This proposal deals with characterization of the absorption process of vitamin B1(thiamine) in the human intestine at the cellular and molecular levels. Thiamine, a water-soluble vitamin, plays an essential role in different cellular metabolic reactions. The importance of thiamine to normal human health and well being is manifested by the serious clinical abnormalities that occur in thiamine deficiency which include cardiovascular and neurological disorders. Thiamine deficiency represents a significant nutritional problem in developed countries and occur in alcoholics, diabetics, coeliac disease patients, renal disease patients, the elderly, in inborn errors of thiamine metabolism, and in long-term users of diuretics. Humans and other mammals can not synthesize thiamine, and thus, must obtain the vitamin from exogenous sources via intestinal absorption. Therefore, the intestine plays a critical role in determining and regulating thiamine normal body homeostasis. Thiamine is presented to the human intestine from two sources: the diet, and as a product of bacterial synthesis by the normal microflora in the large intestine. Very little is known about the absorption mechanism of dietary thiamine in the human small intestine, and no information is available regarding the mechanism of absorption of the bacterially synthesized thiamine in the large intestine. Transport of thiamine across the functionally polarized small intestinal and colonic epithelial cells represents transport of the vitamin across two structurally and functionally different membrane domains (i.e., the luminal and basolateral membrane domains). We propose to characterize the mechanism(s) of thiamine transport across the individual membrane using purified luminal and basolateral membrane vesicle preparations. Intestinal transport processes of variety of nutrients have been shown in recent years to be regulated by specific intracellular protein kinase-mediated pathways, and by extracellular substrate levels. Very little, however, is known about the cellular regulation of the thiamine absorption process in the human intestine. We propose to address this issue in this application. The molecular characteristics of the intestinal thiamine transport process is not known. We propose to clone and characterize the human intestinal thiamine transporters(s) using a method that is based on the strategy of complementation with a human cDNA library of the yeast S. cerevisiae NKC6, a yeast mutant defective in thiamine transport activity. We also propose to clone and characterize the 5'-regulatory region of the human intestinal thiamine transporter(s) gene. Variety of physiological and molecular biology techniques will be used in these studies. Valuable information are expected to emerge from these investigations regarding the cellular/molecular mechanisms and regulation of thiamine absorption in the human intestine. This should ultimately assist us in designing effective strategies to optimize thiamine body homeostasis, and help us understand the causes of aberrations that occur in thiamine nutrition under certain pathophysiological conditions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK056061-05
Application #
6612826
Study Section
General Medicine A Subcommittee 2 (GMA)
Program Officer
May, Michael K
Project Start
1999-08-01
Project End
2004-07-31
Budget Start
2003-08-01
Budget End
2004-07-31
Support Year
5
Fiscal Year
2003
Total Cost
$184,685
Indirect Cost
Name
University of California Irvine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
046705849
City
Irvine
State
CA
Country
United States
Zip Code
92697
Subramanian, Veedamali S; Constantinescu, Alexandru R; Benke, Paul J et al. (2017) Mutations in SLC5A6 associated with brain, immune, bone, and intestinal dysfunction in a young child. Hum Genet 136:253-261
Sabui, Subrata; Subramanian, Veedamali S; Kapadia, Rubina et al. (2016) Structure-function characterization of the human mitochondrial thiamin pyrophosphate transporter (hMTPPT; SLC25A19): Important roles for Ile(33), Ser(34), Asp(37), His(137) and Lys(291). Biochim Biophys Acta 1858:1883-90
Subramanian, Veedamali S; Lambrecht, Nils; Lytle, Christian et al. (2016) Conditional (intestinal-specific) knockout of the riboflavin transporter-3 (RFVT-3) impairs riboflavin absorption. Am J Physiol Gastrointest Liver Physiol 310:G285-93
Nabokina, Svetlana M; Subramanian, Veedamali S; Said, Hamid M (2016) The human colonic thiamine pyrophosphate transporter (hTPPT) is a glycoprotein and N-linked glycosylation is important for its function. Biochim Biophys Acta 1858:866-71
Udhayabanu, Tamilarasan; Subramanian, Veedamali S; Teafatiller, Trevor et al. (2016) SLC52A2 [p.P141T] and SLC52A3 [p.N21S] causing Brown-Vialetto-Van Laere Syndrome in an Indian patient: First genetically proven case with mutations in two riboflavin transporters. Clin Chim Acta 462:210-214
Sassoon, Catherine S; Zhu, Ercheng; Fang, Liwei et al. (2016) Inhibition of Intestinal Thiamin Transport in Rat Model of Sepsis. Crit Care Med 44:e875-81
Moradi, Hamid; Said, Hamid M (2016) Functional thiamine deficiency in end-stage renal disease: malnutrition despite ample nutrients. Kidney Int 90:252-254
Nabokina, Svetlana M; Ramos, Mel Brendan; Said, Hamid M (2016) Mechanism(S) Involved in the Colon-Specific Expression of the Thiamine Pyrophosphate (Tpp) Transporter. PLoS One 11:e0149255
Subramanian, Veedamali S; Kapadia, Rubina; Ghosal, Abhisek et al. (2015) Identification of residues/sequences in the human riboflavin transporter-2 that is important for function and cell biology. Nutr Metab (Lond) 12:13
Srinivasan, Padmanabhan; Nabokina, Svetlana; Said, Hamid M (2015) Chronic alcohol exposure affects pancreatic acinar mitochondrial thiamin pyrophosphate uptake: studies with mouse 266-6 cell line and primary cells. Am J Physiol Gastrointest Liver Physiol 309:G750-8

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