1
|
Faivre N, Verollet C, Dumas F. The chemokine receptor CCR5: multi-faceted hook for HIV-1. Retrovirology 2024; 21:2. [PMID: 38263120 PMCID: PMC10807162 DOI: 10.1186/s12977-024-00634-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 01/13/2024] [Indexed: 01/25/2024] Open
Abstract
Chemokines are cytokines whose primary role is cellular activation and stimulation of leukocyte migration. They perform their various functions by interacting with G protein-coupled cell surface receptors (GPCRs) and are involved in the regulation of many biological processes such as apoptosis, proliferation, angiogenesis, hematopoiesis or organogenesis. They contribute to the maintenance of the homeostasis of lymphocytes and coordinate the function of the immune system. However, chemokines and their receptors are sometimes hijacked by some pathogens to infect the host organism. For a given chemokine receptor, there is a wide structural, organizational and conformational diversity. In this review, we describe the evidence for structural variety reported for the chemokine receptor CCR5, how this variability can be exploited by HIV-1 to infect its target cells and what therapeutic solutions are currently being developed to overcome this problem.
Collapse
Affiliation(s)
- Natacha Faivre
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UPS), Toulouse, France
- International Research Laboratory (IRP) CNRS "IM-TB/HIV", Toulouse, France
- International Research Laboratory (IRP) CNRS "IM-TB/HIV", Buenos Aires, Argentina
| | - Christel Verollet
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UPS), Toulouse, France
- International Research Laboratory (IRP) CNRS "IM-TB/HIV", Toulouse, France
- International Research Laboratory (IRP) CNRS "IM-TB/HIV", Buenos Aires, Argentina
| | - Fabrice Dumas
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UPS), Toulouse, France.
| |
Collapse
|
2
|
Jiang W, Jiang Y, Zhang X, Mu H, Song Y, Zhao H. Metabolomic analysis reveals the influence of HMBOX1 on RAW264.7 cells proliferation based on UPLC-MS/MS. BMC Genomics 2023; 24:272. [PMID: 37208615 DOI: 10.1186/s12864-023-09361-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 05/06/2023] [Indexed: 05/21/2023] Open
Abstract
Macrophages are important effector cells in tumor progression and immune regulation. Previously, we demonstrated that the transcription suppressor homeobox containing 1(HMBOX1) exhibits immunosuppressive activity in LPS-induced acute liver injury by impeding macrophage infiltration and activation. We also observed a lower proliferation in HMBOX1-overexpressed RAW264.7 cells. However, the specific mechanism was unclear. Here, a work was performed to characterize HMBOX1 function related to cell proliferation from a metabolomics standpoint by comparing the metabolic profiles of HMBOX1-overexpressed RAW264.7 cells to those of the controls. Firstly, we assessed HMBOX1 anti-proliferation activity in RAW264.7 cells with CCK8 assay and clone formation. Then, we performed metabolomic analyses by ultra-liquid chromatography coupled with mass spectrometry to explore the potential mechanisms. Our results indicated that HMBOX1 inhibited the macrophage growth curve and clone formation ability. Metabolomic analyses showed significant changes in HMBOX1-overexpressed RAW264.7 metabolites. A total of 1312 metabolites were detected, and 185 differential metabolites were identified based on the criterion of OPLS-DA VIP > 1 and p value < 0.05. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that the elevated HMBOX1 in RAW264.7 inhibited the pathways of amino acid and nucleotide metabolism. Glutamine concentrations decreased significantly in HMBOX1-overexpressed macrophages, and glutamine-related transporter SLC1A5 was also downregulated. Furthermore, SLC1A5 overexpression reversed HMBOX1 inhibition of macrophage proliferation. This study demonstrated the potential mechanism of the HMBOX1/SLC1A5 pathway in cell proliferation by regulating glutamine transportation. The results may help provide a new direction for therapeutic interventions in macrophage-related inflammatory diseases.
