MOLEC GENETIC & BIOCHEM INVESTIGATION OF THIAMINE TRANS

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DESCRIPTION: Thiamine deficiency [TD], a frequent complication of alcoholism, contributes significantly to the development of damage in various organ systems, including the brain, of alcoholics and malnourished individuals. Previous work by a number of investigations has focused on reductions in the activities of thiamine-utilizing enzymes as being involved mechanistically and sensitivity to TD. The understanding of the molecular events leading to TD-induced brain damage and to variable tissue- and individual-sensitivity cannot ignore the dietary and intracellular availability of thiamine. The interrelationship between and the relative contribution of alcohol and TD to neural damage remains to be clarified. Our recent work has indicated a complex, cell-type specific regulation of intracellular pools of thiamine and its phosphorylated derivatives, had led to the cloning of the yeast thiamine transporter, and has indicated some of the consequence of having a defective thiamine uptake system. Thiamine uptake is defined here as the transport of thiamine uptake system. Thiamine uptake is defined here as the transport of thiamine into cells and intracellular compartments and its conversion to thiamine pyrophosphate [TPP]. We would like to obtain a better understanding of thiamine uptake and of the interplay between uptake and alcohol consumption. Additionally, we are interested in how thiamine uptake and the concomitant alterations of uptake due to alcohol exposure contribute to tissue-specific and inter individual differences in sensitivity to TD. Thus, we propose a molecular genetic and biochemical study of thiamine uptake in rats exposed to acute and chronic alcohol, to TD, and to a combination of both rat conditions. We will clone and sequence cDNAs for the rat thiamine transporter and thiamine pyrophosphokinase [TPK]. Antibodies to the encoded proteins will be obtained. The clones and the antibodies will be used to examine the qualitative and quantitative tissue distribution and expression of the transporter and TPK in the exposed rats. The effects of alcohol on the biochemical properties of the transporter will be examined. These experiments will be done on outbred and inbred rat strains, the latter of which are differentially susceptible to TD or show different alcohol drinking preferences.