: 11/26/2012] [Indexed: 12/12/2022]
Abstract
The widely expressed, homo-oligomeric, lipid raft-associated, monotopic integral membrane protein stomatin and its homologues are known to interact with and modulate various ion channels and transporters. Stomatin is a major protein of the human erythrocyte membrane, where it associates with and modifies the glucose transporter GLUT1; however, previous attempts to purify hetero-oligomeric stomatin complexes for biochemical analysis have failed. Because lateral interactions of membrane proteins may be short-lived and unstable, we have used in situ chemical cross-linking of erythrocyte membranes to fix the stomatin complexes for subsequent purification by immunoaffinity chromatography. To further enrich stomatin, we prepared detergent-resistant membranes either before or after cross-linking. Mass spectrometry of the isolated, high molecular, cross-linked stomatin complexes revealed the major interaction partners as glucose transporter-1 (GLUT1), anion exchanger (band 3), and water channel (aquaporin-1). Moreover, ferroportin-1 (SLC40A1), urea transporter-1 (SLC14A1), nucleoside transporter (SLC29A1), the calcium-pump (Ca-ATPase-4), CD47, and flotillins were identified as stomatin-interacting proteins. These findings are in line with the hypothesis that stomatin plays a role as membrane-bound scaffolding protein modulating transport proteins.
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Brand J, Smith ESJ, Schwefel D, Lapatsina L, Poole K, Omerbašić D, Kozlenkov A, Behlke J, Lewin GR, Daumke O. A stomatin dimer modulates the activity of acid-sensing ion channels. EMBO J 2012; 31:3635-46. [PMID: 22850675 PMCID: PMC3433786 DOI: 10.1038/emboj.2012.203] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 07/06/2012] [Indexed: 12/14/2022] Open
Abstract
Stomatins govern membrane trafficking and ion channel activity. The banana-shaped stomatin-domain dimmers oligomerize into a cylindrical structure. A dynamic hydrophobic pocket at the concave side of the dimer mediates repression of acid-sensing ion channel 3 (ASIC3) activity. Stomatin proteins oligomerize at membranes and have been implicated in ion channel regulation and membrane trafficking. To obtain mechanistic insights into their function, we determined three crystal structures of the conserved stomatin domain of mouse stomatin that assembles into a banana-shaped dimer. We show that dimerization is crucial for the repression of acid-sensing ion channel 3 (ASIC3) activity. A hydrophobic pocket at the inside of the concave surface is open in the presence of an internal peptide ligand and closes in the absence of this ligand, and we demonstrate a function of this pocket in the inhibition of ASIC3 activity. In one crystal form, stomatin assembles via two conserved surfaces into a cylindrical oligomer, and these oligomerization surfaces are also essential for the inhibition of ASIC3-mediated currents. The assembly mode of stomatin uncovered in this study might serve as a model to understand oligomerization processes of related membrane-remodelling proteins, such as flotillin and prohibitin.
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Affiliation(s)
- Janko Brand
- Max-Delbrück Center for Molecular Medicine, Crystallography Department, Berlin, Germany
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29
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Voges M, Bachmann V, Naujoks J, Kopp K, Hauck CR. Extracellular IgC2 constant domains of CEACAMs mediate PI3K sensitivity during uptake of pathogens. PLoS One 2012; 7:e39908. [PMID: 22768164 PMCID: PMC3386982 DOI: 10.1371/journal.pone.0039908] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 05/29/2012] [Indexed: 11/22/2022] Open
Abstract
Background Several pathogenic bacteria utilize receptors of the CEACAM family to attach to human cells. Binding to different members of this receptor family can result in uptake of the bacteria. Uptake of Neisseria gonorrhoeae, a Gram-negative human pathogen, via CEACAMs found on epithelial cells, such as CEACAM1, CEA or CEACAM6, differs mechanistically from phagocytosis mediated by CEACAM3, a CEACAM family member expressed selectively by human granulocytes. Principal Findings We find that CEACAM1- as well as CEACAM3-mediated bacterial internalization are accompanied by a rapid increase in phosphatidylinositol-3,4,5 phosphate (PI(3,4,5)P) at the site of bacterial entry. However, pharmacological inhibition of phosphatidylinositol-3′ kinase (PI3K) selectively affects CEACAM1-mediated uptake of Neisseria gonorrhoeae. Accordingly, overexpression of the PI(3,4,5)P phosphatase SHIP diminishes and expression of a constitutive active PI3K increases CEACAM1-mediated internalization of gonococci, without influencing uptake by CEACAM3. Furthermore, bacterial uptake by GPI-linked members of the CEACAM family (CEA and CEACAM6) and CEACAM1-mediated internalization of N. meningitidis by endothelial cells require PI3K activity. Sensitivity of CEACAM1-mediated uptake toward PI3K inhibition is independent of receptor localization in cholesterol-rich membrane microdomains and does not require the cytoplasmic or the transmembrane domain of CEACAM1. However, PI3K inhibitor sensitivity requires the IgC2-like domains of CEACAM1, which are also present in CEA and CEACAM6, but which are absent from CEACAM3. Accordingly, overexpression of CEACAM1 IgC2 domains blocks CEACAM1-mediated internalization. Conclusions Our results provide novel mechanistic insight into CEACAM1-mediated endocytosis and suggest that epithelial CEACAMs associate in cis with other membrane receptor(s) via their extracellular domains to trigger bacterial uptake in a PI3K-dependent manner.
