Linked Life Data

16230354

Source:http://linkedlifedata.com/resource/pubmed/id/16230354

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
51
pubmed:dateCreated
2005-12-19
pubmed:abstractText
Bile acids secreted in the small intestine are reabsorbed in the ileum where they activate the nuclear farnesoid X receptor (FXR), which in turn stimulates expression of the ileal bile acid-binding protein (I-BABP). We first hypothesized that I-BABP may negatively regulate the FXR activity by competing for the ligands, bile acids. Reporter assays using stable HEK293 cell lines expressing I-BABP revealed that I-BABP enhances rather than attenuates FXR activity. In these cells I-BABP localizes predominantly in the cytosol and partially in the nucleus, a distribution that does not shift in response to FXR expression. In vitro binding assays reveal that recombinant I-BABP is able to bind 35S-labeled FXR and that chenodeoxycholic acid (CDCA) stimulates this interaction modestly. When FLAG-tagged FXR was expressed in stable cells, the FXR.I-BABP complex in the nuclear extracts was more efficiently immunoprecipitable with anti-FLAG antibodies in the presence of CDCA. These results indicate that I-BABP stimulates FXR activity through a mutual interaction augmented by bile acids. When stable cells were transfected with an expression plasmid of the ileal bile acid transporter 14(IBAT) essential for the reabsorption of conjugated bile acids, the C-labeled conjugated bile acid, glycocholic acid, was more efficiently imported via IBAT in the presence than absence of I-BABP, whereas no change was observed in 14C-labeled CDCA uptake, which is independent of IBAT. Immunofluorescent staining analysis revealed that these two proteins co-localize in the vicinity of the plasma membrane in stable cells. Taken together, the current data provide the first evidence that I-BABP is functionally associated with FXR and IBAT in the nucleus and on the membrane, respectively, stimulating FXR transcriptional activity and the conjugated bile acid uptake mediated by IBAT in the ileum.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
23
pubmed:volume
280
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
42283-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Ileal bile acid-binding protein, functionally associated with the farnesoid X receptor or the ileal bile acid transporter, regulates bile acid activity in the small intestine.
pubmed:affiliation
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't