1
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Schiffmann A, Ahlswede L, Gimpl G. Reversible translocation of acyl-CoA:cholesterol acyltransferase (ACAT) between the endoplasmic reticulum and vesicular structures. Front Mol Biosci 2023; 10:1258799. [PMID: 38028547 PMCID: PMC10667705 DOI: 10.3389/fmolb.2023.1258799] [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] [Received: 07/14/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023] Open
Abstract
The enzyme acyl-CoA:cholesterol acyltransferase (ACAT) is normally localized in the endoplasmic reticulum (ER) where it can esterify cholesterol for storage in lipid droplets and/or the formation of lipoproteins. Here, we report that ACAT can translocate from the ER into vesicular structures in response to different ACAT inhibitors. The translocation was fast (within minutes), reversible and occurred in different cell types. Interestingly, oleic acid was able to fasten the re-translocation from vesicles back into the reticular ER network. The process of ACAT translocation could also be induced by cyclodextrins, cholesterol, lanosterol (but not 4-cholestene-3 one), 25-hydroxycholesterol, and by certain stress stimuli such as hyperosmolarity (sucrose treatment), temperature change, or high-density cultivation. In vitro esterification showed that ACAT remains fully active after it has been translocated to vesicles in response to hyperosmotic sucrose treatment of the cells. The translocation process was not accompanied by changes in the electrophoretic mobility of ACAT, even after chemical crosslinking. Interestingly, the protein synthesis inhibitor cycloheximide showed a stimulating effect on ACAT activity and prevented the translocation of ACAT from the ER into vesicles.
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Affiliation(s)
| | | | - Gerald Gimpl
- Department of Chemistry and Biochemistry, Biocenter II, Johannes Gutenberg University Mainz, Mainz, Germany
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2
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Anwar MU, Sergeeva OA, Abrami L, Mesquita FS, Lukonin I, Amen T, Chuat A, Capolupo L, Liberali P, D'Angelo G, van der Goot FG. ER-Golgi-localized proteins TMED2 and TMED10 control the formation of plasma membrane lipid nanodomains. Dev Cell 2022; 57:2334-2346.e8. [PMID: 36174556 DOI: 10.1016/j.devcel.2022.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/24/2022] [Accepted: 09/08/2022] [Indexed: 11/03/2022]
Abstract
To promote infections, pathogens exploit host cell machineries such as structural elements of the plasma membrane. Studying these interactions and identifying molecular players are ideal for gaining insights into the fundamental biology of the host cell. Here, we used the anthrax toxin to screen a library of 1,500 regulatory, cell-surface, and membrane trafficking genes for their involvement in the intoxication process. We found that endoplasmic reticulum (ER)-Golgi-localized proteins TMED2 and TMED10 are required for toxin oligomerization at the plasma membrane of human cells, an essential step dependent on localization to cholesterol-rich lipid nanodomains. Biochemical, morphological, and mechanistic analyses showed that TMED2 and TMED10 are essential components of a supercomplex that operates the exchange of both cholesterol and ceramides at ER-Golgi membrane contact sites. Overall, this study of anthrax intoxication led to the discovery that lipid compositional remodeling at ER-Golgi interfaces fully controls the formation of functional membrane nanodomains at the cell surface.
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Affiliation(s)
- Muhammad U Anwar
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Oksana A Sergeeva
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Laurence Abrami
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Francisco S Mesquita
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Ilya Lukonin
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland
| | - Triana Amen
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Audrey Chuat
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Laura Capolupo
- Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Prisca Liberali
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland
| | - Giovanni D'Angelo
- Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
| | - F Gisou van der Goot
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
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3
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Uchida K, Obayashi H, Minamihata K, Wakabayashi R, Goto M, Shimokawa N, Takagi M, Kamiya N. Artificial Palmitoylation of Proteins Controls the Lipid Domain-Selective Anchoring on Biomembranes and the Raft-Dependent Cellular Internalization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9640-9648. [PMID: 35882009 DOI: 10.1021/acs.langmuir.2c01205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Protein palmitoylation, a post-translational modification, is universally observed in eukaryotic cells. The localization of palmitoylated proteins to highly dynamic, sphingolipid- and cholesterol-rich microdomains (called lipid rafts) on the plasma membrane has been shown to play an important role in signal transduction in cells. However, this complex biological system is not yet completely understood. Here, we used a combined approach where an artificial lipidated protein was applied to biomimetic model membranes and plasma membranes in cells to illuminate chemical and physiological properties of the rafts. Using cell-sized giant unilamellar vesicles, we demonstrated the selective partitioning of enhanced green fluorescent protein modified with a C-terminal palmitoyl moiety (EGFP-Pal) into the liquid-ordered phase consisting of saturated phospholipids and cholesterol. Using Jurkat T cells treated with an immunostimulant (concanavalin A), we observed the vesicular transport of EGFP-Pal. Further cellular studies with the treatment of methyl β-cyclodextrin revealed the cholesterol-dependent internalization of EGFP-Pal, which can be explained by a raft-dependent, caveolae-mediated endocytic pathway. The present synthetic approach using artificial and natural membrane systems can be further extended to explore the potential utility of artificially lipidated proteins at biological and artificial interfaces.
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Affiliation(s)
- Kazuki Uchida
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Hiroki Obayashi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Kosuke Minamihata
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Rie Wakabayashi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Masahiro Goto
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- Division of Biotechnology, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Naofumi Shimokawa
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Masahiro Takagi
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Noriho Kamiya
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- Division of Biotechnology, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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4
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Yamaji-Hasegawa A, Murate M, Inaba T, Dohmae N, Sato M, Fujimori F, Sako Y, Greimel P, Kobayashi T. A novel sterol-binding protein reveals heterogeneous cholesterol distribution in neurite outgrowth and in late endosomes/lysosomes. Cell Mol Life Sci 2022; 79:324. [PMID: 35644822 PMCID: PMC11072113 DOI: 10.1007/s00018-022-04339-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 04/26/2022] [Accepted: 04/29/2022] [Indexed: 11/24/2022]
Abstract
We identified a mushroom-derived protein, maistero-2 that specifically binds 3-hydroxy sterol including cholesterol (Chol). Maistero-2 bound lipid mixture in Chol-dependent manner with a binding threshold of around 30%. Changing lipid composition did not significantly affect the threshold concentration. EGFP-maistero-2 labeled cell surface and intracellular organelle Chol with higher sensitivity than that of well-established Chol probe, D4 fragment of perfringolysin O. EGFP-maistero-2 revealed increase of cell surface Chol during neurite outgrowth and heterogeneous Chol distribution between CD63-positive and LAMP1-positive late endosomes/lysosomes. The absence of strictly conserved Thr-Leu pair present in Chol-dependent cytolysins suggests a distinct Chol-binding mechanism for maistero-2.
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Affiliation(s)
| | - Motohide Murate
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- UMR 7021, CNRS, Université de Strasbourg, 67401, Illkirch, France
| | - Takehiko Inaba
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN CSRS, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Masayuki Sato
- Yukiguni Maitake Co, Ltd. Yokawa 89, Minamiuonuma, Niigata, 949-6695, Japan
| | - Fumihiro Fujimori
- Laboratory of Biological Science and Technology, Tokyo Kasei University, 1-18-1 Kaga, Itabashi, Tokyo, 173-8062, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Peter Greimel
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
- UMR 7021, CNRS, Université de Strasbourg, 67401, Illkirch, France.
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5
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Wei R, Sugiyama A, Sato Y, Nozumi M, Nishino H, Takahashi M, Saito T, Ando K, Fukuda M, Tomomura M, Igarashi M, Hisanaga SI. Isoform-dependent subcellular localization of LMTK1A and LMTK1B and their roles in axon outgrowth and spine formation. J Biochem 2021; 168:23-32. [PMID: 32044995 DOI: 10.1093/jb/mvaa019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 01/29/2020] [Indexed: 12/13/2022] Open
Abstract
Lemur kinase 1 (LMTK1) is a membrane-bound Ser/Thr kinase that is expressed in neurons. There are two splicing variants of LMTK1 with different membrane binding modes, viz., cytosolic LMTK1A that binds to membranes through palmitoylation at the N-terminal cysteines and LMTK1B, an integral membrane protein with transmembrane sequences. We recently reported that LMTK1A regulates axon outgrowth and spine formation in neurons. However, data about LMTK1B are scarce. We analysed the expression and cellular localization of LMTK1B along with its role in axon and spine formation. We found that both LMTK1B and LMTK1A were expressed equally in the cerebral cortex and cerebellum of the mouse brain. Similar to LMTK1A, the wild type of LMTK1B was localized to Rab11-positive pericentrosomal compartment. The kinase negative (kn) mutant of LMTK1B was found to be associated with an increase in the tubular form of endoplasmic reticulum (ER), which was not the case with LMTK1A kn. Furthermore, unlike LMTK1A kn, LMTK1B kn did not stimulate the axon outgrowth and spine formation. These results suggest that while LMTK1A and LMTK1B share a common function in recycling endosomal trafficking at the pericentrosomal compartment, LMTK1B has an additional unique function in vesicle transport in the ER region.
