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Hanson K, Fisher K, Hooper N. Exploiting the neuroprotective effects of α-klotho to tackle ageing- and neurodegeneration-related cognitive dysfunction. Neuronal Signal 2021; 5:NS20200101. [PMID: 34194816 PMCID: PMC8204227 DOI: 10.1042/ns20200101] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 12/26/2022] Open
Abstract
Cognitive dysfunction is a key symptom of ageing and neurodegenerative disorders, such as Alzheimer's disease (AD). Strategies to enhance cognition would impact the quality of life for a significant proportion of the ageing population. The α-klotho protein may protect against cognitive decline through multiple mechanisms: such as promoting optimal synaptic function via activation of N-methyl-d-aspartate (NMDA) receptor signalling; stimulating the antioxidant defence system; reducing inflammation; promoting autophagy and enhancing clearance of amyloid-β. However, the molecular and cellular pathways by which α-klotho mediates these neuroprotective functions have yet to be fully elucidated. Key questions remain unanswered: which form of α-klotho (transmembrane, soluble or secreted) mediates its cognitive enhancing properties; what is the neuronal receptor for α-klotho and which signalling pathways are activated by α-klotho in the brain to enhance cognition; how does peripherally administered α-klotho mediate neuroprotection; and what is the molecular basis for the beneficial effect of the VS variant of α-klotho? In this review, we summarise the recent research on neuronal α-klotho and discuss how the neuroprotective properties of α-klotho could be exploited to tackle age- and neurodegeneration-associated cognitive dysfunction.
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Affiliation(s)
- Kelsey Hanson
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, U.K
| | - Kate Fisher
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, U.K
| | - Nigel M. Hooper
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, U.K
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance and University of Manchester, Manchester, U.K
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Kim JH, Park EY, Hwang KH, Park KS, Choi SJ, Cha SK. Soluble αKlotho downregulates Orai1-mediated store-operated Ca 2+ entry via PI3K-dependent signaling. Pflugers Arch 2021; 473:647-658. [PMID: 33386992 PMCID: PMC8049930 DOI: 10.1007/s00424-020-02510-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 12/20/2020] [Accepted: 12/23/2020] [Indexed: 12/17/2022]
Abstract
αKlotho is a type 1 transmembrane anti-aging protein. αKlotho-deficient mice have premature aging phenotypes and an imbalance of ion homeostasis including Ca2+ and phosphate. Soluble αKlotho is known to regulate multiple ion channels and growth factor-mediated phosphoinositide-3-kinase (PI3K) signaling. Store-operated Ca2+ entry (SOCE) mediated by pore-forming subunit Orai1 and ER Ca2+ sensor STIM1 is a ubiquitous Ca2+ influx mechanism and has been implicated in multiple diseases. However, it is currently unknown whether soluble αKlotho regulates Orai1-mediated SOCE via PI3K-dependent signaling. Among the Klotho family, αKlotho downregulates SOCE while βKlotho or γKlotho does not affect SOCE. Soluble αKlotho suppresses serum-stimulated SOCE and Ca2+ release-activated Ca2+ (CRAC) channel currents. Serum increases the cell-surface abundance of Orai1 via stimulating vesicular exocytosis of the channel. The serum-stimulated SOCE and cell-surface abundance of Orai1 are inhibited by the preincubation of αKlotho protein or PI3K inhibitors. Moreover, the inhibition of SOCE and cell-surface abundance of Orai1 by pretreatment of brefeldin A or tetanus toxin or PI3K inhibitors prevents further inhibition by αKlotho. Functionally, we further show that soluble αKlotho ameliorates serum-stimulated SOCE and cell migration in breast and lung cancer cells. These results demonstrate that soluble αKlotho downregulates SOCE by inhibiting PI3K-driven vesicular exocytosis of the Orai1 channel and contributes to the suppression of SOCE-mediated tumor cell migration.
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Affiliation(s)
- Ji-Hee Kim
- Department of Physiology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwondo, 26426, Republic of Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Institute of Mitochondrial Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Eun Young Park
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Obstetrics and Gynecology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwondo, 26426, Republic of Korea
| | - Kyu-Hee Hwang
- Department of Physiology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwondo, 26426, Republic of Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Institute of Mitochondrial Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwondo, 26426, Republic of Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Institute of Mitochondrial Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Seong Jin Choi
- Department of Obstetrics and Gynecology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwondo, 26426, Republic of Korea.
| | - Seung-Kuy Cha
- Department of Physiology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwondo, 26426, Republic of Korea.
