• The Korean Journal of Physiology and Pharmacology
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• v.15 no.6
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• pp.383-388
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• 2011

Regulators of G-protein signaling (RGS) proteins are regulators of $Ca^{2+}$ signaling that accelerate the GTPase activity of the G-protein ${\alpha}$ -subunit. RGS1, RGS2, RGS4, and RGS16 are expressed in the pancreas, and RGS2 regulates G-protein coupled receptor (GPCR)-induced $Ca^{2+}$ oscillations. However, the role of RGS4 in $Ca^{2+}$ signaling in pancreatic acinar cells is unknown. In this study, we investigated the mechanism of GPCR-induced $Ca^{2+}$ signaling in pancreatic acinar cells derived from $RGS4^{-/-}$ mice. $RGS4^{-/-}$ acinar cells showed an enhanced stimulus intensity response to a muscarinic receptor agonist in pancreatic acinar cells. Moreover, deletion of RGS4 increased the frequency of $Ca^{2+}$ oscillations. $RGS4^{-/-}$ cells also showed increased expression of sarco/endoplasmic reticulum $Ca^{2+}$ ATPase type 2. However, there were no significant alterations, such as $Ca^{2+}$ signaling in treated high dose of agonist and its related amylase secretion activity, in acinar cells from $RGS4^{-/-}$ mice. These results indicate that RGS4 protein regulates $Ca^{2+}$ signaling in mouse pancreatic acinar cells.

• International Journal of Oral Biology
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• v.37 no.1
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• pp.37-41
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• 2012

Pancreatic acinar cells exhibit a polarity that is characterized by the localization of secretory granules at the apical membrane. However, the factors that regulate cellular polarity in these cells are not well understood. In this study, we investigated the effect of Mist1, a basic helix-loop-helix transcription factor, on the cellular architecture of pancreatic acinar cells. Mist1-null mice displayed secretory granules that were diffuse throughout the pancreatic acinar cells, from the apical to basolateral membranes, whereas Mist1 heterozygote mice showed apical localization of secretory granules. Deletion of the Mist1 gene decreased the expression of type 3 inositol 1,4,5-triphosphate receptors ($IP_3R$) but did not affect apical localization and expression of $IP_3R2$. Mist1-null mice also displayed an increase in luminal areas and an increase in the expression of zymogen granules in pancreatic acinar cells. These results suggest that Mist1 plays a critical role in polar localization of cellular organelles and in maintaining cellular architecture in mouse pancreatic acinar cells.

• Applied Microscopy
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• v.18 no.2
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• pp.34-46
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• 1988

The stimulation-secretion coupling in the pancreatic acinar cell have been studied by electron microscope. Morphological changes in the cells exhibited the cellular response induced by acetylcholine and MNNG. MNNG, a guanylate cyclase activator, induced the formation of numerous secretory granules in a period after the agent administration. This result suggest that guanylate cyclase potentiated the early sustained response in pancreatic acinar cells stimulated by acetylcholine. Cycloheximide and dibucaine reduced the secretory granules in number during sustained period. In pancreatic acinar cells, the secretion granules were considered to be directly packaged from cisternal space of endoplasmic reticulum.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.6
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• pp.409-416
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• 2009

Acute pancreatitis is a multifactorial disease associated with the premature activation of digestive enzymes. The genes expressed in pancreatic acinar cells determine the severity of the disease. The present study determined the differentially expressed genes in pancreatic acinar cells treated with cerulein as an in vitro model of acute pancreatitis. Pancreatic acinar AR42J cells were stimulated with $10^{-8}$ M cerulein for 4 h, and genes with altered expression were identified using a cDNA microarray for 4,000 rat genes and validated by real-time PCR. These genes showed a 2.5-fold or higher increase with cerulein: lithostatin, guanylate cyclase, myosin light chain kinase 2, cathepsin C, progestin-induced protein, and pancreatic trypsin 2. Stathin 1 and ribosomal protein S13 showed a 2.5-fold or higher decreases in expression. Real-time PCR analysis showed time-dependent alterations of these genes. Using commercially available antibodies specific for guanylate cyclase, myosin light chain kinase 2, and cathepsin C, a time-dependent increase in these proteins were observed by Western blotting. Thus, disturbances in proliferation, differentiation, cytoskeleton arrangement, enzyme activity, and secretion may be underlying mechanisms of acute pancreatitis.

• 대한약리학회:학술대회논문집
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• 2006.11a
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• pp.63-63
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• 2006

• International Journal of Oral Biology
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• v.46 no.3
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• pp.134-139
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• 2021

Under physiological conditions, calcium (Ca²⁺) regulates essential functions of polarized secretory cells by the stimulation of specific Ca²⁺ signaling mechanisms, such as increases in intracellular Ca²⁺ concentration ([Ca²⁺]_i) via the store-operated Ca²⁺ entry (SOCE) and the receptor-operated Ca²⁺ entry (ROCE). Homer proteins are scaffold proteins that interact with G protein-coupled receptors, inositol 1,4,5-triphosphate (IP₃) receptors, Orai1-stromal interaction molecule 1, and transient receptor potential canonical (TRPC) channels. However, their role in the Ca²⁺ signaling in exocrine cells remains unknown. In this study, we investigated the role of Homer2 in the Ca²⁺ signaling and regulatory channels to mediate SOCE and ROCE in pancreatic acinar cells. Deletion of Homer2 (Homer2^-/-) markedly increased the expression of TRPC3, TRPC6, and Orai1 in pancreatic acinar cells, whereas these expressions showed no difference in whole brains of wild-type and Homer2^-/- mice. Furthermore, the response of Ca²⁺ entry by carbachol also showed significant changes to the patterns regulated by specific blockers of SOCE and ROCE in pancreatic acinar cells of Homer2^-/- mice. Thus, these results suggest that Homer2 plays a critical role in the regulatory action of the [Ca²⁺]_i via SOCE and ROCE in mouse pancreatic acinar cells.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.657-663
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• 1998