Collapse
Affiliation(s)
- Wen Jiang
- Central Research Laboratory, the Second Hospital of Shandong University, Jinan, 250033, China
| | - Yu Jiang
- Department of Clinical Research Center, Central Hospital Affiliated to Shandong First Medical University, Jinan, 250013, China
| | - Xinghai Zhang
- Department of Clinical Research Center, Central Hospital Affiliated to Shandong First Medical University, Jinan, 250013, China
| | - Hongli Mu
- Department of Clinical Research Center, Central Hospital Affiliated to Shandong First Medical University, Jinan, 250013, China
| | - Yuanming Song
- Department of Clinical Research Center, Central Hospital Affiliated to Shandong First Medical University, Jinan, 250013, China
| | - Hengli Zhao
- Department of Clinical Research Center, Central Hospital Affiliated to Shandong First Medical University, Jinan, 250013, China.
| |
Collapse
|
3
|
Wang J, Han S, Ye J. Topological regulation of a transmembrane protein by luminal-to-cytosolic retrotranslocation of glycosylated sequence. Cell Rep 2023; 42:112311. [PMID: 36972171 PMCID: PMC10520219 DOI: 10.1016/j.celrep.2023.112311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 02/02/2023] [Accepted: 03/11/2023] [Indexed: 03/28/2023] Open
Abstract
Transmembrane proteins must adopt proper topology to perform their functions. We previously demonstrated that ceramide regulates TM4SF20 (transmembrane 4 L6 family 20) by altering the topology of the transmembrane protein, but the underlying mechanism remains obscure. Here we report that TM4SF20 is synthesized in the endoplasmic reticulum (ER) with a cytosolic C terminus and a luminal loop before the last transmembrane helix where N132, N148, and N163 are glycosylated. In the absence of ceramide, the sequence surrounding glycosylated N163 but not N132 is retrotranslocated from lumen to cytosol independent of ER-associated degradation. Accompanying this retrotranslocation, the C terminus of the protein is relocated from cytosol to lumen. Ceramide delays the retrotranslocation process, causing accumulation of the protein that is originally synthesized. Our findings suggest that N-linked glycans, although synthesized in the lumens, may be exposed to cytosol through retrotranslocation, a reaction that may play a crucial role in topological regulation of transmembrane proteins.
Collapse
Affiliation(s)
- Jingcheng Wang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sungwon Han
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jin Ye
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| |
Collapse
|
4
|
Overview of Sigma-1R Subcellular Specific Biological Functions and Role in Neuroprotection. Int J Mol Sci 2023; 24:ijms24031971. [PMID: 36768299 PMCID: PMC9916267 DOI: 10.3390/ijms24031971] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/15/2023] [Accepted: 01/17/2023] [Indexed: 01/20/2023] Open
Abstract
For the past several years, fundamental research on Sigma-1R (S1R) protein has unveiled its necessity for maintaining proper cellular homeostasis through modulation of calcium and lipid exchange between the endoplasmic reticulum (ER) and mitochondria, ER-stress response, and many other mechanisms. Most of these processes, such as ER-stress response and autophagy, have been associated with neuroprotective roles. In fact, improving these mechanisms using S1R agonists was beneficial in several brain disorders including neurodegenerative diseases. In this review, we will examine S1R subcellular localization and describe S1R-associated biological activity within these specific compartments, i.e., the Mitochondrion-Associated ER Membrane (MAM), ER-Lipid Droplet (ER-LD) interface, ER-Plasma Membreane (ER-PM) interface, and the Nuclear Envelope (NE). We also discussed how the dysregulation of these pathways contributes to neurodegenerative diseases, while highlighting the cellular mechanisms and key binding partners engaged in these processes.
Collapse
|
5
|
Balazova L, Balaz M, Horvath C, Horváth Á, Moser C, Kovanicova Z, Ghosh A, Ghoshdastider U, Efthymiou V, Kiehlmann E, Sun W, Dong H, Ding L, Amri EZ, Nuutila P, Virtanen KA, Niemi T, Ukropcova B, Ukropec J, Pelczar P, Lamla T, Hamilton B, Neubauer H, Wolfrum C. GPR180 is a component of TGFβ signalling that promotes thermogenic adipocyte function and mediates the metabolic effects of the adipocyte-secreted factor CTHRC1. Nat Commun 2021; 12:7144. [PMID: 34880217 PMCID: PMC8655035 DOI: 10.1038/s41467-021-27442-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 11/17/2021] [Indexed: 12/12/2022] Open
Abstract
Activation of thermogenic brown and beige adipocytes is considered as a strategy to improve metabolic control. Here, we identify GPR180 as a receptor regulating brown and beige adipocyte function and whole-body glucose homeostasis, whose expression in humans is associated with improved metabolic control. We demonstrate that GPR180 is not a GPCR but a component of the TGFβ signalling pathway and regulates the activity of the TGFβ receptor complex through SMAD3 phosphorylation. In addition, using genetic and pharmacological tools, we provide evidence that GPR180 is required to manifest Collagen triple helix repeat containing 1 (CTHRC1) action to regulate brown and beige adipocyte activity and glucose homeostasis. In this work, we show that CTHRC1/GPR180 signalling integrates into the TGFβ signalling as an alternative axis to fine-tune and achieve low-grade activation of the pathway to prevent pathophysiological response while contributing to control of glucose and energy metabolism.
