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Abstract
Chronic kidney disease (CKD) is an inherently systemic disease that refers to a long-term loss of kidney function. The progression of CKD has repercussions for other organs, leading to many kinds of extrarenal complications. Intensive studies are now being undertaken to reveal the risk factors and pathophysiological mechanism of this disease. During the past 20 years, increasing evidence from clinical and basic studies has indicated that klotho, which was initially known as an anti-aging gene and is mainly expressed in the kidney, is significantly correlated with the development and progression of CKD and its complications. Here, we discuss in detail the role and pathophysiological implications of klotho in ion disorders, the inflammation response, vascular calcification, mineral bone disorders, and renal fibrosis in CKD. Based on the pathogenic mechanism of klotho deficiency and klotho decline in urine early in CKD stage 2 and even earlier in CKD stage 1, it is not difficult to understand that soluble klotho can serve as an early and sensitive marker of CKD. Moreover, the prevention of klotho decline by several mechanisms can attenuate renal injuries, retard CKD progression, ameliorate extrarenal complications, and improve renal function. In this review, we focus on the functions and pathophysiological implications of klotho in CKD and its extrarenal complications as well as its potential applications as a diagnostic and/or prognostic biomarker for CKD and as a novel treatment strategy to improve and decrease the burden of comorbidity in CKD.
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de Albuquerque Suassuna PG, Sanders-Pinheiro H, de Paula RB. Uremic Cardiomyopathy: A New Piece in the Chronic Kidney Disease-Mineral and Bone Disorder Puzzle. Front Med (Lausanne) 2018; 5:206. [PMID: 30087898 PMCID: PMC6066558 DOI: 10.3389/fmed.2018.00206] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 07/02/2018] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular diseases are the main cause of death in chronic kidney disease (CKD) patients. In dialysis patients, sudden cardiac death accounts for 40% of all deaths. In these patients, sudden cardiac death is usually secondary to an underlying cardiomyopathy, which is clinically identified by the high prevalence of left ventricular hypertrophy and the resultant mechanical and electrical dysfunction. CKD-related cardiomyopathy has a multifactorial pathophysiology. Recent evidence has highlighted the central pathophysiological role of chronic kidney disease-mineral and bone disorder (CKD-MBD) with hyperphosphatemia and high fibroblast growth factor 23 (FGF23) levels in these patients. Further, since CKD is known to be an αKlotho deficiency state, experimental studies have demonstrated that the deleterious effects of FGF23 can be minimized by reestablishing adequate soluble Klotho levels. Herein, we present a review that addresses not only the development of the understanding of CKD-related cardiomyopathy pathophysiology, but also explores the recent data that identify the triad of hyperphosphatemia, high FGF23 levels and αKlotho deficiency as playing a central role on it. Taken together, the data suggest that the uremic cardiomyopathy can be considered a new piece in the CKD-DMO puzzle.
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Affiliation(s)
- Paulo G de Albuquerque Suassuna
- Laboratory of Experimental Nephrology and Interdisciplinary Nucleus of Laboratory Animal Studies, Federal University of Juiz de Fora, Juiz de Fora, Brazil.,Interdisciplinary Center for Studies, Research and Treatment in Nephrology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Helady Sanders-Pinheiro
- Laboratory of Experimental Nephrology and Interdisciplinary Nucleus of Laboratory Animal Studies, Federal University of Juiz de Fora, Juiz de Fora, Brazil.,Interdisciplinary Center for Studies, Research and Treatment in Nephrology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Rogério B de Paula
- Laboratory of Experimental Nephrology and Interdisciplinary Nucleus of Laboratory Animal Studies, Federal University of Juiz de Fora, Juiz de Fora, Brazil.,Interdisciplinary Center for Studies, Research and Treatment in Nephrology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
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Insulin suppresses the production of fibroblast growth factor 23 (FGF23). Proc Natl Acad Sci U S A 2018; 115:5804-5809. [PMID: 29760049 DOI: 10.1073/pnas.1800160115] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23) is produced by bone cells and regulates renal phosphate and vitamin D metabolism, as well as causing left ventricular hypertrophy. FGF23 deficiency results in rapid aging, whereas high plasma FGF23 levels are found in several disorders, including kidney or cardiovascular diseases. Regulators of FGF23 production include parathyroid hormone (PTH), calcitriol, dietary phosphate, and inflammation. We report that insulin and insulin-like growth factor 1 (IGF1) are negative regulators of FGF23 production. In UMR106 osteoblast-like cells, insulin and IGF1 down-regulated FGF23 production by inhibiting the transcription factor forkhead box protein O1 (FOXO1) through phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB)/Akt signaling. Insulin deficiency caused a surge in the serum FGF23 concentration in mice, which was reversed by administration of insulin. In women, a highly significant negative correlation between FGF23 plasma concentration and increase in plasma insulin level following an oral glucose load was found. Our results provide strong evidence that insulin/IGF1-dependent PI3K/PKB/Akt/FOXO1 signaling is a powerful suppressor of FGF23 production in vitro as well as in mice and in humans.