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
- Institute of Mitochondrial Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
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Dongiovanni P, Crudele A, Panera N, Romito I, Meroni M, De Stefanis C, Palma A, Comparcola D, Fracanzani AL, Miele L, Valenti L, Nobili V, Alisi A. β-Klotho gene variation is associated with liver damage in children with NAFLD. J Hepatol 2020; 72:411-419. [PMID: 31655133 DOI: 10.1016/j.jhep.2019.10.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/17/2019] [Accepted: 10/11/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIM Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in adults and children. Along with obesity, diabetes and insulin resistance, genetic factors strongly impact on NAFLD development and progression. Dysregulated bile acid metabolism and the fibroblast growth factor 19 (FGF19) pathway play a pivotal role in NAFLD pathogenesis. However, the mechanism through which the FGF19 receptor system is associated with liver damage in NAFLD remains to be defined. METHODS We evaluated the impact of the rs17618244 G>A β-Klotho (KLB) variant on liver damage in 249 pediatric patients with biopsy-proven NAFLD and the association of this variant with the expression of hepatic and soluble KLB. In vitro models were established to investigate the role of the KLB mutant. RESULTS The KLB rs17618244 variant was associated with an increased risk of ballooning and lobular inflammation. KLB plasma levels were lower in carriers of the rs17618244 minor A allele and were associated with lobular inflammation, ballooning and fibrosis. In HepG2 and Huh7 hepatoma cell lines, exposure to free fatty acids caused a severe reduction of intracellular and secreted KLB. Finally, KLB downregulation obtained by the expression of a KLB mutant in HepG2 and Huh7 cells induced intracellular lipid accumulation and upregulation of p62, ACOX1, ACSL1, IL-1β and TNF-α gene expression. CONCLUSION In conclusion, we showed an association between the rs17618244 KLB variant, which leads to reduced KLB expression, and the severity of NAFLD in pediatric patients. We can speculate that the KLB protein may exert a protective role against lipotoxicity and inflammation in hepatocytes. LAY SUMMARY Genetic and environmental factors strongly impact on the pathogenesis and progression of non-alcoholic fatty liver disease (NAFLD). The FGF19/FGFR4/KLB pathway plays a pivotal role in the pathogenesis of NAFLD. The aim of the study was to investigate the impact of a genetic variant in the KLB gene on the severity of liver disease. Our data suggest that the KLB protein plays a protective role against lipotoxicity and inflammation in hepatocytes.
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Affiliation(s)
- Paola Dongiovanni
- General Medicine and Metabolic Diseases, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - Annalisa Crudele
- Research Unit of Molecular Genetics of Complex Phenotypes, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy
| | - Nadia Panera
- Research Unit of Molecular Genetics of Complex Phenotypes, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy
| | - Ilaria Romito
- Research Unit of Molecular Genetics of Complex Phenotypes, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy
| | - Marica Meroni
- General Medicine and Metabolic Diseases, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy; Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Italy
| | | | - Alessia Palma
- Genomic Facility Unit, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy
| | - Donatella Comparcola
- Hepato-Metabolic Disease Unit, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy
| | - Anna Ludovica Fracanzani
- General Medicine and Metabolic Diseases, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy; Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Italy
| | - Luca Miele
- Fondazione Policlinico Universitario A. Gemelli - IRCCS, Catholic University of the Sacred Heart, Rome, Italy
| | - Luca Valenti
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Italy; Translational Medicine, Department for Transfusion Medicine and Hematology, Fondazione IRCCS Ca' Granda Ospedale Policlinico, Milano, Italy
| | - Valerio Nobili
- Hepatology Gastroenterology and Nutrition Unit, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy; Department of Pediatrics and Infantile Neuropsychiatry, Sapienza University of Rome, Italy
| | - Anna Alisi
- Research Unit of Molecular Genetics of Complex Phenotypes, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy.
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Kashlan OB, Kinlough CL, Myerburg MM, Shi S, Chen J, Blobner BM, Buck TM, Brodsky JL, Hughey RP, Kleyman TR. N-linked glycans are required on epithelial Na + channel subunits for maturation and surface expression. Am J Physiol Renal Physiol 2017; 314:F483-F492. [PMID: 29187368 DOI: 10.1152/ajprenal.00195.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Epithelial Na+ channel (ENaC) subunits undergo N-linked glycosylation in the endoplasmic reticulum where they assemble into an αβγ complex. Six, 13, and 5 consensus sites (Asn-X-Ser/Thr) for N-glycosylation reside in the extracellular domains of the mouse α-, β-, and γ-subunits, respectively. Because the importance of ENaC N-linked glycans has not been fully addressed, we examined the effect of preventing N-glycosylation of specific subunits on channel function, expression, maturation, and folding. Heterologous expression in Xenopus oocytes or Fischer rat thyroid cells with αβγ-ENaC lacking N-linked glycans on a single subunit reduced ENaC activity as well as the inhibitory response to extracellular Na+. The lack of N-linked glycans on the β-subunit also precluded channel activation by trypsin. However, channel activation by shear stress was N-linked glycan independent, regardless of which subunit was modified. We also discovered that the lack of N-linked glycans on any one subunit reduced the total and surface levels of cognate subunits. The lack of N-linked glycans on the β-subunit had the largest effect on total levels, with the lack of N-linked glycans on the γ- and α-subunits having intermediate and modest effects, respectively. Finally, channels with wild-type β-subunits were more sensitive to limited trypsin proteolysis than channels lacking N-linked glycans on the β-subunit. Our results indicate that N-linked glycans on each subunit are required for proper folding, maturation, surface expression, and function of the channel.
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Affiliation(s)
- Ossama B Kashlan
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania.,Department of Computational and Systems Biology, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Carol L Kinlough
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Michael M Myerburg
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Shujie Shi
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Jingxin Chen
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Brandon M Blobner
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Teresa M Buck
- Department of Biological Sciences, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Rebecca P Hughey
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania.,Department of Cell Biology, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Thomas R Kleyman
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania.,Department of Cell Biology, University of Pittsburgh , Pittsburgh, Pennsylvania.,Department of Pharmacology and Chemical Biology, University of Pittsburgh , Pittsburgh, Pennsylvania
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Andrukhova O, Bayer J, Schüler C, Zeitz U, Murali SK, Ada S, Alvarez-Pez JM, Smorodchenko A, Erben RG. Klotho Lacks an FGF23-Independent Role in Mineral Homeostasis. J Bone Miner Res 2017; 32:2049-2061. [PMID: 28600880 DOI: 10.1002/jbmr.3195] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/30/2017] [Accepted: 06/09/2017] [Indexed: 12/30/2022]
Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone regulating vitamin D hormone production and renal handling of minerals by signaling through an FGF receptor/αKlotho (Klotho) receptor complex. Whether Klotho has FGF23-independent effects on mineral homeostasis is a controversial issue. Here, we aimed to shed more light on this controversy by comparing male and female triple knockout mice with simultaneous deficiency in Fgf23 and Klotho and a nonfunctioning vitamin D receptor (VDR) (Fgf23/Klotho/VDR) with double (Fgf23/VDR, Klotho/VDR, and Fgf23/Klotho) and single Fgf23, Klotho, and VDR mutants. As expected, 4-week-old Fgf23, Klotho, and Fgf23/Klotho knockout mice were hypercalcemic and hyperphosphatemic, whereas VDR, Fgf23/VDR, and Klotho/VDR mice on rescue diet were normocalcemic and normophosphatemic. Serum levels of calcium, phosphate, and sodium did not differ between 4-week-old triple Fgf23/Klotho/VDR and double Fgf23/VDR or Klotho/VDR knockout mice. Notably, 3-month-old Fgf23/Klotho/VDR triple knockout mice were indistinguishable from double Fgf23/VDR and Klotho/VDR compound mutants in terms of serum calcium, serum phosphate, serum sodium, and serum PTH, as well as urinary calcium and sodium excretion. Protein expression analysis revealed increased membrane abundance of sodium-phosphate co-transporter 2a (NaPi-2a), and decreased expression of sodium-chloride co-transporter (NCC) and transient receptor potential cation channel subfamily V member 5 (TRPV5) in Fgf23/Klotho/VDR, Fgf23/VDR, and Klotho/VDR mice, relative to wild-type and VDR mice, but no differences between triple and double knockouts. Further, ex vivo treatment of live kidney slices isolated from wild-type and Klotho/VDR mice with soluble Klotho did not induce changes in intracellular phosphate, calcium or sodium accumulation assessed by two-photon microscopy. In conclusion, our data suggest that the main physiological function of Klotho for mineral homeostasis in vivo is its role as co-receptor mediating Fgf23 action. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Olena Andrukhova
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Jessica Bayer
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Christiane Schüler
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Ute Zeitz
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Sathish K Murali
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Sibel Ada
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | | | - Alina Smorodchenko
- Institute for Vegetative Anatomy, Charité University of Berlin, Berlin, Germany
| | - Reinhold G Erben
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
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Yan Y, Wang Y, Xiong Y, Lin X, Zhou P, Chen Z. Reduced Klotho expression contributes to poor survival rates in human patients with ovarian cancer, and overexpression of Klotho inhibits the progression of ovarian cancer partly via the inhibition of systemic inflammation in nude mice. Mol Med Rep 2017; 15:1777-1785. [PMID: 28259911 DOI: 10.3892/mmr.2017.6172] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 07/25/2016] [Indexed: 11/06/2022] Open
Abstract
