title: Acetazolamide sensitive tissue calcification and aging of klotho-hypomorphic mice.
abstract: Klotho, a protein expressed mainly in the kidney, is required for the inhibitory effect of FGF23 on renal 1,25(OH)2D3 formation. Klotho counteracts vascular calcification and diverse age-related disorders. Klotho-hypomorphic mice (kl/kl) suffer from severe vascular calcification and rapid aging. The calcification is at least in part caused by excessive 1,25(OH)2D3, Ca(2+), and phosphate concentrations in blood, which trigger osteogenic signaling including upregulation of alkaline phosphatase (Alpl). As precipitation of calcium and phosphate is fostered by alkaline pH, extracellular acidosis could counteract tissue calcification. In order to induce acidosis, acetazolamide was added to drinking water (0.8 g/l) of kl/kl and wild-type mice. As a result, acetazolamide treatment of kl/kl mice partially reversed the growth deficit, tripled the life span, almost completely reversed the calcifications in trachea, lung, kidney, stomach, intestine, and vascular tissues, the excessive aortic alkaline phosphatase mRNA levels and the plasma concentrations of osteoprotegerin, osteopontin as well as fetuin-A, without significantly decreasing FGF23, 1,25(OH)2D3, Ca(2+), and phosphate plasma concentrations. In primary human aortic smooth muscle cells, acidotic environment prevented phosphate-induced alkaline phosphatase mRNA expression. The present study reveals a completely novel effect of acetazolamide, i.e., interference with osteoinductive signaling and tissue calcification in kl/kl mice.
  
  
  CONCLUSIONS
  Klotho deficient (kl/kl) mice suffer from hyperphosphatemia with dramatic tissue calcification. Acetazolamide (ACM) treatment partially reversed the growth deficit of kl/kl mice. In kl/kl mice, ACM reversed tissue calcification despite continued hyperphosphatemia. ACM tripled the life span of kl/kl mice. In human aortic smooth muscle cells, low extracellular pH prevented osteogenic signaling.
authors: Department of Physiology, Physiologisches Institut der Universität Tübingen, Gmelinstr 5, D-72076, Tübingen, Germany.
authors: Christina B
authors: CB
authors: Leibrock
authors: Department of Physiology, Physiologisches Institut der Universität Tübingen, Gmelinstr 5, D-72076, Tübingen, Germany.
authors: Ioana
authors: I
authors: Alesutan
authors: Department of Physiology, Physiologisches Institut der Universität Tübingen, Gmelinstr 5, D-72076, Tübingen, Germany.
authors: Jakob
authors: J
authors: Voelkl
authors: Department of Physiology, Physiologisches Institut der Universität Tübingen, Gmelinstr 5, D-72076, Tübingen, Germany.
authors: Diana
authors: D
authors: Michael
authors: Department of Physiology, Physiologisches Institut der Universität Tübingen, Gmelinstr 5, D-72076, Tübingen, Germany.
authors: Tatsiana
authors: T
authors: Castor
authors: Department of Pathology, Liebermeisterstr. 8, University of Tübingen, Tübingen, Germany.
authors: Ursula
authors: U
authors: Kohlhofer
authors: Department of Pathology, Liebermeisterstr. 8, University of Tübingen, Tübingen, Germany.
authors: Leticia
authors: L
authors: Quintanilla-Martinez
authors: Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, University of Tübingen, Röntgenweg 13, 72076, Tübingen, Germany.
authors: Laura
authors: L
authors: Kübler
authors: Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, University of Tübingen, Röntgenweg 13, 72076, Tübingen, Germany.
authors: Julia G
authors: JG
authors: Mannheim
authors: Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, University of Tübingen, Röntgenweg 13, 72076, Tübingen, Germany.
authors: Bernd J
authors: BJ
authors: Pichler
authors: Center for Clinical Proteomics, the Brown Foundation Institute of Molecular Medicine, 1825 Pressler Street, SRB, Suite 330E, Houston, TX, USA.
authors: Kevin P
authors: KP
authors: Rosenblatt
authors: Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan.
authors: Makoto
authors: M
authors: Kuro-o
authors: Department of Physiology, Physiologisches Institut der Universität Tübingen, Gmelinstr 5, D-72076, Tübingen, Germany. florian.lang@uni-tuebingen.de.
authors: Florian
authors: F
authors: Lang
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology*; D000138:Acidosis / Q000139:chemically induced*; D000375:Aging / Q000235:genetics / Q000473:pathology; D000469:Alkaline Phosphatase / Q000096:biosynthesis / Q000097:blood; D000818:Animals; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology*; D002478:Cells, Cultured; D000089703:Fibroblast Growth Factor-23; D005966:Glucuronidase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D054559:Hyperphosphatemia / Q000235:genetics; D000090265:Klotho Proteins; D051379:Mice; D018345:Mice, Knockout; D010012:Osteogenesis / Q000187:drug effects*; D010710:Phosphates / Q000097:blood; D015398:Signal Transduction / Q000187:drug effects; D061205:Vascular Calcification / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*
chemical_list: D002257:Carbonic Anhydrase Inhibitors; C000717427:FGF23 protein, human; C000717428:Fgf23 protein, mouse; D010710:Phosphates; D000089703:Fibroblast Growth Factor-23; D000469:Alkaline Phosphatase; D005966:Glucuronidase; D000090265:Klotho Proteins; D002117:Calcitriol; D000086:Acetazolamide; D002118:Calcium
keywords: 1,25(OH)2D3; Acetazolamide; Acidosis; Calcification; Calcium; Phosphate