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Kuo A, Hla T. Regulation of cellular and systemic sphingolipid homeostasis. Nat Rev Mol Cell Biol 2024; 25:802-821. [PMID: 38890457 DOI: 10.1038/s41580-024-00742-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2024] [Indexed: 06/20/2024]
Abstract
One hundred and fifty years ago, Johann Thudichum described sphingolipids as unusual "Sphinx-like" lipids from the brain. Today, we know that thousands of sphingolipid molecules mediate many essential functions in embryonic development and normal physiology. In addition, sphingolipid metabolism and signalling pathways are dysregulated in a wide range of pathologies, and therapeutic agents that target sphingolipids are now used to treat several human diseases. However, our understanding of sphingolipid regulation at cellular and organismal levels and their functions in developmental, physiological and pathological settings is rudimentary. In this Review, we discuss recent advances in sphingolipid pathways in different organelles, how secreted sphingolipid mediators modulate physiology and disease, progress in sphingolipid-targeted therapeutic and diagnostic research, and the trans-cellular sphingolipid metabolic networks between microbiota and mammals. Advances in sphingolipid biology have led to a deeper understanding of mammalian physiology and may lead to progress in the management of many diseases.
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Affiliation(s)
- Andrew Kuo
- Vascular Biology Program, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA, USA
| | - Timothy Hla
- Vascular Biology Program, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA, USA.
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2
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Prudovsky I. Cellular Mechanisms of FGF-Stimulated Tissue Repair. Cells 2021; 10:cells10071830. [PMID: 34360000 PMCID: PMC8304273 DOI: 10.3390/cells10071830] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 01/10/2023] Open
Abstract
Growth factors belonging to the FGF family play important roles in tissue and organ repair after trauma. In this review, I discuss the regulation by FGFs of the aspects of cellular behavior important for reparative processes. In particular, I focus on the FGF-dependent regulation of cell proliferation, cell stemness, de-differentiation, inflammation, angiogenesis, cell senescence, cell death, and the production of proteases. In addition, I review the available literature on the enhancement of FGF expression and secretion in damaged tissues resulting in the increased FGF supply required for tissue repair.
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Affiliation(s)
- Igor Prudovsky
- Maine Medical Center Research Institute, 81 Research Dr., Scarborough, ME 04074, USA
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3
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Sluzalska KD, Slawski J, Sochacka M, Lampart A, Otlewski J, Zakrzewska M. Intracellular partners of fibroblast growth factors 1 and 2 - implications for functions. Cytokine Growth Factor Rev 2020; 57:93-111. [PMID: 32475760 DOI: 10.1016/j.cytogfr.2020.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/04/2020] [Accepted: 05/07/2020] [Indexed: 01/01/2023]
Abstract
Fibroblast growth factors 1 and 2 (FGF1 and FGF2) are mainly considered as ligands of surface receptors through which they regulate a broad spectrum of biological processes. They are secreted in non-canonical way and, unlike other growth factors, they are able to translocate from the endosome to the cell interior. These unique features, as well as the role of the intracellular pool of FGF1 and FGF2, are far from being fully understood. An increasing number of reports address this problem, focusing on the intracellular interactions of FGF1 and 2. Here, we summarize the current state of knowledge of the FGF1 and FGF2 binding partners inside the cell and the possible role of these interactions. The partner proteins are grouped according to their function, including proteins involved in secretion, cell signaling, nucleocytoplasmic transport, binding and processing of nucleic acids, ATP binding, and cytoskeleton assembly. An in-depth analysis of the network of these binding partners could indicate novel, non-classical functions of FGF1 and FGF2 and uncover an additional level of a fine control of the well-known FGF-regulated cellular processes.
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Affiliation(s)
- Katarzyna Dominika Sluzalska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Jakub Slawski
- Department of Biophysics, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Martyna Sochacka
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Agata Lampart
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Jacek Otlewski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Malgorzata Zakrzewska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland.
