Reevaluation of erythropoietin production by the nephron.
Erythropoietin production has been reported to occur in the peritubular interstitial fibroblasts in the kidney. Since the erythropoietin production in the nephron is controversial, we reevaluated the erythropoietin production in the kidney. We examined mRNA expressions of erythropoietin and HIF PHD2 using high-sensitive in situ hybridization system (ISH) and protein expression of HIF PHD2 using immunohistochemistry in the kidney. We further investigated the mechanism of erythropoietin production by hypoxia in vitro using human liver hepatocell (HepG2) and rat intercalated cell line (IN-IC cells). ISH in mice showed mRNA expression of erythropoietin in proximal convoluted tubules (PCTs), distal convoluted tubules (DCTs) and cortical collecting ducts (CCDs) but not in the peritubular cells under normal conditions. Hypoxia induced mRNA expression of erythropoietin largely in peritubular cells and slightly in PCTs, DCTs, and CCDs. Double staining with AQP3 or AE1 indicated that erythropoietin mRNA expresses mainly in β-intercalated or non α/non β-intercalated cells of the collecting ducts. Immunohistochemistry in rat showed the expression of HIF PHD2 in the collecting ducts and peritubular cells and its increase by anemia in peritubular cells. In IN-IC cells, hypoxia increased mRNA expression of erythropoietin, erythropoietin concentration in the medium and protein expression of HIF PHD2. These data suggest that erythropoietin is produced by the cortical nephrons mainly in the intercalated cells, but not in the peritubular cells, in normal hematopoietic condition and by mainly peritubular cells in hypoxia, suggesting the different regulation mechanism between the nephrons and peritubular cells.
Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Takanori
T
Nagai
Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0374, Japan.
Yukiko
Y
Yasuoka
Department of Nephrology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, 1-1-1 Chuo-ku Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Yuichiro
Y
Izumi
Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Kahori
K
Horikawa
Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Miho
M
Kimura
Department of Nephrology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, 1-1-1 Chuo-ku Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Yushi
Y
Nakayama
Biomedical Laboratory, Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto, Saitama 364-8501, Japan.
Takayuki
T
Uematsu
Biomedical Laboratory, Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto, Saitama 364-8501, Japan.
Takashi
T
Fukuyama
Research Center for Medical Environment, Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto, Saitama 364-8501, Japan.
Taiga
T
Yamazaki
Department of Nephrology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, 1-1-1 Chuo-ku Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Yukimasa
Y
Kohda
Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Yukiko
Y
Hasuike
Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Masayoshi
M
Nanami
Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Takahiro
T
Kuragano
Biomedical Laboratory, Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto, Saitama 364-8501, Japan.
Noritada
N
Kobayashi
Department of Cell Biology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryoumachi, Aoba-ku, Sendai 890-8575, Japan.
Masuo
M
Obinata
Department of Nephrology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, 1-1-1 Chuo-ku Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Kimio
K
Tomita
Department of Pharmacology, National Research Institute for Child Health and Development, 2-10-1 Ookura, Setagaya-ku, Tokyo 157-8535, Japan.
Akito
A
Tanoue
Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Takeshi
T
Nakanishi
Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0374, Japan.
Katsumasa
K
Kawahara
Department of Internal Medicine, and Education and Research Center, Kitasato University Medical Center, 6-100 Arai, Kitamoto, Saitama 364-8501, Japan. Electronic address: nono@insti.kitasato-u.ac.jp.
Hiroshi
H
Nonoguchi
D000818:Animals; D015687:Cell Hypoxia; D002460:Cell Line; D004921:Erythropoietin / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D056945:Hep G2 Cells; D006801:Humans; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009399:Nephrons / Q000378:metabolism*; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
C554270:EPO protein, human; D012333:RNA, Messenger; D004921:Erythropoietin; D011393:Procollagen-Proline Dioxygenase; C490189:Egln1 protein, mouse; C580731:Egln1 protein, rat; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases
Anemia; Collecting duct; Erythropoietin; Hypoxia; Hypoxia-inducible factor; Nephron