Document Detail

Identification of rat cell lines that preferentially express insulin-like growth factor binding proteins rlGFBP-1, 2, or 3.
MedLine Citation:
PMID:  1691442     Owner:  NLM     Status:  MEDLINE    
The bioavailability and action of the insulin-like growth factors (IGFs) are determined by specific IGF-binding proteins (IGFBP) to which they are complexed. Complementary DNA clones have been isolated that encode three related IGFBPs: human IGFBP-1 (hIGFBP-1), human IGFBP-3 (hIGFBP-3), and rat IGFBP-2 (rIGFBP-2). IGFBP-1 and IGFBP-3 are regulated differently in human plasma, suggesting that they have different functions. In order to study the molecular basis of the regulation of the different IGFBPs, we have identified a panel of rat cell lines that express a single predominant binding protein and developed an assay strategy to distinguish the different binding proteins. Proteins in conditioned medium were examined by ligand blotting, and by immunoprecipitation and immunoblotting using antibodies to rIGFBP-2 and hIGFBP-1; RNAs were hybridized to cDNA probes for rIGFBP-2 and hIGFBP-1. 1) C6 glial cells and B104 neuroblastoma cells express an approximately 40 kilodalton (kDa) glycosylated binding protein that most likely represents rIGFBP-3, the binding subunit of the 150 kDa IGF: binding protein complex in adult rat serum. The C6 and B104 binding proteins do not react with antibodies to rIGFBP-2, and RNAs from C6 and B104 cells do not hybridize to cDNA probes for rIGFBP-2 or hIGFBP-1. 2) BRL-3A, Clone 9, and TRL 12-15 cell lines derived from normal rat liver express rIGFBP-2, a 30 kDa nonglycosylated IGF-binding protein that is recognized by antibodies to rIGFBP-2 but not by antibodies to hIGFBP-1. RNAs from these cells hybridize to a rIGFBP-2 cDNA probe, but not to a hIGFBP-1 probe. 3) H35 rat hepatoma cells express a 30 kDa nonglycosylated IGFBP that is presumptively identified as rIGFBP-1. It does not react with antibodies to rIGFBP-2, but is recognized by polyclonal and monoclonal antibodies to hIGFBP-1. RNA from H35 cells hybridizes to a hIGFBP-1 cDNA probe, but not to a rIGFBP-2 probe. Expression of rIGFBP-1 by the H35 cell line has enabled us to establish and validate specific assays for this protein that allow us to study its regulation in intact rats. Identification of a panel of rat cell lines expressing specific IGFBPs should be useful in elucidating the molecular mechanisms of IGFBP regulation.
Y W Yang; A L Brown; C C Orlowski; D E Graham; L Y Tseng; J A Romanus; M M Rechler
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Molecular endocrinology (Baltimore, Md.)     Volume:  4     ISSN:  0888-8809     ISO Abbreviation:  Mol. Endocrinol.     Publication Date:  1990 Jan 
Date Detail:
Created Date:  1990-05-16     Completed Date:  1990-05-16     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8801431     Medline TA:  Mol Endocrinol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  29-38     Citation Subset:  IM    
Growth and Development Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
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MeSH Terms
Carrier Proteins / biosynthesis*,  genetics,  immunology
Cell Line* / metabolism
DNA Probes
Gene Expression Regulation
Insulin-Like Growth Factor Binding Proteins
Precipitin Tests
RNA, Messenger / biosynthesis
Tumor Cells, Cultured / metabolism
Reg. No./Substance:
0/Antibodies; 0/Carrier Proteins; 0/DNA Probes; 0/Insulin-Like Growth Factor Binding Proteins; 0/RNA, Messenger

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