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4
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Kirov A, Kacer D, Conley BA, Vary CPH, Prudovsky I. AHNAK2 Participates in the Stress-Induced Nonclassical FGF1 Secretion Pathway. J Cell Biochem 2016; 116:1522-31. [PMID: 25560297 DOI: 10.1002/jcb.25047] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 12/16/2014] [Indexed: 12/22/2022]
Abstract
FGF1 is a nonclassically released growth factor that regulates carcinogenesis, angiogenesis, and inflammation. In vitro and in vivo, FGF1 export is stimulated by cell stress. Upon stress, FGF1 is transported to the plasma membrane where it localizes prior to transmembrane translocation. To determine which proteins participate in the submembrane localization of FGF1 and its export, we used immunoprecipitation mass spectrometry to identify novel proteins that associate with FGF1 during heat shock. The heat shock-dependent association of FGF1 with the large protein AHNAK2 was observed. Heat shock induced the translocation of FGF1 and AHNAK2 to the cytoskeletal fraction. In heat-shocked cells, FGF1 and the C-terminal fragment of AHNAK2 colocalized with F-actin in the vicinity of the cell membrane. Depletion of AHNAK2 resulted in a drastic decrease of stress-induced FGF1 export but did not affect spontaneous FGF2 export and FGF1 release induced by the inhibition of Notch signaling. Thus, AHNAK2 is an important element of the FGF1 nonclassical export pathway.
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Affiliation(s)
- Aleksandr Kirov
- Center for Molecular Medicine, Maine Medical Center Research Institute, Maine Medical Center, Scarborough, 04074, Maine
| | - Doreen Kacer
- Center for Molecular Medicine, Maine Medical Center Research Institute, Maine Medical Center, Scarborough, 04074, Maine
| | - Barbara A Conley
- Center for Molecular Medicine, Maine Medical Center Research Institute, Maine Medical Center, Scarborough, 04074, Maine
| | - Calvin P H Vary
- Center for Molecular Medicine, Maine Medical Center Research Institute, Maine Medical Center, Scarborough, 04074, Maine
| | - Igor Prudovsky
- Center for Molecular Medicine, Maine Medical Center Research Institute, Maine Medical Center, Scarborough, 04074, Maine
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5
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Geng T, Sutter A, Harland MD, Law BA, Ross JS, Lewin D, Palanisamy A, Russo SB, Chavin KD, Cowart LA. SphK1 mediates hepatic inflammation in a mouse model of NASH induced by high saturated fat feeding and initiates proinflammatory signaling in hepatocytes. J Lipid Res 2015; 56:2359-71. [PMID: 26482537 DOI: 10.1194/jlr.m063511] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Indexed: 11/20/2022] Open
Abstract
Steatohepatitis occurs in up to 20% of patients with fatty liver disease and leads to its primary disease outcomes, including fibrosis, cirrhosis, and increased risk of hepatocellular carcinoma. Mechanisms that mediate this inflammation are of major interest. We previously showed that overload of saturated fatty acids, such as that which occurs with metabolic syndrome, induced sphingosine kinase 1 (SphK1), an enzyme that generates sphingosine-1-phosphate (S1P). While data suggest beneficial roles for S1P in some contexts, we hypothesized that it may promote hepatic inflammation in the context of obesity. Consistent with this, we observed 2-fold elevation of this enzyme in livers from humans with nonalcoholic fatty liver disease and also in mice with high saturated fat feeding, which recapitulated the human disease. Mice exhibited activation of NFκB, elevated cytokine production, and immune cell infiltration. Importantly, SphK1-null mice were protected from these outcomes. Studies in cultured cells demonstrated saturated fatty acid induction of SphK1 message, protein, and activity, and also a requirement of the enzyme for NFκB signaling and increased mRNA encoding TNFα and MCP1. Moreover, saturated fat-induced NFκB signaling and elevation of TNFα and MCP1 mRNA in HepG2 cells was blocked by targeted knockdown of S1P receptor 1, supporting a role for this lipid signaling pathway in inflammation in nonalcoholic fatty liver disease.
