Linked Life Data

17828303

Source:http://linkedlifedata.com/resource/pubmed/id/17828303

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2008-2-28
pubmed:abstractText
SAG (sensitive to apoptosis gene) or ROC2/RBX2 is the second family member of ROC1/RBX1, a component of SCF (Skp1, Cullin, F-box protein) and VCB (von Hippel-Lindau (VHL), Cullin and Elongin B/C) E3 ubiquitin ligases. SAG protected cells from hypoxia-induced apoptosis when overexpressed. We report here that SAG was subjected to hypoxia induction at the levels of mRNA and protein. Hypoxia induction of SAG was largely HIF-1alpha dependent. A consensus HIF-1-binding site, GCGTG was identified in the first intron of the SAG gene. In response to hypoxia, HIF-1 bound to this site and transactivated SAG expression. SAG transactivation required both the intact binding site in cis and HIF-1alpha in trans. On the other hand, like its family member, ROC1, SAG promoted VHL-mediated HIF-1alpha ubiquitination and degradation, which was significantly inhibited upon small interfering RNA silencing of SAG or ROC1. Furthermore, the endogenous HIF-1alpha at both basal and hypoxia-induced levels was significantly increased upon SAG silencing. Finally, SAG forms in vivo complex with Cul-5 and VHL under hypoxia condition. These results suggest an HIF-1-SAG feedback loop in response to hypoxia, as follows: hypoxia induces HIF-1 to transactivate SAG. Induced SAG then promotes HIF-1alpha ubiquitination and degradation. This feedback loop may serve as a cellular defensive mechanism to reduce potential cytotoxic effects of prolonged HIF-1 activation under hypoxia.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
1476-5594
pubmed:author
pubmed:issnType
Electronic
pubmed:day
28
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1404-11
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
SAG/ROC2/RBX2 is a HIF-1 target gene that promotes HIF-1 alpha ubiquitination and degradation.
pubmed:affiliation
Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, Ann Arbor, MI 48109-096, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural