Distinct subpopulations of FOXD1 stroma-derived cells regulate renal erythropoietin
Hanako Kobayashi, … , Kenneth W. Gross, Volker H. Haase
Hanako Kobayashi, … , Kenneth W. Gross, Volker H. Haase
Published April 18, 2016
Citation Information: J Clin Invest. 2016;126(5):1926-1938. https://doi.org/10.1172/JCI83551.
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Research Article Nephrology

Distinct subpopulations of FOXD1 stroma-derived cells regulate renal erythropoietin

Abstract

Renal peritubular interstitial fibroblast-like cells are critical for adult erythropoiesis, as they are the main source of erythropoietin (EPO). Hypoxia-inducible factor 2 (HIF-2) controls EPO synthesis in the kidney and liver and is regulated by prolyl-4-hydroxylase domain (PHD) dioxygenases PHD1, PHD2, and PHD3, which function as cellular oxygen sensors. Renal interstitial cells with EPO-producing capacity are poorly characterized, and the role of the PHD/HIF-2 axis in renal EPO-producing cell (REPC) plasticity is unclear. Here we targeted the PHD/HIF-2/EPO axis in FOXD1 stroma-derived renal interstitial cells and examined the role of individual PHDs in REPC pool size regulation and renal EPO output. Renal interstitial cells with EPO-producing capacity were entirely derived from FOXD1-expressing stroma, and Phd2 inactivation alone induced renal Epo in a limited number of renal interstitial cells. EPO induction was submaximal, as hypoxia or pharmacologic PHD inhibition further increased the REPC fraction among Phd2–/– renal interstitial cells. Moreover, Phd1 and Phd3 were differentially expressed in renal interstitium, and heterozygous deficiency for Phd1 and Phd3 increased REPC numbers in Phd2–/– mice. We propose that FOXD1 lineage renal interstitial cells consist of distinct subpopulations that differ in their responsiveness to Phd2 inactivation and thus regulation of HIF-2 activity and EPO production under hypoxia or conditions of pharmacologic or genetic PHD inactivation.

Authors

Hanako Kobayashi, Qingdu Liu, Thomas C. Binns, Andres A. Urrutia, Olena Davidoff, Pinelopi P. Kapitsinou, Andrew S. Pfaff, Hannes Olauson, Annika Wernerson, Agnes B. Fogo, Guo-Hua Fong, Kenneth W. Gross, Volker H. Haase

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Figure 3

Inactivation of Phd2 in FOXD1 stroma-derived renal interstitial cells results in polycythemia.

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Inactivation of Phd2 in FOXD1 stroma-derived renal interstitial cells re...
(A) PCR analysis of genomic brain (Br), liver (L), and kidney (K) DNA isolated from control (Phd2fl/fl Cre–) and Foxd1-Phd2–/– (Phd2fl/fl Cre+) mutant mice. 2-lox denotes the nonrecombined conditional allele and 1-lox the recombined allele. (B) Individual values for hematocrit (Hct), hemoglobin (Hb), rbc counts, and reticulocyte production index (RPI) for control (Co) and Foxd1-Phd2–/– (Phd2–/–) mutant mice (n = 6–11). Data are represented as mean ± SEM; 2-tailed Student’s t test; ***P < 0.001. (C) Renal Epo, Vegf, and Phd3 mRNA and serum EPO (sEPO) level from control and Foxd1-Phd2–/– mutant mice (n = 3–6). Graph bars represent mean ± SEM; 2-tailed Student’s t test; ***P < 0.001 compared with control group. (D) Epo ISH in formalin-fixed, paraffin-embedded kidney sections from control and Foxd1-Phd2–/– kidneys using an HRP-based colorimetric detection method. White arrows indicate positively stained cells and asterisks depict glomeruli. Scale bars: 100 μm (left panels), 50 μm (right panels). (E) Vegf expression is increased in Phd2–/– interstitial cells. Shown are representative images of multiplex ISH studies using formalin-fixed, paraffin-embedded kidney tissue sections from Foxd1-mT/mG (Co) and Foxd1-mT/mG-Phd2–/– (Phd2–/–) mice. Epo+Vegf+ cells are denoted by white arrows; yellow arrows depict Vegf-expressing glomerular cells; glomeruli are marked with asterisks. Scale bar: 50 μm (all panels).