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Affiliation(s)
- Tuoyu Geng
- Departments of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425
| | - Alton Sutter
- Surgery, Medical University of South Carolina, Charleston, SC 29425
| | - Michael D Harland
- Departments of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425
| | - Brittany A Law
- Departments of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425 Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29403
| | - Jessica S Ross
- Departments of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425
| | - David Lewin
- Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425
| | - Arun Palanisamy
- Surgery, Medical University of South Carolina, Charleston, SC 29425
| | - Sarah B Russo
- Departments of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425
| | - Kenneth D Chavin
- Surgery, Medical University of South Carolina, Charleston, SC 29425
| | - L Ashley Cowart
- Departments of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425 Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29403
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6
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Jayanthi S, Kathir KM, Rajalingam D, Furr M, Daily A, Thurman R, Rutherford L, Chandrashekar R, Adams P, Prudovsky I, Kumar TKS. Copper binding affinity of the C2B domain of synaptotagmin-1 and its potential role in the nonclassical secretion of acidic fibroblast growth factor. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:2155-63. [PMID: 25224745 DOI: 10.1016/j.bbapap.2014.09.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 08/20/2014] [Accepted: 09/07/2014] [Indexed: 01/27/2023]
Abstract
Fibroblast growth factor 1 (FGF1) is a heparin-binding proangiogenic protein. FGF1 lacks the conventional N-terminal signal peptide required for secretion through the endoplasmic reticulum (ER)-Golgi secretory pathway. FGF1 is released through a Cu(2+)-mediated nonclassical secretion pathway. The secretion of FGF1 involves the formation of a Cu(2+)-mediated multiprotein release complex (MRC) including FGF1, S100A13 (a calcium-binding protein) and p40 synaptotagmin (Syt1). It is believed that the binding of Cu(2+) to the C2B domain is important for the release of FGF1 into the extracellular medium. In this study, using a variety of biophysical studies, Cu(2+) and lipid interactions of the C2B domain of Syt1 were characterized. Isothermal titration calorimetry (ITC) experiments reveal that the C2B domain binds to Cu(2+) in a biphasic manner involving an initial endothermic and a subsequent exothermic phase. Fluorescence energy transfer experiments using Tb(3+) show that there are two Cu(2+)-binding pockets on the C2B domain, and one of these is also a Ca(2+)-binding site. Lipid-binding studies using ITC demonstrate that the C2B domain preferentially binds to small unilamellar vesicles of phosphatidyl serine (PS). Results of the differential scanning calorimetry and limited trypsin digestion experiments suggest that the C2B domain is marginally destabilized upon binding to PS vesicles. These results, for the first time, suggest that the main role of the C2B domain of Syt1 is to serve as an anchor for the FGF1 MRC on the membrane bilayer. In addition, the binding of the C2B domain to the lipid bilayer is shown to significantly decrease the binding affinity of the protein to Cu(2+). The study provides valuable insights on the sequence of structural events that occur in the nonclassical secretion of FGF1.
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Affiliation(s)
- Srinivas Jayanthi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
| | | | | | - Mercede Furr
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
| | - Anna Daily
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
| | - Ryan Thurman
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
| | - Lindsay Rutherford
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
| | - Reena Chandrashekar
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
| | - Paul Adams
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
| | - Igor Prudovsky
- Maine Medical Center Research Institute, Scarborough, ME 04074, USA.
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7
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Abstract
Copper is an essential element in many biological processes. The critical functions associated with copper have resulted from evolutionary harnessing of its potent redox activity. This same property also places copper in a unique role as a key modulator of cell signal transduction pathways. These pathways are the complex sequence of molecular interactions that drive all cellular mechanisms and are often associated with the interplay of key enzymes including kinases and phosphatases but also including intracellular changes in pools of smaller molecules. A growing body of evidence is beginning to delineate the how, when and where of copper-mediated control over cell signal transduction. This has been driven by research demonstrating critical changes to copper homeostasis in many disorders including cancer and neurodegeneration and therapeutic potential through control of disease-associated cell signalling changes by modulation of copper-protein interactions. This timely review brings together for the first time the diverse actions of copper as a key regulator of cell signalling pathways and discusses the potential strategies for controlling disease-associated signalling processes using copper modulators. It is hoped that this review will provide a valuable insight into copper as a key signal regulator and stimulate further research to promote our understanding of copper in disease and therapy.
