Retinoic acid regulates erythropoietin production cooperatively with hypoxia-inducible factors in human iPSC-derived erythropoietin-producing cells

Naoko Katagiri,Hirofumi Hitomi,Kenji Osafune,Takuya Yamamoto,Maki Kotaka,Akira Nishiyama,Li Lei,Shin-Ichi Mae

doi:10.1038/s41598-021-83431-6

Naoko Katagiri, Hirofumi Hitomi + Show 6 more

Open Access

https://doi.org/10.1038/s41598-021-83431-6

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Abstract

Erythropoietin (EPO) is a crucial hormone for erythropoiesis and produced by adult kidneys. Insufficient EPO production in chronic kidney disease (CKD) can cause renal anemia. Although hypoxia-inducible factors (HIFs) are known as a main regulator, the mechanisms of EPO production have not been fully elucidated. In this study, we aimed to examine the roles of retinoic acid (RA) in EPO production using EPO-producing cells derived from human induced pluripotent stem cells (hiPSC-EPO cells) that we previously established. RA augmented EPO production by hiPSC-EPO cells under hypoxia or by treatment with prolyl hydroxylase domain-containing protein (PHD) inhibitors that upregulate HIF signals. Combination treatment with RA and a PHD inhibitor improved renal anemia in vitamin A-depleted CKD model mice. Our findings using hiPSC-EPO cells and CKD model mice may contribute to clarifying the EPO production mechanism and developing efficient therapies for renal anemia.

Highlights

Erythropoietin (EPO) is a crucial hormone for erythropoiesis and produced by adult kidneys
To evaluate how RA signals work in EPO production, we investigated the effects of two different retinoids, all-trans retinoic acid (ATRA) and bexarotene
The results showed that ATRA additively increased EPO mRNA expression and dose-dependently increased protein secretion with 10 (μM) ATRA (10 μM) FG4592 under normoxic conditions (Fig. 1D,E)

Summary

Introduction

Erythropoietin (EPO) is a crucial hormone for erythropoiesis and produced by adult kidneys. RA augmented EPO production by hiPSC-EPO cells under hypoxia or by treatment with prolyl hydroxylase domain-containing protein (PHD) inhibitors that upregulate HIF signals. The hypoxia-inducible factor (HIF)-prolyl hydroxylase domain-containing protein (PHD) pathway is known as a main regulator, the detailed mechanism of EPO production, especially in humans, has not been fully e lucidated[4]. (B–E) Effects of ATRA treatment on EPO mRNA expression (B–D) and protein secretion (E) by hiPSC-EPO cells under normoxia (21% oxygen; B,E light gray), hypoxia (5% oxygen; C,E, dark gray) and normoxic conditions combined with PHD inhibitor treatment (10 μM FG4592; D,E, black), as analyzed by qRT-PCR and ELISA, respectively. (H,I) Effects of adding various concentrations of an RARα antagonist, AGN193109, to the ATRA treatment on EPO mRNA expression (H) and protein secretion (I) by hiPSC-EPO cells under hypoxic conditions. Statistical analysis was performed using one-way ANOVA with Dunnett’s multiple comparison test in (B–F,H,I) and Student’s t test in (G). #p < 0.05 versus the samples treated with DMSO under hypoxic conditions in (C,E) and those treated with ATRA but without AGN193109 under hypoxic conditions in (H,I). *p < 0.05 versus the samples treated with PHD inhibitors but without ATRA under normoxic conditions in (D,E,G). ☨p < 0.05 versus the samples treated with DMSO under normoxic conditions in (E,F)

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