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Suzuki KGN, Ando H, Komura N, Fujiwara T, Kiso M, Kusumi A. Unraveling of Lipid Raft Organization in Cell Plasma Membranes by Single-Molecule Imaging of Ganglioside Probes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1104:41-58. [DOI: 10.1007/978-981-13-2158-0_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Han X, Ross J, Kolumam G, Pi M, Sonoda J, King G, Quarles LD. Cardiovascular Effects of Renal Distal Tubule Deletion of the FGF Receptor 1 Gene. J Am Soc Nephrol 2018; 29:69-80. [PMID: 28993502 PMCID: PMC5748915 DOI: 10.1681/asn.2017040412] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 08/03/2017] [Indexed: 01/11/2023] Open
Abstract
The bone-derived hormone fibroblast growth factor-23 (FGF-23) activates complexes composed of FGF receptors (FGFRs), including FGFR1, and α-Klotho in the kidney distal tubule (DT), leading to increased sodium retention and hypertension. However, the role of FGFR1 in regulating renal processes linked to hypertension is unclear. Here, we investigated the effects of selective FGFR1 loss in the DT. Conditional knockout (cKO) of FGFR1 in the DT (FGFR1DT-cKO mice) resulted in left ventricular hypertrophy (LVH) and decreased kidney expression of α-Klotho in association with enhanced BP, decreased expression of angiotensin converting enzyme 2, and increased expression of the Na+-K+-2Cl- cotransporter. Notably, recombinant FGF-23 administration similarly decreased the kidney expression of α-Klotho and induced LVH in mice. Pharmacologic activation of FGFR1 with a monoclonal anti-FGFR1 antibody (R1MAb1) normalized BP and significantly attenuated LVH in the Hyp mouse model of excess FGF-23, but did not induce a response in FGFR1DT-cKO mice. The hearts of FGFR1DT-cKO mice showed increased expression of the transient receptor potential cation channel, subfamily C, member 6 (TRPC6), consistent with cardiac effects of soluble Klotho deficiency. Moreover, administration of recombinant soluble Klotho lowered BP in the Hyp mice. Thus, FGFR1 in the DT regulates systemic hemodynamic responses opposite to those predicted by the actions of FGF-23. These cardiovascular effects appear to be mediated by paracrine FGF control of kidney FGFR1 and subsequent regulation of soluble Klotho and TRPC6. FGFR1 in the kidney may provide a new molecular target for treating hypertension.
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MESH Headings
- Angiotensin-Converting Enzyme 2
- Animals
- Antibodies, Monoclonal/pharmacology
- Blood Pressure/drug effects
- Blood Pressure/genetics
- Female
- Fibroblast Growth Factor-23
- Fibroblast Growth Factors/pharmacology
- Glucuronidase/genetics
- Glucuronidase/metabolism
- Hypertension/genetics
- Hypertrophy, Left Ventricular/genetics
- Immunologic Factors/pharmacology
- Kidney Tubules, Distal
- Klotho Proteins
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Myocardium/metabolism
- Peptidyl-Dipeptidase A/genetics
- Peptidyl-Dipeptidase A/metabolism
- RNA, Messenger/metabolism
- Receptor, Fibroblast Growth Factor, Type 1/genetics
- Receptor, Fibroblast Growth Factor, Type 1/immunology
- Recombinant Proteins/pharmacology
- Sodium-Potassium-Chloride Symporters/genetics
- Sodium-Potassium-Chloride Symporters/metabolism
- TRPC Cation Channels/genetics
- TRPC Cation Channels/metabolism
- TRPC6 Cation Channel
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Affiliation(s)
- Xiaobin Han
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Jed Ross
- Department of Molecular Biology and Biomedical Imaging, Genentech, South San Francisco, California; and
| | - Ganesh Kolumam
- Department of Molecular Biology and Biomedical Imaging, Genentech, South San Francisco, California; and
| | - Min Pi
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Junichiro Sonoda
- Department of Molecular Biology and Biomedical Imaging, Genentech, South San Francisco, California; and
| | - Gwendalyn King
- Department of Neurobiology, University of Alabama in Birmingham, Birmingham, Alabama
| | - L Darryl Quarles
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee;
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56
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Richter B, Faul C. FGF23 Actions on Target Tissues-With and Without Klotho. Front Endocrinol (Lausanne) 2018; 9:189. [PMID: 29770125 PMCID: PMC5940753 DOI: 10.3389/fendo.2018.00189] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/06/2018] [Indexed: 12/11/2022] Open
Abstract
Fibroblast growth factor (FGF) 23 is a phosphaturic hormone whose physiologic actions on target tissues are mediated by FGF receptors (FGFR) and klotho, which functions as a co-receptor that increases the binding affinity of FGF23 for FGFRs. By stimulating FGFR/klotho complexes in the kidney and parathyroid gland, FGF23 reduces renal phosphate uptake and secretion of parathyroid hormone, respectively, thereby acting as a key regulator of phosphate metabolism. Recently, it has been shown that FGF23 can also target cell types that lack klotho. This unconventional signaling event occurs in an FGFR-dependent manner, but involves other downstream signaling pathways than in "classic" klotho-expressing target organs. It appears that klotho-independent signaling mechanisms are only activated in the presence of high FGF23 concentrations and result in pathologic cellular changes. Therefore, it has been postulated that massive elevations in circulating levels of FGF23, as found in patients with chronic kidney disease, contribute to associated pathologies by targeting cells and tissues that lack klotho. This includes the induction of cardiac hypertrophy and fibrosis, the elevation of inflammatory cytokine expression in the liver, and the inhibition of neutrophil recruitment. Here, we describe the signaling and cellular events that are caused by FGF23 in tissues lacking klotho, and we discuss FGF23's potential role as a hormone with widespread pathologic actions. Since the soluble form of klotho can function as a circulating co-receptor for FGF23, we also discuss the potential inhibitory effects of soluble klotho on FGF23-mediated signaling which might-at least partially-underlie the pleiotropic tissue-protective functions of klotho.