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8
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Alshaker H, Sauer L, Monteil D, Ottaviani S, Srivats S, Böhler T, Pchejetski D. Therapeutic potential of targeting SK1 in human cancers. Adv Cancer Res 2013; 117:143-200. [PMID: 23290780 DOI: 10.1016/b978-0-12-394274-6.00006-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sphingosine kinase 1 (SK1) is a lipid enzyme with oncogenic properties that converts the proapoptotic lipids ceramide and sphingosine into the antiapoptotic lipid sphingosine-1-phosphate and activates the signal transduction pathways that lead to cell proliferation, migration, the activation of the inflammatory response, and the impairment of apoptosis. There is compelling evidence that SK1 activation contributes to cancer progression leading to increased oncogenic transformation, tumor growth, resistance to therapies, tumor neovascularization, and metastatic spread. High levels of SK1 expression or activity have been associated with a poor prognosis in several human cancers. Recent studies using cancer cell and mouse models demonstrate a significant potential for SK1-targeting therapies to synergize with the effects of chemotherapy and radiotherapy; however, until recently the absence of clinically applicable SK1 inhibitors has limited the translation of these findings into patients. With the recent discovery of SK1 inhibiting properties of a clinically approved drug FTY720 (Fingolimod), SK1 has gained significant attention from both clinicians and the pharmaceutical industry and it is hoped that trials of newly developed SK1 inhibitors may follow soon. This review provides an overview of the SK1 signaling, its relevance to cancer progression, and the potential clinical significance of targeting SK1 for improved local or systemic control of human cancers.
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Affiliation(s)
- Heba Alshaker
- Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, United Kingdom
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9
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Prudovsky I, Kumar TKS, Sterling S, Neivandt D. Protein-phospholipid interactions in nonclassical protein secretion: problem and methods of study. Int J Mol Sci 2013; 14:3734-72. [PMID: 23396106 PMCID: PMC3588068 DOI: 10.3390/ijms14023734] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 12/30/2022] Open
Abstract
Extracellular proteins devoid of signal peptides use nonclassical secretion mechanisms for their export. These mechanisms are independent of the endoplasmic reticulum and Golgi. Some nonclassically released proteins, particularly fibroblast growth factors (FGF) 1 and 2, are exported as a result of their direct translocation through the cell membrane. This process requires specific interactions of released proteins with membrane phospholipids. In this review written by a cell biologist, a structural biologist and two membrane engineers, we discuss the following subjects: (i) Phenomenon of nonclassical protein release and its biological significance; (ii) Composition of the FGF1 multiprotein release complex (MRC); (iii) The relationship between FGF1 export and acidic phospholipid externalization; (iv) Interactions of FGF1 MRC components with acidic phospholipids; (v) Methods to study the transmembrane translocation of proteins; (vi) Membrane models to study nonclassical protein release.
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Affiliation(s)
- Igor Prudovsky
- Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME 04074, USA
| | | | - Sarah Sterling
- Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04469, USA; E-Mails: (S.S.); (D.N.)
| | - David Neivandt
- Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04469, USA; E-Mails: (S.S.); (D.N.)
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10
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Abstract
Many secreted polypeptide regulators of angiogenesis are devoid of signal peptides. These proteins are released through nonclassical pathways independent of endoplasmic reticulum and Golgi. In most cases, the nonclassical protein export is induced by stress. It usually serves to stimulate repair or inflammation in damaged tissues. We review the secreted signal peptide-less regulators of angiogenesis and discuss the mechanisms and biological significance of their unconventional export.
