• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.47-47
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• 2001

Opening of $Ca^{2＋}$ -channels represents the final common pathway for insulin secretion in pancreatic beta-cells and related cell lines. We investigated voltage-sensitive calcium channels (VSCCs) and insulin secretion in RINm5F, an insulinoma cell line derived from rat pancreatic beta-cells. Several types of VSCCs were identified in RINm5f cells： dihydropyridine-sensitive L-type, $\omega$-conotoxin GVIA-sensitive N-type, $\omega$-agatoxin IVA-sensitive P-type channels, and $\omega$-conotoxin MVIIC sensitive Q-type channels.(omitted)

• Korean Journal of Pharmacognosy
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• v.39 no.4
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• pp.335-340
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• 2008

Diabetes mellitus is metabolic disorder characterized by hyperglycemia caused by insufficient insulin secretion or insulin receptor insensitivity to endogenous insulin. It is well-known that hyperglycemia is one of the main causes of oxidative stress in both type 1 and 2 diabetes. Oxidative stress is related by death of pancreatic ${\beta}$ cell and dysfunction of ${\beta}$ cell. Although ${\beta}$ cell death or dysfunction is induced by many substances or molecules, increased evidences that oxidative stress plays a crucial role in ${\beta}$ cell death or dysfunction. Considering the importance of oxidative stress in the pathogenesis of diabetes mellitus, we investigated the cytoprotective effects against hydrogen peroxide-induced oxidative stress in pancreatic ${\beta}$ cell line RIN-m5F cell. 110 Plant sources were collected in Mt. Baek-du, and extracted with methanol. These extracts had been screened the protective effects against hydrogen peroxide-induced oxidative damage in RIN-m5F cells at 50 and 200 ${\mu}g$/ml. Of these, ten methanolic extracts, aerial part of Erigenron cannadensis, aerial part of Lespedeza juncea, whole plant of Alopecurus aequalis, fruit of Lycium chinense, leaf of Morus alba, rhizome of Polygonatum odoratum, root of Ampelosis japonica, whole plant of Ranunculus japonicus, aerial part of Polygonum sieboldii, rhizome of Arisaema amurense var. violaceum showed significant protective effects against hydrogen peroxide-induced oxidative damage in pancreatic ${\beta}$ cell line RIN-m5F cell.

• BMB Reports
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• v.45 no.1
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• pp.51-56
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• 2012

The purpose of this study was to determine the effects of duration and timing of glucocorticoid treatment on the expansion and differentiation of porcine neonatal pancreas cell clusters (NPCCs) into ${\beta}$-cells. After transplantation of NPCCs, the ductal cyst area and ${\beta}$-cell mass in the grafts both showed positive and negative correlations with duration of dexamethasone (Dx) treatment. Pdx-1 and HNF-3${\beta}$ gene expression was significantly downregulated following Dx treatment, whereas PGC-1${\alpha}$ expression increased. Pancreatic duct cell apoptosis significantly increased following Dx treatment, whereas proliferation did not change. Altogether, transdifferentiation of porcine NPCCs into ${\beta}$-cells was influenced by the duration of Dx treatment, which might have been due to the suppression of key pancreatic transcription factors. PGC-1${\alpha}$ plays an important role in the expansion and transdifferentiation of porcine NPCCs, and the initial 2 weeks following transplantation of porcine NPCCs is a critical period in determining the final ${\beta}$-cell mass in grafts.

• BMB Reports
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• v.40 no.6
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• pp.1058-1068
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• 2007

The post-translational modifications of Ser and Thr residues by O-linked $\beta$-N-acetylglucosamine (O-GlcNAc), i.e., O-GlcNAcylation, is considered a key means of regulating signaling, in a manner analogous to protein phosphorylation. Furthermore, it has been suggested that the increased flux of glucose through the hexosamine biosynthetic pathway (HBP) stimulates O-GlcNAcylation, and that this may be responsible for many of the manifestations of type 2 diabetes mellitus. To determine whether excessive O-GlcNAcylation of target proteins results in pancreatic $\beta$ cell dysfunction, we increased nucleocytoplasmic protein O-GlcNAcylation levels in $\beta$ cells by exposing them to streptozotocin and/or glucosamine. Streptozotocin and glucosamine co-treatment increased O-GlcNAcylated proteomic patterns as assessed by immunoblotting, and these increases in nuclear and cytoplasmic protein O-GlcNAcylations were accompanied by impaired insulin secretion and enhanced apoptosis in pancreatic $\beta$ cells. This observed $\beta$cell dysfunction prompted us to examine Akt and Bcl-2 family member proteins to determine which proteins are O-GlcNAcylated under conditions of high HBP throughput, and how these proteins are associated with $\beta$ cell apoptosis. Eventually, we identified ten new O-GlcNAcylated proteins that were expressed during $\beta$ cell apoptosis, and analyzed the functional implications of these proteins in relation to pancreatic $\beta$ cell dysfunction.

• BMB Reports
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• v.51 no.10
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• pp.538-543
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• 2018

Pancreatic beta cell destruction and dysfunction induced by cytokines is a major cause of type 1 diabetes. Paraoxonase 1 (PON1), an arylesterase with antioxidant activity, has been shown to play an important role in preventing the development of diabetes in transgenic mice. However, no studies have examined the anti-diabetic effect of PON1 delivered to beta cells using protein transduction. In this study, we expressed the cell-permeable PON1 fused with PEP-1 protein transduction domain (PEP-1-PON1) to investigate whether transduced PEP-1-PON1 protects beta cells against cytokine-induced cytotoxicity. PEP-1-PON1 was effectively delivered to INS-1 cells and prevented cytokine-induced cell destruction in a dose-dependent manner. Transduced PEP-1-PON1 significantly reduced the levels of reactive oxygen species (ROS) and nitric oxide (NO), DNA fragmentation, and expression of inflammatory mediators, endoplasmic reticulum (ER) stress proteins, and apoptosis-related proteins in cytokine-treated cells. Moreover, transduced PEP-1-PON1 restored the decrease in basal and glucose-stimulated insulin secretion induced by cytokines. These data indicate that PEP-1-PON1 protects beta cells from cytokine-induced cytotoxicity by alleviating oxidative/nitrosative stress, ER stress, and inflammation. Thus, PEP-1-mediated PON1 transduction might be an effective method to reduce the extent of destruction and dysfunction of pancreatic beta cells in autoimmune diabetes.

• 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 the Korean Society of Food Science and Nutrition
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• v.21 no.2
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• pp.117-123
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• 1992

The present study was undertaken in order to elucidate the effects of pretreatment with nicotinamide on changes in serum glucose level, body weight, water consumption, serum insulin concentration, and the activity of pancreatic enzyme in rats treated with streptozotocin (STZ). Histological studies were also carried out to evaluate the effects on pancreatic tissues and Langerhans's islet cells. Nicotinamide pretreatment in STZ diabetic rats inhibited the rise of fasting serum glucose concentration and water consumption. Pretreatment with nicotinamide significantly increased the concentration of serum insulin and body weight changes compared to the STZ-treated group. Pancreatic lipase and trypsin activities were increased, but amylase activity was decreased and pancreatic $\beta$ -cell was destroyed by STZ. Pvetreatment with nicotinamide prevented these STZ-induced changes. These results suggest that nicotinamide pretreatment supresses STZ-induced changes in pancreatic enzymes by preventing $\beta$-cell destruction and therefore maintaining a normal serum insulin revel.