The enzyme responsible for the synthesis of nitric oxide (NO) from L-arginine in mammalian tissues is known as nitric oxide synthase (NOS) (EC.1.14.13.39). In the present study, the role of NO in the regulation of exocrine secretion was investigated in rat pancreatic acinar cells. Treatment of rat pancreatic acinar cells with cholecystokinin-octapeptide (CCK-OP) resulted in an increase in the arginine conversion to citrulline, the amount of $NO_X$, the release of amylase, and the level of CGMP. Especially, CCK-OP-stimulated increase of arginine to citrulline transformation, the amount of $NO_X$, and CGMP level were completely counteracted by the inhibitor of NOS, NG-monomethyl-L-arginine (MMA), by contrast, that of amylase release was partially reduced. Furthermore, MMA-induced decrease of NOS activity and amylase release showed dose-dependent pattern. The data on the time course of CCK-OP-induced citrulline formation and CGMP rise indicate that NOS and guanylate cyclase were activated by treatment of CCK-OP. However, the mechanism of agonist-stimulated guanylate cyclase activation in acinar cells remains unknown. Therefore, activation of NOS is one of the early events in receptor-mediated cascade of reactions in pancreatic acinar cells and NO, not completely, but partially mediate pancreatic enzyme exocrine secretion.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.5
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• pp.521-528
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• 1999

Reactive oxygen species (ROS), generated by infiltrating neutrophils, are considered as an important regulator in the pathogenesis and deveolpment of pancreatitis. The present study aims to investigate whether neutrophils primed by $4{\beta}-phorbol\;12{\beta}-myristate\;13{\alpha}-acetate$ (PMA) affect the productions $H_2O_2$ and lipid peroxide (LPO), $NF-_{\kappa}B$ activation and cytokine production in pancreatic acinar cells, and whether these alterations were inhibited by an antioxidant, N-acetylcysteine (NAC) and superoxide dismutase (SOD). $H_2O_2$ (ferrithiocyanate method), LPO (as thiobarbiturate reactive substances), and cytokines $(IL-l{\bata},\; IL-6,\;TNF-{\alpha};\;enzyme-linked\;immunosorbent\;assay)$ and $NF-_{\kappa}B$ activation (electrophoretic mobility shift assay) were analyzed in acinar cells treated with or without PMA-primed neutrophils in the absence or presence of NAC (10 mM) or SOD (300 U/ml). As a result, the productions of H2O2, LPO and $TNF-{\alpha}$ were increased with the ratio of PMA-primed neutrophils to acinar cells while the productions of LPO, $IL-l{\beta},\;IL-6\;and\;TNF-{\alpha}$ were increased with time. PMA-primed neutrophils resulted in the activation of $NF-_{\kappa}B.$ Both NAC and SOD inhibited neutrophil-induced alterations in acinar cells. In conclusion, ROS, generated by neutrophils, activates $NF-_{\kappa}B,$ resulting in upregulation of inflammatary cytokines in acinar cells. Antioxidants might be clinically useful antiinflammatory agents by inhibiting oxidant-mediated activation of $NF-_{\kappa}B$ and decreasing cytokine production.

• Journal of Life Science
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• v.23 no.11
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• pp.1404-1408
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• 2013

(-)-Epigallocatechin-3-gallate (EGCG), a green tea polyphenol, has been shown to have strong antibacterial, antiviral, antioxidant, anti-inflammatory, and chemopreventive effects. However it is unknown whether EGCG can recover alcohol-associated pancreatitis. The aim of this study was to investigate the effects of EGCG on pancreatic enzyme activities and the expressions of pancreatic regenerating related markers, such as adenosine monophosphate-activated protein kinase (AMPK), raf-1 kinase inhibitor protein (RKIP), and Regenerating gene 1 (Reg1), in mice pancreatic primary acinar cells. Our results revealed that activities of ${\alpha}$-amylase and chymotrypsin were significantly increased in the cells treated with ethanol compared to the untreated control cells; however, the increased activities of both enzymes were markedly reduced by pretreatment with EGCG. Phosphorylation of AMPK and total expression of RKIP were decreased in the ethanol-treated primary acinar cells; however, these were both significantly increased in the EGCG-pretreated cells. In addition, when EGCG was treated, expression of Reg1 was markedly increased compared with that of the control or the ethanol-treated primary acinar cells, demonstrating that EGCG can modulate pancreatic regenerating related genes. Therefore, our findings suggest that EGCG may have therapeutic utility in the prevention or treatment of alcohol-associated pancreatitis.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.56-56
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• 2003

Isolated single pancreatic acinar cells have long been used as a good model for studying many kinds of signaling processes due to their good structural and functional polarities without a significant validation. In this study, we have examined morphological and functional changes of the dissociated single pancreatic acinar cells by imaging cytosolic Ca$\^$2+/ concentration, exocytosis of granules, and by observing their shapes with confocal microscopy.