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Affiliation(s)
- Igor Prudovsky
- Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME 04074, USA
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11
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Kirov A, Al-Hashimi H, Solomon P, Mazur C, Thorpe PE, Sims PJ, Tarantini F, Kumar TKS, Prudovsky I. Phosphatidylserine externalization and membrane blebbing are involved in the nonclassical export of FGF1. J Cell Biochem 2012; 113:956-66. [PMID: 22034063 DOI: 10.1002/jcb.23425] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mechanisms of nonclassical export of signal peptide-less proteins remain insufficiently understood. Here, we demonstrate that stress-induced unconventional export of FGF1, a potent and ubiquitously expressed mitogenic and proangiogenic protein, is associated with and dependent on the formation of membrane blebs and localized cell surface exposure of phosphatidylserine (PS). In addition, we found that the differentiation of promonocytic cells results in massive FGF1 release, which also correlates with membrane blebbing and exposure of PS. These findings indicate that the externalization of acidic phospholipids could be used as a pharmacological target to regulate the availability of FGF1 in the organism.
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Affiliation(s)
- Aleksandr Kirov
- Maine Medical Center Research Institute, Scarborough, Maine Medical Center, ME 04074, USA
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12
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Kacer D, McIntire C, Kirov A, Kany E, Roth J, Liaw L, Small D, Friesel R, Basilico C, Tarantini F, Verdi J, Prudovsky I. Regulation of non-classical FGF1 release and FGF-dependent cell transformation by CBF1-mediated notch signaling. J Cell Physiol 2011; 226:3064-75. [PMID: 21302306 DOI: 10.1002/jcp.22663] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
FGF1, a widely expressed proangiogenic factor involved in tissue repair and carcinogenesis, is released from cells through a non-classical pathway independent of endoplasmic reticulum and Golgi. Although several proteins participating in FGF1 export were identified, genetic mechanisms regulating this process remained obscure. We found that FGF1 export and expression are regulated through Notch signaling mediated by transcription factor CBF1 and its partner MAML. The expression of a dominant negative (dn) form of CBF1 in 3T3 cells induces transcription of FGF1 and sphingosine kinase 1 (SphK1), which is a component of FGF1 export pathway. dnCBF1 expression stimulates the stress-independent release of transduced FGF1 from NIH 3T3 cells and endogenous FGF1 from A375 melanoma cells. NIH 3T3 cells transfected with dnCBF1 form colonies in soft agar and produce rapidly growing highly angiogenic tumors in nude mice. The transformed phenotype of dnCBF1 transfected cells is efficiently blocked by dn forms of FGF receptor 1 and S100A13, which is a component of FGF1 export pathway. FGF1 export and acceleration of cell growth induced by dnCBF1 depend on SphK1. Similar to dnCBF1, dnMAML transfection induces FGF1 expression and release, and accelerates cell proliferation. The latter effect is strongly decreased in FGF1 null cells. We suggest that the regulation of FGF1 expression and release by CBF1-mediated Notch signaling can play an important role in tumor formation.
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Affiliation(s)
- Doreen Kacer
- Maine Medical Center Research Institute, Scarborough, Maine 04074, USA
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13
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Pitson SM. Regulation of sphingosine kinase and sphingolipid signaling. Trends Biochem Sci 2011; 36:97-107. [DOI: 10.1016/j.tibs.2010.08.001] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Revised: 08/16/2010] [Accepted: 08/16/2010] [Indexed: 01/09/2023]
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14
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Mohan SK, Yu C. The IL1alpha-S100A13 heterotetrameric complex structure: a component in the non-classical pathway for interleukin 1alpha secretion. J Biol Chem 2011; 286:14608-17. [PMID: 21270123 DOI: 10.1074/jbc.m110.201954] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Interleukin 1α (IL1α) plays an important role in several key biological functions, such as angiogenesis, cell proliferation, and tumor growth in several types of cancer. IL1α is a potent cytokine that induces a wide spectrum of immunological and inflammatory activities. The biological effects of IL1α are mediated through the activation of transmembrane receptors (IL1Rs) and therefore require the release of the protein into the extracellular space. IL1α is exported through a non-classical release pathway involving the formation of a specific multiprotein complex, which includes IL1α and S100A13. Because IL1α plays an important role in cell proliferation and angiogenesis, inhibiting the formation of the IL1α-S100A13 complex would be an effective strategy to inhibit a wide range of cancers. To understand the molecular events in the IL1α release pathway, we studied the structure of the IL1α-S100A13 tetrameric complex, which is the key complex formed during the non-classical pathway of IL1α release.