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Affiliation(s)
- Ran Wei
- Department of Biological Sciences, Faculty of Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Arika Sugiyama
- Department of Biological Sciences, Faculty of Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Yuta Sato
- Department of Neurochemistry and Molecular Cell Biology, Graduate School of Medical and Dental Sciences, Niigata University, Asahimachi, Chuo-ku, Niigata 951-8510, Japan
| | - Motohiro Nozumi
- Department of Neurochemistry and Molecular Cell Biology, Graduate School of Medical and Dental Sciences, Niigata University, Asahimachi, Chuo-ku, Niigata 951-8510, Japan
| | - Hironori Nishino
- Department of Biological Sciences, Faculty of Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Miyuki Takahashi
- Miyuki Takahashi, Department of Life Science and Medical Bioscience, Laboratory for Molecular Brain Science, Waseda University, Tokyo 162-8480
| | - Taro Saito
- Department of Biological Sciences, Faculty of Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Kanae Ando
- Department of Biological Sciences, Faculty of Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Mitsunori Fukuda
- Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Mineko Tomomura
- Department of Oral Health Sciences, Meikai University School of Health Sciences, Urayasu, Chiba 279-9950, Japan
| | - Michihiro Igarashi
- Department of Neurochemistry and Molecular Cell Biology, Graduate School of Medical and Dental Sciences, Niigata University, Asahimachi, Chuo-ku, Niigata 951-8510, Japan
| | - Shin-Ichi Hisanaga
- Department of Biological Sciences, Faculty of Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
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6
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Zulkefli KL, Mahmoud IS, Williamson NA, Gosavi PK, Houghton FJ, Gleeson PA. A role for Rab30 in retrograde trafficking and maintenance of endosome-TGN organization. Exp Cell Res 2021; 399:112442. [PMID: 33359467 DOI: 10.1016/j.yexcr.2020.112442] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/09/2020] [Accepted: 12/12/2020] [Indexed: 10/22/2022]
Abstract
Rab30 is a poorly characterized small GTPase. Here we show that Rab30 is localised primarily to the TGN and recycling endosomes in a range of cell types, including primary neurons; minor levels of Rab30 were also detected throughout the Golgi stack and early endosomes. Silencing of Rab30 resulted in the dispersal of both early and recycling endosomes and TGN compartments in HeLa cells. By analyzing cargo trafficking in Rab30-silenced and Rab30-overexpressing HeLa cells, we demonstrate that Rab30 plays a role in retrograde trafficking of TGN38 from endosomes to the Golgi, but has no apparent role in the endocytic recycling of the transferrin receptor to the plasma membrane. Five interactive partners with Rab30 were identified by pull-down and MS analysis using GFP-tagged Rab30 mutant, Rab30(Q68L). Two of the interactive partners identified were Arf1 and Arf4, known regulators of endosome to TGN retrograde transport. Knockdown of Arf1 and Arf4 results in GFP-Rab30 decorated tubules arising from the recycling endosomes, suggesting association of Rab30 with tubular carriers. Overall our data demonstrates a role for Rab30 in regulating retrograde transport to the TGN and maintenance of endosomal-TGN organization.
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Affiliation(s)
- Khalisah L Zulkefli
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia
| | - Ismail S Mahmoud
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia
| | - Nicholas A Williamson
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia; The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia
| | - Prajakta Kulkarni Gosavi
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia
| | - Fiona J Houghton
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia
| | - Paul A Gleeson
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia.
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7
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Huber K, Mestres-Arenas A, Fajas L, Leal-Esteban LC. The multifaceted role of cell cycle regulators in the coordination of growth and metabolism. FEBS J 2020; 288:3813-3833. [PMID: 33030287 PMCID: PMC8359344 DOI: 10.1111/febs.15586] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/08/2020] [Accepted: 10/05/2020] [Indexed: 12/15/2022]
Abstract
Adapting to changes in nutrient availability and environmental conditions is a fundamental property of cells. This adaptation requires a multi‐directional coordination between metabolism, growth, and the cell cycle regulators (consisting of the family of cyclin‐dependent kinases (CDKs), their regulatory subunits known as cyclins, CDK inhibitors, the retinoblastoma family members, and the E2F transcription factors). Deciphering the mechanisms accountable for this coordination is crucial for understanding various patho‐physiological processes. While it is well established that metabolism and growth affect cell division, this review will focus on recent observations that demonstrate how cell cycle regulators coordinate metabolism, cell cycle progression, and growth. We will discuss how the cell cycle regulators directly regulate metabolic enzymes and pathways and summarize their involvement in the endolysosomal pathway and in the functions and dynamics of mitochondria.
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Affiliation(s)
- Katharina Huber
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | | | - Lluis Fajas
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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8
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Samarelli AV, Ziegler T, Meves A, Fässler R, Böttcher RT. Rabgap1 promotes recycling of active β1 integrins to support effective cell migration. J Cell Sci 2020; 133:jcs243683. [PMID: 32843574 PMCID: PMC7522031 DOI: 10.1242/jcs.243683] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 08/13/2020] [Indexed: 12/13/2022] Open
Abstract
Integrin function depends on the continuous internalization of integrins and their subsequent endosomal recycling to the plasma membrane to drive adhesion dynamics, cell migration and invasion. Here we assign a pivotal role for Rabgap1 (GAPCenA) in the recycling of endocytosed active β1 integrins to the plasma membrane. The phosphotyrosine-binding (PTB) domain of Rabgap1 binds to the membrane-proximal NPxY motif in the cytoplasmic domain of β1 integrin subunits on endosomes. Silencing Rabgap1 in mouse fibroblasts leads to the intracellular accumulation of active β1 integrins, alters focal adhesion formation, and decreases cell migration and cancer cell invasion. Functionally, Rabgap1 facilitates active β1 integrin recycling to the plasma membrane through attenuation of Rab11 activity. Taken together, our results identify Rabgap1 as an important factor for conformation-specific integrin trafficking and define the role of Rabgap1 in β1-integrin-mediated cell migration in mouse fibroblasts and breast cancer cells.
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Affiliation(s)
- Anna V Samarelli
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
| | - Tilman Ziegler
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
| | - Alexander Meves
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
- Department of Dermatology, Mayo Clinic, Rochester, MN 55905, USA
| | - Reinhard Fässler
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
| | - Ralph T Böttcher
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, 82152 Martinsried, Germany
- DZHK - German Centre for Cardiovascular Research, partner site Munich Heart Alliance, 80802 Munich, Germany
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9
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Kishimoto T, Tomishige N, Murate M, Ishitsuka R, Schaller H, Mély Y, Ueda K, Kobayashi T. Cholesterol asymmetry at the tip of filopodia during cell adhesion. FASEB J 2020; 34:6185-6197. [PMID: 32162745 DOI: 10.1096/fj.201900065rr] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/26/2020] [Accepted: 02/26/2020] [Indexed: 12/28/2022]
Abstract
During adhesion, cells develop filopodia to facilitate the attachment to the extracellular matrix. The small guanosine triphosphate (GTP)-binding protein, Cdc42, plays a central role in the formation of filopodia. It has been reported that Cdc42 activity is regulated by cholesterol (Chol). We examined Chol distribution in filopodia using Chol-binding domain 4 (D4) fragment of bacterial toxin, perfringolysin O that senses high membrane concentration of Chol. Our results indicate that fluorescent D4 was enriched at the tip of the outer leaflet of filopodia in the initiation phase of cell adhesion. This enrichment was accompanied by a defect of D4 labeling in the inner leaflet. Steady phase adhered cell experiment indicated that both Cdc42 and ATP-binding cassette transporter, ABCA1, were involved in the binding of D4 to the cell surface. Depletion of Chol activated Cdc42. Our results suggest that asymmetric distribution of Chol at the tip of filopodia induces activation of Cdc42, and thus, facilitates filopodia formation.
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Affiliation(s)
- Takuma Kishimoto
- Lipid Biology Laboratory, RIKEN, Saitama, Japan.,Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Sapporo, Japan
| | - Nario Tomishige
- Lipid Biology Laboratory, RIKEN, Saitama, Japan.,UMR 7021 CNRS, Université de Strasbourg, Illkirch, France
| | - Motohide Murate
- Lipid Biology Laboratory, RIKEN, Saitama, Japan.,UMR 7021 CNRS, Université de Strasbourg, Illkirch, France
| | | | - Hubert Schaller
- Institut de Biologie Moléculaire des Plantes, UPR 2357, CNRS, Université de Strasbourg, Strasbourg, France
| | - Yves Mély
- UMR 7021 CNRS, Université de Strasbourg, Illkirch, France
| | - Kazumitsu Ueda
- Division of Applied Life Sciences, Graduate School of Agriculture, Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Saitama, Japan.,UMR 7021 CNRS, Université de Strasbourg, Illkirch, France
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10
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Wanikawa M, Nakamura H, Emori S, Hashimoto N, Murayama T. Accumulation of sphingomyelin in Niemann‐Pick disease type C cells disrupts Rab9‐dependent vesicular trafficking of cholesterol. J Cell Physiol 2019; 235:2300-2309. [DOI: 10.1002/jcp.29137] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 08/23/2019] [Indexed: 01/19/2023]
Affiliation(s)
- Masahiro Wanikawa
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences Chiba University Chuo‐ku Chiba Japan
| | - Hiroyuki Nakamura
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences Chiba University Chuo‐ku Chiba Japan
| | - Shunsuke Emori
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences Chiba University Chuo‐ku Chiba Japan
| | - Naohiro Hashimoto
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences Chiba University Chuo‐ku Chiba Japan
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences Chiba University Chuo‐ku Chiba Japan
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11
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Raft-dependent endocytic movement and intracellular cluster formation during T cell activation triggered by concanavalin A. J Biosci Bioeng 2017; 124:685-693. [PMID: 28711300 DOI: 10.1016/j.jbiosc.2017.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 06/22/2017] [Accepted: 06/23/2017] [Indexed: 01/10/2023]
Abstract
Certain food ingredients can stimulate the human immune system. A lectin, concanavalin A (ConA), from Canavalia ensiformis (jack bean) is one of the most well-known food-derived immunostimulants and mediates activation of cell-mediated immunity through T cell proliferation. Generally, T cell activation is known to be triggered by the interaction between T cells and antigen-presenting cells (APCs) via a juxtacrine (contact-dependent) signaling pathway. The mechanism has been well characterized and is referred to as formation of the immunological synapse (IS). We were interested in the mechanism behind the T cell activation by food-derived ConA which might be different from that of T cell activation by APCs. The purpose of this study was to characterize T cell activation by ConA with regard to (i) movement of raft domain, (ii) endocytic vesicular transport, (iii) the cytoskeleton (actin and microtubules), and (iv) cholesterol composition. We found that raft-dependent endocytic movement was important for T cell activation by ConA and this movement was dependent on actin, microtubules, and cholesterol. The T cell signaling mechanism triggered by ConA can be defined as endocrine signaling which is distinct from the activation process triggered by interaction between T cells and APCs by juxtacrine signaling. Therefore, we hypothesized that T cell activation by ConA includes both two-dimensional superficial raft movement on the membrane surface along actin filaments and three-dimensional endocytic movement toward the inside of the cell along microtubules. These findings are important for developing new methods for immune stimulation and cancer therapy based on the function of ConA.
