?Prograrii.Director/Prlnclpal Investigator (Last, First, Middle): H a r h i d : S a i d M . PRQJECPTSLJMMARY (See;instructions):'' The long-term objectives pf this renewal application continue to focus on developing a Comprehensive understanding of the physiology and pathophysidlpgy of the intestirial absorptibh process of the: waterrSolub|e vitarfiiri Bl (thiamine) at the cellular and molecular levels, how the: process is regulated', and how it i$-affected by external factors like chronic alcohol exposure. Thiamine;is indispensable for norrinal hurnan health arid is obtained from exogenous sources via intestinal absorption. Studies during the current funding period have used "Slci:9a2 -/-and Slcl 9a3 -/- knockout mouse models to show that both thiamin transporter 1 &;i2 (THTR-1 .&2) are invPlved in, intestinal thiamin absorption;that the intestinal thiamine uptake process is a'daptively regulated by extracellular substrate levelvia transcriptional mechanism involving the transciriptiphal factor SP1;Vthat tetraspanin-1 (,Tspan-1) and transmembrane 4 super-family member 4'(TM4SF4)" proteins;are ihteractihg. partners with intestinal THTR-1 and THTR-2, respectively! and thai they affect their physiolpgy/cell biology;and that enteropat.hogenic Escherichia cpli and enterotoxigenic E. Coll inhibit ihtestirial thiamine uptake;Twoadditional and very relevant studies were also'initiated during the current funding period with the first dealing with the identification pf existence of a specificand efficient carrier-riiediated systerh for uptake of the niicrpbiota-generated thiamin pyrophosphate (TPP) in the colon (i. e., the SL:G44A4 system), and the second isthedennonstration that the inhibitory effect of chronic alcohol feedihg/expoisure: on intestinal thiamine uptake is mediated at the level of transcription of the'SLCi9A2 and SLG19A3: genes. Based pn these new findings', pur working hypotheses during, the next.peribd will be that the SL'G44A4 system is a specific and regulated colonic TPP uptake system, and that transcriptional (e. g., epigenetic). mechanisms are involved in mediating the inhibitory effect of ch j-onic alcohol exposure oh intestihal thiiamin uptake. Four specifiG'aims are proposed to address these hypptheses, and N utilize state-pif the art eellular/mdlecular approaches. Hesults of these studies :sh6uld cdntinue to prbvid^ novel iriformatipn regarding the physiolpgy/pathophysiblogy of the intestinal vitamin B1 absorption process.

Public Health Relevance

fSee ihstruclions): Humans cannot synthesize vitaniinBI (thianiin) but obtain it from exogenous sources via intestinal absprptipn. The ai.ms pf this proposal are focused ph delineating how our ihtestine absorb,thiamin, how fhe prpGess:is regulated, and how certain conditions affect the prociess leading to defieiency. The ultimate;goal istbfind waystdQiitihiizetbpdythiaimih nutritilDn cdriditions of deficiency/sufaoptimal levels.

Agency
National Institute of Health (NIH)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
4R37DK056061-16
Application #
8791430
Study Section
No Study Section (in-house review) (NSS)
Program Officer
Maruvada, Padma
Project Start
Project End
Budget Start
Budget End
Support Year
16
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of California Irvine
Department
Type
DUNS #
City
Irvine
State
CA
Country
United States
Zip Code
92697
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
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
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
Srinivasan, Padmanabhan; Thrower, Edwin C; Gorelick, Fred S et al. (2016) Inhibition of pancreatic acinar mitochondrial thiamin pyrophosphate uptake by the cigarette smoke component 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Am J Physiol Gastrointest Liver Physiol 310:G874-83
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
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
Said, Hamid M (2015) Water-soluble vitamins. World Rev Nutr Diet 111:30-7
Nabokina, Svetlana M; Ramos, Mel Brendan; Valle, Judith E et al. (2015) Regulation of basal promoter activity of the human thiamine pyrophosphate transporter SLC44A4 in human intestinal epithelial cells. Am J Physiol Cell Physiol 308:C750-7
Subramanian, Veedamali S; Ghosal, Abhisek; Kapadia, Rubina et al. (2015) Molecular Mechanisms Mediating the Adaptive Regulation of Intestinal Riboflavin Uptake Process. PLoS One 10:e0131698
Ghosal, Abhisek; Sabui, Subrata; Said, Hamid M (2015) Identification and characterization of the minimal 5'-regulatory region of the human riboflavin transporter-3 (SLC52A3) in intestinal epithelial cells. Am J Physiol Cell Physiol 308:C189-96

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