Hydrogen Sulfide Induced Erythropoietin Synthesis is Regulated by HIF Proteins

Abstract

Anemia of end stage renal disease affects 90% of patients on hemodialysis and it is a tremendous concern of patients and health care providers. Renal disease creates a state of renal hypoxia, which may contribute to a lack of erythropoietin production from the kidney when low oxygen levels are sensed. This necessitates the use of exogenous erythropoietin preparations. Recent evidence suggests that endogenously derived hydrogen sulfide may mediate oxygen sensing in tissues. Given the known involvement of other small molecules such as nitric oxide in erythropoietin production and the observation of decreased urinary H2S levels in patients with renal failure, we postulated that H2S may be the primary mediator of erythropoietin production during hypoxia. PK1, 786-O and Hep3B cells were incubated in hypoxia (1% O2) for 24 hours. Hypoxic cells were treated with the H2S donor GYY 4137 and the H2S inhibitor hydroxylamine. Following hypoxia erythropoietin, HIF-1α, HIF-2α and CBS expression was measured by quantitative real-time polymerase chain reaction and Western blot. Hydroxylamine administration led to a significant decrease in erythropoietin, HIF-1α, HIF-2α and CBS protein levels during hypoxia. This was rescued by administration of GYY 4137 for erythropoietin, CBS and HIF-2α. Additionally, CSE -/- mice placed in hypoxia for 72 hours showed decreased renal erythropoietin production compared to wild-type mice. These data suggest previously undocumented interplay of the production and action of H2S during hypoxia with subsequent erythropoietin production. The use of novel hydrogen sulfide donors could represent an alternative to standard therapies of anemia of renal failure.