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Jaturakan O, Buranakarl C, Dissayabutra T, Chaiyabutr N, Kijtawornrat A, Rungsipipat A. Changes of Klotho protein and Klotho mRNA expression in a hydroxy-L-proline induced hyperoxaluric rat model. J Vet Med Sci 2017; 79:1861-1869. [PMID: 28943597 PMCID: PMC5709566 DOI: 10.1292/jvms.17-0340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Klotho protein is recognized as having a renoprotective effect and is used as a biomarker for kidney injury. We investigated the level of Klotho protein in hyperoxaluria-induced kidney injury and the effects of vitamin E (Vit E)
and vitamin C (Vit C) supplementation. Hyperoxaluria was induced by feeding 2% (w/v) Hydroxy-L-proline (HLP) in the drinking water for 21 days. Rats were divided into 5 groups; control (Group 1, n=7), HLP treated rats that
received nothing else (Group 2, n=7), Vit E (Group 3, n=6), Vit C (Group 4, n=6) and both Vit E and Vit C (Group 5, n=7). Vit E (200 mg/kg) was injected on days 1, 6, 11 and 16, while Vit C (500 mg/kg) was given intravenously on
days 1 and 11. The Klotho protein levels and oxidative status were measured. The expression level of kidney Klotho protein expression was significantly reduced by HLP-treatment, while the mRNA expression was higher
(P<0.05), the plasma and kidney malondialdehyde and kidney superoxide dismutase activities were increased, and the kidney reduced glutathione and urinary total antioxidant status were decreased
(P<0.05). All of these changes were ameliorated by administration of Vit E, Vit C or especially the co-administration of both. In conclusion, HLP-induced hyperoxaluria reduced the kidney Klotho protein level,
which could be restored by Vit E and/or Vit C.
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Affiliation(s)
- Orapun Jaturakan
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Rd., Pathumwan, Bangkok 10330, Thailand
| | - Chollada Buranakarl
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Rd., Pathumwan, Bangkok 10330, Thailand
| | - Thasinas Dissayabutra
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand
| | - Narongsak Chaiyabutr
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Rd., Pathumwan, Bangkok 10330, Thailand
| | - Anusak Kijtawornrat
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Rd., Pathumwan, Bangkok 10330, Thailand
| | - Anudep Rungsipipat
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Rd., Pathumwan, Bangkok 10330, Thailand
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58
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Zhu H, Gao Y, Zhu S, Cui Q, Du J. Klotho Improves Cardiac Function by Suppressing Reactive Oxygen Species (ROS) Mediated Apoptosis by Modulating Mapks/Nrf2 Signaling in Doxorubicin-Induced Cardiotoxicity. Med Sci Monit 2017; 23:5283-5293. [PMID: 29107939 PMCID: PMC5687120 DOI: 10.12659/msm.907449] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Background Anthracyclines-induced cardiotoxicity has become one of the major restrictions of their clinical applications. Klotho showed cardioprotective effects. This study aimed to investigate the effects and possible mechanisms of klotho on doxorubicin (DOX)-induced cardiotoxicity. Material/Methods Rats and isolated myocytes were exposed to DOX and treated with exogenous klotho. Specific inhibitors and siRNAs silencing MAPKs were also used to treat the animals and/or myocytes. An invasive hemodynamic method was used to determine cardiac functions. Intracellular ROS generation was evaluated by DHE staining. Western blotting was used to determine the phosphorylation levels of JNK, ERK, and p38 MAPKs in plasma extracts and Nrf2 in nuclear extracts. Nuclear translocation of Nrf2 in myocytes was evaluated by immunohistochemistry. Cell apoptosis was evaluated by TUNEL assay and flow cytometry. Results Klotho treatment improved DOX-induced cardiac dysfunction in rats. The DOX-induced ROS accumulation and cardiac apoptosis were attenuated by klotho. Impaired phosphorylations of MAPKs, Nrf2 translocation and expression levels of HO1 and Prx1 were also attenuated by klotho treatment. However, the anti-oxidant and anti-apoptotic effects of klotho on DOX-exposed myocardium and myocytes were impaired by both specific inhibitors and siRNAs against MAPKs. Moreover, the recovery effects of klotho on phosphorylations of MAPKs, Nrf2 translocation and expression levels of HO1 and Prx1 were also impaired by specific inhibitors and siRNAs against MAPKs. Conclusions By recovering the activation of MAPKs signaling, klotho improved cardiac function loss which was triggered by DOX-induced ROS mediated cardiac apoptosis.
