Mechanisms of Pancreatic Thiamin Uptake:Effect of Alcohol

描述（由申请人提供）：本提案的长期目标是研究水溶性维生素B1（硫胺素）转运到胰腺细胞及其调控的细胞和分子机制。我们还旨在研究慢性乙醇消耗对胰腺硫胺素摄取过程的细胞和分子参数的影响。硫胺素对胰腺细胞的功能、生长和发育至关重要。细胞缺乏硫胺素会导致细胞内能量代谢受损、氧化应激增加和细胞凋亡。在胰腺生理水平上，硫胺素缺乏导致外分泌和内分泌功能的损害。目前尚不清楚胰腺腺泡细胞和β细胞摄取硫胺素及其调控的细胞和分子机制，以及影响/干扰这些事件的条件/因素。在新的初步研究中，我们获得的证据表明，胰腺腺泡和β细胞对硫胺素的摄取涉及载体介导的过程，两种细胞类型都表达硫胺素转运蛋白-1和2 （THTR-1和THTR-2）。我们建议继续这些研究，以描述参与胰腺腺泡细胞和β细胞摄取硫胺素及其调控的细胞和分子机制（Sp. Aims 1和2）。我们将使用从野生型小鼠、THTR-1- /-和THTR-2 -/-小鼠以及携带人类SLC19A2和SLC19A3启动子的转基因小鼠分离的胰腺细胞进行实验。我们还将使用培养的小鼠胰腺腺泡细胞和β细胞作为模型。众所周知，慢性乙醇消耗对胰腺生理和基因表达产生深远影响，是胰腺炎的主要原因。然而，长期饮酒对胰腺腺泡细胞摄取和代谢硫胺素的影响尚不清楚。在新的初步研究中，我们获得的证据表明，小鼠长期摄入乙醇会导致胰腺中THTR-1和THTR-2信息水平显著降低。我们建议继续这些研究，并将描述这些影响的功能后果和所涉及的分子机制，以及长期饮酒对胰腺腺泡细胞中硫胺素代谢的影响（Sp. Aim 3）。这些研究结果将提供有关胰腺细胞中硫胺素生理和营养以及长期饮酒如何影响这些参数的宝贵信息。这最终将有助于制定有效的策略来优化硫胺素胰腺稳态，特别是在与硫胺素缺乏和次优水平相关的情况下。维生素B1（硫胺素）对胰腺的正常功能、生长和发育至关重要，缺乏维生素B1会导致胰腺的外分泌和内分泌功能受损。目前还不清楚胰腺细胞如何吸收硫胺素，以及哪些因素/条件（包括长期饮酒）会影响这些过程。我们在本提案中的目标是解决这些问题，因为这些研究不仅将提供有关胰腺细胞的硫胺素生理/营养以及慢性酒精使用如何对这些参数产生不利影响的有价值的信息，而且还可以帮助我们制定有效的策略来优化胰腺硫胺素水平，特别是在与硫胺素缺乏和次优水平相关的情况下。公共卫生相关性：维生素B1（硫胺素）对胰腺的正常功能、生长和发育至关重要，缺乏维生素B1会导致其外分泌和内分泌功能受损。目前还不清楚胰腺细胞如何吸收硫胺素，以及哪些因素/条件（包括长期饮酒）会影响这些过程。我们在本提案中的目标是解决这些问题，因为这些研究不仅将提供有关胰腺细胞的硫胺素生理/营养以及慢性酒精使用如何对这些参数产生不利影响的有价值的信息，而且还可以帮助我们制定有效的策略来优化胰腺硫胺素水平，特别是在与硫胺素缺乏和次优水平相关的情况下。

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.