Linked Life Data

17519353

Source:http://linkedlifedata.com/resource/pubmed/id/17519353

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2007-7-26
pubmed:abstractText
Using a conditional knockout approach, we previously demonstrated that the Janus kinase 2 (Jak2) is crucial for prolactin (PRL) signaling and normal mammary gland development. PRL is suggested to synchronously activate multiple signaling cascades that emerge on the PRL receptor (PRLR). This study demonstrates that Jak2 is essential for the activation of the signal transducer and activator of transcription 5 (Stat5) and expression of Cish (cytokine-inducible SH2-containing protein), a Stat5-responsive negative regulator of Jak/Stat signaling. However, Jak2 is dispensable for the PRL-induced activation of c-Src, focal adhesion kinase, and the MAPK pathway. Despite activation of these kinases that are commonly associated with proliferative responses, the ablation of Jak2 reduces the multiplication of immortalized mammary epithelial cells (MECs). Our studies show that signaling through Jak2 controls not only the transcriptional activation of the Cyclin D1 gene, but, more importantly, it regulates the accumulation of the Cyclin D1 protein in the nucleus by altering the activity of signal transducers that mediate the phosphorylation and subsequent nuclear export of Cyclin D1. In particular, the levels of activated Akt (protein kinase B) and inactive glycogen synthase kinase-3beta (i.e. a kinase that regulates the nuclear export and degradation of Cyclin D1) are reduced in MECs lacking Jak2. The proliferation of Jak2-deficient MECs can be rescued by expressing of a mutant form of Cyclin D1 that cannot be phosphorylated by glycogen synthase kinase-3beta and therefore constitutively resides in the nucleus. Besides discriminating Jak2-dependent and Jak2-independent signaling events emerging from the PRLR, our observations provide a possible mechanism for phenotypic similarities between Cyclin D1 knockouts and females lacking individual members of the PRLR signaling cascade, in particular the PRLR, Jak2, and Stat5.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0888-8809
pubmed:author
pubmed:issnType
Print
pubmed:volume
21
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1877-92
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
The Janus kinase 2 is required for expression and nuclear accumulation of cyclin D1 in proliferating mammary epithelial cells.
pubmed:affiliation
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural