Mechanisms of Pancreatic Thiamin Uptake:Effect of Alcohol

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DESCRIPTION (provided by applicant): The long-term objectives of this proposal are to investigate the cellular and molecular mechanisms involved in the transport of the water-soluble vitamin B1 (thiamin) into pancreatic cells and their regulation. We also aim at examining the effect of chronic ethanol consumption on cellular and molecular parameters of pancreatic thiamin uptake process. Thiamin is essential for the function, growth and development of pancreatic cells. Cellular deficiency of thiamin leads to impairments in intracellular energy metabolism, an increase in oxidative stress, and apoptosis. At the level of pancreatic physiology, thiamin deficiency leads to impairment in both exocrine and endocrine functions. Nothing is currently known about the cellular and molecular mechanisms involved in thiamin uptake by pancreatic acinar and beta cells and their regulation, and about the conditions/factors that affect/interfere with these events. In new preliminary studies we obtained evidence to show that thiamin uptake by pancreatic acinar as well as beta cells to involve carrier- mediated process(es) and that both cell types express thiamin transporter-1 & 2 (THTR-1 and THTR-2). We propose to continue these investigations to delineate the cellular and molecular mechanisms involved in thiamin uptake by pancreatic acinar and beta cells and their regulation (Sp. Aims 1 and 2). We will do so using pancreatic cells isolated from wild-type mice, THTR-1- /- and THTR-2 -/- mice, and transgenic mice carrying the human SLC19A2 and SLC19A3 promoters. We will also use cultured mouse pancreatic acinar and beta cells as models. Chronic ethanol consumption is known to exert profound effects on pancreatic physiology and gene expression, and is a leading cause of pancreatitis. Nothing, however, is known about the effect(s) of chronic alcohol consumption on thiamin uptake and metabolism by pancreatic acinar cells. In new preliminary studies we obtained evidence to show that chronic ethanol consumption in mice leads to a marked decrease in THTR-1 and THTR-2 message levels in the pancreas. We propose to continue these investigations and will delineate the functional consequences of these effects and the molecular mechanism(s) involved as well as the effect of chronic alcohol consumption on thiamin metabolism in pancreatic acinar cells (Sp. Aim 3). Results of these investigations will provide valuable information regarding thiamin physiology and nutrition in pancreatic cells, and on how chronic alcohol consumption affects these parameters. This should ultimately assist in the development of effective strategies to optimize thiamin pancreatic homeostasis, especially in conditions associated with thiamin deficiency and sub-optimal levels. Vitamin B1 (thiamin) is essential for the normal functions, growth and development of the pancreas and its deficiency leads to impairment in both its exocrine and endocrine functions. There is nothing currently known about how pancreatic cells takes up thiamin and what factors/conditions (including chronic alcohol consumption) affect these processes. Our aims in this proposal are to address these issues as such investigations will not only provide valuable information regarding thiamin physiology/nutrition of pancreatic cells and how chronic alcohol use adversely affect these parameters, but they may also assist us in the development of effective strategies to optimize thiamin pancreatic levels, especially in conditions associated with thiamin deficiency and sub-optimal levels. PUBLIC HEALTH RELEVANCE: Vitamin B1 (thiamin) is essential for the normal functions, growth and development of the pancreas and its deficiency leads to impairment in both its exocrine and endocrine functions. There is nothing currently known about how pancreatic cells takes up thiamin and what factors/conditions (including chronic alcohol consumption) affect these processes. Our aims in this proposal are to address these issues as such investigations will not only provide valuable information regarding thiamin physiology/nutrition of pancreatic cells and how chronic alcohol use adversely affect these parameters, but they may also assist us in the development of effective strategies to optimize thiamin pancreatic levels, especially in conditions associated with thiamin deficiency and sub-optimal levels.