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 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 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 Chronic alcohol consumption and intestinal thiamin absorption: effects on physiological and molecular parameters of the uptake process

2010 ◽  
Vol 299 (1) ◽  
pp. G23-G31 ◽  
Author(s):  
Sandeep B. Subramanya ◽  
Veedamali S. Subramanian ◽  
Hamid M. Said
Keyword(s):  
Alcohol Consumption ◽  
Basolateral Membrane ◽  
Significant Inhibition ◽  
Model Systems ◽  
Rat Colon ◽  
Activity Levels ◽  
Mrna Levels ◽  
Chronic Alcohol ◽  
Chronic Alcohol Consumption ◽  
Uptake Process

Thiamin is essential for normal cellular functions, and its deficiency leads to a variety of clinical abnormalities. Humans and other mammals obtain the vitamin via intestinal absorption. The intestine is exposed to two sources of thiamin, a dietary and a bacterial (i.e., normal microflora of the large intestine) source. Chronic alcohol consumption is associated with thiamin deficiency, which is caused (in part) by inhibition in intestinal thiamin absorption. However, little is known about the physiological and molecular aspects of the intestinal thiamin uptake process that are affected by chronic alcohol use. To address these issues, we used rats fed an alcohol-liquid diet and human intestinal epithelial HuTu-80 cells chronically exposed to ethanol as model systems. The results showed that chronic alcohol feeding to rats led to a significant inhibition in carrier-mediated thiamin transport across both the jejunal brush-border membrane and basolateral membrane domains. This was associated with a significant reduction in level of expression of thiamin transporter-1 (THTR-1), but not THTR-2, at the protein and mRNA levels. Level of expression of the heterogenous nuclear RNA of THTR-1 in the intestine of alcohol-fed rats was also decreased compared with their pair-fed controls. Chronic alcohol feeding also caused a significant inhibition in carrier-mediated thiamin uptake in rat colon. Studies with HuTu-80 cells chronically exposed to ethanol also showed a significant inhibition in carrier-mediated thiamin uptake. This inhibition was associated with a reduction in level of expression of human THTR-1 and THTR-2 at the protein, mRNA, and transcriptional (promoter activity) levels. These studies demonstrate that chronic alcohol feeding inhibits intestinal thiamin absorption via inhibition of the individual membrane transport event across the polarized absorptive epithelial cells. Furthermore, the inhibition is, at least in part, mediated via transcriptional mechanism(s).

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.

Expression of cell volume-regulated kinase h-sgk in pancreatic tissue

2000 ◽  
Vol 279 (5) ◽  
pp. G998-G1002 ◽  
Author(s):  
K. Klingel ◽  
S. Wärntges ◽  
J. Bock ◽  
C. A. Wagner ◽  
M. Sauter ◽  
...  
Keyword(s):  
Cell Volume ◽  
Phorbol Esters ◽  
Acinar Cells ◽  
Northern Blotting ◽  
Pancreatic Tissue ◽  
Normal Function ◽  
Pancreatic Acinar Cells ◽  
Mrna Levels ◽  
Serine Threonine Kinase ◽  
Intracellular Ca

Transcript levels of the human serine/threonine kinase h-sgk have been found to be highest in pancreas. In the present study, localization and regulation of h-sgk transcription in pancreatic tissue were elucidated. As was apparent from radioactive in situ hybridization, most pancreatic acinar cells expressed high levels of h-sgk mRNA. h-sgk mRNA-positive cells were also found in ductal epithelia but not in pancreatic islets. In biopsy specimens from patients with pancreatitis, h-sgk mRNA levels were decreased in acinar cells but abundant in numerous mononuclear interstitial cells within areas of pancreatic necrosis and fibrosis. As shown by Northern blotting, h-sgk transcription in DAN-G pancreatic tumor cells is upregulated by osmotic cell shrinkage, serum, phorbol esters (phorbol 12,13-didecanoate), and Ca2+ ionophore A-23187 and decreased by staurosporine and cAMP. In conclusion, h-sgk transcription is regulated not only by cell volume but also by serum, protein kinase C stimulation, cAMP, and increase of intracellular Ca2+activity. The kinase may participate not only in normal function of exocrine pancreas but also in fibrosing pancreatitis.

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 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 Chronic alcohol exposure affects pancreatic acinar mitochondrial thiamin pyrophosphate uptake: studies with mouse 266-6 cell line and primary cells

2015 ◽  
Vol 309 (9) ◽  
pp. G750-G758 ◽  
Author(s):  
Padmanabhan Srinivasan ◽  
Svetlana Nabokina ◽  
Hamid M. Said
Keyword(s):  
Cell Line ◽  
Mammalian Cells ◽  
Alcohol Exposure ◽  
Significant Inhibition ◽  
Epigenetic Mechanism ◽  
Pancreatic Acinar Cells ◽  
Chronic Alcohol ◽  
Ethyl Palmitate ◽  
Chronic Alcohol Exposure ◽  
Thiamin Pyrophosphate

Thiamin is essential for normal metabolic activity of all mammalian cells, including those of the pancreas. Cells obtain thiamin from their surroundings and enzymatically convert it into thiamin pyrophosphate (TPP) in the cytoplasm; TPP is then taken up by mitochondria via a specific carrier the mitochondrial TPP transporter (MTPPT; product of the SLC25A19 gene). Chronic alcohol exposure negatively impacts the health of pancreatic acinar cells (PAC), but its effect on physiological/molecular parameters of MTPPT is not known. We addressed this issue using mouse pancreatic acinar tumor cell line 266-6 and primary PAC of wild-type and transgenic mice carrying the SLC25A19 promoter that were fed alcohol chronically. Chronic alcohol exposure of 266-6 cells (but not to its nonoxidative metabolites ethyl palmitate and ethyl oleate) led to a significant inhibition in mitochondrial TPP uptake, which was associated with a decreased expression of MTPPT protein, mRNA, and activity of the SLC25A19 promoter. Similarly, chronic alcohol feeding of mice led to a significant inhibition in expression of MTPPT protein, mRNA, heterogeneous nuclear RNA, as well as in activity of SLC25A19 promoter in PAC. While chronic alcohol exposure did not affect DNA methylation of the Slc25a19 promoter, a significant decrease in histone H3 euchromatin markers and an increase in H3 heterochromatin marker were observed. These findings show, for the first time, that chronic alcohol exposure negatively impacts pancreatic MTPPT, and that this effect is exerted, at least in part, at the level of Slc25a19 transcription and appears to involve epigenetic mechanism(s).

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