scholarly journals Relative contribution of THTR-1 and THTR-2 in thiamin uptake by pancreatic acinar cells: studies utilizing Slc19a2 and Slc19a3 knockout mouse models

2012 ◽  
Vol 302 (5) ◽  
pp. G572-G578 ◽  
Author(s):  
Veedamali S. Subramanian ◽  
Sandeep B. Subramanya ◽  
Hamid M. Said
Keyword(s):  
Mouse Models ◽  
Knockout Mouse ◽  
Acinar Cells ◽  
Normal Function ◽  
Significant Inhibition ◽  
Pancreatic Acinar Cells ◽  
Human Pancreas ◽  
Relative Contribution ◽  
First Time ◽  
Knockout Model

Thiamin is essential for normal function of pancreatic acinar cells, and its deficiency leads to a reduction in pancreatic digestive enzymes. We have recently shown that thiamin uptake by rat pancreatic acinar cells is carrier-mediated and that both thiamin transporter (THTR)-1 and THTR-2 are expressed in these cells; little, however, is known about the relative contribution of these transporters toward total carrier-mediated thiamin uptake by these cells. We addressed this issue using a gene-specific silencing approach (siRNA) in mouse-derived pancreatic acinar 266–6 cells and Slc19a2 and Slc19a3 knockout mouse models. First we established that thiamin uptake by mouse pancreatic acinar cells is via a carrier-mediated process. We also established that these cells as well as native human pancreas express THTR-1 and THTR-2, with expression of the former (and activity of its promoter) being significantly higher than that of the latter. Using gene-specific siRNA against mouse THTR-1 and THTR-2, we observed a significant inhibition in carrier-mediated thiamin uptake by 266–6 cells in both cases. Similarly, thiamin uptake by freshly isolated primary pancreatic acinar cells of the Slc19a2 and Slc19a3 knockout mice was significantly lower than uptake by acinar cells of the respective littermates; the degree of inhibition observed in the former knockout model was greater than that of the latter. These findings demonstrate, for the first time, that both mTHTR-1 and mTHTR-2 are involved in carrier-mediated thiamin uptake by pancreatic acinar cells.

scholarly journals Thiamin uptake by pancreatic acinar cells: effect of chronic alcohol feeding/exposure

2011 ◽  
Vol 301 (5) ◽  
pp. G896-G904 ◽  
Author(s):  
Sandeep B. Subramanya ◽  
Veedamali S. Subramanian ◽  
V. Thillai Sekar ◽  
Hamid M. Said
Keyword(s):  
Acinar Cells ◽  
Normal Function ◽  
Significant Inhibition ◽  
Pancreatic Acinar Cells ◽  
Transcriptional Level ◽  
Mrna Levels ◽  
Chronic Alcohol ◽  
Metabolizing Enzymes ◽  
Uptake Process ◽  
First Time

Thiamin is important for normal function of pancreatic acinar cells, but little is known about its mechanism of uptake and about the effect of chronic alcohol use on the process. We addressed these issues using freshly isolated rat primary and rat-derived cultured AR42J pancreatic acinar cells as models. Results showed thiamin uptake by both primary and cultured AR42J pancreatic acinar cells to be via a specific carrier-mediated mechanism and that both of the thiamin transporters 1 and 2 (THTR-1 and THTR-2) are expressed in these cells. Chronic alcohol feeding of rats was found to lead to a significant inhibition of carrier-mediated thiamin uptake by pancreatic acinar cells and was associated with a significant reduction in level of expression of THTR-1 and THTR-2 at the protein and mRNA levels. Chronic exposure (96 h) of AR42J cells to alcohol also led to a significant decreased carrier-mediated thiamin uptake, an effect that was associated with a significant decrease in the activity of the human SLC19A2 and SLC19A3 promoters expressed in these cells. We also examined the effect of chronic alcohol feeding of rats on level of expression of key thiamin metabolizing enzymes (thiamin phosphokinase and thiamin pyrophosphatase) as well as on level of expression of the mitochondrial thiamin pyrophosphate transporter of pancreatic acinar cells and observed a significant inhibition in all these parameters. These results demonstrate for the first time that thiamin uptake by pancreatic acinar cells is via a carrier-mediated process and that both the THTR-1 as well as THTR-2 are expressed in these cells. Also, chronic alcohol feeding/exposure inhibits thiamin uptake process and the inhibition is, at least in part, being exerted at the transcriptional level. Furthermore, chronic alcohol feeding also negatively impacts intracellular parameters of thiamin metabolism in pancreatic acinar cells.

