The vacuolar-ATPase complex and assembly factors, TMEM199 and CCDC115, control HIF1? prolyl hydroxylation by regulating cellular iron levels.

ABSTRACT: Hypoxia Inducible transcription Factors (HIFs) are principally regulated by the 2-oxoglutarate and Iron(II) prolyl hydroxylase (PHD) enzymes, which hydroxylate the HIF? subunit, facilitating its proteasome-mediated degradation. Observations that HIF? hydroxylation can be impaired even when oxygen is sufficient emphasise the importance of understanding the complex nature of PHD regulation. Here, we use an unbiased genome-wide genetic screen in near-haploid human cells to uncover cellular processes that regulate HIF1?. We identify that genetic disruption of the Vacuolar H+ ATPase (V-ATPase), the key proton pump for endo-lysosomal acidification, and two previously uncharacterised V-ATPase assembly factors, TMEM199 and CCDC115, stabilise HIF1? in aerobic conditions. Rather than preventing the lysosomal degradation of HIF1?, disrupting the V-ATPase results in intracellular iron depletion, thereby impairing PHD activity and leading to HIF activation. Iron supplementation directly restores PHD catalytic activity following V-ATPase inhibition, revealing important links between the V-ATPase, iron metabolism and HIFs.

SUBMITTER: Miles AL 

PROVIDER: S-EPMC5391204 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature