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)

Retinitis pigmentosa (RP), the hereditary degenerative disease of the photoreceptor neurons of the retina, probably represents the most prevalent cause of registered blindness amongst those of working age in developed countries. Mutations within the gene encoding inosine monophosphate dehydrogenase 1 (IMPDH1), the widely expressed rate-limiting enzyme of the de novo pathway of guanine nucleotide biosynthesis, have recently been shown to cause the RP10 form of autosomal dominant RP. We examined the expression of IMPDH1, IMPDH2 and HPRT transcripts, encoding enzymes of the de novo and salvage pathways of guanine nucleotide biosynthesis, respectively, in retinal sections of mice, the data indicating that the bulk of GTP within photoreceptors is generated by IMPDH1. Impdh1(-/-) null mice are shown here to display a slowly progressive form of retinal degeneration in which visual transduction, analysed by electroretinographic wave functions, becomes gradually compromised, although at 12 months of age most photoreceptors remain structurally intact. In contrast, the human form of RP caused by mutations within the IMPDH1 gene is a severe autosomal dominant degenerative retinopathy in those families that have been examined to date. Expression of mutant IMPDH1 proteins in bacterial and mammalian cells, together with computational simulations, indicate that protein misfolding and aggregation, rather than reduced IMPDH1 enzyme activity, is the likely cause of the severe phenotype experienced by human subjects. Taken together, these findings suggest that RP10 may represent an attractive target for therapeutic intervention, based upon a strategy combining simultaneous suppression of transcripts from normal and mutant IMPDH1 alleles with supplementation of GTP within retinal tissues.
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PMID:On the molecular pathology of neurodegeneration in IMPDH1-based retinitis pigmentosa. 1498 Oct 49

Thiopurines (such as azathioprine and 6-mercaptopurine) are widely used for the treatment of patients suffering from malignancies, rheumatic disease, inflammatory bowel disease and solid organ transplant rejection. These drugs are activated and eliminated by a number of enzymes in the human body. This analyzes all the exons and exon-intron junctions of 5 enzyme genes (hypoxanthine-guanine phosphoribosyltransferase, HGPRT; inosine triphosphate pyrophosphatase, ITPA; inosine monophosphate dehydrogenases 1 and 2, IMPDH1 and IMPDH2 and guanosine monophosphate synthetase, GMPS) involved in the metabolism of thiopurine drugs. Twelve novel single nucleotide polymorphisms (SNPs) (HGPRT: IVS6-12C>A (frequency:0.003); ITPA: 569T>C (Phe189Phe, 0.003); IMPDH1: IVS8-15C>A (0.003), IVS9+227A>G (0.003), IVS17+115C>T (0.003), and 930C>T (Thr310Thr, 0.005); IMPDH2: IVS1+50G>T (0.003), IVS2+15G>A (0.010), IVS3-20G>A (0.003), 609C>T (Arg203Arg, 0.003), and 1534C>T (Arg512Trp, 0.003); and GMPS: 1563T>C (Gly521Gly, 0.003)) and 7 known SNPs (ITPA: 94C>A (Pro32Thr, 0.005), 138G>A (Gln46Gln, 0.586), and 563G>A (Glu187Glu, 0.433); IMPDH1: 987G>C (Leu329Leu, 0.113) and 1575A>G (Ala525Ala, 0.620) and GMPS: IVS5-7T>C (0.153), 993A>G (Thr331Thr, 0.153)) were identified in 200 Japanese subjects. These data should provide useful information for thiopurine therapy in the Japanese and as well as other Asian populations.
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PMID:Genetic variations in the HGPRT, ITPA, IMPDH1, IMPDH2, and GMPS genes in Japanese individuals. 2004 92