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12
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Bajimaya S, Hayashi T, Frankl T, Bryk P, Ward B, Takimoto T. Cholesterol reducing agents inhibit assembly of type I parainfluenza viruses. Virology 2016; 501:127-135. [PMID: 27915128 DOI: 10.1016/j.virol.2016.11.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/15/2016] [Accepted: 11/18/2016] [Indexed: 11/18/2022]
Abstract
Many enveloped RNA viruses utilize lipid rafts for the assembly of progeny virions, but the role of cholesterol, a major component of rafts, on paramyxovirus budding and virion formation is controversial. In this study, we analyzed the effects of FDA-approved cholesterol-reducing agents, gemfibrozil and lovastatin, on raft formation and assembly of human parainfluenza virus type 1 (hPIV1) and Sendai virus (SeV). Treatment of the human airway epithelial A549 cells with the agents, especially when combined, significantly decreased production of infectious hPIV1 and SeV. Mechanistic analysis indicated that depletion of cellular cholesterol reduced cell surface accumulation of envelope glycoproteins and association of viral matrix and nucleocapsids with raft membrane, which resulted in impaired virus budding and release from the cells. These results indicate that cellular cholesterol is required for assembly and formation of type 1 parainfluenza viruses and suggest that cholesterol could be an attractive target for antiviral agents against hPIV1.
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Affiliation(s)
- Shringkhala Bajimaya
- Department of Microbiology and Immunology, University of Rochester Medical Center, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Tsuyoshi Hayashi
- Department of Microbiology and Immunology, University of Rochester Medical Center, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Tünde Frankl
- Department of Microbiology and Immunology, University of Rochester Medical Center, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Peter Bryk
- Department of Microbiology and Immunology, University of Rochester Medical Center, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Brian Ward
- Department of Microbiology and Immunology, University of Rochester Medical Center, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Toru Takimoto
- Department of Microbiology and Immunology, University of Rochester Medical Center, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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13
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Woodruff G, Reyna SM, Dunlap M, Van Der Kant R, Callender JA, Young JE, Roberts EA, Goldstein LSB. Defective Transcytosis of APP and Lipoproteins in Human iPSC-Derived Neurons with Familial Alzheimer's Disease Mutations. Cell Rep 2016; 17:759-773. [PMID: 27732852 PMCID: PMC5796664 DOI: 10.1016/j.celrep.2016.09.034] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 07/22/2016] [Accepted: 09/12/2016] [Indexed: 12/16/2022] Open
Abstract
We investigated early phenotypes caused by familial Alzheimer's disease (fAD) mutations in isogenic human iPSC-derived neurons. Analysis of neurons carrying fAD PS1 or APP mutations introduced using genome editing technology at the endogenous loci revealed that fAD mutant neurons had previously unreported defects in the recycling state of endocytosis and soma-to-axon transcytosis of APP and lipoproteins. The endocytosis reduction could be rescued through treatment with a β-secretase inhibitor. Our data suggest that accumulation of β-CTFs of APP, but not Aβ, slow vesicle formation from an endocytic recycling compartment marked by the transcytotic GTPase Rab11. We confirm previous results that endocytosis is affected in AD and extend these to uncover a neuron-specific defect. Decreased lipoprotein endocytosis and transcytosis to the axon suggest that a neuron-specific impairment in endocytic axonal delivery of lipoproteins and other key materials might compromise synaptic maintenance in fAD.
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Affiliation(s)
- Grace Woodruff
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sol M Reyna
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Mariah Dunlap
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Rik Van Der Kant
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Julia A Callender
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jessica E Young
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Elizabeth A Roberts
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA; Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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14
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Sharma G, Tsutsumi K, Saito T, Asada A, Ando K, Tomomura M, Hisanaga SI. Kinase activity of endosomal kinase LMTK1A regulates its cellular localization and interactions with cytoskeletons. Genes Cells 2016; 21:1080-1094. [PMID: 27600567 DOI: 10.1111/gtc.12404] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/31/2016] [Indexed: 01/07/2023]
Abstract
Neurite formation, a fundamental process in neuronal maturation, requires the coordinated regulation of cytoskeletal reorganization and membrane transport. Compared to the understanding of cytoskeletal functions, less is known about the supply of membranes to growing neurites. Lemur kinase 1A (LMTK1A) is an endosomal protein kinase that is highly expressed in neurons. We recently reported that LMTK1A regulates the trafficking of Rab11-positive recycling endosomes in growing axons and dendrites. Here, we used the kinase-negative (kn) mutant to investigate the role of the kinase activity of LMTK1A in its cellular localization and interactions with the cytoskeleton in Neuro2A and PC-12 cells. Kinase activity was required for the localization of LMTK1A in the perinuclear endocytic recycling compartment. Perinuclear accumulation was microtubule dependent, and LMTK1A wild type (wt) localized mainly on microtubules, whereas kn LMTK1A was found in the actin-rich cell periphery. In the neurites of PC-12 cells, LMTK1A showed contrasting distributions depending on the kinase activity, with wt being located in the microtubule-rich shaft and the kn form in the actin-rich tip. Taken together, these results suggest that the kinase activity of LMTK1A regulates the pathway for endosomal vesicles to transfer from microtubules to actin filaments at the tip of growing neurites.
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Affiliation(s)
- Govinda Sharma
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Koji Tsutsumi
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Taro Saito
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Akiko Asada
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Kanae Ando
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Mineko Tomomura
- Integral Education Center, Meikai University, Urayasu, Chiba, 279-9950, Japan
| | - Shin-Ichi Hisanaga
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan.
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15
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Makino A, Hullin-Matsuda F, Murate M, Abe M, Tomishige N, Fukuda M, Yamashita S, Fujimoto T, Vidal H, Lagarde M, Delton I, Kobayashi T. Acute accumulation of free cholesterol induces the degradation of perilipin 2 and Rab18-dependent fusion of ER and lipid droplets in cultured human hepatocytes. Mol Biol Cell 2016; 27:3293-3304. [PMID: 27582390 PMCID: PMC5170862 DOI: 10.1091/mbc.e15-10-0730] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 08/26/2016] [Indexed: 01/19/2023] Open
Abstract
Free cholesterol accumulation in the liver is relevant to the pathogenesis of nonalcoholic steatohepatitis. Acute free cholesterol accumulation induced the fusion of LDs, followed by degradation of the coat protein of LDs, perilipin 2, and association of apolipoprotein 100 to LDs in Rab18-dependent manner. Dysregulated hepatic cholesterol homeostasis with free cholesterol accumulation in the liver is relevant to the pathogenesis of nonalcoholic steatohepatitis, contributing to the chronicity of liver toxicity. Here we examined the effect of free cholesterol accumulation on the morphology and biochemical properties of lipid droplets (LDs) in cultured hepatocytes. Acute free cholesterol accumulation induced the fusion of LDs, followed by degradation of the coat protein of LDs, perilipin 2 (PLIN2; also called adipophilin or adipose differentiation–related protein), and association of apolipoprotein B 100 (ApoB 100) to LDs. The degradation of PLIN2 was inhibited by inhibitors of ubiquitination, autophagy, and protein synthesis. The results indicate that association of ApoB 100 with LDs is dependent on the activity of low–molecular weight GTP-binding protein Rab18 and highlight the role of LDs as targets of free cholesterol toxicity in hepatocytes.