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Affiliation(s)
- Maike Voges
- Lehrstuhl Zellbiologie, Universität Konstanz, Konstanz, Germany
- Konstanz Research School Chemical Biology, Universität Konstanz, Konstanz, Germany
| | - Verena Bachmann
- Lehrstuhl Zellbiologie, Universität Konstanz, Konstanz, Germany
| | - Jan Naujoks
- Lehrstuhl Zellbiologie, Universität Konstanz, Konstanz, Germany
| | - Kathrin Kopp
- Lehrstuhl Zellbiologie, Universität Konstanz, Konstanz, Germany
| | - Christof R. Hauck
- Lehrstuhl Zellbiologie, Universität Konstanz, Konstanz, Germany
- Konstanz Research School Chemical Biology, Universität Konstanz, Konstanz, Germany
- * E-mail:
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Christie DA, Kirchhof MG, Vardhana S, Dustin ML, Madrenas J. Mitochondrial and plasma membrane pools of stomatin-like protein 2 coalesce at the immunological synapse during T cell activation. PLoS One 2012; 7:e37144. [PMID: 22623988 PMCID: PMC3356372 DOI: 10.1371/journal.pone.0037144] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 04/13/2012] [Indexed: 01/29/2023] Open
Abstract
Stomatin-like protein 2 (SLP-2) is a member of the stomatin-prohibitin-flotillin-HflC/K (SPFH) superfamily. Recent evidence indicates that SLP-2 is involved in the organization of cardiolipin-enriched microdomains in mitochondrial membranes and the regulation of mitochondrial biogenesis and function. In T cells, this role translates into enhanced T cell activation. Although the major pool of SLP-2 is associated with mitochondria, we show here that there is an additional pool of SLP-2 associated with the plasma membrane of T cells. Both plasma membrane-associated and mitochondria-associated pools of SLP-2 coalesce at the immunological synapse (IS) upon T cell activation. SLP-2 is not required for formation of IS nor for the re-localization of mitochondria to the IS because SLP-2-deficient T cells showed normal re-localization of these organelles in response to T cell activation. Interestingly, upon T cell activation, we found the surface pool of SLP-2 mostly excluded from the central supramolecular activation complex, and enriched in the peripheral area of the IS where signalling TCR microclusters are located. Based on these results, we propose that SLP-2 facilitates the compartmentalization not only of mitochondrial membranes but also of the plasma membrane into functional microdomains. In this latter location, SLP-2 may facilitate the optimal assembly of TCR signalosome components. Our data also suggest that there may be a net exchange of membrane material between mitochondria and plasma membrane, explaining the presence of some mitochondrial proteins in the plasma membrane.
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Affiliation(s)
- Darah A. Christie
- The Centre for Human Immunology, Robarts Research Institute, and the Departments of Microbiology and Immunology, and Medicine, The University of Western Ontario, London, Ontario, Canada
| | - Mark G. Kirchhof
- The Centre for Human Immunology, Robarts Research Institute, and the Departments of Microbiology and Immunology, and Medicine, The University of Western Ontario, London, Ontario, Canada
| | - Santosh Vardhana
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, New York, New York, United States of America
| | - Michael L. Dustin
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, New York, New York, United States of America
| | - Joaquín Madrenas
- The Centre for Human Immunology, Robarts Research Institute, and the Departments of Microbiology and Immunology, and Medicine, The University of Western Ontario, London, Ontario, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
- * E-mail:
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31
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Yokoyama H, Takizawa N, Kobayashi D, Matsui I, Fujii S. Crystal structure of a membrane stomatin-specific protease in complex with a substrate peptide. Biochemistry 2012; 51:3872-80. [PMID: 22475127 DOI: 10.1021/bi300098k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Membrane-bound proteases are involved in various regulatory functions. A previous report indicated that the N-terminal region of PH1510p (1510-N) from the hyperthermophilic archaeon Pyrococcus horikoshii is a serine protease with a catalytic Ser-Lys dyad (Ser97 and Lys138) and specifically cleaves the C-terminal hydrophobic region of the p-stomatin PH1511p. In humans, an absence of stomatin is associated with a form of hemolytic anemia known as hereditary stomatocytosis. Here, the crystal structure of 1510-N K138A in complex with a peptide substrate was determined at 2.25 Å resolution. In the structure, a 1510-N dimer binds to one peptide. The six central residues (VIVLML) of the peptide are hydrophobic and in a pseudopalindromic structure and therefore favorably fit into the hydrophobic active tunnel of the 1510-N dimer, although 1510-N degrades the substrate at only one point. A comparison with unliganded 1510-N K138A revealed that the binding of the substrate causes a large rotational and translational displacement between protomers and produces a tunnel suitable for binding the peptide. When the peptide binds, the flexible L2 loop of one protomer forms β-strands, whereas that of the other protomer remains in a loop form, indicating that one protomer binds to the peptide more tightly than the other protomer. The Ala138 residues of the two protomers are located very close together (the distance between the two Cβ atoms is 3.6 Å). Thus, in wild-type 1510-N, the close positioning of the catalytic Ser97 and Lys138 residues may be induced by electrostatic repulsion of the two Lys138 side chains of the protomers.