Collapse
Affiliation(s)
- Lucia Balazova
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Miroslav Balaz
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
- Institute of Experimental Endocrinology, Biomedical Research Center at the Slovak Academy of Sciences, 84505, Bratislava, Slovakia
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University in Bratislava, 84215, Bratislava, Slovakia
| | - Carla Horvath
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Áron Horváth
- Biomechanics Laboratory, University Hospital Balgrist, University of Zurich, 8008, Zurich, Switzerland
- Institute of Biomechanics, ETH Zurich, 8093, Zurich, Switzerland
| | - Caroline Moser
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Zuzana Kovanicova
- Institute of Experimental Endocrinology, Biomedical Research Center at the Slovak Academy of Sciences, 84505, Bratislava, Slovakia
| | - Adhideb Ghosh
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
- Functional Genomics Centre Zurich, ETH Zurich/ University of Zurich, 8057, Zurich, Switzerland
| | - Umesh Ghoshdastider
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Vissarion Efthymiou
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Elke Kiehlmann
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Wenfei Sun
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Hua Dong
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Lianggong Ding
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland
| | - Ez-Zoubir Amri
- Université Côte d'Azur, French National Centre for Scientific Research, Inserm, iBV, 06107, Nice, France
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, 20520, Turku, Finland
| | | | - Tarja Niemi
- Department of Surgery, Turku University Hospital, 20520, Turku, Finland
| | - Barbara Ukropcova
- Institute of Experimental Endocrinology, Biomedical Research Center at the Slovak Academy of Sciences, 84505, Bratislava, Slovakia
- Institute of Pathophysiology, Faculty of Medicine, Comenius University, 81108, Bratislava, Slovakia
| | - Jozef Ukropec
- Institute of Experimental Endocrinology, Biomedical Research Center at the Slovak Academy of Sciences, 84505, Bratislava, Slovakia
| | - Pawel Pelczar
- Center for Transgenic Models, University of Basel, 3350, Basel, Switzerland
| | - Thorsten Lamla
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397, Biberach an der Riss, Germany
| | - Bradford Hamilton
- Cardiometabolic Diseases Research Department, Boehringer Ingelheim Pharma GmbH and Co. KG, 88397, Biberach an der Riss, Germany
| | - Heike Neubauer
- Cardiometabolic Diseases Research Department, Boehringer Ingelheim Pharma GmbH and Co. KG, 88397, Biberach an der Riss, Germany
| | - Christian Wolfrum
- Institute of Food, Nutrition and Health, ETH Zürich, 8603, Schwerzenbach, Switzerland.
| |
Collapse
|
6
|
Deng Y, You L, Lu Y, Han S, Wang J, Vicas N, Chen C, Ye J. Identification of TRAMs as sphingolipid-binding proteins using a photoactivatable and clickable short-chain ceramide analog. J Biol Chem 2021; 297:101415. [PMID: 34793833 PMCID: PMC8665359 DOI: 10.1016/j.jbc.2021.101415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/03/2021] [Accepted: 11/11/2021] [Indexed: 11/25/2022] Open
Abstract
Ceramide is a lipid molecule that regulates diverse physiological and pathological reactions in part through inverting the topology of certain transmembrane proteins. This topological inversion is achieved through regulated alternative translocation (RAT), which reverses the direction by which membrane proteins are translocated across the endoplasmic reticulum during translation. However, owing to technical challenges in studying protein-ceramide interaction, it remains unclear how ceramide levels are sensed in cells to trigger RAT. Here, we report the synthesis of pac-C7-Cer, a photoactivatable and clickable short-chain ceramide analog that can be used as a probe to study protein-ceramide interactions. We demonstrate that translocating chain-associated membrane protein 2 (TRAM2), a protein known to control RAT of transmembrane 4 L6 subfamily member 20, and TRAM1, a homolog of TRAM2, interacted with molecules derived from pac-C7-Cer. This interaction was competed by naturally existing long-chain ceramide molecules. We showed that binding of ceramide and its analogs to TRAM2 correlated with their ability to induce RAT of transmembrane 4 L6 subfamily member 20. In addition to probing ceramide-TRAM interactions, we provide evidence that pac-C7-cer could be used for proteome-wide identification of ceramide-binding proteins. Our study provides mechanistic insights into RAT by identifying TRAMs as potential ceramide-binding proteins and establishes pac-C7-Cer as a valuable tool for future study of ceramide-protein interactions.