Klotho is a recently discovered anti‑aging gene, which has been reported as a tumor suppressor in numerous human malignancies; however, the role of Klotho in human ovarian cancer remains to be elucidated. The aim of the present study was to detect the expression of Klotho and evaluate its association with the progression of human ovarian cancer. A clinical follow‑up study of 120 patients with ovarian cancer and 78 normal controls was conducted. The expression levels of Klotho were determined by western blotting and immunohistochemistry. The results demonstrated that high Klotho expression levels were detected in all normal controls, whereas the positive rate of Klotho was 61.6% in the ovarian cancer group, which was significantly decreased compared with in the control group (P<0.01). Furthermore, reduced Klotho expression was significantly correlated with decreased survival rates in patients with ovarian cancer (P=0.025). Subsequently, Klotho levels were detected in seven human ovarian cancer cell lines by western blotting. The results demonstrated that the highest levels of Klotho were detected in CaOV3 cells, medium levels of Klotho were detected in CaOV4 and SKOV‑3 cells, and almost no Klotho was detected in the other four cell lines: OVCA 432, OVCAR‑5, OVCAR‑8 and A2780 cells. The association between Klotho levels and cell proliferation was determined by MTT assay, and the results indicated that higher levels of Klotho inhibited the proliferation of A2780 and OVCAR‑5 cells, whereas reduced Klotho expression promoted cell growth of CaOV3 and SKOV‑3 cells. In addition, the plasma levels of inflammatory cytokines in tumor‑bearing mice and normal control mice were detected by enzyme‑linked immunosorbent assay, and plasma interleukin (IL)‑6 and IL‑1β levels were elevated in all tumor‑bearing mice. Notably, the mRNA expression levels of IL‑6 were significantly higher in the liver, ovaries and kidneys of Klotho‑/‑ mice compared with in wild type mice (P<0.01), thus indicating that aberrant Klotho expression may contribute to systemic inflammation in Klotho‑/‑ mice. Finally, the in vivo antitumor role of aberrant Klotho expression was determined in a nude mice model. A2780 cells were transfected with pCMV6‑Klotho and the stably transfected cells were screened; the mice were injected with the stably transfected cells. The results indicated that tumor volume and tumor weight were significantly decreased in the pCMV6‑Klotho group compared with in the pCMV6 vector group (P<0.01). These findings suggest that overexpression of Klotho may suppress tumor growth in animal models. In conclusion, Klotho was demonstrated to act as a potent tumor suppressor in human ovarian cancer cells. Reduced Klotho expression was detected in the specimens of patients with ovarian cancer, and overexpression of Klotho significantly inhibited cell proliferation of human ovarian cancer cells. Therefore, Klotho may be considered a useful key target for the molecular therapy of human ovarian cancer.
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Affiliation(s)
- Youliang Yan
- Department of Obstetrics and Gynecology, Boai Hospital of Zhongshan of Southern Medical University, Guangzhou, Guangdong 528403, P.R. China
| | - Yifeng Wang
- Department of Obstetrics and Gynecology, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Yi Xiong
- Department of Obstetrics and Gynecology, Boai Hospital of Zhongshan of Southern Medical University, Guangzhou, Guangdong 528403, P.R. China
| | - Xiufeng Lin
- Department of Obstetrics and Gynecology, Boai Hospital of Zhongshan of Southern Medical University, Guangzhou, Guangdong 528403, P.R. China
| | - Ping Zhou
- Department of Obstetrics and Gynecology, Boai Hospital of Zhongshan of Southern Medical University, Guangzhou, Guangdong 528403, P.R. China
| | - Zhiying Chen
- Department of Obstetrics and Gynecology, Boai Hospital of Zhongshan of Southern Medical University, Guangzhou, Guangdong 528403, P.R. China
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Leibrock CB, Voelkl J, Kuro-O M, Lang F, Lang UE. 1,25(OH)2D3 dependent overt hyperactivity phenotype in klotho-hypomorphic mice. Sci Rep 2016; 6:24879. [PMID: 27109615 PMCID: PMC4843009 DOI: 10.1038/srep24879] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/05/2016] [Indexed: 02/06/2023] Open
Abstract
Klotho, a protein mainly expressed in kidney and cerebral choroid plexus, is a powerful regulator of 1,25(OH)2D3 formation. Klotho-deficient mice (kl/kl) suffer from excessive plasma 1,25(OH)2D3-, Ca2+- and phosphate-concentrations, leading to severe soft tissue calcification and accelerated aging. NH4Cl treatment prevents tissue calcification and premature ageing without affecting 1,25(OH)2D3-formation. The present study explored the impact of excessive 1,25(OH)2D3 formation in NH4Cl-treated kl/kl-mice on behavior. To this end kl/kl-mice and wild-type mice were treated with NH4Cl and either control diet or vitamin D deficient diet (LVD). As a result, plasma 1,25(OH)2D3-, Ca2+- and phosphate-concentrations were significantly higher in untreated and in NH4Cl-treated kl/kl-mice than in wild-type mice, a difference abrogated by LVD. In each, open field, dark-light box, and O-maze NH4Cl-treated kl/kl-mice showed significantly higher exploratory behavior than untreated wild-type mice, a difference abrogated by LVD. The time of floating in the forced swimming test was significantly shorter in NH4Cl treated kl/kl-mice compared to untreated wild-type mice and to kl/kl-mice on LVD. In wild-type animals, NH4Cl treatment did not significantly alter 1,25(OH)2D3, calcium and phosphate concentrations or exploratory behavior. In conclusion, the excessive 1,25(OH)2D3 formation in klotho-hypomorphic mice has a profound effect on murine behavior.
