Rik Mencke1, Geert Harms1, Katarina Mirković2, Joyce Struik3, Joris Van Ark1, Ellen Van Loon4, Melissa Verkaik3, Martin H De Borst2, Clark J Zeebregts5, Joost G Hoenderop4, Marc G Vervloet6, Jan-Luuk Hillebrands7. 1. 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. 2. Department of Internal Medicine (Division of Nephrology), University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. 3. Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands. 4. Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands. 5. Department of Surgery (Division of Vascular Surgery), University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. 6. Department of Nephrology, VU University Medical Center, Amsterdam, The Netherlands. 7. 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 j.l.hillebrands@umcg.nl.
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. Published on behalf of the European Society of Cardiology. All rights reserved.
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, murineKlothodeficiency 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. Published on behalf of the European Society of Cardiology. All rights reserved.
Authors: Jakob L Rukov; Eva Gravesen; Maria L Mace; Jacob Hofman-Bang; Jeppe Vinther; Claus B Andersen; Ewa Lewin; Klaus Olgaard Journal: Am J Physiol Renal Physiol Date: 2016-01-06