Collapse
Affiliation(s)
- Yaqin Deng
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Lin You
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Yong Lu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sungwon Han
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jingcheng Wang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Nikitha Vicas
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Chuo Chen
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jin Ye
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
| |
Collapse
|
7
|
Fowell DJ, Kim M. The spatio-temporal control of effector T cell migration. Nat Rev Immunol 2021; 21:582-596. [PMID: 33627851 PMCID: PMC9380693 DOI: 10.1038/s41577-021-00507-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2021] [Indexed: 02/08/2023]
Abstract
Effector T cells leave the lymph nodes armed with specialized functional attributes. Their antigenic targets may be located anywhere in the body, posing the ultimate challenge: how to efficiently identify the target tissue, navigate through a complex tissue matrix and, ultimately, locate the immunological insult. Recent advances in real-time in situ imaging of effector T cell migratory behaviour have revealed a great degree of mechanistic plasticity that enables effector T cells to push and squeeze their way through inflamed tissues. This process is shaped by an array of 'stop' and 'go' guidance signals including target antigens, chemokines, integrin ligands and the mechanical cues of the inflamed microenvironment. Effector T cells must sense and interpret these competing signals to correctly position themselves to mediate their effector functions for complete and durable responses in infectious disease and malignancy. Tuning T cell migration therapeutically will require a new understanding of this complex decision-making process.
Collapse
Affiliation(s)
- Deborah J. Fowell
- David H. Smith Center for Vaccine Biology and Immunology, Aab Institute for Biomedical Sciences, Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY.,Department of Microbiology and Immunology, Cornell University, Ithaca, NY
| | - Minsoo Kim
- David H. Smith Center for Vaccine Biology and Immunology, Aab Institute for Biomedical Sciences, Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY
| |
Collapse
|
8
|
Olona A, Hateley C, Muralidharan S, Wenk MR, Torta F, Behmoaras J. Sphingolipid metabolism during Toll-like receptor 4 (TLR4)-mediated macrophage activation. Br J Pharmacol 2021; 178:4575-4587. [PMID: 34363204 DOI: 10.1111/bph.15642] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/18/2021] [Accepted: 07/27/2021] [Indexed: 12/14/2022] Open
Abstract
Macrophage activation in response to stimulation of Toll-like receptor 4 (TLR4) provides a paradigm for investigating energy metabolism that regulates the inflammatory response. TLR4-mediated pro-inflammatory macrophage activation is characterized by increased glycolysis and altered mitochondrial metabolism, supported by selective amino acid uptake and/or usage. Fatty acid metabolism remains as a highly complex rewiring that accompanies classical macrophage activation. TLR4 activation leads to de novo synthesis of fatty acids, which flux into sphingolipids, complex lipids that form the building blocks of eukaryotic cell membranes and regulate cell function. Here, we review the importance of TLR4-mediated de novo synthesis of membrane sphingolipids in macrophages. We first highlight fatty acid metabolism during TLR4-driven macrophage immunometabolism. We then focus on the temporal dynamics of sphingolipid biosynthesis and emphasize the modulatory role of some sphingolipid species (i.e. sphingomyelins, ceramides and glycosphingolipids) on the pro-inflammatory and pro-resolution phases of LPS/TLR4 activation in macrophages.
Collapse
Affiliation(s)
- Antoni Olona
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - Charlotte Hateley
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | | | - Markus R Wenk
- SLING, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Federico Torta
- SLING, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Jacques Behmoaras
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.,Programme in Cardiovascular and Metabolic Disorders and Centre for Computational Biology, Duke-NUS Medical School Singapore, Republic of Singapore
| |
Collapse
|
9
|
Ye J. Regulated Alternative Translocation: A Mechanism Regulating Transmembrane Proteins Through Topological Inversion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 21:183-190. [PMID: 32986129 DOI: 10.1007/5584_2020_585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2023]
Abstract
Transmembrane proteins must adopt a proper topology to execute their functions. In mammalian cells, a transmembrane protein is believed to adopt a fixed topology. This assumption has been challenged by recent reports that ceramide or related sphingolipids regulate some transmembrane proteins by inverting their topology. Ceramide inverts the topology of certain newly synthesized polytopic transmembrane proteins by altering the direction through which their first transmembrane helices are translocated across membranes. Thus, this regulatory mechanism has been designated as Regulated Alternative Translocation (RAT). The physiological importance of this topological regulation has been demonstrated by the finding that ceramide-induced RAT of TM4SF20 (Transmembrane 4 L6 family member 20) is crucial for the effectiveness of doxorubicin-based chemotherapy, and that dihydroceramide-induced RAT of CCR5 (C-C chemokine receptor type 5), a G protein-coupled receptor, is required for lipopolysaccharide (LPS) to inhibit chemotaxis of macrophages. These observations suggest that topological inversion through RAT could be an emerging mechanism to regulate transmembrane proteins.
