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Firmke, Bettina K. M. ; Fuchs, Michaela A. A. ; Süß, Lena M. ; Forst, Anna‐Lena ; Kurtz, Armin ; Broeker, Katharina A.‐E.

Hypoxia‐inducible factor‐2 stabilization is not sufficient to induce erythropoietin production in deeper medullary fibroblasts

Article

Firmke, Bettina K. M., Fuchs, Michaela A. A., Süß, Lena M., Forst, Anna‐Lena, Kurtz, Armin and Broeker, Katharina A.‐E. (2025) Hypoxia‐inducible factor‐2 stabilization is not sufficient to induce erythropoietin production in deeper medullary fibroblasts. The Journal of Physiology.

DOI to cite this document: 10.5283/epub.77594


Abstract

Under hypoxaemic conditions, cortical fibroblasts primarily produce erythropoietin (EPO). However, we have previously shown that most interstitial fibroblasts positive for platelet-derived growth factor receptor β (PDGFR-β) in all kidney zones are also able to produce EPO. Therefore, we wondered if either the physiological stimuli might not be sufficient to stabilize the hypoxia-inducible factor ...

Under hypoxaemic conditions, cortical fibroblasts primarily produce erythropoietin (EPO). However, we have previously shown that most interstitial fibroblasts positive for platelet-derived growth factor receptor β (PDGFR-β) in all kidney zones are also able to produce EPO. Therefore, we wondered if either the physiological stimuli might not be sufficient to stabilize the hypoxia-inducible factor (HIF)-2 in medullary fibroblasts or if different expression patterns or functions of the HIF-regulating prolyl-4-hydroxylases (PHD) 2 and 3 might explain the restrictive EPO cell recruitment. This study shows that although HIF-2 can be clearly stabilized in deeper medullary fibroblasts by pharmacological PHD-inhibition, this is not sufficient to induce EPO in these cells. In contrast, genetic stabilization of HIF-2 by cell-specific deletion of either PHD2 or PHD2 and PHD3 in mice resulted in EPO production in all kidney zones. EPO induction in PHD2/3-KO mice was twice as high as in PHD2-KOs. PHD3 deletion slightly increased basal EPO expression. Accordingly, in contrast to PHD2, PHD3 expression was only detected in a subset of interstitial fibroblasts, without zonal accumulation or hypoxaemic upregulation. Exposure of PHD3-deficient mice to a hypoxaemic stimulus resulted in significantly higher EPO levels compared to controls, with EPO induction restricted to the cortex. Overall, our data suggest the existence of additional regulatory mechanisms beyond the HIF-2 signalling pathway that control EPO expression in deeper medullary fibroblasts. Furthermore, they identify PHD3 as an attenuating factor that delays EPO induction in a subset of cortical PDGFR-β+ cells, but its expression pattern is not the determining factor responsible for the cortical restriction of EPO.



Involved Institutions


Details

Item typeArticle
Journal or Publication TitleThe Journal of Physiology
PublisherWiley
Open Access TypeDEAL (Wiley)
Date25 August 2025
Date of publication27 Aug 2025 08:05
InstitutionsBiology, Preclinical Medicine > Institut für Physiologie > Prof. Dr. Armin Kurtz
Projects
Funded by: Deutsche Forschungsgemeinschaft (DFG) (509149993)
Identification Number
ValueType
10.1113/JP288798DOI
Keywordserythropoietin, hypoxia signalling, interstitial fibroblasts, PHD inhibition, prolyl-4-hydroxylases, renal endocrine functio
Dewey Decimal Classification500 Science > 570 Life sciences
StatusPublished
RefereedYes, this version has been refereed
Created at the University of RegensburgYes
URN of the UB Regensburgurn:nbn:de:bvb:355-epub-775941
Item ID77594

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