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Affiliation(s)
- Christina B Leibrock
- Department of Physiology, Cardiology &Vascular Medicine, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
| | - Jakob Voelkl
- Department of Physiology, Cardiology &Vascular Medicine, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
| | - Makoto Kuro-O
- Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Florian Lang
- Department of Physiology, Cardiology &Vascular Medicine, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
| | - Undine E Lang
- Department of Psychiatry, University of Basel, Wilhelm Klein-Strasse 27, CH-4012 Basel, Switzerland
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8
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Pulskens WP, Verkaik M, Sheedfar F, van Loon EP, van de Sluis B, Vervloet MG, Hoenderop JG, Bindels RJ. Deregulated Renal Calcium and Phosphate Transport during Experimental Kidney Failure. PLoS One 2015; 10:e0142510. [PMID: 26566277 PMCID: PMC4643984 DOI: 10.1371/journal.pone.0142510] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 10/22/2015] [Indexed: 12/17/2022] Open
Abstract
Impaired mineral homeostasis and inflammation are hallmarks of chronic kidney disease (CKD), yet the underlying mechanisms of electrolyte regulation during CKD are still unclear. Here, we applied two different murine models, partial nephrectomy and adenine-enriched dietary intervention, to induce kidney failure and to investigate the subsequent impact on systemic and local renal factors involved in Ca(2+) and Pi regulation. Our results demonstrated that both experimental models induce features of CKD, as reflected by uremia, and elevated renal neutrophil gelatinase-associated lipocalin (NGAL) expression. In our model kidney failure was associated with polyuria, hypercalcemia and elevated urinary Ca(2+) excretion. In accordance, CKD augmented systemic PTH and affected the FGF23-αklotho-vitamin-D axis by elevating circulatory FGF23 levels and reducing renal αklotho expression. Interestingly, renal FGF23 expression was also induced by inflammatory stimuli directly. Renal expression of Cyp27b1, but not Cyp24a1, and blood levels of 1,25-dihydroxy vitamin D3 were significantly elevated in both models. Furthermore, kidney failure was characterized by enhanced renal expression of the transient receptor potential cation channel subfamily V member 5 (TRPV5), calbindin-D28k, and sodium-dependent Pi transporter type 2b (NaPi2b), whereas the renal expression of sodium-dependent Pi transporter type 2a (NaPi2a) and type 3 (PIT2) were reduced. Together, our data indicates two different models of experimental kidney failure comparably associate with disturbed FGF23-αklotho-vitamin-D signalling and a deregulated electrolyte homeostasis. Moreover, this study identifies local tubular, possibly inflammation- or PTH- and/or FGF23-associated, adaptive mechanisms, impacting on Ca(2+)/Pi homeostasis, hence enabling new opportunities to target electrolyte disturbances that emerge as a consequence of CKD development.
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Affiliation(s)
- Wilco P. Pulskens
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
- Dept. of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Melissa Verkaik
- Dept. of Nephrology, VU University Medical Center, Amsterdam, The Netherlands
| | - Fareeba Sheedfar
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ellen P. van Loon
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bart van de Sluis
- Dept. of Pediatrics, Molecular Genetics Section, University Medical Center Groningen, Groningen, The Netherlands
| | - Mark G. Vervloet
- Dept. of Nephrology, VU University Medical Center, Amsterdam, The Netherlands
| | - Joost G. Hoenderop
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J. Bindels
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
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Almilaji A, Honisch S, Liu G, Elvira B, Ajay SS, Hosseinzadeh Z, Ahmed M, Munoz C, Sopjani M, Lang F. Regulation of the voltage gated K channel Kv1.3 by recombinant human klotho protein. Kidney Blood Press Res 2014; 39:609-22. [PMID: 25571875 DOI: 10.1159/000368472] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Klotho, a protein mainly produced in the kidney and released into circulating blood, contributes to the negative regulation of 1,25(OH)2D3 formation and is thus a powerful regulator of mineral metabolism. As β-glucuronidase, alpha Klotho protein further regulates the stability of several carriers and channels in the plasma membrane and thus regulates channel and transporter activity. Accordingly, alpha Klotho protein participates in the regulation of diverse functions seemingly unrelated to mineral metabolism including lymphocyte function. The present study explored the impact of alpha Klotho protein on the voltage gated K+ channel Kv1.3. METHODS cRNA encoding Kv1.3 (KCNA3) was injected into Xenopus oocytes and depolarization induced outward current in Kv1.3 expressing Xenopus oocytes determined utilizing dual electrode voltage clamp. Experiments were performed without or with prior treatment with recombinant human Klotho protein (50 ng/ml, 24 hours) in the absence or presence of a β-glucuronidase inhibitor D-saccharic acid-1,4-lactone (DSAL, 10 µM). Moreover, the voltage gated K+ current was determined in Jcam lymphoma cells by whole cell patch clamp following 24 hours incubation without or with recombinant human Klotho protein (50 ng/ml, 24 hours). Kv1.3 protein abundance in Jcam cells was determined utilising fluorescent antibodies in flow cytometry. RESULTS In Kv1.3 expressing Xenopus oocytes the Kv1.3 currents and the protein abundance of Kv1.3 were both significantly enhanced after treatment with recombinant human Klotho protein (50 ng/ml, 24 hours), an effect reversed by presence of DSAL. Moreover, treatment with recombinant human Klotho protein increased Kv currents and Kv1.3 protein abundance in Jcam cells. CONCLUSION Alpha Klotho protein enhances Kv1.3 channel abundance and Kv1.3 currents in the plasma membrane, an effect depending on its β-glucuronidase activity.