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Affiliation(s)
- Hideshi Yokoyama
- School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
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32
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Pednekar D, Wang Y, Fedotova TV, Wojcikiewicz RJH. Clustered hydrophobic amino acids in amphipathic helices mediate erlin1/2 complex assembly. Biochem Biophys Res Commun 2011; 415:135-40. [PMID: 22020079 DOI: 10.1016/j.bbrc.2011.10.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 10/07/2011] [Indexed: 12/11/2022]
Abstract
Erlin1 and erlin2 are highly homologous, ∼40kDa, endoplasmic reticulum membrane proteins that assemble into a ring-shaped complex with a mass of ∼2 MDa. How this complex is formed is not understood, but appears to involve multiple interactions, including a coiled-coil region that mediates lower-order erlin assembly, and a short hydrophobic region, termed the "assembly domain", that mediates higher-order assembly into ∼2 MDa complexes. Here we have used molecular modeling, mutagenesis and cross-linking to examine the role of the assembly domain in higher-order assembly. We find (i) that the assembly domains of erlin1 and erlin2 are amphipathic helices, (ii) that erlin1 alone and erlin2 alone can assemble into ∼2 MDa complexes, (iii) that higher-order assembly is strongly inhibited by point mutations to the assembly domain, (iv) that three interacting hydrophobic residues in the assembly domain and aromaticity are essential for higher-order assembly, and (iv) that while erlins1 and 2 are equally capable of forming lower-order homo- and hetero-oligomers, hetero-oligomers are the most prevalent form when erlin1 and erlin2 are co-expressed. Overall, we conclude that the ∼2 MDa erlin1/2 complex is composed of an assemblage of lower-order hetero-oligomers, probably heterotrimers, linked together by assembly domain hydrophobic residues.
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Affiliation(s)
- Deepa Pednekar
- Department of Pharmacology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
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33
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Summers WAT, Wilkins JA, Dwivedi RC, Ezzati P, Court DA. Mitochondrial dysfunction resulting from the absence of mitochondrial porin in Neurospora crassa. Mitochondrion 2011; 12:220-9. [PMID: 21946565 DOI: 10.1016/j.mito.2011.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 09/01/2011] [Accepted: 09/09/2011] [Indexed: 12/20/2022]
Abstract
Porin, the voltage-dependent anion-selective channel (VDAC) in the mitochondrial outer membrane, contributes to metabolism and apoptosis. VDAC function was investigated in Neurospora, an obligate aerobe with a single porin. Porinless strains are viable, with cold-sensitive growth, cytochrome deficiencies and overexpression of alternative oxidase. iTRAQ labeling of mitochondria from a porinless strain and its progenitor revealed a small group of proteins with altered expression levels in the mutant organelles. Porinless Neurospora appears to compensate not by inducing alternative pores, but by altering electron flow and nucleotide metabolism. Transcriptional and post-transcriptional mechanisms contribute to the response, reflecting the extent of porin influence.
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Affiliation(s)
- William A T Summers
- Department of Microbiology, University of Manitoba, 301 Buller Building, Winnipeg, MB, Canada R3T 2N2.
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34
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Wang Y, Cao D, Chen J, Liu A, Yu Q, Song X, Xiang Z, Lu J. Distribution of stomatin expressing in the central nervous system and its up-regulation in cerebral cortex of rat by hypoxia. J Neurochem 2010; 116:374-84. [PMID: 21091477 DOI: 10.1111/j.1471-4159.2010.07117.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Stomatin is an important membrane raft protein which can combine skeleton protein, some ion channel, and transporter to regulate their functions. However, until now no data on its expression and function in CNS are available. In this study, we examined distribution of stomatin in CNS of rat, and investigated the effects of hypoxia exposure and glucocorticoid on stomatin expression in cerebral cortex of rat. Immunofluorescence staining revealed a broad expression of stomatin protein in many areas of adult rat brain and spinal cord, including the ventral horn of spinal cord, causal magnocellular nucleus of hypothalamus, the V layer of the cerebral cortex, solitary nucleus, 10 and 12 nuclei, and so on. Hypoxia or ischemic hypoxia significantly up-regulated stomatin expression in cerebral cortex, and the up-regulation was independent on adrenocortical steroids since it also occurred in adrenalectomized (ADX) rats. Moreover, treatment of ADX or sham-operated rats with dexamethasone, a synthetic glucocorticoid alone could significantly stimulate expression of stomatin in lung and heart, but not in cerebral cortex. However, dexamethasone could enhance the hypoxia-stimulated expression of stomatin in cerebral cortex of ADX rats. These findings suggested that stomatin might be involved in various physiological functions and cellular events of neurons in CNS under physiological conditions and play a potential protective role under hypoxic conditions.
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Affiliation(s)
- Yan Wang
- Department of Pathophysiology, Second Military Medical University, Shanghai, China
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35
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Yokoyama H. [Three-dimensional structure of membrane protein stomatin and function of stomatin-specific protease]. YAKUGAKU ZASSHI 2010; 130:1289-93. [PMID: 20930480 DOI: 10.1248/yakushi.130.1289] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Stomatin is a major integral membrane protein of human erythrocytes, the absence of which is associated with a form of hemolytic anemia known as hereditary stomatocytosis. It is reported that stomatin regulates the gating of acid-sensing ion channels in mammalian neurons. However, the function of stomatin is not fully understood. In the genomic sequence of the hyperthermophilic archaeon Pyrococcus horikoshii, the putative operon-forming genes PH1511 and PH1510 encode stomatin and its partner protein, respectively. The N-terminal region of PH1510p (1510-N) is a serine protease, and specifically cleaves the C-terminal hydrophobic region of stomatin PH1511p. We have determined the first crystal structure of the core domain of stomatin PH1511p (residues 56-234, designated as PhSto(CD)). This review focuses on the three-dimensional structure of PhSto(CD), and discusses the function of stomatin and its specific protease 1510-N. PhSto(CD) forms a novel homotrimeric structure. Three α/β domains form a triangle of about 50 Å on each side, and three α-helical segments about 60 Å in length extend from the apexes of the triangle. The α/β domain of PhSto(CD) is partly similar in structure to the band-7 domain of mouse flotillin-2. While the α/β domain is relatively rigid, the α-helical segment shows a conformational flexibility, adapting to the neighboring environment. One α-helical segment forms an anti-parallel coiled-coil with another α-helical segment from a symmetry-related molecule. The α-helical segment shows a heptad repeat pattern, and mainly hydrophobic residues form a coiled-coil interface. The coiled-coil fold observed in the crystal probably contributes to the self-association.