scholarly journals Effect of bacterial flagellin on thiamin uptake by human and mouse pancreatic acinar cells: inhibition mediated at the level of transcription of thiamin transporters 1 and 2

2019 ◽  
Vol 316 (6) ◽  
pp. G735-G743 ◽  
Author(s):  
Padmanabhan Srinivasan ◽  
Kasin Yadunandam Anandam ◽  
Vignesh Ramesh ◽  
Erica T. Geltz ◽  
Hamid M. Said
Keyword(s):  
Prolonged Exposure ◽  
Acinar Cells ◽  
Significant Inhibition ◽  
Pancreatic Acinar Cells ◽  
Vitamin B ◽  
Mrna Levels ◽  
Molecular Parameters ◽  
Atp Production ◽  
First Time

Thiamin (vitamin B1) is essential for normal cellular metabolism and function. Pancreatic acinar cells (PACs) obtain thiamin from the circulation via a specific carrier-mediated process that involves the plasma membrane thiamin transporters 1 and 2 (THTR-1 and THTR-2; products of SLC19A2 and SLC19A3 genes, respectively). There is nothing known about the effect of bacterial products/toxins on thiamin uptake by PACs. We addressed this issue in the present investigation by examining the effect of bacterial flagellin on physiological and molecular parameters of thiamin uptake by PACs. We used human primary PACs, mice in vivo, and cultured mouse-derived pancreatic acinar 266-6 cells in our investigation. The results showed that exposure of human primary PACs to flagellin led to a significant inhibition in thiamin uptake; this inhibition was associated with a significant decrease in expression of THTR-1 and -2 at the protein and mRNA levels. These findings were confirmed in mice in vivo as well as in cultured 266-6 cells. Subsequent studies showed that flagellin exposure markedly suppressed the activity of the SLC19A2 and SLC19A3 promoters and that this effect involved the Sp1 regulatory factor. Finally, knocking down Toll-like receptor 5 by use of gene-specific siRNA was found to lead to abrogation in the inhibitory effect of flagellin on PAC thiamin uptake. These results show, for the first time, that exposure of PACs to flagellin negatively impacts the physiological and molecular parameters of thiamin uptake and that this effect is mediated at the level of transcription of the SLC19A2 and SLC19A3 genes. NEW & NOTEWORTHY The present study demonstrates, for the first time, that prolonged exposure of pancreatic acinar cells to flagellin inhibits uptake of vitamin B1, a micronutrient that is essential for energy metabolism and ATP production. This effect is mediated at the level of transcription of the SLC19A2 and SLC19A3 genes and involves the Sp1 transcription factor.

scholarly journals Chronic alcohol exposure inhibits biotin uptake by pancreatic acinar cells: possible involvement of epigenetic mechanisms

2014 ◽  
Vol 307 (9) ◽  
pp. G941-G949 ◽  
Author(s):  
Padmanabhan Srinivasan ◽  
Rubina Kapadia ◽  
Arundhati Biswas ◽  
Hamid M. Said
Keyword(s):  
Transgenic Mice ◽  
Chronic Exposure ◽  
Methylation Status ◽  
Acinar Cells ◽  
Alcohol Exposure ◽  
Significant Inhibition ◽  
Pancreatic Acinar Cells ◽  
Chronic Alcohol ◽  
Wild Type ◽  
Chronic Alcohol Exposure