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Affiliation(s)
- Ahmad Almilaji
- Department of Physiology, University of Tübingen, Tübingen, Germany
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10
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Gravesen E, Mace ML, Hofman-Bang J, Olgaard K, Lewin E. Circulating FGF23 levels in response to acute changes in plasma Ca(2+). Calcif Tissue Int 2014; 95:46-53. [PMID: 24801007 DOI: 10.1007/s00223-014-9861-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/15/2014] [Indexed: 12/20/2022]
Abstract
The regulation of fibroblast growth factor 23 (FGF23) synthesis and secretion is still incompletely understood. FGF23 is an important regulator of renal phosphate excretion and has regulatory effects on the calciotropic hormones calcitriol and parathyroid hormone (PTH). Calcium (Ca) and phosphate homeostasis are closely interrelated, and it is therefore likely that Ca is involved in FGF23 regulation. It has recently been reported that dietary Ca influenced FGF23 levels, with high Ca increasing FGF23. The mechanism remains to be clarified. It remains unknown whether acute changes in plasma Ca influence FGF23 levels and whether a close relationship, similar that known for Ca and PTH, exists between Ca and FGF23. Thus, the aim of the present study was to examine whether acute hypercalcemia and hypocalcemia regulate FGF23 levels in the rat. Acute hypercalcemia was induced by an intravenous Ca infusion and hypocalcemia by infusion of ethylene glycol tetraacetic acid (EGTA) in normal and acutely parathyroidectomized rats. Intact plasma FGF23 and intact plasma PTH and plasma Ca(2+) and phosphate were measured. Acute hypercalcemia and hypocalcemia resulted as expected in adequate PTH secretory responses. Plasma FGF23 levels remained stable at all plasma Ca(2+) levels; acute parathyroidectomy did not affect FGF23 secretion. In conclusion, Ca is not a regulator of acute changes in FGF23 secretion.
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Affiliation(s)
- Eva Gravesen
- Nephrological Department P, Rigshospitalet, University of Copenhagen, 2100, Copenhagen, Denmark
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11
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Klotho regulates retinal pigment epithelial functions and protects against oxidative stress. J Neurosci 2013; 33:16346-59. [PMID: 24107965 DOI: 10.1523/jneurosci.0402-13.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The retinal pigment epithelium (RPE) is a highly specialized CNS tissue that plays crucial roles in retinal homeostasis. Age-related morphological changes in the RPE have been associated with retinal degenerative disorders; our understanding of the underlying molecular mechanisms, however, remains incomplete. Here we report on a key role of Klotho (Kl), an aging-suppressor gene, in retinal health and RPE physiology. Kl(-/-) mice show RPE and photoreceptor degeneration, reduced pigment synthesis in the RPE, and impaired phagocytosis of the outer segment of the photoreceptors. Klotho protein (KL) is expressed in primary cultured human RPE, and regulates pigment synthesis by increasing the expression of MITF (microphthalmia transcription factor) and TYR (tyrosinase), two pivotal genes in melanogenesis. Importantly, KL increases phagocytosis in cultured RPE by inducing gene expression of MERTK/AXL/TYRO3. These effects of KL are mediated through cAMP-PKA-dependent phosphorylation of transcription factor CREB. In cultured human RPE, KL increases the l-3,4-dihydroxyphenylalanine synthesis and inhibits vascular endothelial growth factor (VEGF) secretion from basal membrane by inhibiting IGF-1 signaling and VEGF receptor 2 phosphorylation. KL also regulates the expression of stress-related genes in RPE, lowers the production of reactive oxygen species, and thereby, protects RPE from oxidative stress. Together, our results demonstrate a critical function for KL in mouse retinal health in vivo, and a protective role toward human RPE cells in vitro. We conclude that KL is an important regulator of RPE homeostasis, and propose that an age-dependent decline of KL expression may contribute to RPE degeneration and retinal pathology.
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Abstract
Acromegaly is characterized by excessively high GH and IGF1 levels. Recent data suggest that soluble Klotho (sKlotho) is also elevated in patients with active acromegaly. sKlotho decreases towards normal following removal of the GH-producing pituitary adenoma. The Klotho gene was identified in mice following its accidental disruption by ectopic DNA. It is an ageing suppressor gene of restricted expression (mainly in kidneys, brain, and parathyroid and pituitary glands) encoding a transmembrane protein, mKlotho. mKlotho serves as a co-receptor in fibroblast growth factor 23 (FGF23) signalling. FGF23 promotes urinary phosphate excretion and inhibits the synthesis of calcitriol. The ectodomain of mKlotho is enzymatically released to result in a humoral factor, sKlotho, which exerts systemic effects (on ion channels and signalling pathways), possibly by working as an enzyme that modifies glycans of cell surface glycoproteins. GH enhances renal phosphate reabsorption and calcitriol production, i.e. exerts effects in the proximal tubule opposing those attributed to mKlotho, and attenuates calciuria in the distal tubule similar to sKlotho. sKlotho can be measured in extracellular fluids (serum, urine and cerebrospinal fluid (CSF)) by an ELISA. In line with predominant expression of Klotho in kidneys and choroid plexus, concentrations of sKlotho are particularly high in urine and CSF. Determination of sKlotho in serum and urine (both presumably reflecting GH action on the kidneys) could be used as a supplementary tool in the diagnosis and follow-up of patients with acromegaly. The question arises whether GH exerts selected actions via modifying activities of Klotho.
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Affiliation(s)
- Christoph Schmid
- Division of Endocrinology and Diabetology, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091 Zurich, Switzerland Division of Endocrinology and Diabetology, Kantonsspital St Gallen, 9007 St Gallen, Switzerland Department of Neurosurgery, Clinic Hirslanden, Witellikerstrasse 40, 8032 Zurich, Switzerland
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Lam-Rachlin J, Romero R, Korzeniewski SJ, Schwartz AG, Chaemsaithong P, Hernandez-Andrade E, Dong Z, Yeo L, Hassan SS, Chaiworapongsa T. Infection and smoking are associated with decreased plasma concentration of the anti-aging protein, α-klotho. J Perinat Med 2013; 41:581-94. [PMID: 23770558 PMCID: PMC4144357 DOI: 10.1515/jpm-2013-0084] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/14/2013] [Indexed: 02/06/2023]
Abstract
OBJECTIVE The objective of this study was to determine whether maternal plasma concentrations of soluble α-klotho are different between women with microbial invasion of the intra-amniotic cavity (MIAC) and those without MIAC among preterm labor and intact membranes (PTL) or preterm prelabor rupture of membranes (pPROM). METHODS A cross-sectional study was conducted to include women in the following groups: i) PTL with MIAC (n=14); ii) PTL without MIAC (n=79); iii) pPROM with MIAC (n=30); and iv) pPROM without MIAC (n=33). MIAC was defined as a positive amniotic fluid culture for microorganisms (aerobic/anaerobic bacteria or genital mycoplasmas). Amniotic fluid samples were obtained within 48 h of maternal blood collection. Plasma concentration of soluble α-klotho was determined by ELISA. RESULTS i) The median plasma concentration (pg/mL) of soluble α-klotho was significantly lower in patients with MIAC than in those without MIAC (787.0 vs. 1117.8; P<0.001). ii) Among patients with PTL, those with MIAC had a lower median plasma concentration (pg/mL) of soluble α-klotho than those without MIAC (787.0 vs. 1138.9; P=0.007). iii) Among patients with pPROM, those with MIAC had a lower median plasma concentration (pg/mL) of soluble α-klotho than those without MIAC (766.4 vs. 1001.6; P=0.045). iv) There was no significant difference in the median plasma concentration of soluble α-klotho between PPROM without MIAC and PTL without MIAC (1001.6 pg/mL vs. 1138.9 pg/mL, respectively; P=0.5). v) After adjustment for potential confounders (maternal age, tobacco use, gestational age at venipuncture), soluble α-klotho remained significantly associated with MIAC (P=0.02); and vi) Among patients without MIAC, smoking was significantly associated with a lower median plasma concentration soluble α-klotho than in non-smokers (794.2 pg/mL vs. 1382.0 pg/mL, respectively; P<0.001); however, this difference was not observed in patients with MIAC. CONCLUSIONS Intra-amniotic infection occurring at preterm gestations (regardless of membrane status) was associated with a decrease in maternal plasma concentrations of soluble α-klotho. Moreover, among patients without infection, the plasma concentration of α-klotho was lower in smokers.
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Affiliation(s)
- Jennifer Lam-Rachlin
- Perinatology Research Branch, Wayne State University/Hutzel Women ’ s Hospital, MI 48201, USA.
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14
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Alisi A, Ceccarelli S, Panera N, Prono F, Petrini S, De Stefanis C, Pezzullo M, Tozzi A, Villani A, Bedogni G, Nobili V. Association between Serum Atypical Fibroblast Growth Factors 21 and 19 and Pediatric Nonalcoholic Fatty Liver Disease. PLoS One 2013; 8:e67160. [PMID: 23840612 PMCID: PMC3694051 DOI: 10.1371/journal.pone.0067160] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 05/14/2013] [Indexed: 01/09/2023] Open
Abstract
Atypical fibroblast growth factors (FGF) 21 and 19 play a central role in energy metabolism through the mediation of Klotho coreceptor. Contradictory findings are available about the association of FGF21 and FGF19 with nonalcoholic fatty liver disease (NAFLD) in humans. We investigated the association of serum FGF21, FGF19 and liver Klotho coreceptor with non-alcoholic steatohepatitis (NASH) and fibrosis in children with NAFLD. Serum FGF21 and FGF19 were measured in 84 children with biopsy-proven NAFLD and 23 controls (CTRL). The hepatic expression of Klotho coreceptor was measured in 7 CTRL, 9 patients with NASH (NASH+) and 11 patients without NASH (NASH−). FGF21 and FGF19 showed a tendency to decrease from CTRL (median FGF21 = 196 pg/mL; median FGF19 = 201 pg/mL) to NASH− (FGF21 = 89 pg/mL; FGF19 = 81 pg/mL) to NASH+ patients (FGF21 = 54 pg/mL; FGF19 = 41 pg/mL) (p<0.001 for all comparisons) and were inversely associated with the probability of NASH and fibrosis in children with NAFLD. The hepatic expression of Klotho coreceptor was inversely associated with NASH (R2 = 0.87, p<0.0001) and directly associated with serum FGF21 (R2 = 0.57, p<0.0001) and FGF19 (R2 = 0.67, p<0.0001). In conclusion, serum FGF19 and FGF21 and hepatic Klotho expression are inversely associated with hepatic damage in children with NAFLD and these findings may have important implications for understanding the mechanisms of NAFLD progression.