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Affiliation(s)
- Asami Makino
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France.,Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan
| | - Françoise Hullin-Matsuda
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France.,Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan
| | | | - Mitsuhiro Abe
- Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan
| | | | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Shizuya Yamashita
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Toyoshi Fujimoto
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Hubert Vidal
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France
| | - Michel Lagarde
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France
| | - Isabelle Delton
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France.,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France
| | - Toshihide Kobayashi
- INSERM-RIKEN Lipidomics Unit, Université Lyon 1, 69621 Villeurbanne, France .,INSERM U1060, INSA-Lyon, Université Lyon 1, 69621 Villeurbanne, France.,Lipid Biology Laboratory, RIKEN, Wako 351-0198, Japan.,UMR 7213 CNRS, University of Strasbourg, 67401 Illkirch, France
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16
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Vale-Costa S, Amorim MJ. Clustering of Rab11 vesicles in influenza A virus infected cells creates hotspots containing the 8 viral ribonucleoproteins. Small GTPases 2016; 8:71-77. [PMID: 27337591 PMCID: PMC5464114 DOI: 10.1080/21541248.2016.1199190] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Influenza A virus is an important human pathogen causative of yearly epidemics and occasional pandemics. The ability to replicate within the host cell is a determinant of virulence, amplifying viral numbers for host-to-host transmission. This process requires multiple rounds of entering permissive cells, replication, and virion assembly at the plasma membrane, the site of viral budding and release. The assembly of influenza A virus involves packaging of several viral (and host) proteins and of a segmented genome, composed of 8 distinct RNAs in the form of viral ribonucleoproteins (vRNPs). The selective assembly of the 8-segment core remains one of the most interesting unresolved problems in virology. The recycling endosome regulatory GTPase Rab11 was shown to contribute to the process, by transporting vRNPs to the periphery, giving rise to enlarged cytosolic puncta rich in Rab11 and the 8 vRNPs. We recently reported that vRNP hotspots were formed of clustered vesicles harbouring protruding electron-dense structures that resembled vRNPs. Mechanistically, vRNP hotspots were formed as vRNPs outcompeted the cognate effectors of Rab11, the Rab11-Family-Interacting-Proteins (FIPs) for binding, and as a consequence impair recycling sorting at an unknown step. Here, we speculate on the impact that such impairment might have in host immunity, membrane architecture and viral assembly.
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Affiliation(s)
- Sílvia Vale-Costa
- a Cell Biology of Viral Infection Lab , Instituto Gulbenkian de Ciência , Oeiras , Portugal
| | - Maria João Amorim
- a Cell Biology of Viral Infection Lab , Instituto Gulbenkian de Ciência , Oeiras , Portugal
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17
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Kishimoto T, Ishitsuka R, Kobayashi T. Detectors for evaluating the cellular landscape of sphingomyelin- and cholesterol-rich membrane domains. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:812-829. [PMID: 26993577 DOI: 10.1016/j.bbalip.2016.03.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/09/2016] [Accepted: 03/09/2016] [Indexed: 12/11/2022]
Abstract
Although sphingomyelin and cholesterol are major lipids of mammalian cells, the detailed distribution of these lipids in cellular membranes remains still obscure. However, the recent development of protein probes that specifically bind sphingomyelin and/or cholesterol provides new information about the landscape of the lipid domains that are enriched with sphingomyelin or cholesterol or both. Here, we critically summarize the tools to study distribution and dynamics of sphingomyelin and cholesterol. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
| | - Reiko Ishitsuka
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; INSERM U1060, Université Lyon 1, Villeurbanne 69621, France.
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18
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Abstract
Many viruses exploit specific arms of the endomembrane system. The unique composition of each arm prompts the development of remarkably specific interactions between viruses and sub-organelles. This review focuses on the viral–host interactions occurring on the endocytic recycling compartment (ERC), and mediated by its regulatory Ras-related in brain (Rab) GTPase Rab11. This protein regulates trafficking from the ERC and the trans-Golgi network to the plasma membrane. Such transport comprises intricate networks of proteins/lipids operating sequentially from the membrane of origin up to the cell surface. Rab11 is also emerging as a critical factor in an increasing number of infections by major animal viruses, including pathogens that provoke human disease. Understanding the interplay between the ERC and viruses is a milestone in human health. Rab11 has been associated with several steps of the viral lifecycles by unclear processes that use sophisticated diversified host machinery. For this reason, we first explore the state-of-the-art on processes regulating membrane composition and trafficking. Subsequently, this review outlines viral interactions with the ERC, highlighting current knowledge on viral-host binding partners. Finally, using examples from the few mechanistic studies available we emphasize how ERC functions are adjusted during infection to remodel cytoskeleton dynamics, innate immunity and membrane composition.
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Affiliation(s)
- Sílvia Vale-Costa
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156 Oeiras, Portugal.
| | - Maria João Amorim
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156 Oeiras, Portugal.
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19
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Dekky B, Wahart A, Sartelet H, Féré M, Angiboust JF, Dedieu S, Piot O, Devy J, Emonard H. Cellular Cholesterol Distribution Influences Proteolytic Release of the LRP-1 Ectodomain. Front Pharmacol 2016; 7:25. [PMID: 26903870 PMCID: PMC4751253 DOI: 10.3389/fphar.2016.00025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/26/2016] [Indexed: 11/13/2022] Open
Abstract
Low-density lipoprotein receptor-related protein-1 (LRP-1) is a multifunctional matricellular receptor composed of a large ligand-binding subunit (515-kDa α-chain) associated with a short trans-membrane subunit (85-kDa β-chain). LRP-1, which exhibits both endocytosis and cell signaling properties, plays a key role in tumor invasion by regulating the activity of proteinases such as matrix metalloproteinases (MMPs). LRP-1 is shed at the cell surface by proteinases such as membrane-type 1 MMP (MT1-MMP) and a disintegrin and metalloproteinase-12 (ADAM-12). Here, we show by using biophysical, biochemical, and cellular imaging approaches that efficient extraction of cell cholesterol and increased LRP-1 shedding occur in MDA-MB-231 breast cancer cells but not in MDA-MB-435 cells. Our data show that cholesterol is differently distributed in both cell lines; predominantly intracellularly for MDA-MB-231 cells and at the plasma membrane for MDA-MB-435 cells. This study highlights the relationship between the rate and cellular distribution of cholesterol and its impact on LRP-1 shedding modulation. Altogether, our data strongly suggest that the increase of LRP-1 shedding upon cholesterol depletion induces a higher accessibility of the sheddase substrate, i.e., LRP-1, at the cell surface rather than an increase of expression of the enzyme.
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Affiliation(s)
- Bassil Dekky
- Laboratoire de Signalisation et Récepteurs Matriciels, UFR de Sciences Exactes et Naturelles, Université de Reims Champagne-ArdenneReims, France; CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France
| | - Amandine Wahart
- Laboratoire de Signalisation et Récepteurs Matriciels, UFR de Sciences Exactes et Naturelles, Université de Reims Champagne-ArdenneReims, France; CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France
| | - Hervé Sartelet
- Laboratoire de Signalisation et Récepteurs Matriciels, UFR de Sciences Exactes et Naturelles, Université de Reims Champagne-ArdenneReims, France; CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France
| | - Michaël Féré
- CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France; MéDIAN-Biophotonique et Technologies pour la Santé, UFR de Pharmacie, Université de Reims Champagne-ArdenneReims, France; Plateforme d'Imagerie Cellulaire et Tissulaire, Université de Reims Champagne-ArdenneReims, France
| | - Jean-François Angiboust
- CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France; MéDIAN-Biophotonique et Technologies pour la Santé, UFR de Pharmacie, Université de Reims Champagne-ArdenneReims, France; Plateforme d'Imagerie Cellulaire et Tissulaire, Université de Reims Champagne-ArdenneReims, France
| | - Stéphane Dedieu
- Laboratoire de Signalisation et Récepteurs Matriciels, UFR de Sciences Exactes et Naturelles, Université de Reims Champagne-ArdenneReims, France; CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France
| | - Olivier Piot
- CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France; MéDIAN-Biophotonique et Technologies pour la Santé, UFR de Pharmacie, Université de Reims Champagne-ArdenneReims, France; Plateforme d'Imagerie Cellulaire et Tissulaire, Université de Reims Champagne-ArdenneReims, France
| | - Jérôme Devy
- Laboratoire de Signalisation et Récepteurs Matriciels, UFR de Sciences Exactes et Naturelles, Université de Reims Champagne-ArdenneReims, France; CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France
| | - Hervé Emonard
- Laboratoire de Signalisation et Récepteurs Matriciels, UFR de Sciences Exactes et Naturelles, Université de Reims Champagne-ArdenneReims, France; CNRS, Matrice Extracellulaire et Dynamique Cellulaire, UMR 7369Reims, France
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20
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Shim SY, Karri S, Law S, Schatzl HM, Gilch S. Prion infection impairs lysosomal degradation capacity by interfering with rab7 membrane attachment in neuronal cells. Sci Rep 2016; 6:21658. [PMID: 26865414 PMCID: PMC4749993 DOI: 10.1038/srep21658] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/28/2016] [Indexed: 11/24/2022] Open
Abstract
Prions are proteinaceous infectious particles which cause fatal neurodegenerative disorders in humans and animals. They consist of a mostly β-sheeted aggregated isoform (PrPSc) of the cellular prion protein (PrPc). Prions replicate autocatalytically in neurons and other cell types by inducing conformational conversion of PrPc into PrPSc. Within neurons, PrPSc accumulates at the plasma membrane and in vesicles of the endocytic pathway. To better understand the mechanisms underlying neuronal dysfunction and death it is critical to know the impact of PrPSc accumulation on cellular pathways. We have investigated the effects of prion infection on endo-lysosomal transport. Our study demonstrates that prion infection interferes with rab7 membrane association. Consequently, lysosomal maturation and degradation are impaired. Our findings indicate a mechanism induced by prion infection that supports stable prion replication. We suggest modulation of endo-lysosomal vesicle trafficking and enhancement of lysosomal maturation as novel targets for the treatment of prion diseases.