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Affiliation(s)
- Sepuru K Mohan
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
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15
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An active form of sphingosine kinase-1 is released in the extracellular medium as component of membrane vesicles shed by two human tumor cell lines. JOURNAL OF ONCOLOGY 2010; 2010:509329. [PMID: 20508814 PMCID: PMC2875746 DOI: 10.1155/2010/509329] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Accepted: 03/08/2010] [Indexed: 01/23/2023]
Abstract
Expression of sphingosine kinase-1 (SphK-1) correlates with a poor survival rate of tumor patients. This effect is probably due to the ability of SphK-1 to be released into the extracellular medium where it catalyzes the biosynthesis of sphingosine-1-phosphate (S1P), a signaling molecule endowed with profound proangiogenic effects. SphK-1 is a leaderless protein which is secreted by an unconventional mechanism. In this paper, we will show that in human hepatocarcinoma Sk-Hep1 cells, extracellular signaling is followed by targeting the enzyme to the cell surface and parallels targeting of FGF-2 to the budding vesicles. We will also show that SphK-1 is present in a catalitycally active form in vesicles shed by SK-Hep1 and human breast carcinoma 8701-BC cells. The enzyme substrate sphingosine is present in shed vesicles where it is produced by neutral ceramidase. Shed vesicles are therefore a site for S1P production in the extracellular medium and conceivably also within host cell following vesicle endocytosis.
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16
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Mohan SK, Rani SG, Yu C. The heterohexameric complex structure, a component in the non-classical pathway for fibroblast growth factor 1 (FGF1) secretion. J Biol Chem 2010; 285:15464-15475. [PMID: 20220137 DOI: 10.1074/jbc.m109.066357] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fibroblast growth factors (FGFs) are key regulators of cell proliferation, tumor-induced angiogenesis, and migration. FGFs are essential for early embryonic development, organ formation, and angiogenesis. FGF1 also plays an important role in inflammation, wound healing, and restenosis. The biological effects of FGF1 are mediated through the activation of the four transmembrane phosphotyrosine kinase fibroblast growth factor receptors in the presence of heparin sulfate proteoglycans and, therefore, require the release of the protein into the extracellular space. FGF1 is exported through a non-classical release pathway involving the formation of a specific multiprotein complex. The protein constituents of this complex include FGF1, S100A13, and the p40 form of synaptotagmin 1 (Syt1). Because FGF1 plays an important role in tumor formation, it is clear that preventing the formation of the multiprotein complex would be an effective strategy to inhibit a wide range of cancers. To understand the molecular events in the FGF1 release pathway, we studied the FGF1-S100A13 tetrameric and FGF1-S100A13-C2A hexameric complex structures, which are both complexes possibly formed during the non-classical pathway of FGF1 release.
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Affiliation(s)
- Sepuru K Mohan
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Sandhya G Rani
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chin Yu
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
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17
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NMR characterization of copper and lipid interactions of the C2B domain of synaptotagmin I-relevance to the non-classical secretion of the human acidic fibroblast growth factor (hFGF-1). BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:297-302. [PMID: 19835837 DOI: 10.1016/j.bbamem.2009.09.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 09/18/2009] [Accepted: 09/30/2009] [Indexed: 11/21/2022]
Abstract
Human fibroblast growth factor (hFGF-1) is a approximately 17 kDa heparin binding cytokine. It lacks the conventional hydrophobic N-terminal signal sequence and is secreted through non-classical secretion routes. Under stress, hFGF-1 is released as a multiprotein complex consisting of hFGF-1, S100A13 (a calcium binding protein), and p40 synaptotagmin (Syt1). Copper (Cu(2+)) is shown to be required for the formation of the multiprotein hFGF-1 release complex (Landriscina et al. ,2001; Di Serio et al., 2008). Syt1, containing the lipid binding C2B domain, is believed to play an important role in the eventual export of the hFGF-1 across the lipid bilayer. In this study, we characterize Cu(2+) and lipid interactions of the C2B domain of Syt1 using multidimensional NMR spectroscopy. The results highlight how Cu(2+) appears to stabilize the protein bound to pS vesicles. Cu(2+) and lipid binding interface mapped using 2D (1)H-(15)N heteronuclear single quantum coherence experiments reveal that residues in beta-strand I contributes to the unique Cu(2+) binding site in the C2B domain. In the absence of metal ions, residues located in Loop II and beta-strand IV contribute to binding to unilamelar pS vesicles. In the presence of Cu(2+), additional residues located in Loops I and III appear to stabilize the protein-lipid interactions. The results of this study provide valuable information towards understanding the molecular mechanism of the Cu(2+)-induced non-classical secretion of hFGF-1.
