Cellular oxygen sensing: Importins and exportins are mediators of intracellular localisation of prolyl-4-hydroxylases PHD1 and PHD2.
Hypoxia-inducible factors are crucial in the regulatory process of oxygen homeostasis of vertebrate cells. Inhibition of prolyl hydroxylation of HIF-alpha subunits by prolyl-hydroxylases (PHD1, PHD2 and PHD3) leads to transcription of a greater number of hypoxia responsive genes. We have investigated the subcellular distribution and the molecular mechanisms regulating the intracellular allocation of PHD1 and PHD2. As reported earlier we find PHD1 located exclusively in the nucleus. We demonstrate that nuclear import of PHD1 occurs importin alpha/beta dependently and relies on a nuclear localisation signal (NLS). By contrast PHD2 is cycling between nucleus and cytoplasm, and nuclear import seems to be independent of "classical" importin alpha/beta receptors. Furthermore, we reveal that the exit of PHD2 from the nucleus requires CRM1 and the N-terminal 100 amino acids of the protein. Our findings provide new insights into the mechanisms of the regulation of the oxygen sensor cascade of PHDs in different cellular compartments.
Steinhoff
Amrei
A
Department of Physiology, Center for Structural and Cell Biology in Medicine, University of Lübeck, Germany.
Pientka
Friederike Katharina
FK
Möckel
Sylvia
S
Kettelhake
Antje
A
Hartmann
Enno
E
Köhler
Matthias
M
Depping
Reinhard
R
D021581:Active Transport, Cell Nucleus; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D006801:Humans; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D028884:Karyopherins / Q000378:metabolism*; D019913:Nuclear Localization Signals / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary
D028884:Karyopherins; D019913:Nuclear Localization Signals; C490190:EGLN1 protein, human; C510863:P4HA1 protein, human; D011393:Procollagen-Proline Dioxygenase; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D010100:Oxygen