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Affiliation(s)
- Hideshi Yokoyama
- Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Suruga-ku, Shizuoka, Japan.
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36
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Mrówczyńska L, Salzer U, Perutková S, Iglič A, Hägerstrand H. Echinophilic proteins stomatin, sorcin, and synexin locate outside gangliosideM1 (GM1) patches in the erythrocyte membrane. Biochem Biophys Res Commun 2010; 401:396-400. [PMID: 20858460 DOI: 10.1016/j.bbrc.2010.09.065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 09/15/2010] [Indexed: 10/19/2022]
Abstract
The detergent (Triton X-100, 4°C)-resistant membrane (DRM)-associated membrane proteins stomatin, sorcin, and synexin (anexin VII) exposed on the cytoplasmic side of membrane were investigated for their lateral distribution in relation to induced ganglioside(M1) (GM1) raft patches in flat (discocytic) and curved (echinocytic) human erythrocyte membrane. In discocytes, no accumulation of stomatin, sorcin, and synexin in cholera toxin subunit B (CTB) plus anti-CTB-induced GM1 patches was detected by fluorescence microscopy. In echinocytes, stomatin, sorcin, and synexin showed a similar curvature-dependent lateral distribution as GM1 patches by accumulating to spiculae induced by ionophore A23187 plus calcium. Stomatin was partly and synexin and sorcin were fully recruited to the spiculae. However, the DRM-associated proteins only partially co-localized with GM1 and were frequently distributed into different spiculae than GM1. The study indicates that stomatin, sorcin, and synexin are echinophilic membrane components that mainly locate outside GM1 rafts in the human erythrocyte membrane. Echinophilicity is suggested to contribute to the DRM association of a membrane component in general.
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Affiliation(s)
- Lucyna Mrówczyńska
- Department of Cell Biology, A. Mickiewicz University, PL-61614, Poznań, Poland.
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37
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Mairhofer M, Steiner M, Salzer U, Prohaska R. Stomatin-like protein-1 interacts with stomatin and is targeted to late endosomes. J Biol Chem 2009; 284:29218-29. [PMID: 19696025 DOI: 10.1074/jbc.m109.014993] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The human stomatin-like protein-1 (SLP-1) is a membrane protein with a characteristic bipartite structure containing a stomatin domain and a sterol carrier protein-2 (SCP-2) domain. This structure suggests a role for SLP-1 in sterol/lipid transfer and transport. Because SLP-1 has not been investigated, we first studied the molecular and cell biological characteristics of the expressed protein. We show here that SLP-1 localizes to the late endosomal compartment, like stomatin. Unlike stomatin, SLP-1 does not localize to the plasma membrane. Overexpression of SLP-1 leads to the redistribution of stomatin from the plasma membrane to late endosomes suggesting a complex formation between these proteins. We found that the targeting of SLP-1 to late endosomes is caused by a GYXXPhi (Phi being a bulky, hydrophobic amino acid) sorting signal at the N terminus. Mutation of this signal results in plasma membrane localization. SLP-1 and stomatin co-localize in the late endosomal compartment, they co-immunoprecipitate, thus showing a direct interaction, and they associate with detergent-resistant membranes. In accordance with the proposed lipid transfer function, we show that, under conditions of blocked cholesterol efflux from late endosomes, SLP-1 induces the formation of enlarged, cholesterol-filled, weakly LAMP-2-positive, acidic vesicles in the perinuclear region. This massive cholesterol accumulation clearly depends on the SCP-2 domain of SLP-1, suggesting a role for this domain in cholesterol transfer to late endosomes.
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Affiliation(s)
- Mario Mairhofer
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Vienna A-1030, Austria
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38
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Hetero-oligomerization of reggie-1/flotillin-2 and reggie-2/flotillin-1 is required for their endocytosis. Cell Signal 2009; 21:1287-97. [DOI: 10.1016/j.cellsig.2009.03.012] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 03/09/2009] [Accepted: 03/11/2009] [Indexed: 10/21/2022]
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Pearce MMP, Wormer DB, Wilkens S, Wojcikiewicz RJH. An endoplasmic reticulum (ER) membrane complex composed of SPFH1 and SPFH2 mediates the ER-associated degradation of inositol 1,4,5-trisphosphate receptors. J Biol Chem 2009; 284:10433-45. [PMID: 19240031 DOI: 10.1074/jbc.m809801200] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
How endoplasmic reticulum (ER) proteins that are substrates for the ER-associated degradation (ERAD) pathway are recognized for polyubiquitination and proteasomal degradation is largely unresolved. Inositol 1,4,5-trisphosphate receptors (IP(3)Rs) form tetrameric calcium channels in ER membranes, whose primary role is to control the release of ER calcium stores, but whose levels are also regulated, in an activation-dependent manner, by the ERAD pathway. Here we report that the ER membrane protein SPFH1 and its homolog SPFH2 form a heteromeric approximately 2 MDa complex that binds to IP(3)R tetramers immediately after their activation and is required for their processing. The complex is ring-shaped (diameter approximately 250A(),) and RNA interference-mediated depletion of SPFH1 and SPFH2 blocks IP(3)R polyubiquitination and degradation. We propose that this novel SPFH1/2 complex is a recognition factor that targets IP(3)Rs and perhaps other substrates for ERAD.
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Affiliation(s)
- Margaret M P Pearce
- Departments of Pharmacology and Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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40
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Hoegg MB, Browman DT, Resek ME, Robbins SM. Distinct regions within the erlins are required for oligomerization and association with high molecular weight complexes. J Biol Chem 2009; 284:7766-76. [PMID: 19131330 DOI: 10.1074/jbc.m809127200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The group of stomatin/prohibitin/flotillin/HflK/C (SPFH) domain-containing proteins comprise members of diverse subcellular localization and function. Association with detergent-resistant membranes (DRMs) and the propensity to form oligomers are two common properties of SPFH domain proteins and likely important for the function of these proteins. Our laboratory recently discovered two novel members of this protein group, which, based on their endoplasmic reticulum (ER) localization and association with DRMs, were named ER lipid raft-associated protein (erlin)-1 and -2. Here we characterized erlin oligomerization and identified domains within the erlins responsible for oligomerization and DRM association. Using co-immunoprecipitation and sucrose density gradient centrifugation approaches on endogenous and ectopically expressed erlin proteins, we found that they formed homo- and hetero-oligomers and were part of large multimeric complexes. These properties were independent of their DRM association. By analyzing truncation and point mutants of erlin-2 we discovered that interaction between erlin monomers (oligomerization) and association with high molecular weight complexes require distinct regions within the protein. Although oligomerization and DRM association were mediated by a region immediately downstream of the SPFH domain (residues 228-300), integration into high molecular weight complexes was absolutely dependent on a phenylalanine residue C-terminal of this region (Phe-305), which lies within a short stretch of hydrophobic residues. Our data demonstrate that lower order oligomerization and incorporation into multimeric complexes are two separate biochemical properties of the erlins, because they are mediated by distinct regions.
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Affiliation(s)
- Maja B Hoegg
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Min CK, Bang SY, Cho BA, Choi YH, Yang JS, Lee SH, Seong SY, Kim KW, Kim S, Jung JU, Choi MS, Kim IS, Cho NH. Role of amphipathic helix of a herpesviral protein in membrane deformation and T cell receptor downregulation. PLoS Pathog 2008; 4:e1000209. [PMID: 19023411 PMCID: PMC2581436 DOI: 10.1371/journal.ppat.1000209] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 10/16/2008] [Indexed: 11/18/2022] Open
Abstract
Lipid rafts are membrane microdomains that function as platforms for signal transduction and membrane trafficking. Tyrosine kinase interacting protein (Tip) of T lymphotropic Herpesvirus saimiri (HVS) is targeted to lipid rafts in T cells and downregulates TCR and CD4 surface expression. Here, we report that the membrane-proximal amphipathic helix preceding Tip's transmembrane (TM) domain mediates lipid raft localization and membrane deformation. In turn, this motif directs Tip's lysosomal trafficking and selective TCR downregulation. The amphipathic helix binds to the negatively charged lipids and induces liposome tubulation, the TM domain mediates oligomerization, and cooperation of the membrane-proximal helix with the TM domain is sufficient for localization to lipid rafts and lysosomal compartments, especially the mutivesicular bodies. These findings suggest that the membrane-proximal amphipathic helix and TM domain provide HVS Tip with the unique ability to deform the cellular membranes in lipid rafts and to downregulate TCRs potentially through MVB formation.
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Affiliation(s)
- Chan-Ki Min
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
| | - Sun-Young Bang
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
| | - Bon-A Cho
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
| | - Yun-Hui Choi
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
| | - Jae-Seong Yang
- Department of Life Science and School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Kyungbuk, Korea
| | - Sun-Hwa Lee
- Seoul National University Hospital, Innovative Research Institute for Cell Therapy, Chongno-Gu, Seoul, Korea
| | - Seung-Yong Seong
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
- Seoul National University Hospital, Innovative Research Institute for Cell Therapy, Chongno-Gu, Seoul, Korea
| | - Ki Woo Kim
- National Instrumentation Center for Environmental Management, Seoul National University, Gwanak-Gu, Seoul, Korea
| | - Sanguk Kim
- Department of Life Science and School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Kyungbuk, Korea
| | - Jae Ung Jung
- Department of Molecular Microbiology and Immunology, University of Southern California School of Medicine, Los Angeles, California, United States of America
| | - Myung-Sik Choi
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
| | - Ik-Sang Kim
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
| | - Nam-Hyuk Cho
- Department of Microbiology and Immunology, College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Korea
- * E-mail:
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42
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Rubin O, Crettaz D, Canellini G, Tissot JD, Lion N. Microparticles in stored red blood cells: an approach using flow cytometry and proteomic tools. Vox Sang 2008; 95:288-97. [PMID: 19138258 DOI: 10.1111/j.1423-0410.2008.01101.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND AND OBJECTIVES Microparticles (MPs) are small phospholipid vesicles of less than 1 microm, shed in blood flow by various cell types. These MPs are involved in several biological processes and diseases. MPs have also been detected in blood products; however, their role in transfused patients is unknown. The purpose of this study was to characterize those MPs in blood bank conditions. MATERIALS AND METHODS Qualitative and quantitative experiments using flow cytometry or proteomic techniques were performed on MPs derived from erythrocytes concentrates. In order to count MPs, they were either isolated by various centrifugation procedures or counted directly in erythrocyte concentrates. RESULTS A 20-fold increase after 50 days of storage at 4 degrees C was observed (from 3370 +/- 1180 MPs/microl at day 5 to 64 850 +/- 37 800 MPs/microl at day 50). Proteomic analysis revealed changes of protein expression comparing MPs to erythrocyte membranes. Finally, the expression of Rh blood group antigens was shown on MPs generated during erythrocyte storage. CONCLUSIONS Our work provides evidence that storage of red blood cell is associated with the generation of MPs characterized by particular proteomic profiles. These results contribute to fundamental knowledge of transfused blood products.