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Veldhuis NA, Valova VA, Gaeth AP, Palstra N, Hannan KM, Michell BJ, Kelly LE, Jennings I, Kemp BE, Pearson RB, Robinson PJ, Camakaris J. Phosphorylation regulates copper-responsive trafficking of the Menkes copper transporting P-type ATPase. Int J Biochem Cell Biol 2009; 41:2403-12. [PMID: 19576997 DOI: 10.1016/j.biocel.2009.06.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Revised: 06/24/2009] [Accepted: 06/25/2009] [Indexed: 12/25/2022]
Abstract
The Menkes copper-translocating P-type ATPase (ATP7A) is a critical copper transport protein functioning in systemic copper absorption and supply of copper to cuproenzymes in the secretory pathway. Mutations in ATP7A can lead to the usually lethal Menkes disease. ATP7A function is regulated by copper-responsive trafficking between the trans-Golgi Network and the plasma membrane. We have previously reported basal and copper-responsive kinase phosphorylation of ATP7A but the specific phosphorylation sites had not been identified. As copper stimulates both trafficking and phosphorylation of ATP7A we aimed to identify all the specific phosphosites and to determine whether trafficking and phosphorylation are linked. We identified twenty in vivo phosphorylation sites in the human ATP7A and eight in hamster, all clustered within the N- and C-terminal cytosolic domains. Eight sites were copper-responsive and hence candidates for regulating copper-responsive trafficking or catalytic activity. Mutagenesis of the copper-responsive phosphorylation site Serine-1469 resulted in mislocalization of ATP7A in the presence of added copper in both polarized (Madin Darby canine kidney) and non-polarized (Chinese Hamster Ovary) cells, strongly suggesting that phosphorylation of specific serine residues is required for copper-responsive ATP7A trafficking to the plasma membrane. A constitutively phosphorylated site, Serine-1432, when mutated to alanine also resulted in mislocalization in the presence of added copper in polarized Madin Darby kidney cells. These studies demonstrate that phosphorylation of specific serine residues in ATP7A regulates its sub-cellular localization and hence function and will facilitate identification of the kinases and signaling pathways involved in regulating this pivotal copper transporter.
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Affiliation(s)
- Nicholas A Veldhuis
- Genetics Department, The University of Melbourne, Melbourne, Victoria, Australia
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Graziani I, Doyle A, Sterling S, Kirov A, Tarantini F, Landriscina M, Kumar TKS, Neivandt D, Prudovsky I. Protein folding does not prevent the nonclassical export of FGF1 and S100A13. Biochem Biophys Res Commun 2009; 381:350-4. [PMID: 19233122 DOI: 10.1016/j.bbrc.2009.02.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Accepted: 02/10/2009] [Indexed: 11/18/2022]
Abstract
Newly synthesized proteins are usually exported through the endoplasmic reticulum (ER) and Golgi due to the presence in their primary sequence of a hydrophobic signal peptide that is recognized by the ER translocation system. However, some secreted proteins lack a signal peptide and are exported independently of ER-Golgi. Fibroblast growth factor (FGF)1 is included in this group of polypeptides, as well as S100A13 that is a small calcium-binding protein critical for FGF1 export. Classically secreted proteins are transported into ER in their unfolded states. To determine the role of protein tertiary structure in FGF1 export through the cell membrane, we produced the chimeras of FGF1 and S100A13 with dihydrofolate reductase (DHFR). The specific DHFR inhibitor, aminopterin, prevents its unfolding. We found that aminopterin did not inhibit the release of FGF1:DHFR and S100A13:DHFR. Thus, FGF1 and S100A13 can be exported in folded conformation.
