The vacuolar-ATPase complex and assembly factors, TMEM199 and CCDC115, control HIF1alpha prolyl hydroxylation by regulating cellular iron levels.
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Miles AL, Burr SP, Grice GL, Nathan JA
The vacuolar-ATPase complex and assembly factors, TMEM199 and CCDC115, control HIF1alpha prolyl hydroxylation by regulating cellular iron levels.
Elife. 2017 Mar 15;6. doi: 10.7554/eLife.22693.
- PubMed ID
- 28296633 [ View in PubMed]
- Abstract
Hypoxia Inducible transcription Factors (HIFs) are principally regulated by the 2-oxoglutarate and Iron(II) prolyl hydroxylase (PHD) enzymes, which hydroxylate the HIFalpha subunit, facilitating its proteasome-mediated degradation. Observations that HIFalpha 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 HIF1alpha. 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 HIF1alpha in aerobic conditions. Rather than preventing the lysosomal degradation of HIF1alpha, 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.