TY  - JOUR
A1  - Hafizi, Redona
A1  - Imeri, Faik
A1  - Stepanovska Tanturovska, Bisera
A1  - Manaila, Roxana
A1  - Schwalm, Stephanie
A1  - Trautmann, Sandra
A1  - Wenger, Roland H.
A1  - Pfeilschifter, Josef
A1  - Huwiler, Andrea
T1  - Sphk1 and Sphk2 differentially regulate erythropoietin synthesis in mouse renal interstitial fibroblast-like cells
T2  - International journal of molecular sciences
N2  - Erythropoietin (Epo) is a crucial hormone regulating red blood cell number and consequently the hematocrit. Epo is mainly produced in the kidney by interstitial fibroblast-like cells. Previously, we have shown that in cultures of the immortalized mouse renal fibroblast-like cell line FAIK F3-5, sphingosine 1-phosphate (S1P), by activating S1P1 and S1P3 receptors, can stabilize hypoxia-inducible factor (HIF)-2α and upregulate Epo mRNA and protein synthesis. In this study, we have addressed the role of intracellular iS1P derived from sphingosine kinases (Sphk) 1 and 2 on Epo synthesis in F3-5 cells and in mouse primary cultures of renal fibroblasts. We show that stable knockdown of Sphk2 in F3-5 cells increases HIF-2α protein and Epo mRNA and protein levels, while Sphk1 knockdown leads to a reduction of hypoxia-stimulated HIF-2α and Epo protein. A similar effect was obtained using primary cultures of renal fibroblasts isolated from wildtype mice, Sphk1−/−, or Sphk2−/− mice. Furthermore, selective Sphk2 inhibitors mimicked the effect of genetic Sphk2 depletion and also upregulated HIF-2α and Epo protein levels. The combined blockade of Sphk1 and Sphk2, using Sphk2−/− renal fibroblasts treated with the Sphk1 inhibitor PF543, resulted in reduced HIF-2α and Epo compared to the untreated Sphk2−/− cells. Exogenous sphingosine (Sph) enhanced HIF-2α and Epo, and this was abolished by the combined treatment with the selective S1P1 and S1P3 antagonists NIBR-0213 and TY52156, suggesting that Sph was taken up by cells and converted to iS1P and exported to then act in an autocrine manner through S1P1 and S1P3. The upregulation of HIF-2α and Epo synthesis by Sphk2 knockdown was confirmed in the human hepatoma cell line Hep3B, which is well-established to upregulate Epo production under hypoxia. In summary, these data show that sphingolipids have diverse effects on Epo synthesis. While accumulation of intracellular Sph reduces Epo synthesis, iS1P will be exported to act through S1P1+3 to enhance Epo synthesis. Furthermore, these data suggest that selective inhibition of Sphk2 is an attractive new option to enhance Epo synthesis and thereby to reduce anemia development in chronic kidney disease.
KW  - Sphk2
KW  - Sphk1
KW  - sphingosine
KW  - sphingosine 1-phosphate
KW  - HIF-2α, erythropoietin
KW  - renal fibroblasts
KW  - anemia
Y1  - 2022
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/69249
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-692490
SN  - 1422-0067
SN  - 1661-6596
N1  - This work was supported by the Swiss National Science Foundation (310030_175561/1 to A.H., 310030_184813 and NCCR “Kidney.ch”, 183774, to R.H.W.), the Hochschulstiftung der Universität Bern (20/2020, to F.I.), and the German Research Foundation (SFB 1039, project-ID: 204083920 to J.P.).
VL  - 23
IS  - 11, art. 5882
SP  - 1
EP  - 16
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  -