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Affiliation(s)
- O Rubin
- Service Régional Vaudois de Transfusion Sanguine, Lausanne, Switzerland
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43
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Yokoyama H, Fujii S, Matsui I. Crystal structure of a core domain of stomatin from Pyrococcus horikoshii Illustrates a novel trimeric and coiled-coil fold. J Mol Biol 2008; 376:868-78. [PMID: 18182167 DOI: 10.1016/j.jmb.2007.12.024] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Revised: 12/06/2007] [Accepted: 12/12/2007] [Indexed: 11/19/2022]
Abstract
Stomatin is a major integral membrane protein of human erythrocytes, the absence of which is associated with a form of hemolytic anemia known as hereditary stomatocytosis. However, the function of stomatin is not fully understood. An open reading frame, PH1511, from the hyperthermophilic archaeon Pyrococcus horikoshii encodes p-stomatin, a prokaryotic stomatin. Here, we report the first crystal structure of a stomatin ortholog, the core domain of the p-stomatin PH1511p (residues 56-234 of PH1511p, designated as PhSto(CD)). PhSto(CD) forms a novel homotrimeric structure. Three alpha/beta domains form a triangle of about 50 A on each side, and three alpha-helical segments of about 60 A in length extend from the apexes of the triangle. The alpha/beta domain of PhSto(CD) is partly similar in structure to the band-7 domain of mouse flotillin-2. While the alpha/beta domain is relatively rigid, the alpha-helical segment shows conformational flexibility, adapting to the neighboring environment. One alpha-helical segment forms an anti-parallel coiled coil with another alpha-helical segment from a symmetry-related molecule. The alpha-helical segment shows a heptad repeat pattern, and mainly hydrophobic residues form a coiled-coil interface. According to chemical cross-linking experiments, PhSto(CD) would be able to assemble into an oligomeric form. The coiled-coil fold observed in the crystal probably contributes to self-association.
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Affiliation(s)
- Hideshi Yokoyama
- School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
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44
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Muenzner P, Bachmann V, Kuespert K, Hauck CR. The CEACAM1 transmembrane domain, but not the cytoplasmic domain, directs internalization of human pathogens via membrane microdomains. Cell Microbiol 2007; 10:1074-92. [PMID: 18081725 DOI: 10.1111/j.1462-5822.2007.01106.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Several bacterial pathogens exploit carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) to promote attachment and uptake into eukaryotic host cells. The widely expressed isoform CEACAM1 is involved in cell-cell adhesion, regulation of cell proliferation, insulin homeostasis, and neo-angiogenesis, processes that depend on the cytoplasmic domain of CEACAM1. By analysing the molecular requirements for CEACAM1-mediated internalization of bacteria, we surprisingly find that the CEACAM1 cytoplasmic domain is completely obsolete for bacterial uptake. Accordingly, CEACAM1-4L as well as a CEACAM1 mutant with a complete deletion of the cytoplasmic domain (CEACAM1 DeltaCT) promote equivalent internalization of several human pathogens. CEACAM1-4L- and CEACAM1 DeltaCT-mediated uptake proceeds in the presence of inhibitors of actin microfilament dynamics, which is in contrast to CEACAM3-mediated internalization. Bacteria-engaged CEACAM1-4L and CEACAM1 DeltaCT, but not CEACAM3, localize to a gangliosid GM1- and GPI-anchored protein-containing portion of the plasma membrane. In addition, interference with cholesterol-rich membrane microdomains severely blocks bacterial uptake via CEACAM1-4L and CEACAM1 DeltaCT, but not CEACAM3. Similar to GPI-anchored CEACAM6, both CEACAM1-4L as well as CEACAM1 DeltaCT partition into a low-density, Triton-insoluble membrane fraction upon receptor clustering, whereas CEACAM3 is not detected in this fraction. Bacterial uptake by truncated CEACAM1 or chimeric CEACAM1/CEACAM3 molecules reveals that the transmembrane domain of CEACAM1 is responsible for its association with membrane microdomains. Together, these data argue for a functional role of lipid rafts in CEACAM1-mediated endocytosis that is promoted by the transmembrane domain of the receptor and that might be relevant for CEACAM1 function in physiologic settings.