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Affiliation(s)
- Irene Graziani
- Maine Medical Center Research Institute, Scarborough, 81 Research Dr., Scarborough, ME 04074, USA
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The multi-layered regulation of copper translocating P-type ATPases. Biometals 2009; 22:177-90. [PMID: 19130269 DOI: 10.1007/s10534-008-9183-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 12/07/2008] [Indexed: 12/21/2022]
Abstract
The copper-translocating Menkes (ATP7A, MNK protein) and Wilson (ATP7B, WND protein) P-type ATPases are pivotal for copper (Cu) homeostasis, functioning in the biosynthetic incorporation of Cu into copper-dependent enzymes of the secretory pathway, Cu detoxification via Cu efflux, and specialized roles such as systemic Cu absorption (MNK) and Cu excretion (WND). Essential to these functions is their Cu and hormone-responsive distribution between the trans-Golgi network (TGN) and exocytic vesicles located at or proximal to the apical (WND) or basolateral (MNK) cell surface. Intriguingly, MNK and WND Cu-ATPases expressed in the same tissues perform distinct yet complementary roles. While intramolecular differences may specify their distinct roles, cellular signaling components are predicted to be critical for both differences and synergy between these enzymes. This review focuses on these mechanisms, including the cell signaling pathways that influence trafficking and bi-functionality of Cu-ATPases. Phosphorylation events are hypothesized to play a central role in Cu homeostasis, promoting multi-layered regulation and cross-talk between cuproenzymes and Cu-independent mechanisms.
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Prudovsky I, Tarantini F, Landriscina M, Neivandt D, Soldi R, Kirov A, Small D, Kathir KM, Rajalingam D, Kumar TKS. Secretion without Golgi. J Cell Biochem 2008; 103:1327-43. [PMID: 17786931 PMCID: PMC2613191 DOI: 10.1002/jcb.21513] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A growing number of proteins devoid of signal peptides have been demonstrated to be released through the non-classical pathways independent of endoplasmic reticulum and Golgi. Among them are two potent proangiogenic cytokines FGF1 and IL1alpha. Stress-induced transmembrane translocation of these proteins requires the assembly of copper-dependent multiprotein release complexes. It involves the interaction of exported proteins with the acidic phospholipids of the inner leaflet of the cell membrane and membrane destabilization. Not only stress, but also thrombin treatment and inhibition of Notch signaling stimulate the export of FGF1. Non-classical release of FGF1 and IL1alpha presents a promising target for treatment of cardiovascular, oncologic, and inflammatory disorders.
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Affiliation(s)
- Igor Prudovsky
- Maine Medical Center Research Institute, Maine Medical Center, Scarborough, Maine 04074, USA.
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Stem cell regulation by lysophospholipids. Prostaglandins Other Lipid Mediat 2007; 84:83-97. [PMID: 17991611 DOI: 10.1016/j.prostaglandins.2007.08.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 08/29/2007] [Indexed: 11/24/2022]
Abstract
Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) regulate a diverse range of mammalian cell processes, largely through engaging multiple G protein-coupled receptors specific for these lysophospholipids. LPA and S1P have been clearly identified to have widespread physiological and pathophysiological actions, controlling events within the reproductive, gastrointestinal, vascular, nervous and immune systems, and also having a prominent role in cancer. Here we review the recent literature showing the additional emerging role for LPA and S1P in the regulation of stem cells and their progenitors. We discuss the role of these lysophospholipids in regulating the proliferation, survival, differentiation and migration of a range of adult and embryonic stem cells and progenitors, and thus are likely to play a substantial role in the maintenance, generation, mobilisation and homing of stem cell and progenitor populations in the body.
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