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Affiliation(s)
- Huolan Zhu
- Department of Cardiology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi, China (mainland)
| | - Yan Gao
- ECG Exam Room, Function Testing Lab, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi, China (mainland)
| | - Shunming Zhu
- Department of Cardiology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi, China (mainland)
| | - Qianwei Cui
- Department of Cardiology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi, China (mainland)
| | - Jie Du
- Health Examination Center, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi, China (mainland)
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59
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Mencke R, Olauson H, Hillebrands JL. Effects of Klotho on fibrosis and cancer: A renal focus on mechanisms and therapeutic strategies. Adv Drug Deliv Rev 2017; 121:85-100. [PMID: 28709936 DOI: 10.1016/j.addr.2017.07.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 06/28/2017] [Accepted: 07/07/2017] [Indexed: 12/21/2022]
Abstract
Klotho is a membrane-bound protein predominantly expressed in the kidney, where it acts as a permissive co-receptor for Fibroblast Growth Factor 23. In its shed form, Klotho exerts anti-fibrotic effects in several tissues. Klotho-deficient mice spontaneously develop fibrosis and Klotho deficiency exacerbates the disease progression in fibrotic animal models. Furthermore, Klotho overexpression or supplementation protects against fibrosis in various models of renal and cardiac fibrotic disease. These effects are mediated at least partially by the direct inhibitory effects of soluble Klotho on TGFβ1 signaling, Wnt signaling, and FGF2 signaling. Soluble Klotho, as present in the circulation, appears to be the primary mediator of anti-fibrotic effects. Similarly, through inhibition of the TGFβ1, Wnt, FGF2, and IGF1 signaling pathways, Klotho also inhibits tumorigenesis. The Klotho promoter gene is generally hypermethylated in cancer, and overexpression or supplementation of Klotho has been found to inhibit tumor growth in various animal models. This review focuses on the protective effects of soluble Klotho in inhibiting renal fibrosis and fibrosis in distant organs secondary to renal Klotho deficiency. We also discuss the structure-function relationships of Klotho domains and biological effects in the context of potential targeted treatment strategies.
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Affiliation(s)
- Rik Mencke
- Department of Pathology and Medical Biology (Division of Pathology), University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Hannes Olauson
- Department of Clinical Science, Intervention and Technology (Division of Renal Medicine), Karolinska Institutet, Stockholm, Sweden
| | - Jan-Luuk Hillebrands
- Department of Pathology and Medical Biology (Division of Pathology), University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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60
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Revealing the Raft Domain Organization in the Plasma Membrane by Single-Molecule Imaging of Fluorescent Ganglioside Analogs. Methods Enzymol 2017; 598:267-282. [PMID: 29306438 DOI: 10.1016/bs.mie.2017.06.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Gangliosides have been implicated in a variety of physiological processes, particularly in the formation and function of raft domains in the plasma membrane. However, the scarcity of suitable fluorescent ganglioside analogs had long prevented us from determining exactly how gangliosides perform their functions in the live-cell plasma membrane. With the development of new fluorescent ganglioside analogs, as described by Komura et al. (2017), this barrier has been broken. We can now address the dynamic behaviors of gangliosides in the live-cell plasma membrane, using fluorescence microscopy, particularly by single-fluorescent molecule imaging and tracking. Single-molecule tracking of fluorescent GM1 and GM3 revealed that these molecules are transiently and dynamically recruited to monomers (monomer-associated rafts) and homodimer rafts of the raftophilic GPI-anchored protein CD59 in quiescent cells, with exponential residency times of 12 and 40ms, respectively, in a manner dependent on raft-lipid interactions. Upon CD59 stimulation, which induces CD59-cluster signaling rafts, the fluorescent GM1 and GM3 analogs were recruited to the signaling rafts, with a lifetime of 48ms. These results represent the first direct evidence that GPI-anchored receptors and gangliosides interact in a cholesterol-dependent manner. Furthermore, they show that gangliosides continually move in and out of rafts that contain CD59 in an extremely dynamic manner, with much higher frequency than expected previously. Such studies would not have been possible without fluorescent ganglioside probes, which exhibit native-like behavior and single-molecule tracking. In this chapter, we review the methods for single-molecule tracking of fluorescent ganglioside analogs and the results obtained by applying these methods.
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61
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Boksha IS, Prokhorova TA, Savushkina OK, Tereshkina EB. Klotho protein: Its role in aging and central nervous system pathology. BIOCHEMISTRY (MOSCOW) 2017; 82:990-1005. [DOI: 10.1134/s0006297917090024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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62
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Wright JD, An SW, Xie J, Yoon J, Nischan N, Kohler JJ, Oliver N, Lim C, Huang CL. Modeled structural basis for the recognition of α2-3-sialyllactose by soluble Klotho. FASEB J 2017; 31:3574-3586. [PMID: 28442546 PMCID: PMC5503716 DOI: 10.1096/fj.201700043r] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/11/2017] [Indexed: 01/09/2023]
Abstract
Soluble Klotho (sKlotho) is the shed ectodomain of antiaging membrane Klotho that contains 2 extracellular domains KL1 and KL2, each of which shares sequence homology to glycosyl hydrolases. sKlotho elicits pleiotropic cellular responses with a poorly understood mechanism of action. Notably, in injury settings, sKlotho confers cardiac and renal protection by down-regulating calcium-permeable transient receptor potential canonical type isoform 6 (TRPC6) channels in cardiomyocytes and glomerular podocytes. Inhibition of PI3K-dependent exocytosis of TRPC6 is thought to be the underlying mechanism, and recent studies showed that sKlotho interacts with α2-3-sialyllactose-containing gangliosides enriched in lipid rafts to inhibit raft-dependent PI3K signaling. However, the structural basis for binding and recognition of α2-3-sialyllactose by sKlotho is unknown. Using homology modeling followed by docking, we identified key protein residues in the KL1 domain that are likely involved in binding sialyllactose. Functional experiments based on the ability of Klotho to down-regulate TRPC6 channel activity confirm the importance of these residues. Furthermore, KL1 domain binds α2-3-sialyllactose, down-regulates TRPC6 channels, and exerts protection against stress-induced cardiac hypertrophy in mice. Our results support the notion that sialogangliosides and lipid rafts are membrane receptors for sKlotho and that the KL1 domain is sufficient for the tested biologic activities. These findings can help guide the design of a simpler Klotho mimetic.-Wright, J. D., An, S.-W., Xie, J., Yoon, J., Nischan, N., Kohler, J. J., Oliver, N., Lim, C., Huang, C.-L. Modeled structural basis for the recognition of α2-3-sialyllactose by soluble Klotho.
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Affiliation(s)
- Jon D Wright
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Sung-Wan An
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Texas, USA
| | - Jian Xie
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Texas, USA
| | - Joonho Yoon
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Texas, USA
| | - Nicole Nischan
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jennifer J Kohler
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Noelynn Oliver
- Cardiometabolic Disease Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut, USA
| | - Carmay Lim
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan;
- Department of Chemistry, National Tsing Hua University, HsinChu, Taiwan
| | - Chou-Long Huang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Texas, USA;
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Lu J, Yao XQ, Luo X, Wang Y, Chung SK, Tang HX, Cheung CW, Wang XY, Meng C, Li Q. Monosialoganglioside 1 may alleviate neurotoxicity induced by propofol combined with remifentanil in neural stem cells. Neural Regen Res 2017; 12:945-952. [PMID: 28761428 PMCID: PMC5514870 DOI: 10.4103/1673-5374.208589] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Monosialoganglioside 1 (GM1) is the main ganglioside subtype and has neuroprotective properties in the central nervous system. In this study, we aimed to determine whether GM1 alleviates neurotoxicity induced by moderate and high concentrations of propofol combined with remifentanil in the immature central nervous system. Hippocampal neural stem cells were isolated from newborn Sprague-Dawley rats and treated with remifentanil (5, 10, 20 ng/mL) and propofol (1.0, 2.5, 5.0 μg/mL), and/or GM1 (12.5, 25, 50 μg/mL). GM1 reversed combined propofol and remifentanil-induced decreases in the percentage of 5-bromodeoxyuridine(+) cells and also reversed the increase in apoptotic cell percentage during neural stem cell proliferation and differentiation. However, GM1 with combined propofol and remifentanil did not affect β-tubulin(+) or glial fibrillary acidic protein(+) cell percentage during neural stem cell differentiation. In conclusion, we show that GM1 alleviates the damaging effects of propofol combined with remifentanil at moderate and high exposure concentrations in neural stem cells in vitro, and exerts protective effects on the immature central nervous system.