Collapse
Affiliation(s)
- Jin Ye
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| |
Collapse
|
10
|
Ye J. Transcription factors activated through RIP (regulated intramembrane proteolysis) and RAT (regulated alternative translocation). J Biol Chem 2020; 295:10271-10280. [PMID: 32487748 DOI: 10.1074/jbc.rev120.012669] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 05/26/2020] [Indexed: 12/21/2022] Open
Abstract
Transmembrane proteins are membrane-anchored proteins whose topologies are important for their functions. These properties enable regulation of certain transmembrane proteins by regulated intramembrane proteolysis (RIP) and regulated alternative translocation (RAT). RIP enables a protein fragment of a transmembrane precursor to function at a new location, and RAT leads to an inverted topology of a transmembrane protein by altering the direction of its translocation across membranes during translation. RIP mediated by site-1 protease (S1P) and site-2 protease (S2P) is involved in proteolytic activation of membrane-bound transcription factors. In resting cells, these transcription factors remain in the endoplasmic reticulum (ER) as inactive transmembrane precursors. Upon stimulation by signals within the ER, they are translocated from the ER to the Golgi. There, they are cleaved first by S1P and then by S2P, liberating their N-terminal domains from membranes and enabling them to activate genes in the nucleus. This signaling pathway regulates lipid metabolism, unfolded protein responses, secretion of extracellular matrix proteins, and cell proliferation. Remarkably, ceramide-induced RIP of cAMP response element-binding protein 3-like 1 (CREB3L1) also involves RAT. In resting cells, RIP of CREB3L1 is blocked by transmembrane 4 L6 family member 20 (TM4SF20). Ceramide inverts the orientation of newly synthesized TM4SF20 in membranes through RAT, converting TM4SF20 from an inhibitor to an activator of RIP of CREB3L1. Here, I review recent insights into RIP of membrane-bound transcription factors, focusing on CREB3L1 activation through both RIP and RAT, and discuss current open questions about these two signaling pathways.
Collapse
Affiliation(s)
- Jin Ye
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| |
Collapse
|
11
|
Tachida Y, Kumagai K, Sakai S, Ando S, Yamaji T, Hanada K. Chlamydia trachomatis-infected human cells convert ceramide to sphingomyelin without sphingomyelin synthases 1 and 2. FEBS Lett 2019; 594:519-529. [PMID: 31596951 DOI: 10.1002/1873-3468.13632] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/27/2019] [Accepted: 09/27/2019] [Indexed: 12/19/2022]
Abstract
The obligate intracellular bacterium Chlamydia trachomatis proliferates in the membranous compartment inclusion formed in host cells. The host ceramide transport protein CERT delivers ceramide from the endoplasmic reticulum to the Golgi complex for the synthesis of sphingomyelin (SM). Chlamydia trachomatis has been suggested to employ CERT to produce SM in the inclusion by host SM synthases (SMSs). Here, we found that C. trachomatis proliferates and produces infective progeny even in SMS1 and SMS2 double-knockout HeLa cells, but not in the SMS1/SMS2/CERT triple-knockout cells. Interestingly, infected cells convert ceramide to SM without host SMSs. These results suggest that C. trachomatis-infected cells can convert ceramide to SM without host SMSs after CERT-mediated transfer of ceramide to the inclusions.
Collapse
Affiliation(s)
- Yuriko Tachida
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Japan
| | - Keigo Kumagai
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Japan
| | - Shota Sakai
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Japan
| | - Shuji Ando
- Department of Virology I, National Institute of Infectious Diseases, Shinjuku-ku, Japan
| | - Toshiyuki Yamaji
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Japan
| | - Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Japan
| |
Collapse
|