• Molecules and Cells
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• v.40 no.7
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• pp.457-465
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• 2017

Streptozotocin (STZ)-induced murine models of type 1 diabetes have been used to examine ER stress during pancreatic ${\beta}$-cell apoptosis, as this ER stress plays important roles in the pathogenesis and development of the disease. However, the mechanisms linking type 1 diabetes to the ER stress-modulating anti-diabetic signaling pathway remain to be addressed, though it was recently established that ERK5 (Extracellular-signal-regulated kinase 5) contributes to the pathogeneses of diabetic complications. This study was undertaken to explore the mechanism whereby ERK5 inhibition instigates pancreatic ${\beta}$-cell apoptosis via an ER stress-dependent signaling pathway. STZ-induced diabetic WT and CHOP deficient mice were i.p. injected every 2 days for 6 days under BIX02189 (a specific ERK5 inhibitor) treatment in order to evaluate the role of ERK5. Hyperglycemia was exacerbated by co-treating C57BL/6J mice with STZ and BIX02189 as compared with mice administered with STZ alone. In addition, immunoblotting data revealed that ERK5 inhibition activated the unfolded protein response pathway accompanying apoptotic events, such as, PARP-1 and caspase-3 cleavage. Interestingly, ERK5 inhibition-induced exacerbation of pancreatic ${\beta}$-cell apoptosis was inhibited in CHOP deficient mice. Moreover, transduction of adenovirus encoding an active mutant form of $MEK5{\alpha}$, an upstream kinase of ERK5, inhibited STZ-induced unfolded protein responses and ${\beta}$-cell apoptosis. These results suggest that ERK5 protects against STZ-induced pancreatic ${\beta}$-cell apoptosis and hyperglycemia by interrupting the ER stress-mediated apoptotic pathway.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.1
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• pp.51-55
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• 2004

Sopungsungi-won has been used as a traditional medicine for diabetes and it has been proved to be a potential remedy for type 2 diabetes mellitus. We previously reported that water extract of Sopungsungi-won exhibits anti-diabetic effects both in vivo and in vitro experiments. In the present study, we have chosen to examined anti-apoptotic effect of Rheum undulatum, which is the main component of Sopungsungi-won, on pancreatic ${\beta}-cells$, HIT-T15, against hydrogen peroxide $(H_2O_2)$. oxidative stress. To investigate the anti-apoptotic effect of Rheum undulatum water extract (RUWE) against $H_2O_2-induced$ apoptosis in pancreatic ${\beta}-cell$ line of hamster, HIT-T15, MTT assay, DAPI staining, TUNEL assay, RT-PCR and caspase-3 enzyme assay were performed. The morphological analysis demonstrated that cells treated with $H_2O_2$ exhibited classical apoptotic features, while such changes was reduced in cells pre-treated with RUWE. In addition, RUWE pre-treated cells prior to $H_2O_2$ treatment induced increase of levels of bcl-2 expression and decrease of caspase-3 enzyme activity compared to cells treated with $H_2O_2$ only. These results provide the possibility of usage of RU in patients with progressively deteriorated diabetes.

• Molecules and Cells
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• v.25 no.1
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• pp.105-111
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• 2008

Radiotherapy is an important treatment for many malignant tumors, but there are recent reports that radiation may increase the malignancy of cancer cells by stimulating expression of type IV collagenases. In this study, we examined changes in matrix metalloproteinase (MMP) inhibitors, such as the tissue inhibitors of metalloproteinase (TIMP)-1, TIMP-2 and RECK, in response to irradiation in Panc-1 pancreatic cancer cells. Irradiation increased RECK protein levels but not mRNA levels, whereas no significant changes were found in TIMP-1 and TIMP-2. The enhanced RECK protein levels were associated with an increase in MMP inhibitory activity. However, irradiation slightly but reproducibly increased the invasiveness of the Panc-1 cells. Like irradiation, treatment of Panc-1 cells with transforming growth factor $(TGF)-{\beta}1$ led to a 2-fold increase in RECK protein levels. Transient transfection with Smad3 also increased RECK protein levels, but transfection with Smad7 markedly reduced them. Stable expression of Smad7 and treatment with SB431542, an inhibitor of $TGF-{\beta}$ receptor I kinase, abolished $TGF-{\beta}1$- and radiation-mediated effects on RECK. Furthermore, irradiation increased levels of phosphorylated Smad3. We conclude that radiation post-transciptionally enhances RECK protein levels in Panc-1 cells, at least in part, via $TGF-{\beta}$ signaling, and that irradiation increases Panc-1 invasiveness via a mechanism that may not be linked to MMP-2 activity.