Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mitogenic and metabolic effects of insulin-like growth factor-II (IGF-II) can be modulated by six distinct IGF binding proteins (IGFBPs). As a first step toward understanding the role of IGFs and their binding proteins in intestinal epithelial cell differentiation, the expression of IGF-II and IGFBPs was characterized in the human colon adenocarcinoma Caco-2 cell line. Northern blot analysis revealed two IGF-II transcripts of 5.4 and 4.5 kb, and ribonuclease protection assays indicated that IGF-II mRNA levels are regulated during Caco-2 differentiation. A specific radioimmunoassay detected IGF-II in serum-free conditioned medium, the level of which was three- to fivefold higher in proliferating cells than in differentiated cells. Immunoprecipitation and ligand blot analyses of conditioned medium demonstrated that IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-6 are synthesized by Caco-2 cells, with IGFBP-2 and IGFBP-4 being the major IGFBPs secreted, and that the levels of IGFBP-2 and IGFBP-6 decreased as differentiation proceeded. These results indicate that the expression of IGF-II, IGFBP-2, and IGFBP-6 is regulated in a differentiation-dependent manner in Caco-2 cells.
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PMID:Expression of IGF-II and IGF binding proteins in differentiating human intestinal Caco-2 cells. 749 29

Recently a family of six distinct insulin-like growth factor binding proteins (IGFBPs) have been identified and the gene structures of the first five (IGFBP-1, -2, -3, -4 and -5) characterized. We now isolated the IGFBP-6 gene from a rat genomic library and determined its organization as well as the DNA sequence at the 5' flanking region of the gene. The rat IGFBP-6 gene spans 5.1 kb of the genomic sequence and contains four exons interrupted by three introns of approximately 2.4, 0.2 and 1.2 kb in length, respectively. Primer extension analysis and ribonuclease protection assay using RNA from rat lung tissues demonstrated two transcriptional start sites located at 85 and 82 nucleotides upstream of the ATG translational initiation codon. The promoter region of the rat IGFBP-6 gene is devoid of a TATA or a CAAT consensus sequence motif, but putative regulatory cis elements, including a Sp1, an estrogen receptor binding site and a retinoic acid responsive element, are present in the promoter region.
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PMID:Structural characterization of the rat insulin-like growth factor binding protein-6 gene. 768 65

The insulin-like growth factors (IGFs) have been implicated in the growth regulation of human breast cancer. Since the IGFs are associated with specific binding proteins (IGFBPs) which may modulate receptor/ligand interactions, production of IGFBPs by breast cancer cells could alter their IGF-dependent growth. This study examined the expression of IGFBPs 4, 5, and 6 in eight breast cancer cell lines (BCCLs) using ribonuclease (RNase) protection assays. IGFBP-4 mRNA was detected in all BCCLs studied. IGFBP-5 expression was higher in estrogen receptor (ER) positive cells, while IGFBP-6 mRNA was detected in only two ER negative BCCLs. We also found that E2 treatment enhanced the expression of IGFBPs 2, 4, and 5 in T47-D cells. We next studied IGFBP mRNA expression in 40 primary breast tumors. All tumors expressed mRNA for IGFBPs 2-6 but none expressed IGFBP-1 message. IGFBP-3 expression was higher in ER negative tumors, while that of IGFBP-4 and -5 was higher in ER positive specimens. These differences were statistically significant (P < .05). Ligand blot analysis of tumor extracts confirmed the presence of IGFBPs in breast cancer tissues. Thus, differential IGFBP expression in ER positive and negative tumors suggests an important role for this protein in breast cancer biology.
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PMID:Expression of insulin-like growth factor binding proteins in human breast cancer correlates with estrogen receptor status. 769 42