Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are mitogenic to the intestinal epithelium. To further clarify their role in the developing human fetal gut, their expression was studied in fetuses at 15 to 20 wk of gestation. TGF-alpha mRNA was present throughout the gastrointestinal tract, most abundantly in the duodenum. EGF mRNA could be detected only with ribonuclease protection assay and reverse transcription-polymerase chain reaction analysis. The effect of EGF and TGF-alpha on TGF-alpha mRNA expression was studied by culturing explants of fetal jejunum, ileum, and colon for 7 d in Leibowitz L-15 medium supplemented with 100 micrograms/L of either EGF or TGF-alpha. EGF receptor-like immunoreactivity was detected in both the villi and the crypts. In the jejunum, exogenous EGF up-regulated TGF-alpha mRNA 3-fold. However, exogenous TGF-alpha reduced its own mRNA by 40%. No mature 6-kD TGF-alpha was detected in the culture medium by Western blotting, but precursor forms of approximately 30 and 68 kD were present. The ileum and colon did not respond to either growth factor. Besides the gut, TGF-alpha was expressed in the gallbladder, salivary gland, adrenals, brain, kidney, liver, and placenta. The data imply an important role for TGF-alpha and EGF in the developing intestine.
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PMID:Transforming growth factor-alpha and epidermal growth factor expression in human fetal gastrointestinal tract. 851 Oct 20

Proto-oncogenes are involved in the regulation of gene expression, for example after ligand binding to growth factor receptors. Expression of the proto-oncogenes c-fos, c-jun, c-ha-ras and c-myc was studied in in vivo grown and in vitro cultured bovine preimplantation blastocysts employing RT-PCR, ribonuclease protection assay and immunohistochemistry. Thirteen- and 14- day-old preimplantation blastocysts, i.e. stages before and during trophoblast elongation, were used. In in vivo-grown blastocysts c-fos, c-jun and c-ha-ras transcripts as well as c-Fos, c-Jun and c-Myc proteins were detected in all stages studied. Cultured blastocysts were treated with 10 nM epidermal growth factor and 10 nM transforming growth factor-alpha simultaneously. Epidermal growth factor and transforming growth factor-alpha treatment induced c-fos mRNA and c-Myc protein expression. The induction of downstream targets of the epidermal growth factor receptor by epidermal growth factor and transforming growth factor-alpha indicates a functional epidermal growth factor signal transduction pathway in elongating bovine blastocysts.
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PMID:Expression of proto-oncogenes in bovine preimplantation blastocysts. 1083 31