Linked Life Data

10811646

Source:http://linkedlifedata.com/resource/pubmed/id/10811646

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
31
pubmed:dateCreated
2000-9-7
pubmed:abstractText
Although insulin-like growth factor-binding protein (IGFBP)-3 and IGFBP-5 are known to modulate cell growth by reversibly sequestering extracellular insulin-like growth factors, several reports have suggested that IGFBP-3, and possibly also IGFBP-5, have important insulin-like growth factor-independent effects on cell growth. These effects may be related to the putative nuclear actions of IGFBP-3 and IGFBP-5, which we have recently shown are transported to the nuclei of T47D breast cancer cells. We now describe the mechanism for nuclear import of IGFBP-3 and IGFBP-5. In digitonin-permeabilized cells, where the nuclear envelope remained intact, nuclear translocation of wild-type IGFBP-3 appears to occur by a nuclear localization sequence (NLS)-dependent pathway mediated principally by the importin beta nuclear transport factor and requiring both ATP and GTP hydrolysis. Under identical conditions, an NLS mutant form of IGFBP-3, IGFBP-3[(228)KGRKR --> MDGEA], was unable to translocate to the nucleus. In cells where both the plasma membrane and nuclear envelope were permeabilized, wild-type IGFBP-3, but not the mutant form, accumulated in the nucleus, implying that the NLS was also involved in mediating binding to nuclear components. By fusing wild-type and mutant forms of NLS sequences (IGFBP-3 [215-232] and IGFBP-5 [201-218]) to the green fluorescent protein, we identified the critical residues of the NLS necessary and sufficient for nuclear accumulation. Using a Western ligand binding assay, wild-type IGFBP-3 and IGFBP-5, but not an NLS mutant form of IGFBP-3, were shown to be recognized by importin beta and the alpha/beta heterodimer but only poorly by importin alpha. Together these results suggest that the NLSs within the C-terminal domain of IGFBP-3 and IGFBP-5 are required for importin-beta-dependent nuclear uptake and probably also accumulation through mediating binding to nuclear components.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
275
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
23462-70
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:10811646-Adenosine Triphosphate, pubmed-meshheading:10811646-Amino Acid Sequence, pubmed-meshheading:10811646-Base Sequence, pubmed-meshheading:10811646-Biological Transport, pubmed-meshheading:10811646-Cell Nucleus, pubmed-meshheading:10811646-DNA Primers, pubmed-meshheading:10811646-Dimerization, pubmed-meshheading:10811646-Energy Metabolism, pubmed-meshheading:10811646-Guanosine Triphosphate, pubmed-meshheading:10811646-Humans, pubmed-meshheading:10811646-Insulin-Like Growth Factor Binding Protein 3, pubmed-meshheading:10811646-Insulin-Like Growth Factor Binding Protein 5, pubmed-meshheading:10811646-Karyopherins, pubmed-meshheading:10811646-Molecular Sequence Data, pubmed-meshheading:10811646-Mutation, pubmed-meshheading:10811646-Nuclear Localization Signals, pubmed-meshheading:10811646-Nuclear Proteins, pubmed-meshheading:10811646-Peptide Fragments, pubmed-meshheading:10811646-Recombinant Fusion Proteins
pubmed:year
2000
pubmed:articleTitle
Nuclear import of insulin-like growth factor-binding protein-3 and -5 is mediated by the importin beta subunit.
pubmed:affiliation
Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, Sydney, New South Wales 2065, Australia. lyns@med.usyd.edu.au
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't