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Affiliation(s)
- Anna Alisi
- Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- * E-mail:
| | - Sara Ceccarelli
- Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Nadia Panera
- Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Federica Prono
- Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Stefania Petrini
- Microscopy Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Cristiano De Stefanis
- Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Marco Pezzullo
- Core Facilities, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Alberto Tozzi
- Epidemiology Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Alberto Villani
- Pediatrics and Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Giorgio Bedogni
- Clinical Epidemiology Unit, Liver Research Center, Trieste, Italy
| | - Valerio Nobili
- Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
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Munoz C, Pakladok T, Almilaji A, Elvira B, Seebohm G, Voelkl J, Föller M, Shumilina E, Lang F. Klotho sensitivity of the hERG channel. FEBS Lett 2013; 587:1663-8. [PMID: 23603386 DOI: 10.1016/j.febslet.2013.04.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 04/08/2013] [Accepted: 04/08/2013] [Indexed: 01/24/2023]
Abstract
Klotho, a hormone and enzyme, is a powerful regulator of ageing and life span. Klotho deficiency leads to cardiac arrythmia and sudden cardiac death. We thus explored whether klotho modifies cardiac K(+)-channel hERG. Current was determined utilizing dual electrode voltage clamp and hERG protein abundance utilizing immunohistochemistry and chemiluminescence in Xenopus oocytes expressing hERG with or without klotho. Coexpression of klotho increased cell membrane hERG-protein abundance and hERG current at any given voltage without significantly modifying the voltage required to activate the channel. The effect of klotho coexpression was mimicked by recombinant klotho protein and reversed by β-glucuronidase-inhibitor D-saccharic acid-1,4-lactone.
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Affiliation(s)
- Carlos Munoz
- Department of Physiology, University of Tübingen, Tübingen, Germany
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Kacso IM, Bondor CI, Kacso G. Soluble serum Klotho in diabetic nephropathy: relationship to VEGF-A. Clin Biochem 2012; 45:1415-20. [PMID: 22836100 DOI: 10.1016/j.clinbiochem.2012.07.098] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 06/14/2012] [Accepted: 07/15/2012] [Indexed: 01/13/2023]
Abstract
OBJECTIVES Both kidney expression and soluble serum Klotho are influenced by chronic kidney disease (CKD) and diabetes. Serum Klotho is a yet poorly explored biomarker. We describe, for the first time to our knowledge, serum Klotho in diabetic patients with CKD and its relationship to vascular endothelial growth factor A (VEGF-A). DESIGN AND METHODS We included 43 controls and 146 diabetic patients with different stages of CKD. Laboratory evaluation, urinary albumin/creatinine ratio (UACR), Klotho (ELISA), VEGF-A (ELISA) were performed. RESULTS Klotho was 0.40(0.10-1.30)ng/mL in diabetic patients without CKD and 0.80(0.30-1.30)ng/mL in controls, p=0.20; VEGF-A was higher in diabetic patients 73.85(57.32-119.00)pg/mL than in controls 43.20(30.1-65.9)pg/mL, p<0.0001. Klotho increased with CKD stage: 0.2(0.10-0.40)ng/mL in CKD 1/2, 0.60(0.20-1.1)ng/mL in CKD 3/4 and 1.45(0.425-2.90)ng/mL in dialysis patients, p<0.0001; it also increased with decreasing glomerular filtration rate (GFR). Klotho was lower in albuminuric (UACR>30 mg/g) patients 0.20(0.10-0.70)ng/mL than in normoalbuminuric (UACR<30 mg/g) ones 0.50(0.20-1.30)ng/mL, p=0.03; lowest Klotho was found in microalbuminuric (UACR 30-300 mg/g) patients, p=0.07. VEGF was lower in microalbuminuric patients but was not influenced by GFR. In diabetic patients but not in controls, Klotho correlated to VEGF-A (r=0.29, p=0.0003); in multiple regression VEGF-A was the only significant predictor of Klotho: b=0.27, 95%CI (0.01-0.04), p=0.001. CONCLUSIONS In diabetic patients, Klotho is decreased in early CKD and increases thereafter, paralleling reduced GFR. VEGF-A is higher in diabetic patients than in controls. Both Klotho and VEGF-A are decreased in the presence of microalbuminuria. In diabetes, Klotho strongly correlates to VEGF-A.
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Affiliation(s)
- Ina Maria Kacso
- University of Medicine and Pharmacy Iuliu Hatieganu Cluj Napoca, Department of Nephrology, Romania
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