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Affiliation(s)
- Petra Muenzner
- Lehrstuhl für Zellbiologie, Universität Konstanz, Postfach X908, D-78457 Konstanz, Germany
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45
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Salzer U, Zhu R, Luten M, Isobe H, Pastushenko V, Perkmann T, Hinterdorfer P, Bosman GJCGM. Vesicles generated during storage of red cells are rich in the lipid raft marker stomatin. Transfusion 2007; 48:451-62. [PMID: 18067507 DOI: 10.1111/j.1537-2995.2007.01549.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The release of vesicles by red blood cells (RBCs) occurs in vivo and in vitro under various conditions. Vesiculation also takes place during RBC storage and results in the accumulation of vesicles in RBC units. The membrane protein composition of the storage-associated vesicles has not been studied in detail. The characterization of the vesicular membrane might hint at the underlying mechanism of the storage-associated changes in general and the vesiculation process in particular. STUDY DESIGN AND METHODS Vesicles from RBCs that had been stored for various periods were isolated and RBCs of the same RBC units were used to generate calcium-induced microvesicles. These two vesicle types were compared with respect to their size with atomic force microscopy, their raft protein content with detergent-resistant membrane (DRM) analysis, and their thrombogenic potential and activity with annexin V binding and thrombin generation, respectively. RESULTS The storage-associated vesicles and the calcium-induced microvesicles are similar in size, in thrombogenic activity, and in membrane protein composition. The major differences were the relative concentrations of the major integral DRM proteins. In storage-associated vesicles, stomatin is twofold enriched and flotillin-2 is threefold depleted. CONCLUSION These data indicate that a stomatin-specific, raft-based process is involved in storage-associated vesiculation. A model of the vesiculation process in RBCs is proposed considering the raft-stabilizing properties of stomatin, the low storage temperature favoring raft aggregation, and the previously reported storage-associated changes in the cytoskeletal organization.
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Affiliation(s)
- Ulrich Salzer
- Department of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria.
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46
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Tong J, Nguyen L, Vidal A, Simon SA, Skene JHP, McIntosh TJ. Role of GAP-43 in sequestering phosphatidylinositol 4,5-bisphosphate to Raft bilayers. Biophys J 2007; 94:125-33. [PMID: 17827240 PMCID: PMC2134862 DOI: 10.1529/biophysj.107.110536] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The lipid phosphatidylinositol 4,5-bisphosphate (PIP(2)) is critical for a number of physiological functions, and its presence in membrane microdomains (rafts) appears to be important for several of these spatially localized events. However, lipids like PIP(2) that contain polyunsaturated hydrocarbon chains are usually excluded from rafts, which are enriched in phospholipids (such as sphingomyelin) containing saturated or monounsaturated chains. Here we tested a mechanism by which multivalent PIP(2) molecules could be transferred into rafts through electrostatic interactions with polybasic cytoplasmic proteins, such as GAP-43, which bind to rafts via their acylated N-termini. We analyzed the interactions between lipid membranes containing raft microdomains and a peptide (GAP-43P) containing the linked N-terminus and the basic effector domain of GAP-43. In the absence or presence of nonacylated GAP-43P, PIP(2) was found primarily in detergent-soluble membranes thought to correspond to nonraft microdomains. However, when GAP-43P was acylated by palmitoyl coenzyme A, both the peptide and PIP(2) were greatly enriched in detergent-resistant membranes that correspond to rafts; acylation of GAP-43P changed the free energy of transfer of PIP(2) from detergent-soluble membranes to detergent-resistant membranes by -1.3 kcal/mol. Confocal microscopy of intact giant unilamellar vesicles verified that in the absence of GAP-43P PIP(2) was in nonraft microdomains, whereas acylated GAP-43P laterally sequestered PIP(2) into rafts. These data indicate that sequestration of PIP(2) to raft microdomains could involve interactions with acylated basic proteins such as GAP-43.
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Affiliation(s)
- Jihong Tong
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA
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47
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Babuke T, Tikkanen R. Dissecting the molecular function of reggie/flotillin proteins. Eur J Cell Biol 2007; 86:525-32. [PMID: 17482313 DOI: 10.1016/j.ejcb.2007.03.003] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Revised: 03/19/2007] [Accepted: 03/20/2007] [Indexed: 12/11/2022] Open
Abstract
Reggie-1/flotillin-2 and reggie-2/flotillin-1 are ubiquitously expressed, well-conserved proteins that are associated with membrane microdomains known as rafts. Studies from us and others have suggested a role in various cellular processes such as insulin signaling, T cell activation, membrane trafficking, phagocytosis, and epidermal growth factor receptor signaling. Recent findings also demonstrate that reggie-1 is associated with cell motility and transformation. However, the exact function of reggie proteins remains to be clarified. In this review, we will focus on some recent findings that have shed new light on the elusive molecular function of these highly interesting proteins. We will especially discuss the emerging role of reggie proteins in membrane receptor signaling and membrane trafficking, with emphasis on the regulation of the molecular function of reggies by post-translational modifications such as phosphorylation and lipid modifications.