Chronic exposure to alcohol affects different physiological aspects of pancreatic acinar cells (PAC), but its effect on the uptake process of biotin is not known. We addressed this issue using mouse-derived pancreatic acinar 266-6 cells chronically exposed to alcohol and wild-type and transgenic mice (carrying the human SLC5A6 5′-promoter) fed alcohol chronically. First we established that biotin uptake by PAC is Na+ dependent and carrier mediated and involves sodium-dependent multivitamin transporter (SMVT). Chronic exposure of 266-6 cells to alcohol led to a significant inhibition in biotin uptake, expression of SMVT protein, and mRNA as well as in the activity of the SLC5A6 promoter. Similarly, chronic alcohol feeding of wild-type and transgenic mice carrying the SLC5A6 promoter led to a significant inhibition in biotin uptake by PAC, as well as in the expression of SMVT protein and mRNA and the activity of the SLC5A6 promoters expressed in the transgenic mice. We also found that chronic alcohol feeding of mice is associated with a significant increase in the methylation status of CpG islands predicted to be in the mouse Slc5a6 promoters and a decrease in the level of expression of transcription factor KLF-4, which plays an important role in regulating SLC5A6 promoter activity. These results demonstrate, for the first time, that chronic alcohol exposure negatively impacts biotin uptake in PAC and that this effect is exerted (at least in part) at the level of transcription of the SLC5A6 gene and may involve epigenetic/molecular mechanisms.

scholarly journals Mechanism and regulation of folate uptake by pancreatic acinar cells: effect of chronic alcohol consumption

2010 ◽  
Vol 298 (6) ◽  
pp. G985-G993 ◽  
Author(s):  
Hamid M. Said ◽  
Lisa Mee ◽  
V. Thillai Sekar ◽  
Balasubramaniem Ashokkumar ◽  
Stephen J. Pandol
Keyword(s):  
Acinar Cells ◽  
Pancreatic Acinar Cell ◽  
Pancreatic Acinar Cells ◽  
Exocrine Function ◽  
Acid Uptake ◽  
Human Pancreas ◽  
Chronic Alcohol ◽  
Transport Inhibitors ◽  
Pancreatic Exocrine ◽  
One Carbon Metabolism

Folate plays an essential role in one-carbon metabolism, and a relationship exists between methyl group metabolism and pancreatic exocrine function. Little, however, is known about the mechanism(s) and regulation of folate uptake by pancreatic acinar cells and the effect of chronic alcohol use on the process. We addressed these issues using the rat-derived pancreatic acinar cell line AR42J and freshly isolated primary rat pancreatic acinar cells as models. We found [3H]folic acid uptake to be 1) temperature and pH dependent with a higher uptake at acidic than at neutral/alkaline pH; 2) saturable as a function of substrate concentration at both buffer pH 7.4 and 6.0; 3) inhibited by folate structural analogs and by anion transport inhibitors at both buffer pH 7.4 and 6.0; 4) trans-stimulated by unlabeled folate; 5) adaptively regulated by the prevailing extracellular folate level, and 6) inhibited by modulators of the cAMP/PKA-mediated pathway. Both the reduced folate carrier (RFC) and the proton-coupled folate transporter (PCFT) were found to be expressed in AR42J and in primary pancreatic acinar cells, as well as in native human pancreas with expression of RFC being higher than PCFT. Chronic alcohol feeding of rats (4 wk; 36% of calories from ethanol) led to a significant decrease in folate uptake by freshly isolated primary pancreatic acinar cells compared with cells from pair-fed controls; this effect was associated with a parallel decrease in the level of expression of RFC and PCFT. These studies reveal that folate uptake by pancreatic acinar cells is via a regulated carrier-mediated process which may involve RFC and PCFT. In addition, chronic alcohol feeding leads to a marked inhibition in folate uptake by pancreatic acinar cells, an effect that is associated with reduction in level of expression of RFC and PCFT.

scholarly journals Inhibitors of ORAI1 Prevent Cytosolic Calcium-Associated Injury of Human Pancreatic Acinar Cells and Acute Pancreatitis in 3 Mouse Models

