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 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).

scholarly journals Uptake of ascorbic acid by pancreatic acinar cells is negatively impacted by chronic alcohol exposure

2016 ◽  
Vol 311 (1) ◽  
pp. C129-C135 ◽  
Author(s):  
Veedamali S. Subramanian ◽  
Padmanabhan Srinivasan ◽  
Hamid M. Said
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Mammalian Cells ◽  
Marked Reduction ◽  
Acinar Cells ◽  
Alcohol Exposure ◽  
Epigenetic Mechanism ◽  
Pancreatic Acinar Cells ◽  
Chronic Alcohol ◽  
Chronic Alcohol Exposure

Vitamin C (ascorbic acid, AA) is indispensable for normal metabolism of all mammalian cells including pancreatic acinar cells (PACs). PACs obtain AA from their surroundings via transport across the cell membrane. Chronic alcohol exposure negatively affects body AA homeostasis; it also inhibits uptake of other micronutrients into PACs, but its effect on AA uptake is not clear. We examined this issue using both in vitro (266-6 cells) and in vivo (mice) models of chronic alcohol exposure. First, we determined the relative expression of the AA transporters 1 and 2 [i.e., sodium-dependent vitamin C transporter-1 (SVCT-1) and SVCT-2] in mouse and human PACs and found SVCT-2 to be the predominant transporter. Chronic exposure of 266-6 cells to alcohol significantly inhibited AA uptake and caused a marked reduction in SVCT-2 expression at the protein, mRNA, and heterogeneous nuclear RNA (hnRNA) levels. Similarly, chronic alcohol feeding of mice significantly inhibited AA uptake and caused a marked reduction in level of expression of the SVCT-2 protein, mRNA, and hnRNA. These findings suggest possible involvement of transcriptional mechanism(s) in mediating chronic alcohol effect on AA uptake by PACs. We also observed significant epigenetic changes (histone modifications) in the Slc23a2 gene (reduction in H3K4me3 level and an increase in H3K27me3 level) in the alcohol-exposed 266-6 cells. These findings show that chronic alcohol exposure inhibits PAC AA uptake and that the effect is mediated, in part, at the level of transcription of the Slc23a2 gene and may involve epigenetic mechanism(s).

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 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 Transgenic expression of cyclooxygenase-2 in pancreatic acinar cells induces chronic pancreatitis

2019 ◽  
Vol 316 (1) ◽  
pp. G179-G186
Author(s):  
Haojie Huang ◽  
Jiaxiang Chen ◽  
Lisi Peng ◽  
Yao Yao ◽  
Defeng Deng ◽  
...  
Keyword(s):  
Chronic Pancreatitis ◽  
Transgenic Mice ◽  
Fibrous Tissue ◽  
Acinar Cells ◽  
Cyclooxygenase 2 ◽  
Therapeutic Interventions ◽  
Pancreatic Stellate Cells ◽  
Pancreatic Acinar Cells ◽  
Transgenic Expression ◽  
Cox 2

Replacement of the exocrine parenchyma by fibrous tissue is a main characteristic of chronic pancreatitis. Understanding the mechanisms of pancreatic fibrogenesis is critical for the development of preventive and therapeutic interventions. Cyclooxygenase-2 (COX-2), a rate-limiting enzyme for prostaglandin synthesis, is expressed in patients with chronic pancreatitis. However, it is unknown whether COX-2 can cause chronic pancreatitis. To investigate the roles of pancreatic acinar COX-2 in fibrogenesis and the development of chronic pancreatitis, COX-2 was ectopically expressed specifically in pancreatic acinar cells in transgenic mice. Histopathological changes and expression levels of several profibrogenic factors related to chronic pancreatitis were evaluated. COX-2 was expressed in the pancreas of the transgenic mice, as detected by Western blot analysis. Immunohistochemical staining showed COX-2 was specifically expressed in pancreatic acinar cells. COX-2 expression led to progressive changes in the pancreas, including pancreas megaly, persistent inflammation, collagen deposition, and acinar-to-ductal metaplasia. Quantitative RT-PCR and immunostaining showed that profibrogenic factors were upregulated and pancreatic stellate cells were activated in the COX-2 transgenic mice. Expression of COX-2 in pancreatic acinar cells is sufficient to induce chronic pancreatitis. Targeting this pathway may be valuable in the prevention of chronic pancreatitis. NEW & NOTEWORTHY COX-2 expression is observed in pancreatic tissues of human chronic pancreatitis. In this study, we showed that COX-2 expression caused the development of chronic pancreatitis in transgenic mice, supporting the idea that COX-2 inhibition may be an effective preventive and therapeutic strategy.

Metallothionein is a component of exocrine pancreas secretion: implications for zinc homeostasis

1996 ◽  
Vol 271 (4) ◽  
pp. C1103-C1110 ◽  
Author(s):  
R. C. De Lisle ◽  
M. P. Sarras ◽  
J. Hidalgo ◽  
G. K. Andrews
Keyword(s):  
Transgenic Mice ◽  
Pancreatic Juice ◽  
Secretory Pathway ◽  
Physiological Role ◽  
Acinar Cells ◽  
Transgenic Animals ◽  
Light Level ◽  
Zinc Homeostasis ◽  
Pancreatic Acinar Cells ◽  
Pancreatic Ducts

Using transgenic mice that overexpress metallothionein-I (MT-I) and zinc-induced normal and transgenic animals, we have explored the localization of MT in the pancreas. Light-level immunocytochemistry demonstrated MT in acinar cells but not islet cells. Immunolabeling also revealed the presence of MT in pancreatic ducts, suggesting that it is released from acinar cells. Ultrastructural immunolocalization showed that MT was cytoplasmic, and no MT immunoreactivity was detected in lumens of the vesicular secretory pathway. Secreted pancreatic juice was collected from pilocarpine-stimulated mice and assayed for MT by a 109Cd-labeled hemoglobin-exchange assay and by radioimmunoassay. Both methods revealed high (> 1,000 ng/ml) levels of MT in the stimulated secretion. The level of MT in pancreatic juice from transgenic mice was only slightly (2-fold) increased despite dramatic overexpression of MT-I in the pancreas (> 20-fold). In contrast, zinc induction of MT significantly increased MT by 5- to 10-fold in the pancreatic juice, in normal and transgenic mice. These data indicate that MT is released from pancreatic acinar cells but not by the classical vesicular secretory pathway. In addition, MT levels in pancreatic juice are regulated by zinc, suggesting a physiological role of the pancreas in metal homeostasis.

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