Fang Yu1, Sarah B. White1,2, Quan Zhao1,2, Frank S. Lee1,2
1Department of Pathology and Laboratory Medicine, University of
Pennsylvania Cancer Center, University of Pennsylvania School of
Medicine, 605 Stellar-Chance Laboratories, 422 Curie Boulevard,
Philadelphia, PA 19104
2Harvard University, Cambridge, MA
Tóm tắt
Hypoxia-inducible factor-1α (HIF-1α)
1
is a global
transcriptional regulator of the hypoxic response. Under normoxic
conditions, HIF-1α is recognized by the von Hippel-Lindau
tumor-suppressor protein (VHL), a component of an E3 ubiquitin ligase
complex. This interaction thereby promotes the rapid degradation of
HIF-1α. Under hypoxic conditions, HIF-1α is stabilized. We have
previously shown that VHL binds in a hypoxia-sensitive manner to a
27-aa segment of HIF-1α, and that this regulation depends on a
posttranslational modification of HIF-1α. Through a combination of
in vivo
coimmunoprecipitation assays using VHL and a
panel of point mutants of HIF-1α in this region, as well as MS and
in vitro
binding assays, we now provide evidence that
this modification, which occurs under normoxic conditions, is
hydroxylation of Pro-564 of HIF-1α. The data furthermore show that
this proline hydroxylation is the primary regulator of VHL binding.