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Affiliation(s)
- Tanja Babuke
- Institute of Biochemistry II and Cluster of Excellence Frankfurt Macromolecular Complexes, University Clinic of Frankfurt am Main, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
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48
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Browman DT, Hoegg MB, Robbins SM. The SPFH domain-containing proteins: more than lipid raft markers. Trends Cell Biol 2007; 17:394-402. [PMID: 17766116 DOI: 10.1016/j.tcb.2007.06.005] [Citation(s) in RCA: 259] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 06/06/2007] [Accepted: 06/06/2007] [Indexed: 01/03/2023]
Abstract
Membrane microdomains with distinct lipid compositions, called lipid rafts, represent a potential mechanism for compartmentalizing cellular functions within the plane of biological membranes. SPFH domain-containing proteins are found in lipid raft microdomains in diverse cellular membranes. The functions of these proteins are just beginning to be elucidated. Recent advances in the understanding of structural features and their roles within lipid rafts include a potential function for SPFH proteins in the formation of membrane microdomains and lipid raft-associated processes, such as endocytosis and mechanosensation.
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Affiliation(s)
- Duncan T Browman
- Southern Alberta Cancer Research Institute, Department of Oncology, University of Calgary, Calgary, AB, T2N 4N1, Canada
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49
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Pearce MMP, Wang Y, Kelley GG, Wojcikiewicz RJH. SPFH2 Mediates the Endoplasmic Reticulum-associated Degradation of Inositol 1,4,5-Trisphosphate Receptors and Other Substrates in Mammalian Cells. J Biol Chem 2007; 282:20104-15. [PMID: 17502376 DOI: 10.1074/jbc.m701862200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,4,5-trisphosphate (IP(3)) receptors are endoplasmic reticulum (ER) membrane calcium channels that, upon activation, become substrates for the ER-associated degradation (ERAD) pathway. Although it is clear that IP(3) receptors are polyubiquitinated upon activation and are transferred to the proteasome by a p97-based complex, currently nothing is known about the proteins that initially select activated IP(3) receptors for ERAD. Here, we sought to identify novel proteins that associate with and mediate the ERAD of endogenous activated IP(3) receptors. SPFH2, an uncharacterized SPFH domain-containing protein, rapidly associated with IP(3) receptors in a manner that preceded significant polyubiquitination and the association of p97 and related proteins. SPFH2 was found to be an ER membrane protein largely residing within the ER lumen and in resting and stimulated cells was linked to ERAD pathway components, apparently via endogenous substrates undergoing degradation. Suppression of SPFH2 expression by RNA interference markedly inhibited IP(3) receptor polyubiquitination and degradation and the processing of other ERAD substrates. Overall, these studies identify SPFH2 as a key ERAD pathway component and suggest that it may act as a substrate recognition factor.
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Affiliation(s)
- Margaret M P Pearce
- Departments of Pharmacology and Medicine, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
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50
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Huber TB, Schermer B, Müller RU, Höhne M, Bartram M, Calixto A, Hagmann H, Reinhardt C, Koos F, Kunzelmann K, Shirokova E, Krautwurst D, Harteneck C, Simons M, Pavenstädt H, Kerjaschki D, Thiele C, Walz G, Chalfie M, Benzing T. Podocin and MEC-2 bind cholesterol to regulate the activity of associated ion channels. Proc Natl Acad Sci U S A 2006; 103:17079-86. [PMID: 17079490 PMCID: PMC1859892 DOI: 10.1073/pnas.0607465103] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The prohibitin (PHB)-domain proteins are membrane proteins that regulate a variety of biological activities, including mechanosensation, osmotic homeostasis, and cell signaling, although the mechanism of this regulation is unknown. We have studied two members of this large protein family, MEC-2, which is needed for touch sensitivity in Caenorhabditis elegans, and Podocin, a protein involved in the function of the filtration barrier in the mammalian kidney, and find that both proteins bind cholesterol. This binding requires the PHB domain (including palmitoylation sites within it) and part of the N-terminally adjacent hydrophobic domain that attaches the proteins to the inner leaflet of the plasma membrane. By binding to MEC-2 and Podocin, cholesterol associates with ion-channel complexes to which these proteins bind: DEG/ENaC channels for MEC-2 and TRPC channels for Podocin. Both the MEC-2-dependent activation of mechanosensation and the Podocin-dependent activation of TRPC channels require cholesterol. Thus, MEC-2, Podocin, and probably many other PHB-domain proteins by binding to themselves, cholesterol, and target proteins regulate the formation and function of large protein-cholesterol supercomplexes in the plasma membrane.
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Affiliation(s)
- Tobias B. Huber
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Bernhard Schermer
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | | | - Martin Höhne
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Malte Bartram
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Andrea Calixto
- Department of Biological Sciences, Columbia University, New York, NY 10027-6902
| | - Henning Hagmann
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Christian Reinhardt
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
- University Hospital Münster, D-48129 Münster, Germany
| | - Fabienne Koos
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, 93053 Regensburg, Germany
| | - Elena Shirokova
- Department of Molecular Genetics, German Institute of Human Nutrition, 14558 Nuthetal, Germany
| | - Dietmar Krautwurst
- Department of Molecular Genetics, German Institute of Human Nutrition, 14558 Nuthetal, Germany
| | | | - Matias Simons
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | | | - Dontscho Kerjaschki
- **Department of Pathology, University of Vienna, A-1010 Vienna, Austria; and
| | - Christoph Thiele
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Gerd Walz
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Martin Chalfie
- Department of Biological Sciences, Columbia University, New York, NY 10027-6902
- To whom correspondence may be addressed at:
Department of Biological Sciences, Columbia University, 1012 Fairchild Center, M.C. 2446 New York, NY 10027. E-mail:
| | - Thomas Benzing
- *Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
- To whom correspondence may be addressed at:
Renal Division, University Hospital Freiburg, Hugstetterstrasse 55, 79106 Freiburg, Germany. E-mail:
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