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Promoter methylation confers kidney‐specific expression of the Klotho gene
Author(s) -
Azuma Masahiro,
Koyama Daisuke,
Kikuchi Jiro,
Yoshizawa Hiromichi,
Thasinas Dissayabutra,
Shiizaki Kazuhiro,
Kuroo Makoto,
Furukawa Yusuke,
Kusano Eiji
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.12-211631
Subject(s) - klotho , dna methylation , promoter , methylation , biology , chromatin , microbiology and biotechnology , cpg site , kidney , transfection , gene expression , regulation of gene expression , reporter gene , gene , cancer research , endocrinology , genetics
The aging suppressor geneKlotho is predominantly expressed in the kidney irrespective of species. Because Klotho protein is an essential component of an endocrine axis that regulates renal phosphate handling, the kidney‐specific expression is biologically relevant; however, little is known about its underlying mechanisms. Here we provide in vitro and in vivo evidence indicating that promoter methylation restricts the expression of the Klotho gene in the kidney. Based on evolutionary conservation and histone methylation patterns, the region up to –1200 bp was defined as a major promoter element of the human Klotho gene. This region displayed promoter activity equally in Klotho‐expressing and ‐nonexpressing cells in transient reporter assays, but the activity was reduced to ~20% when the constructs were integrated into the chromatin in the latter. Both endogenous and transfected Klotho promoters were 30–40% methylated in Klotho‐nonexpressing cells, but unmethylated in Klotho‐expressing renal tubular cells. DNA demethylating agents increased Klotho expression 1.5‐ to 3.0‐fold in nonexpressing cells and restored the activity of silenced reporter constructs. Finally, we demonstrated that a severe hypomorphic allele of Klotho had aberrant CpG methylation in kl/kl mice. These findings might be useful in therapeutic intervention for accelerated aging and several complications caused by Klotho downregulation.—Azuma, M., Koyama, D., Kikuchi, J., Yoshizawa, H., Thasinas, D., Shiizaki, K., Kuro‐o, M., Furukawa, Y., Kusano, E. Promoter methylation confers kidney‐specific expression of the Klotho gene. FASEB J. 26, 4264–4274 (2012). www.fasebj.org