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Affiliation(s)
- Su Yeon Shim
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Srinivasarao Karri
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Sampson Law
- Dept. of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Hermann M Schatzl
- Dept. of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Sabine Gilch
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
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21
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Ogawa Y, Tanaka M. A fluorescent cholesterol analogue for observation of free cholesterol in the plasma membrane of live cells. Anal Biochem 2016; 492:49-55. [DOI: 10.1016/j.ab.2015.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/14/2015] [Accepted: 09/03/2015] [Indexed: 01/16/2023]
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22
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SONG WEI, WANG WEI, WANG YU, DOU LIYANG, CHEN LIANFENG, YAN XIAOWEI. Characterization of fluorescent NBD-cholesterol efflux in THP-1-derived macrophages. Mol Med Rep 2015; 12:5989-96. [DOI: 10.3892/mmr.2015.4154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 06/26/2015] [Indexed: 11/06/2022] Open
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23
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Albulescu L, Wubbolts R, van Kuppeveld FJM, Strating JRPM. Cholesterol shuttling is important for RNA replication of coxsackievirus B3 and encephalomyocarditis virus. Cell Microbiol 2015; 17:1144-56. [PMID: 25645595 DOI: 10.1111/cmi.12425] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 01/21/2015] [Accepted: 01/26/2015] [Indexed: 11/29/2022]
Abstract
Picornaviruses are a family of positive-strand RNA viruses that includes important human and animal pathogens. Upon infection, picornaviruses induce an extensive remodelling of host cell membranes into replication organelles (ROs), which is critical for replication. Membrane lipids and lipid remodelling processes are at the base of RO formation, yet their involvement remains largely obscure. Recently, phosphatidylinositol-4-phosphate was the first lipid discovered to be important for the replication of a number of picornaviruses. Here, we investigate the role of the lipid cholesterol in picornavirus replication. We show that two picornaviruses from distinct genera that rely on different host factors for replication, namely the enterovirus coxsackievirus B3 (CVB3) and the cardiovirus encephalomyocarditis virus (EMCV), both recruited cholesterol to their ROs. Although CVB3 and EMCV both required cholesterol for efficient genome replication, the viruses appeared to rely on different cellular cholesterol pools. Treatments that altered the distribution of endosomal cholesterol inhibited replication of both CVB3 and EMCV, showing the importance of endosomal cholesterol shuttling for the replication of these viruses. Summarizing, we here demonstrate the importance of cholesterol homeostasis for efficient replication of CVB3 and EMCV.
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Affiliation(s)
- Lucian Albulescu
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Richard Wubbolts
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Frank J M van Kuppeveld
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Jeroen R P M Strating
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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24
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Hullin-Matsuda F, Taguchi T, Greimel P, Kobayashi T. Lipid compartmentalization in the endosome system. Semin Cell Dev Biol 2014; 31:48-56. [DOI: 10.1016/j.semcdb.2014.04.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 04/01/2014] [Accepted: 04/03/2014] [Indexed: 11/15/2022]
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25
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Glutathione as the end capper for cyclodextrin/PEG polyrotaxanes. CHINESE JOURNAL OF POLYMER SCIENCE 2014. [DOI: 10.1007/s10118-014-1477-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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26
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dAcsl, the Drosophila ortholog of acyl-CoA synthetase long-chain family member 3 and 4, inhibits synapse growth by attenuating bone morphogenetic protein signaling via endocytic recycling. J Neurosci 2014; 34:2785-96. [PMID: 24553921 DOI: 10.1523/jneurosci.3547-13.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Fatty acid metabolism plays an important role in brain development and function. Mutations in acyl-CoA synthetase long-chain family member 4 (ACSL4), which converts long-chain fatty acids to acyl-CoAs, result in nonsyndromic X-linked mental retardation. ACSL4 is highly expressed in the hippocampus, a structure critical for learning and memory. However, the underlying mechanism by which mutations of ACSL4 lead to mental retardation remains poorly understood. We report here that dAcsl, the Drosophila ortholog of ACSL4 and ACSL3, inhibits synaptic growth by attenuating BMP signaling, a major growth-promoting pathway at neuromuscular junction (NMJ) synapses. Specifically, dAcsl mutants exhibited NMJ overgrowth that was suppressed by reducing the doses of the BMP pathway components, accompanied by increased levels of activated BMP receptor Thickveins (Tkv) and phosphorylated mothers against decapentaplegic (Mad), the effector of the BMP signaling at NMJ terminals. In addition, Rab11, a small GTPase involved in endosomal recycling, was mislocalized in dAcsl mutant NMJs, and the membrane association of Rab11 was reduced in dAcsl mutant brains. Consistently, the BMP receptor Tkv accumulated in early endosomes but reduced in recycling endosomes in dAcsl mutant NMJs. dAcsl was also required for the recycling of photoreceptor rhodopsin in the eyes, implying a general role for dAcsl in regulating endocytic recycling of membrane receptors. Importantly, expression of human ACSL4 rescued the endocytic trafficking and NMJ phenotypes of dAcsl mutants. Together, our results reveal a novel mechanism whereby dAcsl facilitates Rab11-dependent receptor recycling and provide insights into the pathogenesis of ACSL4-related mental retardation.
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Takano T, Urushibara T, Yoshioka N, Saito T, Fukuda M, Tomomura M, Hisanaga SI. LMTK1 regulates dendritic formation by regulating movement of Rab11A-positive endosomes. Mol Biol Cell 2014; 25:1755-68. [PMID: 24672056 PMCID: PMC4038502 DOI: 10.1091/mbc.e14-01-0675] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Neurons extend two types of neurites-axons and dendrites-that differ in structure and function. Although it is well understood that the cytoskeleton plays a pivotal role in neurite differentiation and extension, the mechanisms by which membrane components are supplied to growing axons or dendrites is largely unknown. We previously reported that the membrane supply to axons is regulated by lemur kinase 1 (LMTK1) through Rab11A-positive endosomes. Here we investigate the role of LMTK1 in dendrite formation. Down-regulation of LMTK1 increases dendrite growth and branching of cerebral cortical neurons in vitro and in vivo. LMTK1 knockout significantly enhances the prevalence, velocity, and run length of anterograde movement of Rab11A-positive endosomes to levels similar to those expressing constitutively active Rab11A-Q70L. Rab11A-positive endosome dynamics also increases in the cell body and growth cone of LMTK1-deficient neurons. Moreover, a nonphosphorylatable LMTK1 mutant (Ser34Ala, a Cdk5 phosphorylation site) dramatically promotes dendrite growth. Thus LMTK1 negatively controls dendritic formation by regulating Rab11A-positive endosomal trafficking in a Cdk5-dependent manner, indicating the Cdk5-LMTK1-Rab11A pathway as a regulatory mechanism of dendrite development as well as axon outgrowth.
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Affiliation(s)
- Tetsuya Takano
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Tomoki Urushibara
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Nozomu Yoshioka
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Taro Saito
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Mitsunori Fukuda
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Mineko Tomomura
- Meikai Pharmaco-Medical Laboratory, Meikai University School of Dentistry, Sakado 350-0283, Japan
| | - Shin-Ichi Hisanaga
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
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Goonasekara CL, Balse E, Hatem S, Steele DF, Fedida D. Cholesterol and cardiac arrhythmias. Expert Rev Cardiovasc Ther 2014; 8:965-79. [DOI: 10.1586/erc.10.79] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Anchisi L, Dessì S, Pani A, Mandas A. Cholesterol homeostasis: a key to prevent or slow down neurodegeneration. Front Physiol 2013; 3:486. [PMID: 23316166 PMCID: PMC3539713 DOI: 10.3389/fphys.2012.00486] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 12/12/2012] [Indexed: 11/29/2022] Open
Abstract
Neurodegeneration, a common feature for many brain disorders, has severe consequences on the mental and physical health of an individual. Typically human neurodegenerative diseases are devastating illnesses that predominantly affect elderly people, progress slowly, and lead to disability and premature death; however they may occur at all ages. Despite extensive research and investments, current therapeutic interventions against these disorders treat solely the symptoms. Therefore, since the underlying mechanisms of damage to neurons are similar, in spite of etiology and background heterogeneous, it will be of interest to identify possible trigger point of neurodegeneration enabling development of drugs and/or prevention strategies that target many disorders simultaneously. Among the factors that have been identified so far to cause neurodegeneration, failures in cholesterol homeostasis are indubitably the best investigated. The aim of this review is to critically discuss some of the main results reported in the recent years in this field mainly focusing on the mechanisms that, by recovering perturbations of cholesterol homeostasis in neuronal cells, may correct clinically relevant features occurring in different neurodegenerative disorders and, in this regard, also debate the current potential therapeutic interventions.
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Affiliation(s)
- Laura Anchisi
- Child Neuropsychiatry Unit, Azienda Sanitaria Locale (ASL) n°5 Oristano, Italy ; Department of Clinical and Experimental Medicine and Pharmacology, University of Messina Messina, Italy
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Wilson RL, Kraft ML. Quantifying the molar percentages of cholesterol in supported lipid membranes by time-of-flight secondary ion mass spectrometry and multivariate analysis. Anal Chem 2012. [PMID: 23199099 DOI: 10.1021/ac301856z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The uneven cholesterol distribution among organelles and within the plasma membrane is postulated to be critical for proper cellular function. To study how interactions between cholesterol and specific lipid species contribute to the uneven cholesterol distribution between and within cellular membranes, model lipid membranes are frequently employed. Although the cholesterol distributions within membranes can be directly imaged without labels by using time-of-flight secondary ion mass spectrometry (TOF-SIMS), quantifying the cholesterol abundance at specific membrane locations in a label-free manner remains a challenge. Here, partial least-squares regression (PLSR) of TOF-SIMS data is used to quantitatively measure the local molar percentage (mol %) of cholesterol within supported lipid membranes. With the use of TOF-SIMS data from lipid membranes of known composition, a PLSR model was constructed that correlated the spectral variation to the mol % cholesterol in the membrane. The PLSR model was then used to measure the mol % cholesterol in test membranes and to measure cholesterol exchange between vesicles and supported lipid membranes. The accuracy of these measurements was assessed by comparison to the mol % cholesterol measured with conventional assays. By using this TOF-SIMS/PLSR approach to quantify the mol % cholesterol with location specificity, a better understanding of how the regional lipid composition influences cholesterol abundance and exchange in membranes may be obtained.
