Vitamin B1 (thiamin) is indispensable for normal function/health of pancreatic cells due its critical roles in oxidative energy metabolism, ATP production, and in maintaining normal cellular redox state. Low intracellular level of thiamin leads to acute energy failure, oxidative stress, and impairment in mitochondrial function. At the organ level, the metabolically active pancreas maintains high levels of thiamin, and deficiency of the vitamin impairs its functions. The pancreas cannot synthesis thiamin endogenously; rather it obtains it from circulation. The overall goal of this research program since its inception has been focused on developing a comprehensive understanding of the molecular mechanisms involved in thiamin uptake by pancreatic acinar cells (PACs) and the subsequent transport (compartmentalization) of its major intracellular form, i. e., thiamin pyrophosphate (TPP), into mitochondria, how these processes are regulated, and how they are affected by exposure to external/internal factors that are known to adversely affect the normal physiology/health of the pancreas. We have addressed many of these issues, and in the current proposal aim at determining: i) the role of microRNAs in post-transcriptional regulation of THTR-1, THTR-2, and the mitochondrial TPP transporter (MTPPT) expression in PACS, and the uptake processes that they mediate; ii) whether THTR- 1 and THTR-2 of PACs have interacting partners that affect/regulate their physiology/cell biology; and iii) the effect of specific factors that PACs are exposed to under certain pathophysiological conditions [pro-inflammatory cytokines, and the bacterial lipopolysaccharide (LPS) and flagellin] on thiamin uptake and on transport of TPP into their mitochondria. Thus, in new preliminary studies evidence were obtained to suggest that microRNAs regulate THTR-1 expression and thiamin uptake by PACs, that THTR-1 has interacting partner(s), and that exposure of PACs to pro-inflammatory cytokines (especially those implicated in pancreatic disorders like IL- 6, TNF-? and IL-1?), as well as to LPS and flagellin, inhibit cellular thiamin uptake and transport of TPP into mitochondria. Based on these new findings, our working hypotheses are: i) microRNAs play an important role in post-transcriptional regulation of THTR-1, THTR-2, and MTPPT expression in PACs and the uptake events they mediate; ii) PACs THTR-1 and THTR-2 have interacting partners that affect/regulate their physiology/cell biology; and iii) pro- inflammatory cytokines, LPS and flagellin negatively impact PACs thiamin transport physiology. We plan to test these hypotheses by accomplishing two specific aims and will utilize state-of the art cellular/molecular approaches, human and mouse PACs, and appropriate transgenic mouse models. Results of these investigations should provide novel information regarding vitamin B1 cellular/molecular transport physiology in PACs and how internal/external factors affect the involved transport events. Such knowledge may ultimately assist in the designing of effective strategies to optimize pancreatic thiamin homeostasis, and thus, improve the health of the pancreas.
Diseases that affect the physiology/health of the pancreas lead to significant morbidity and mortality. Despite that, there has been little known about the physiology/nutrition of water-soluble vitamins in cells of this vital organ, and how external/internal factors and disease conditions affect these parameters. The studies proposed here aim at delineating physiological/pathophysiological aspects of transport of vitamin B1 (a micronutrient that plays critical roles in oxidative energy metabolism, ATP production, reduction of oxidative stress, and in mitochondrial function) into and within pancreatic acinar cells. Results should ultimately assist in the designing of effective strategies to optimize pancreatic thiamin level, and thus, improve the health/physiology of this vital organ.
|Elahi, Asif; Sabui, Subrata; Narasappa, Nell N et al. (2018) Biotin Deficiency Induces Th1- and Th17-Mediated Proinflammatory Responses in Human CD4+ T Lymphocytes via Activation of the mTOR Signaling Pathway. J Immunol 200:2563-2570|
|Sabui, Subrata; Subramanian, Veedamali S; Kapadia, Rubina et al. (2017) Adaptive regulation of pancreatic acinar mitochondrial thiamin pyrophosphate uptake process: possible involvement of epigenetic mechanism(s). Am J Physiol Gastrointest Liver Physiol 313:G448-G455|
|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|
|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|
|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|
|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; Srinivasan, Padmanabhan; Said, Hamid M (2016) Uptake of ascorbic acid by pancreatic acinar cells is negatively impacted by chronic alcohol exposure. Am J Physiol Cell Physiol 311:C129-35|
|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|
Showing the most recent 10 out of 45 publications