The Hsp90 chaperone complex is both a facilitator and a repressor of the dsRNA-dependent kinase PKR.
EMBO J
; 20(14): 3771-80, 2001 Jul 16.
Article
in En
| MEDLINE
| ID: mdl-11447118
ABSTRACT
PKR, a member of the eukaryotic initiation-factor 2alpha (eIF-2alpha) kinase family, mediates the host antiviral response and is implicated in tumor suppression and apoptosis. Here we show that PKR is regulated by the heat shock protein 90 (Hsp90) molecular chaperone complex. Mammalian PKR expressed in budding yeast depends on several components of the Hsp90 complex for accumulation and activity. In mammalian cells, inhibition of Hsp90 function with geldanamycin (GA) during de novo synthesis of PKR also interferes with its accumulation and activity. Hsp90 and its co-chaperone p23 bind to PKR through its N-terminal double-stranded (ds) RNA binding region as well as through its kinase domain. Both dsRNA and GA induce the rapid dissociation of Hsp90 and p23 from mature PKR, activate PKR both in vivo and in vitro and within minutes trigger the phosphorylation of the PKR substrate eIF-2alpha. A short-term exposure of cells to the Hsp90 inhibitors GA or radicicol not only derepresses PKR, but also activates the Raf-MAPK pathway. This suggests that the Hsp90 complex may more generally assist the regulatory domains of kinases and other Hsp90 substrates.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Repressor Proteins
/
HSP90 Heat-Shock Proteins
/
EIF-2 Kinase
Limits:
Humans
Language:
En
Journal:
EMBO J
Year:
2001
Document type:
Article
Affiliation country:
Switzerland
Country of publication:
ENGLAND
/
ESCOCIA
/
GB
/
GREAT BRITAIN
/
INGLATERRA
/
REINO UNIDO
/
SCOTLAND
/
UK
/
UNITED KINGDOM