Erythropoietin synthesis in renal myofibroblasts is restored by activation of hypoxia signaling

Tomokazu Souma, Masahiro Nezu, Daisuke Nakano, Shun Yamazaki, Ikuo Hirano, Hiroki Sekine, Takashi Dan, Kotaro Takeda, Guo Hua Fong, Akira Nishiyama, Sadayoshi Ito, Toshio Miyata, Masayuki Yamamoto, Norio Suzuki

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Erythropoietin (Epo) is produced by renal Epo-producing cells (REPs) in a hypoxia-inducible manner. The conversion of REPs into myofibroblasts and coincident loss of Epo-producing ability are the major cause of renal fibrosis and anemia. However, the hypoxic response of these transformed myofibroblasts remains unclear. Here, we used complementary in vivo transgenic and live imaging approaches to better understand the importance of hypoxia signaling in Epo production. Live imaging of REPs in transgenic mice expressing green fluorescent protein fromamodified Epo-gene locus revealed that healthy REPs tightly associated with endothelium by wrapping processes around capillaries. However, this association was hampered in states of renal injury-induced inflammation previously shown to correlate with the transition tomyofibroblast-transformed renal Epo-producing cells (MF-REPs). Furthermore, activation of hypoxia-inducible factors (HIFs) by genetic inactivation of HIF-prolyl hydroxylases (PHD1,PHD2, andPHD3) selectively inEpo-producingcells reactivated Epo production in MF-REPs. Loss of PHD2 in REPs restored Epo-gene expression in injured kidneys but caused polycythemia. Notably, combined deletions of PHD1 and PHD3 prevented loss of Epo expression without provoking polycythemia. Mice with PHD-deficient REPs also showed resistance to LPS-induced Epo repression in kidneys, suggesting that augmented HIF signaling counterbalances inflammatory stimuli in regulation of Epo production. Thus, augmentation of HIF signaling may be an attractive therapeutic strategy for treating renal anemia by reactivating Epo synthesis in MF-REPs.

Original languageEnglish
Pages (from-to)428-438
Number of pages11
JournalJournal of the American Society of Nephrology
Volume27
Issue number2
DOIs
Publication statusPublished - 2016 Feb

ASJC Scopus subject areas

  • Nephrology

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