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Mencke R, Harms G, Mirković K, Struik J, Van Ark J, Van Loon E, Verkaik M, De Borst MH, Zeebregts CJ, Hoenderop JG, Vervloet MG, Hillebrands JL. Membrane-bound Klotho is not expressed endogenously in healthy or uraemic human vascular tissue. Cardiovasc Res 2015; 108:220-31. [PMID: 26116633 DOI: 10.1093/cvr/cvv187] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 06/23/2015] [Indexed: 01/29/2023] Open
Abstract
AIMS Cardiovascular disease (CVD) is the leading cause of death in patients with chronic kidney disease (CKD), a disease state that is strongly associated with loss of renal and systemic (alpha-)Klotho. Reversely, murine Klotho deficiency causes marked medial calcification. It is therefore thought that Klotho conveys a vasculoprotective effect. Klotho expression in the vessel wall, however, is disputed. METHODS AND RESULTS We assessed Klotho expression in healthy human renal donor arteries (n = 9), CKD (renal graft recipient) arteries (n = 10), carotid endarterectomy specimens (n = 8), other elastic arteries (three groups of n = 3), and cultured human aortic smooth muscle cells (HASMCs) (three primary cell lines), using immunohistochemistry (IHC), immunofluorescence, quantitative reverse transcriptase-polymerase chain reaction, and western blotting (WB). We have extensively validated anti-Klotho antibody KM2076 by comparing staining patterns with other anti-Klotho antibodies (SC-22220, SC-22218, and AF1819), competition assays with recombinant Klotho, IHC on Klotho-deficient kl/kl mouse kidney, and WB with recombinant Klotho. Using KM2076, we could not detect full-length Klotho in vascular tissues or HASMCs. On the mRNA level, using primers against all four exon junctions, klotho expression could not be detected either. Fibroblast growth factor 23 (FGF23) injections in mice induced FGF23 signalling in kidneys but not in the aorta, indicating the absence of Klotho-dependent FGF23 signalling in the aorta. CONCLUSION Using several independent and validated methods, we conclude that full-length, membrane-bound Klotho is not expressed in healthy or uraemic human vascular tissue.
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Affiliation(s)
- Rik Mencke
- Department of Pathology and Medical Biology (Division of Pathology), University of Groningen, University Medical Center Groningen, HPC EA10, PO Box 30.001, Groningen 9700 RB, The Netherlands
| | - Geert Harms
- Department of Pathology and Medical Biology (Division of Pathology), University of Groningen, University Medical Center Groningen, HPC EA10, PO Box 30.001, Groningen 9700 RB, The Netherlands
| | - Katarina Mirković
- Department of Internal Medicine (Division of Nephrology), University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Joyce Struik
- Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands
| | - Joris Van Ark
- Department of Pathology and Medical Biology (Division of Pathology), University of Groningen, University Medical Center Groningen, HPC EA10, PO Box 30.001, Groningen 9700 RB, The Netherlands
| | - Ellen Van Loon
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Melissa Verkaik
- Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands
| | - Martin H De Borst
- Department of Internal Medicine (Division of Nephrology), University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Clark J Zeebregts
- Department of Surgery (Division of Vascular Surgery), University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Joost G Hoenderop
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marc G Vervloet
- Department of Nephrology, VU University Medical Center, Amsterdam, The Netherlands
| | - Jan-Luuk Hillebrands
- Department of Pathology and Medical Biology (Division of Pathology), University of Groningen, University Medical Center Groningen, HPC EA10, PO Box 30.001, Groningen 9700 RB, The Netherlands
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