Reevaluation of erythropoietin production by the nephron.

Abstract

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.

• Authors: Takanori Nagai, Yukiko Yasuoka, Yuichiro Izumi, Kahori Horikawa, Miho Kimura, Yushi Nakayama, Takayuki Uematsu, Takashi Fukuyama, Taiga Yamazaki, Yukimasa Kohda, Yukiko Hasuike, Masayoshi Nanami, Takahiro Kuragano, Noritada Kobayashi, Masuo Obinata, Kimio Tomita, Akito Tanoue, Takeshi Nakanishi, Katsumasa Kawahara, Hiroshi Nonoguchi
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 449 Issue 2 Pg. 222-8 (Jun 27 2014) ISSN: 1090-2104 [Electronic] United States
• PMID: 24832733 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Chemical References

• EPO protein, human
• RNA, Messenger
• Erythropoietin
• Procollagen-Proline Dioxygenase
• Egln1 protein, mouse
• Egln1 protein, rat
• Hypoxia-Inducible Factor-Proline Dioxygenases

Topics

• Animals
• Cell Hypoxia
• Cell Line
• Erythropoietin (biosynthesis, genetics)
• Gene Expression Regulation
• Hep G2 Cells
• Humans
• Hypoxia-Inducible Factor-Proline Dioxygenases (genetics, metabolism)
• Immunohistochemistry
• In Situ Hybridization
• Kidney (cytology, metabolism)
• Mice
• Mice, Inbred C57BL
• Nephrons (metabolism)
• Procollagen-Proline Dioxygenase (genetics, metabolism)
• RNA, Messenger (genetics, metabolism)
• Rats
• Rats, Sprague-Dawley
• Tissue Distribution