title: Expression of 25 kDa thiamine triphosphatase in rodent tissues using quantitative PCR and characterization of its mRNA.
abstract: Thiamine triphosphate (ThTP) is found in most organisms, but its biological role remains unclear. In mammalian tissues, cellular ThTP concentrations remain low, probably because of hydrolysis by a specific 25 kDa thiamine triphosphatase (ThTPase). The aim of the present study was to use quantitative PCR, for comparing the 25 kDa ThTPase mRNA expression in various mouse tissues with its enzyme activities. ThTPase mRNA was expressed at only a few copies per cell. The highest amount of mRNA was found in testis, followed by lung and muscle, while the highest enzyme activities were found in liver and kidney. The poor correlation between mRNA levels and enzyme activities might result either from tissue-specific post-transcriptional regulation of mRNA processing and/or translation or from the regulation of enzyme activities by post-translational mechanisms. Purified recombinant human ThTPase was phosphorylated by casein kinase II, but this phosphorylation did not modify the enzyme activity. However, the characterization of the 3'-untranslated mRNA region revealed a unique, highly conserved, 200-nucleotide sequence that might be involved in translational control. In situ hybridization studies in testis suggest a predominant localization of ThTPase mRNA in poorly differentiated spermatogenic cells. This is the first study demonstrating a cell-specific 25 kDa ThTPase mRNA expression, suggesting that this enzyme might be related to the degree of differentiation or the metabolic state of the cell.
authors.affiliation: Center for Cellular and Molecular Neurobiology, University of Liège, 17 Place Delcour, 4020 Liège, Belgium.
authors.forename: Bernard
authors.initials: B
authors.lastname: Lakaye
authors.forename: Myriam
authors.initials: M
authors.lastname: Verlaet
authors.forename: Johanne
authors.initials: J
authors.lastname: Dubail
authors.forename: Jan
authors.initials: J
authors.lastname: Czerniecki
authors.forename: Sébastien
authors.initials: S
authors.lastname: Bontems
authors.forename: Alexander F
authors.initials: AF
authors.lastname: Makarchikov
authors.forename: Pierre
authors.initials: P
authors.lastname: Wins
authors.forename: Jacques
authors.initials: J
authors.lastname: Piette
authors.forename: Thierry
authors.initials: T
authors.lastname: Grisar
authors.forename: Lucien
authors.initials: L
authors.lastname: Bettendorff
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D047390:Casein Kinase II / Q000378:metabolism; D002417:Cattle; D017124:Conserved Sequence / Q000235:genetics; D020869:Gene Expression Profiling; D006801:Humans; D008251:Macaca / Q000235:genetics; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D016415:Sequence Alignment; D013552:Swine / Q000235:genetics; D013737:Testis / Q000378:metabolism; D013837:Thiamin-Triphosphatase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D012333:RNA, Messenger; D047390:Casein Kinase II; D013837:Thiamin-Triphosphatase