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Affiliation(s)
- Jiang Lu
- Anesthesiology Research Institute of Hubei University of Medicine, Shiyan, Hubei Province, China.,Department of Anesthesiology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China
| | - Xue-Qin Yao
- Anesthesiology Research Institute of Hubei University of Medicine, Shiyan, Hubei Province, China.,Department of Anesthesiology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China
| | - Xin Luo
- Department of Anesthesiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.,Laboratory and Clinical Research Institute for Pain, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Yu Wang
- Department of Anesthesiology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China
| | - Sookja Kim Chung
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - He-Xin Tang
- Anesthesiology Research Institute of Hubei University of Medicine, Shiyan, Hubei Province, China
| | - Chi Wai Cheung
- Anesthesiology Research Institute of Hubei University of Medicine, Shiyan, Hubei Province, China.,Department of Anesthesiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.,Laboratory and Clinical Research Institute for Pain, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Xian-Yu Wang
- Anesthesiology Research Institute of Hubei University of Medicine, Shiyan, Hubei Province, China.,Department of Anesthesiology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China
| | - Chen Meng
- Anesthesiology Research Institute of Hubei University of Medicine, Shiyan, Hubei Province, China.,Department of Anesthesiology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China
| | - Qing Li
- Anesthesiology Research Institute of Hubei University of Medicine, Shiyan, Hubei Province, China.,Department of Anesthesiology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China
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Dalton GD, Xie J, An SW, Huang CL. New Insights into the Mechanism of Action of Soluble Klotho. Front Endocrinol (Lausanne) 2017; 8:323. [PMID: 29250031 PMCID: PMC5715364 DOI: 10.3389/fendo.2017.00323] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/02/2017] [Indexed: 12/31/2022] Open
Abstract
The klotho gene encodes a type I single-pass transmembrane protein that contains a large extracellular domain, a membrane spanning segment, and a short intracellular domain. Klotho protein exists in several forms including the full-length membrane form (mKl) and a soluble circulating form [soluble klotho (sKl)]. mKl complexes with fibroblast growth factor receptors to form coreceptors for FGF23, which allows it to participate in FGF23-mediated signal transduction and regulation of phosphate and calcium homeostasis. sKl is present in the blood, urine, and cerebrospinal fluid where it performs a multitude of functions including regulation of ion channels/transporters and growth factor signaling. How sKl exerts these pleiotropic functions is poorly understood. One hurdle in understanding sKl's mechanism of action as a "hormone" has been the inability to identify a receptor that mediates its effects. In the body, the kidneys are a major source of sKl and sKl levels decline during renal disease. sKl deficiency in chronic kidney disease makes the heart susceptible to stress-induced injury. Here, we summarize the current knowledge of mKl's mechanism of action, the mechanistic basis of sKl's protective, FGF23-independent effects on the heart, and provide new insights into the mechanism of action of sKl focusing on recent findings that sKl binds sialogangliosides in membrane lipid rafts to regulate growth factor signaling.
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Affiliation(s)
- George D. Dalton
- Department of Medicine, Division of Gastroenterology, Duke University Medical Center, Durham, NC, United States
| | - Jian Xie
- Department of Internal Medicine, Division of Nephrology and Hypertension, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Sung-Wan An
- Department of Internal Medicine, Division of Nephrology and Hypertension, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Chou-Long Huang
- Department of Internal Medicine, Division of Nephrology and Hypertension, University of Iowa Carver College of Medicine, Iowa City, IA, United States
- *Correspondence: Chou-Long Huang,
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