Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT01586 (G418)
 2,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mouse P19 embryonal carcinoma cells can be reproducibly differentiated into neurons and glial cells upon treatment with high concentrations of retinoic acid (RA). To understand the molecular mechanisms that control early neural differentiation, we constructed P19 cell lines carrying an insertion of a gene-trap vector containing lacZ as the reporter gene and a G418 resistance gene. We tested expression of the lacZ gene during the RA-induced differentiation process of 300 clones selected with G418. Ten of these clones were stained with X-gal, and five of these ten clones showed up- or down-regulation of lacZ expression. We analyzed one clone, GT1, in which expression of the lacZ gene was markedly up-regulated. The 5'-flanking genomic DNA of the GT1 gene present at the site of integration was isolated by the plasmid rescue method, and we screened a cDNA library using this DNA gene as a probe. The GT1 cDNA is about 9000 bp long, with an open reading frame encoding 1840 amino acids. This amino acid sequence has a potential glycosaminoglycan attachment site (Ser-Gly-Gly-Gly) and three N-linked glycosylation sites, but no signal peptide. The sequence of GT1 does not show significant homology with any other known proteins, suggesting that GT1 may be a novel proteoglycan core protein. In situ hybridization revealed that GT1 mRNA was expressed ubiquitiously in the adult mouse brain. This expression was specifically localized in neurons but not in glial cells. Immunohistochemistry revealed that GT1 protein was also localized in neurons. These results suggest that this protein may play a fundamental role in neurons.
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PMID:Cloning of a retinoic acid-induced gene, GT1, in the embryonal carcinoma cell line P19: neuron-specific expression in the mouse brain. 747 16

Murine embryonal carcinoma cells do not express detectable cell-surface epidermal growth factor receptors (EGF-R) but after 2 days of differentiation induced by retinoic acid (RA) increasingly express mRNA and protein encoded by the EGF receptor gene (Joh et al., Cell Growth and Differentiation 3, 315, 1992). The effect on morphology, growth, and differentiation of the introduction of expression vectors that produce either a truncated, kinase-negative mouse EGF receptor or an antisense mRNA was studied in P19 embryonal carcinoma (EC) cells before and after differentiation. The presence of either construct should lead to the reduction of EGF-R expression by either the dominant negative effects of a truncated protein or the inhibition of endogenous EGF-R mRNA production/translation by complementary RNA, respectively. Cells were cotransfected with the bacterial neomycin resistance gene and constitutively expressing clones were selected with G418. The cytomegalovirus LTR promoter/enhancer was found to be very inefficiently activated in P19 EC cells. After RA addition, changes in gene expression included induction of both the exogenous truncated constructs and endogenous EGF-R. Differentiation was gauged by the expression of tissue-type plasminogen activator and intermediate filament protein markers of neural tissues, as well as EGF-R. The expression of 120-kDa truncated EGF-Rs was high in four clones, but all 10 clones examined had diminished abilities to differentiate after RA induction compared to four control cell lines. Similarly, the majority of antisense transfected clones was unable to differentiate normally. The results indicate that the reduced expression of EGF-Rs in differentiating EC cells inhibits the rate, frequency, and extent of differentiation after RA induction. We conclude that the expression of EGF-Rs plays a role in the stimulation of differentiation and we speculate that the mechanism involves the tyrosine kinase activity of the receptor.
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PMID:Inhibition of differentiation in P19 embryonal carcinoma cells by the expression of vectors encoding truncated or antisense EGF receptor. 836 61