2015 ◽  
Vol 149 (2) ◽  
pp. 481-492.e7 ◽  
Author(s):  
Li Wen ◽  
Svetlana Voronina ◽  
Muhammad A. Javed ◽  
Muhammad Awais ◽  
Peter Szatmary ◽  
...  
Keyword(s):  
Acute Pancreatitis ◽  
Mouse Models ◽  
Acinar Cells ◽  
Cytosolic Calcium ◽  
Pancreatic Acinar Cells ◽  
Associated Injury

scholarly journals SEC23B is required for pancreatic acinar cell function in adult mice

2017 ◽  
Vol 28 (15) ◽  
pp. 2146-2154 ◽  
Author(s):  
Rami Khoriaty ◽  
Nancy Vogel ◽  
Mark J. Hoenerhoff ◽  
M. Dolors Sans ◽  
Guojing Zhu ◽  
...  
Keyword(s):  
Acinar Cell ◽  
Cell Function ◽  
Acinar Cells ◽  
Cell Loss ◽  
Normal Function ◽  
Pancreatic Acinar Cell ◽  
Pancreatic Acinar Cells ◽  
Total Protein Content ◽  
Pancreatic Cell ◽  
Adult Mice

Mice with germline absence of SEC23B die perinatally, exhibiting massive pancreatic degeneration. We generated mice with tamoxifen-inducible, pancreatic acinar cell–specific Sec23b deletion. Inactivation of Sec23b exclusively in the pancreatic acinar cells of adult mice results in decreased overall pancreatic weights from pancreatic cell loss (decreased pancreatic DNA, RNA, and total protein content), as well as degeneration of exocrine cells, decreased zymogen granules, and alterations in the endoplasmic reticulum (ER), ranging from vesicular ER to markedly expanded cisternae with accumulation of moderate-density content or intracisternal granules. Acinar Sec23b deletion results in induction of ER stress and increased apoptosis in the pancreas, potentially explaining the loss of pancreatic cells and decreased pancreatic weight. These findings demonstrate that SEC23B is required for normal function of pancreatic acinar cells in adult mice.

scholarly journals Adaptive regulation of pancreatic acinar mitochondrial thiamin pyrophosphate uptake process: possible involvement of epigenetic mechanism(s)

2017 ◽  
Vol 313 (5) ◽  
pp. G448-G455 ◽  
Author(s):  
Subrata Sabui ◽  
Veedamali S. Subramanian ◽  
Rubina Kapadia ◽  
Hamid M. Said
Keyword(s):  
Transgenic Mice ◽  
Mammalian Cells ◽  
Acinar Cells ◽  
Epigenetic Mechanism ◽  
Pancreatic Acinar Cells ◽  
Adaptive Regulation ◽  
Oxidative Energy Metabolism ◽  
Uptake Process ◽  
First Time ◽  
Thiamin Pyrophosphate

The essentiality of thiamin stems from its roles as a cofactor [mainly in the form of thiamin pyrophosphate (TPP)] in critical metabolic reactions including oxidative energy metabolism and reduction of cellular oxidative stress. Like other mammalian cells, pancreatic acinar cells (PAC) obtain thiamin from their surroundings and convert it to TPP; mitochondria then take up TPP by a carrier-mediated process that involves the mitochondrial TPP (MTPP) transporter (MTPPT; product of SLC25A19 gene). Previous studies have characterized different physiological/biological aspects of the MTPP uptake process, but little is known about its possible adaptive regulation. We addressed this issue using pancreatic acinar 266-6 cells (PAC 266-6) maintained under thiamin-deficient (DEF) and oversupplemented (OS) conditions, as well as thiamin-DEF and -OS transgenic mice carrying the SLC25A19 promoter. We found that maintaining PAC 266-6 under the thiamin-DEF condition leads to a significant induction in mitochondrial [3H]TPP uptake, as well as in the level of expression of the MTPPT protein and mRNA compared with thiamin-OS cells. Similar findings were observed in mitochondria from thiamin-DEF mice compared with thiamin-OS. Subsequently, we demonstrated that adaptive regulation of MTTP protein was partly mediated via transcriptional mechanism(s) via studies with PAC 266-6 transfected with the SLC25A19 promoter and transgenic mice carrying the SLC25A19 promoter. This transcriptional regulation appeared to be, at least in part, mediated via epigenetic mechanism(s) involving histone modifications. These studies report, for the first time, that the PAC mitochondrial TPP uptake process is adaptively regulated by the prevailing thiamin level and that this regulation is transcriptionally mediated and involves epigenetic mechanism(s). NEW & NOTEWORTHY Our findings show, for the first time, that the mitochondrial thiamin pyrophosphate (MTPP) uptake process is adaptively regulated by the prevailing thiamin level in pancreatic acinar cells and this regulation is mediated, at least in part, by transcriptional and epigenetic mechanism(s) affecting the SLC25A19 promoter.

