Linked Life Data

15632195

Source:http://linkedlifedata.com/resource/pubmed/id/15632195

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
2005-4-4
pubmed:abstractText
The 90-kDa ribosomal S6 kinases (RSK1-3) are important mediators of growth factor stimulation of cellular proliferation, survival, and differentiation and are activated via coordinated phosphorylation by ERK and 3-phosphoinositide-dependent protein kinase-1 (PDK1). Here we performed the functional characterization of a predicted new human RSK homologue, RSK4. We showed that RSK4 is a predominantly cytosolic protein with very low expression and several characteristics of the RSK family kinases, including the presence of two functional kinase domains and a C-terminal docking site for ERK. Surprisingly, however, in all cell types analyzed, endogenous RSK4 was maximally (constitutively) activated under serum-starved conditions where other RSKs are inactive due to their requirement for growth factor stimulation. Constitutive activation appeared to result from constitutive phosphorylation of Ser232, Ser372, and Ser389, and the low basal ERK activity in serum-starved cells appeared to be sufficient for induction of approximately 50% of the constitutive RSK4 activity. Finally experiments in mouse embryonic stem cells with targeted deletion of the PDK1 gene suggested that PDK1 was not required for phosphorylation of Ser232, a key regulatory site in the activation loop of the N-terminal kinase domain, that in other RSKs is phosphorylated by PDK1. The unusual regulation and growth factor-independent kinase activity indicate that RSK4 is functionally distinct from other RSKs and may help explain recent findings suggesting that RSK4 can participate in non-growth factor signaling as for instance p53-induced growth arrest.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
280
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13304-14
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Functional characterization of human RSK4, a new 90-kDa ribosomal S6 kinase, reveals constitutive activation in most cell types.
pubmed:affiliation
Department of Clinical Biochemistry, Glostrup Hospital, 2600 Glostrup, Denmark.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't