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Affiliation(s)
- Robert L Wilson
- Department of Chemistry, University of Illinois at Urbana-Champaign, 61801, United States
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31
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Abstract
Clostridium perfringens iota-toxin is composed of an enzymatic component (Ia) and a binding component (Ib). Ib binds to a cell surface receptor, undergoes oligomerization in lipid rafts, and binds Ia. The resulting complex is then endocytosed. Here, we show the intracellular trafficking of iota-toxin. After the binding of the Ib monomer with cells at 4°C, oligomers of Ib formed at 37°C and later disappeared. Immunofluorescence staining of Ib revealed that the internalized Ib was transported to early endosomes. Some Ib was returned to the plasma membrane through recycling endosomes, whereas the rest was transported to late endosomes and lysosomes for degradation. Degraded Ib was delivered to the plasma membrane by an increase in the intracellular Ca(2+) concentration caused by Ib. Bafilomycin A1, an endosomal acidification inhibitor, caused the accumulation of Ib in endosomes, and both nocodazole and colchicine, microtubule-disrupting agents, restricted Ib's movement in the cytosol. These results indicated that an internalized Ia and Ib complex was delivered to early endosomes and that subsequent delivery of Ia to the cytoplasm occurs mainly in early endosomes. Ib was either sent back to the plasma membranes through recycling endosomes or transported to late endosomes and lysosomes for degradation. Degraded Ib was transported to plasma membranes.
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32
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Lee S, Uchida Y, Emoto K, Umeda M, Kuge O, Taguchi T, Arai H. Impaired retrograde membrane traffic through endosomes in a mutant CHO cell defective in phosphatidylserine synthesis. Genes Cells 2012; 17:728-36. [PMID: 22747682 DOI: 10.1111/j.1365-2443.2012.01622.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 05/13/2012] [Indexed: 11/28/2022]
Abstract
Phosphatidylserine (PS), a relatively minor constituent in the plasma membrane (PM), participates in various cellular processes such as clearance of apoptotic cells and recruitment of signaling molecules. PS also localizes in the membranes of endocytic organelles, such as recycling endosomes (REs). We recently showed that in REs, PS binds to the pleckstrin homology (PH) domain of evectin-2, thereby regulating retrograde traffic from REs to the Golgi. However, direct evidence that PS has a role in retrograde traffic is lacking. Here, we examined the contribution of PS to endosomal membrane traffic by exploiting a mutant CHO cell line (PSA-3) that is defective in PS synthesis. In PSA-3 cells, the Golgi localization of TGN38, a protein that circulates between the Golgi and the PM through endosomes by retrograde traffic, was abolished, whereas the localizations of other organelle markers remained unchanged. Increasing the cellular PS level by adding ethanolamine to the culture medium restored the Golgi localization of TGN38. Tracking the endocytic fate of cell surface TGN38 that was labeled by anti-TGN38 antibody showed that retrograde transport of TGN38 was impaired at endosomes, not at the PM. These findings provide direct evidence that intracellular PS is required for retrograde traffic through endosomes.
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Affiliation(s)
- Shoken Lee
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
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33
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He Q, Wang G, Dasgupta S, Dinkins M, Zhu G, Bieberich E. Characterization of an apical ceramide-enriched compartment regulating ciliogenesis. Mol Biol Cell 2012. [PMID: 22718902 DOI: 10.1091/mbc.e12–02-0079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We show that in Madin-Darby canine kidney (MDCK) cells, an apical ceramide-enriched compartment (ACEC) at the base of primary cilia is colocalized with Rab11a. Ceramide and Rab11a vesicles isolated by magnetic sorting contain a highly similar profile of proteins (atypical protein kinase C [aPKC], Cdc42, Sec8, Rab11a, and Rab8) and ceramide species, suggesting the presence of a ciliogenic protein complex associated with ceramide at the ACEC. It is intriguing that C16 and C18 ceramide, although less abundant ceramide species in MDCK cells, are highly enriched in ceramide and Rab11a vesicles. Expression of a ceramide-binding but dominant-negative mutant of aPKC suppresses ciliogenesis, indicating that the association of ceramide with aPKC is critical for the formation of this complex. Our results indicate that ciliogenic ceramide is derived from apical sphingomyelin (SM) that is endocytosed and then converted to the ACEC. Consistently, inhibition of acid sphingomyelinase with imipramine disrupts ACEC formation, association of ciliogenic proteins with Rab11a vesicles, and cilium formation. Ciliogenesis is rescued by the histone deacetylase (HDAC) inhibitor trichostatin A, indicating that ceramide promotes tubulin acetylation in cilia. Taken together, our results suggest that the ACEC is a novel compartment in which SM-derived ceramide induces formation of a ciliogenic lipid-protein complex that sustains primary cilia by preventing deacetylation of microtubules.
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Affiliation(s)
- Qian He
- Program in Developmental Neurobiology, Institute of Molecular Medicine and Genetics, School of Medicine, Georgia Health Sciences University, Augusta, GA 30912, USA
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34
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He Q, Wang G, Dasgupta S, Dinkins M, Zhu G, Bieberich E. Characterization of an apical ceramide-enriched compartment regulating ciliogenesis. Mol Biol Cell 2012; 23:3156-66. [PMID: 22718902 PMCID: PMC3418310 DOI: 10.1091/mbc.e12-02-0079] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The sphingolipid ceramide is essential for the formation, elongation, or maintenance of primary cilia. A novel, apical ceramide-enriched compartment induces formation of a ciliogenic protein complex with Rab11a, which sustains formation and maintenance of primary cilia by preventing deacetylation of microtubules. We show that in Madin–Darby canine kidney (MDCK) cells, an apical ceramide-enriched compartment (ACEC) at the base of primary cilia is colocalized with Rab11a. Ceramide and Rab11a vesicles isolated by magnetic sorting contain a highly similar profile of proteins (atypical protein kinase C [aPKC], Cdc42, Sec8, Rab11a, and Rab8) and ceramide species, suggesting the presence of a ciliogenic protein complex associated with ceramide at the ACEC. It is intriguing that C16 and C18 ceramide, although less abundant ceramide species in MDCK cells, are highly enriched in ceramide and Rab11a vesicles. Expression of a ceramide-binding but dominant-negative mutant of aPKC suppresses ciliogenesis, indicating that the association of ceramide with aPKC is critical for the formation of this complex. Our results indicate that ciliogenic ceramide is derived from apical sphingomyelin (SM) that is endocytosed and then converted to the ACEC. Consistently, inhibition of acid sphingomyelinase with imipramine disrupts ACEC formation, association of ciliogenic proteins with Rab11a vesicles, and cilium formation. Ciliogenesis is rescued by the histone deacetylase (HDAC) inhibitor trichostatin A, indicating that ceramide promotes tubulin acetylation in cilia. Taken together, our results suggest that the ACEC is a novel compartment in which SM-derived ceramide induces formation of a ciliogenic lipid–protein complex that sustains primary cilia by preventing deacetylation of microtubules.
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Affiliation(s)
- Qian He
- Program in Developmental Neurobiology, Institute of Molecular Medicine and Genetics, School of Medicine, Georgia Health Sciences University, Augusta, GA 30912, USA
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35
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Hullin-Matsuda F, Tomishige N, Sakai S, Ishitsuka R, Ishii K, Makino A, Greimel P, Abe M, Laviad EL, Lagarde M, Vidal H, Saito T, Osada H, Hanada K, Futerman AH, Kobayashi T. Limonoid compounds inhibit sphingomyelin biosynthesis by preventing CERT protein-dependent extraction of ceramides from the endoplasmic reticulum. J Biol Chem 2012; 287:24397-411. [PMID: 22605339 DOI: 10.1074/jbc.m112.344432] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify novel inhibitors of sphingomyelin (SM) metabolism, a new and selective high throughput microscopy-based screening based on the toxicity of the SM-specific toxin, lysenin, was developed. Out of a library of 2011 natural compounds, the limonoid, 3-chloro-8β-hydroxycarapin-3,8-hemiacetal (CHC), rendered cells resistant to lysenin by decreasing cell surface SM. CHC treatment selectively inhibited the de novo biosynthesis of SM without affecting glycolipid and glycerophospholipid biosynthesis. Pretreatment with brefeldin A abolished the limonoid-induced inhibition of SM synthesis suggesting that the transport of ceramide (Cer) from the endoplasmic reticulum to the Golgi apparatus is affected. Unlike the Cer transporter (CERT) inhibitor HPA-12, CHC did not change the transport of a fluorescent short chain Cer analog to the Golgi apparatus or the formation of fluorescent and short chain SM from the corresponding Cer. Nevertheless, CHC inhibited the conversion of de novo synthesized Cer to SM. We show that CHC specifically inhibited the CERT-mediated extraction of Cer from the endoplasmic reticulum membranes in vitro. Subsequent biochemical screening of 21 limonoids revealed that some of them, such as 8β-hydroxycarapin-3,8-hemiacetal and gedunin, which exhibits anti-cancer activity, inhibited SM biosynthesis and CERT-mediated extraction of Cer from membranes. Model membrane studies suggest that 8β-hydroxycarapin-3,8-hemiacetal reduced the miscibility of Cer with membrane lipids and thus induced the formation of Cer-rich membrane domains. Our study shows that certain limonoids are novel inhibitors of SM biosynthesis and suggests that some biological activities of these limonoids are related to their effect on the ceramide metabolism.
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36
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Coordinated regulation of caveolin-1 and Rab11a in apical recycling compartments of polarized epithelial cells. Exp Cell Res 2011; 318:103-13. [PMID: 22036648 DOI: 10.1016/j.yexcr.2011.10.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 09/24/2011] [Accepted: 10/11/2011] [Indexed: 12/29/2022]
Abstract
Recent studies have identified caveolin-1, a protein best known for its functions in caveolae, in apical endocytic recycling compartments in polarized epithelial cells. However, very little is known about the regulation of caveolin-1 in the endocytic recycling pathway. To address this question, in the current study we compared the relationship between compartments enriched in sub-apical caveolin-1 and Rab11a, a well-defined marker of apical recycling endosomes, using polarized MDCK cells as a model. We show that caveolin-1-containing vesicles define a compartment that partially overlaps with Rab11a, and that the distribution of subapical caveolin-1 and Rab11a shows a similar dependence on microtubule disruption. Mutants of the Rab11a effector, Rab11-FIP2 also altered the localization of caveolin-1. These findings indicate that caveolin-1 is coordinately regulated with Rab11a within the apical recycling system of polarized epithelial cells, suggesting that the two proteins are components of the same pathway.
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37
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Vogel PA, Halpin ST, Martin RS, Spence DM. Microfluidic transendothelial electrical resistance measurement device that enables blood flow and postgrowth experiments. Anal Chem 2011; 83:4296-301. [PMID: 21513343 DOI: 10.1021/ac2004746] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Transendothelial electronic resistance (TEER) measurements are performed across a cell layer immobilized on a microfluidic device that also enables the cell layer to interact with a flowing stream of red blood cells (RBCs). A bipolar pulsed square wave potential is applied across a monolayer of bovine pulmonary artery endothelial cells, and the resulting current response is measured and integrated. The overall impedance of the cell layer provides an indicator of cell layer integrity. After cell seeding on the device, a decrease in TEER signal from 22.3 ± 1.6 μC to 3.5 ± 0.4 μC (corresponding to a resistance of 40.9 ± 2.9 Ω·cm(2) to 259.1 ± 27.4 Ω·cm(2)) was observed after 8 h of cell growth. Intracellular nitric oxide (NO) production by the immobilized endothelial cells that had reached confluence was 34% higher than those cells that had not reached confluence, as indicated by the integrated TEER system. Importantly, this NO production by the confluent endothelium was stimulated by ATP released from RBCs flowing under the endothelial cells. In this construct, the described microfluidic device enables both a TEER-based evaluation of cell layer integrity and molecularly communicated interactions of these cells with a flowing stream of blood components.
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Affiliation(s)
- Paul A Vogel
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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38
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Gimpl G, Gehrig-Burger K. Probes for studying cholesterol binding and cell biology. Steroids 2011; 76:216-31. [PMID: 21074546 DOI: 10.1016/j.steroids.2010.11.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 11/03/2010] [Accepted: 11/05/2010] [Indexed: 11/20/2022]
Abstract
Cholesterol is a multifunctional lipid in eukaryotic cells. It regulates the physical state of the phospholipid bilayer, is crucially involved in the formation of membrane microdomains, affects the activity of many membrane proteins, and is the precursor for steroid hormones and bile acids. Thus, cholesterol plays a profound role in the physiology and pathophysiology of eukaryotic cells. The cholesterol molecule has achieved evolutionary perfection to fulfill its different functions in membrane organization. Here, we review basic approaches to explore the interaction of cholesterol with proteins, with a particular focus on the high diversity of fluorescent and photoreactive cholesterol probes available today.
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Affiliation(s)
- Gerald Gimpl
- Institute of Pharmacy and Biochemistry, Department of Biochemistry, Johannes Gutenberg-University of Mainz, Mainz, Germany.
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Transbilayer organization of membrane cholesterol at low concentrations: Implications in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:19-25. [PMID: 21035427 DOI: 10.1016/j.bbamem.2010.10.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 10/20/2010] [Accepted: 10/22/2010] [Indexed: 02/06/2023]
Abstract
Cholesterol is an essential and representative lipid in higher eukaryotic cellular membranes and is often found distributed nonrandomly in domains in biological membranes. A large body of literature exists on the organization of cholesterol in plasma membranes or membranes with high cholesterol content. However, very little is known about organization of cholesterol in membranes containing low amounts of cholesterol such as the endoplasmic reticulum or inner mitochondrial membranes. In this review, we have traced the discovery and subsequent development of the concept of transbilayer cholesterol dimers (domains) in membranes at low concentrations. We have further discussed the role of membrane curvature and thickness on the transbilayer organization of cholesterol. Interestingly, this type of cholesterol organization could be relevant in cellular sorting and trafficking, and in pathological conditions.
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40
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Huynh KK, Plumb JD, Downey GP, Valvano MA, Grinstein S. Inactivation of macrophage Rab7 by Burkholderia cenocepacia. J Innate Immun 2010; 2:522-33. [PMID: 20829607 DOI: 10.1159/000319864] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 08/03/2010] [Indexed: 02/02/2023] Open
Abstract
Strains of the Burkholderia cepacia complex can survive within macrophages by arresting the maturation of phagocytic vacuoles. The bacteria preclude fusion of the phagosome with lysosomes by a process that is poorly understood. Using murine macrophages, we investigated the stage at which maturation is arrested and analyzed the underlying mechanism. Vacuoles containing B. cenocepacia strain J2315, an isolate of the transmissible ET12 clone, recruited Rab5 and synthesized phosphatidylinositol-3-phosphate, indicating progression to the early phagosomal stage. Despite the fact that the B. cenocepacia-containing vacuoles rarely fused with lysosomes, they could nevertheless acquire the late phagosomal markers CD63 and Rab7. Fluorescence recovery after photobleaching and use of a probe that detects Rab7-guanosine triphosphate indicated that activation of Rab7 was impaired by B. cenocepacia, accounting at least in part for the inability of the vacuole to merge with lysosomes. The Rab7 defect was not due to excessive cholesterol accumulation and was confined to the infected vacuoles. Jointly, these experiments indicate that B. cenocepacia express virulence factors capable of interfering with Rab7 function and thereby with membrane traffic.
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Affiliation(s)
- Kassidy K Huynh
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
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41
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Liu HP, Wu CC, Kao HY, Huang YC, Liang Y, Chen CC, Yu JS, Chang YS. Proteome-wide dysregulation by PRA1 depletion delineates a role of PRA1 in lipid transport and cell migration. Mol Cell Proteomics 2010; 10:M900641MCP200. [PMID: 20592422 DOI: 10.1074/mcp.m900641-mcp200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously identified prenylated Rab acceptor 1 (PRA1) as a novel cellular interacting partner for Epstein-Barr virus-encoded oncoprotein, latent membrane protein 1 (LMP1). The intracellular trafficking and full signaling of LMP1 requires its interaction with PRA1. To further explore the role of PRA1 in Epstein-Barr virus-associated nasopharyngeal carcinoma (NPC) cells, we generated several PRA1-knockdown cell clones, which exhibited altered cell morphology and increased cell motility. We identified proteins differentially expressed in the knockdown clones by means of isobaric mass tags labeling coupled with multidimensional liquid chromatography-mass spectrometry. We validated a panel of proteins, which showed consistent up-regulation in PRA1-knockdown clones and participated in regulating lipid homeostasis and cell migration. Immunofluorescence staining further revealed altered localization of these proteins and accumulation of intracellular cholesterol in PRA1-knockdown clones. These effects were phenocopied by treatment with a cholesterol transport inhibitor, U18666A. Moreover, overexpressed PRA1 was able to alleviate the dysregulation of these affected proteins either from PRA1 knockdown or U18666A treatment, implying a role for PRA1 in regulating the levels of these affected proteins in response to altered cholesterol homeostasis. We further demonstrated that LMP1 expression caused PRA1 sequestration in NPC cells, leading to a consequence reminiscent of PRA1 knockdown. Finally, the immunohistochemistry showed a physiological relevance of the PRA1-associated proteome-wide changes in NPC biopsy tissues. In sum, our findings delineated novel roles of PRA1 in lipid transport and cell migration, and provided additional insights into the molecular basis of NPC morphogenesis, namely a consequence of LMP1-PRA1 interaction.
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Affiliation(s)
- Hao-Ping Liu
- Molecular Medicine Research Center, Department of Medical Biotechnology and Laboratory Science, Graduate Institute of Biomedical Sciences, Chang Gung University, Tao-Yuan, Taiwan
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42
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Takano T, Tsutsumi K, Saito T, Asada A, Tomomura M, Fukuda M, Hisanaga SI. AATYK1A phosphorylation by Cdk5 regulates the recycling endosome pathway. Genes Cells 2010; 15:783-97. [PMID: 20553326 DOI: 10.1111/j.1365-2443.2010.01419.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Trafficking of recycling endosomes (REs) is regulated by the small GTPase, Rab11A; however, the regulatory mechanism remains elusive. Apoptosis-associated tyrosine kinase 1A (AATYK1A) is a Ser/Thr kinase expressed highly in brain. We have recently shown that AATYK1A localizes to Rab11A-positive RE and is phosphorylated at Ser34 by cyclin-dependent kinase 5 (Cdk5). Here, we have investigated a role of AATYK1A and its phosphorylation in recycling endosomal trafficking using Chinese hamster ovary-K1 (CHO-K1) cells. AATYK1A localizes predominantly to Rab11A-positive pericentrosomal endocytic recycling compartment (ERC). Phosphorylation at Ser34 of AATYK1A disrupts its accumulation in the pericentrosomal ERC. Consistently, phosphorylation-mimic mutant (AATYK1A-S34D) did not accumulate in the ERC and additionally attenuated ERC formation. ERC formation suppression can be reversed by constitutively active Rab11A-Q70L, suggesting a functional link between AATYK1A phosphorylation and Rab11A activity. Although no direct interaction between AATYK1A and Rab11A could be detected, the exchange of guanine nucleotides bound to Rab11A was significantly reduced in the presence of the phosphorylation-mimic AATYK1A-S34D. Together, our results reveal a regulatory role for AATYK1A in the formation of pericentrosomal ERC. They furthermore indicate that Cdk5 can disrupt ERC formation via Ser34 phosphorylation of AATYK1A. Finally, our data suggest a mechanism by which AATYK1A signaling couples Cdk5 to Rab11A activity.
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Affiliation(s)
- Tetsuya Takano
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa, Hachioji, Japan.
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Beel AJ, Sakakura M, Barrett PJ, Sanders CR. Direct binding of cholesterol to the amyloid precursor protein: An important interaction in lipid-Alzheimer's disease relationships? Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:975-82. [PMID: 20304095 DOI: 10.1016/j.bbalip.2010.03.008] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 03/10/2010] [Accepted: 03/10/2010] [Indexed: 12/21/2022]
Abstract
It is generally believed that cholesterol homoeostasis in the brain is both linked to and impacted by Alzheimer's disease (AD). For example, elevated levels of cholesterol in neuronal plasma and endosome membranes appear to be a pro-amyloidogenic factor. The recent observation that the C-terminal transmembrane domain (C99, also known as the beta-C-terminal fragment, or beta-CTF) of the amyloid precursor protein (APP) specifically binds cholesterol helps to tie together previously loose ends in the web of our understanding of Alzheimer's-cholesterol relationships. In particular, binding of cholesterol to C99 appears to favor the amyloidogenic pathway in cells by promoting localization of C99 in lipid rafts. In turn, the products of this pathway-amyloid-beta and the intracellular domain of the APP (AICD)-may down-regulate ApoE-mediated cholesterol uptake and cholesterol biosynthesis. If confirmed, this negative-feedback loop for membrane cholesterol levels has implications for understanding the function of the APP and for devising anti-amyloidogenic preventive strategies for AD.
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Affiliation(s)
- Andrew J Beel
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-8725, USA
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Imaging lipid membrane domains with lipid-specific probes. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2010; 580:203-20. [PMID: 19784601 DOI: 10.1007/978-1-60761-325-1_11] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Imaging membrane lipid domains to characterize their organization and function has been hindered by the lack of reliable lipid-specific probes. In this paper, we provide detailed methods to investigate, mainly by confocal microscopy, the distribution and dynamics of two components of the "lipid rafts," sphingomyelin (SM) and cholesterol, using two specific lipid probes that have been extensively studied in the laboratory: lysenin, a SM-binding toxin and the fluorescent esters of poly(ethylene glycol) cholesteryl ether (PEG-Chol) that label cholesterol-rich domains. The production of nontoxic forms of lysenin as well as its specific binding behavior have allowed monitoring the distribution and the dynamics of SM-rich domains in living cell membranes. Because of its water-solubility and low toxicity, the fluorescent PEG-Chol can be used to follow the reorganization of cell surface cholesterol-rich domains as well as intracellular cholesterol dynamics in living cells. These probes can thus provide important informations on lipid distribution and traffic in living cell membranes.
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Abstract
Cholesterol is a major constituent of the plasma membrane in eukaryotic cells. It regulates the physical state of the phospholipid bilayer and is crucially involved in the formation of membrane microdomains. Cholesterol also affects the activity of several membrane proteins, and is the precursor for steroid hormones and bile acids. Here, methods are described that are used to explore the binding and/or interaction of proteins to cholesterol. For this purpose, a variety of cholesterol probes bearing radio-, spin-, photoaffinity- or fluorescent labels are currently available. Examples of proven cholesterol binding molecules are polyene compounds, cholesterol-dependent cytolysins, enzymes accepting cholesterol as substrate, and proteins with cholesterol binding motifs. Main topics of this report are the localization of candidate membrane proteins in cholesterol-rich microdomains, the issue of specificity of cholesterol- protein interactions, and applications of the various cholesterol probes for these studies.
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Affiliation(s)
- Gerald Gimpl
- Institut für Biochemie, Johannes Gutenberg-Universität, Johann-Joachim-Becherweg 30, Mainz, Germany.
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Singh RD, Marks DL, Holicky EL, Wheatley CL, Kaptzan T, Sato SB, Kobayashi T, Ling K, Pagano RE. Gangliosides and beta1-integrin are required for caveolae and membrane domains. Traffic 2009; 11:348-60. [PMID: 20051050 DOI: 10.1111/j.1600-0854.2009.01022.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Caveolae are plasma membrane domains involved in the uptake of certain pathogens and toxins. Internalization of some cell surface integrins occurs via caveolae suggesting caveolae may play a crucial role in modulating integrin-mediated adhesion and cell migration. Here we demonstrate a critical role for gangliosides (sialo-glycosphingolipids) in regulating caveolar endocytosis in human skin fibroblasts. Pretreatment of cells with endoglycoceramidase (cleaves glycosphingolipids) or sialidase (modifies cell surface gangliosides and glycoproteins) selectively inhibited caveolar endocytosis by >70%, inhibited the formation of plasma membrane domains enriched in sphingolipids and cholesterol ('lipid rafts'), reduced caveolae and caveolin-1 at the plasma membrane by approximately 80%, and blunted activation of beta1-integrin, a protein required for caveolar endocytosis in these cells. These effects could be reversed by a brief incubation with gangliosides (but not with asialo-gangliosides or other sphingolipids) at 10 degrees C, suggesting that sialo-lipids are critical in supporting caveolar endocytosis. Endoglycoceramidase treatment also caused a redistribution of focal adhesion kinase, paxillin, talin, and PIP Kinase Igamma away from focal adhesions. The effects of sialidase or endoglycoceramidase on membrane domains and the distribution of caveolin-1 could be recapitulated by beta1-integrin knockdown. These results suggest that both gangliosides and beta1-integrin are required for maintenance of caveolae and plasma membrane domains.
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Affiliation(s)
- Raman Deep Singh
- Departments of Medicine, Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Nakamitsu S, Kurokawa A, Yamasaki T, Uryu M, Hasebe R, Horiuchi M. Cell density-dependent increase in the level of protease-resistant prion protein in prion-infected Neuro2a mouse neuroblastoma cells. J Gen Virol 2009; 91:563-9. [DOI: 10.1099/vir.0.016287-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Huynh KK, Gershenzon E, Grinstein S. Cholesterol accumulation by macrophages impairs phagosome maturation. J Biol Chem 2008; 283:35745-55. [PMID: 18955491 DOI: 10.1074/jbc.m806232200] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Macrophages are key to the pathogenesis of atherosclerosis. They take up and store excessive amounts of cholesterol associated with modified low density lipoprotein, eventually becoming foam cells that display altered immune responsiveness. We studied the effects of cholesterol accumulation on phagosome formation and maturation, using lipid transport antagonists and cholesterol transport-deficient mutants. In macrophages treated with U18666A, a transport antagonist that prevents cholesterol exit from late endosomes/lysosomes, the early stages of maturation proceeded normally; phagosomes acquired Rab5, phosphatidylinositol 3-phosphate, and EEA1 and merged with LAMP-containing vesicles. However, fusion with lysosomes was impaired. Rab7, which is required for phagolysosome formation, was acquired by phagosomes but remained inactive. Maturation was also studied in fibroblasts from Niemann-Pick type C individuals that have defective cholesterol transport. Transfection of FcgammaIIA receptors was used to confer phagocytic capability to these fibroblasts. Niemann-Pick type C phagosomes failed to fuse with lysosomes, whereas wild type fibroblasts formed normal phagolysosomes. These findings indicate that cholesterol accumulation can have a detrimental effect on phagosome maturation by impairing the activation of Rab7, sequestering it and its effectors in cholesterol-enriched multilamellar compartments.
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Affiliation(s)
- Kassidy K Huynh
- Programme in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
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Cholesterol regulation of rab-mediated sphingolipid endocytosis. Glycoconj J 2008; 26:705-10. [PMID: 18841464 DOI: 10.1007/s10719-008-9191-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 09/05/2008] [Accepted: 09/08/2008] [Indexed: 12/21/2022]
Abstract
Despite a tight regulation of its intracellular content, cholesterol is found accumulated in pathological conditions such as sphingolipidosis as well as after cell treatment with drugs like hydrophobic amines. Furthermore, cellular cholesterol increases when cultured cells approach confluence. Under these conditions, the endocytic pathways of plasma membrane sphingolipids are differently affected. In this short review, we will summarize recent results from our laboratory as well as those of other groups, indicating that the intracellular accumulation of cholesterol inhibits the dissociation of rab GTPases from the target membranes, causing the alteration of rab-mediated membrane traffic.
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Abstract
Cholesterol is an essential structural component in the cell membranes of most vertebrates. The biophysical properties of cholesterol and the enzymology of cholesterol metabolism provide the basis for how cells handle cholesterol and exchange it with one another. A tightly controlled--but only partially characterized--network of cellular signalling and lipid transfer systems orchestrates the functional compartmentalization of this lipid within and between organellar membranes. This largely dictates the exchange of cholesterol between tissues at the whole body level. Increased understanding of these processes and their integration at the organ systems level provides fundamental insights into the physiology of cholesterol trafficking.
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Affiliation(s)
- Elina Ikonen
- Institute of Biomedicine/Anatomy, University of Helsinki, Haartmaninkatu 8, University of Helsinki, Helsinki FI-00014, Finland.
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