scholarly journals Posttranscriptional regulation of thiamin transporter-1 expression by microRNA-200a-3p in pancreatic acinar cells

2020 ◽  
Vol 319 (3) ◽  
pp. G323-G332
Author(s):  
Kalidas Ramamoorthy ◽  
Kasin Yadunandam Anandam ◽  
Tomoya Yasujima ◽  
Padmanabhan Srinivasan ◽  
Hamid M. Said
Keyword(s):  
Posttranscriptional Regulation ◽  
Vitamin B1 ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Membrane Transporter ◽  
Functional Consequences ◽  
First Time

The findings of this study show, for the first time, that the membrane transporter of vitamin B1, i.e., thiamin transporter-1 (THTR-1), is subject to regulation by microRNAs (specifically miR-200a-3p) in mouse and human primary pancreatic acinar cells (PACs). The results also show that this posttranscriptional regulation has functional consequences on the ability of PACs to take in the essential micronutrient thiamin.

Halothane and octanol block Ca2+ oscillations in pancreatic acini by multiple mechanisms

1995 ◽  
Vol 269 (5) ◽  
pp. G779-G788 ◽  
Author(s):  
D. E. Deutsch ◽  
J. A. Williams ◽  
D. I. Yule
Keyword(s):  
Gap Junction ◽  
Oscillation Frequency ◽  
Lucifer Yellow ◽  
Single Cells ◽  
Acinar Cells ◽  
Significant Inhibition ◽  
Pancreatic Acinar Cells ◽  
Inhibitory Effects ◽  
Pancreatic Acini ◽  
Agonist Stimulation

This study has investigated halothane and octanol, reported inhibitors of gap junction permeability, for their effects on acinar cell intracellular Ca2+ concentration ([Ca2+]i) signaling. Halothane and octanol alone at maximal concentrations induced a sustained rise in [Ca2+]i of 23 +/- 4 and 29 +/- 5 nM, respectively. Cholecystokinin (CCK, 20 pM) induced [Ca2+]i oscillations in single acinar cells within the acinus to a peak of 275 +/- 17 nM, rising from a basal level of 55 +/- 3 nM. These oscillations were completely abolished by superfusion with both halothane (4 mM) and octanol (1 mM), concentrations that blocked the spread of Lucifer yellow from cell to cell within an acinus. Lower concentrations of octanol markedly reduced the oscillation frequency (0.2 and 0.5 mM octanol: reduction in oscillation frequency of 69 +/- 6 and 43 +/- 6%, respectively). These agents however, over the same concentration range, also exhibited similar inhibitory effects on [Ca2+]i oscillations in single cells dispersed from the acinus (reduction in oscillation frequency of 75 +/- 10 and 32 +/- 12% for 0.2 and 0.5 mM octanol, respectively), suggesting additional effects other than on gap junctions. Halothane inhibited inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] production in response to both 1 and 10 nM CCK (31 and 40% inhibition, respectively), possibly explaining its effects on [Ca2+]i oscillations, whereas octanol showed no significant inhibition. Octanol, unlike halothane, blocked Ins(1,4,5)P3-induced Ca2+ release from permeabilized acini, an effect that was most pronounced at a more physiological Ins(1,4,5)P3 concentration. Octanol did not affect Ins(1,4,5)P3 binding to Ins(1,4,5)P3 receptor preparation. In conclusion, although halothane and octanol block gap junction permeability in pancreatic acinar cells, these agents also affect Ins(1,4,5)P3 production and Ca2+ mobilization in response to agonist stimulation.

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