Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An important limitation of standard transgenic assays is that multiple copies of the transgene are inserted randomly into the mouse genome, resulting in line-to-line variation in expression. One way to control for these variables is to target a single copy of the transgene to a defined locus of the mouse genome by homologous recombination. In the present study, we have used such an approach to target the promoters of 2 different genes, namely von Willebrand factor (VWF) and Flt-1, to the hypoxanthine phosphoribosyltransferase (Hprt) gene locus. Consistent with previous findings in standard transgenic animals, we report that the VWF promoter contains information for expression in a subset of endothelial cells in the heart, skeletal muscle, and brain. In contrast, the Flt-1 promoter directs expression in all vascular beds except for the liver. The Flt-1 transgene was active in the endothelium of tumor xenografts, whereas the VWF promoter was not. Under in vitro conditions, conditioned medium from tumor cells resulted in a significant up-regulation of Flt-1 mRNA and promoter activity, but no change in VWF levels. Taken together, these results suggest that (1) Hprt locus targeting is a valuable tool for studying vascular bed-specific gene regulation, (2) the VWF and Flt-1 promoters are regulated by distinct transcriptional mechanisms in the intact endothelium, and (3) tumor angiogenesis results in the differential activation of endothelial cell-specific promoters.
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PMID:Differential regulation of the von Willebrand factor and Flt-1 promoters in the endothelium of hypoxanthine phosphoribosyltransferase-targeted mice. 1239 68

Single nucleotide polymorphisms (SNPs) may influence protein function possibly contributing to phenotype; yet, for most SNPs their potential influence is unknown. Here, we present a technique in mouse embryonic stem cells that enables high-throughput knock-in (the placement of coding sequences adjacent to a specific endogenous promoter). Our methodology utilizes gene targeting with a combination of two selection cassettes (SAbetageo and the HPRT minigene) along with site-specific recombinases (Cre/loxP and FLP/FRT) to efficiently introduce multiple DNA sequences, including enhanced green fluorescent protein (eGFP), adjacent to the DNA topoisomerase 3beta (Top3beta) promoter. This technology enables rapid and efficient introduction of DNA sequences to a specific location and advances high-throughput analysis of many SNPs with control for expression and genetic background.
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PMID:High-throughput knock-in coupling gene targeting with the HPRT minigene and Cre-mediated recombination. 1893 56