Diabetes & Metabolism Journal

Original Articles

Protective Effects of Glucagon Like Peptide-1 on HIT-T15 beta Cell Apoptosis via ER Stress Induced by 2-deoxy-D-glucose.: Ju Young Kim, Seong Kyu Lee, Haing Woon Baik, Ki Ho Lee, Hyun Jin Kim, Kang Seo Park, Byung Joon Kim; Korean Diabetes J. 2008;32(6):477-487. Published online December 1, 2008; DOI: https://doi.org/10.4093/kdj.2008.32.6.477

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BACKGROUND
The characteristic feature of pancreatic beta cells is highly developed endoplasmic reticulum (ER) due to a heavy engagement in insulin secretion. The ER serves several important function, including post-translational modification, folding, and assembly of newly synthesized secretory proteins, and its proper function is essential to cell survival. Various stress conditions can interfere with ER function. Pancreatic beta cells may be particularly vulnerable to ER stress that causes to impair insulin biosynthesis and beta cell survival through apoptosis. Glucagon like peptide-1 (GLP-1) is a new drug for treatment of type 2 diabetes and has effects on stimulation of insulin secretion and beta cell preservation. Also, it may have an antiapoptotic effect on beta cells, but detailed mechanisms are not proven. Therefore, we investigated the protective mechanism of GLP-1 in beta cells through ER stress response induced by 2-deoxy-D-glucose (2DG). METHODS: For induction of the ER stress, HIT-T15 cells (hamster beta cell line) were treated with 2DG (10 mM). Apoptosis was evaluated with MTT assay, hoechst 33342 staining and Annexin/PI flow cytometry. Expression of ER stress-related molecules was determined by real-time PCR or western blot. For blocking ER stress, we pretreated HIT-T15 cells with exendin-4 (Ex-4; GLP-1 receptor agonist) for 1 hour before stress induction. RESULTS: After induction with ER stress (2DG), beta cells were lost by apoptosis. We found that Ex-4 had a protective effect through ER stress related molecules (GRP78, GRP94, XBP-1, eIF2alpha, CHOP) modulation. Also, Ex-4 recovered the expression of insulin2 mRNA in beta cells. CONCLUSION: These results suggest that GLP-1 may protect beta cells apoptosis through ER stress modulation.

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Exendin-4 Protects Against Sulfonylurea-Induced β-Cell Apoptosis
Ju-Young Kim, Dong-Mee Lim, Hyung-Seo Park, Chan-Il Moon, Kyung-Jin Choi, Seong-Kyu Lee, Haing-Woon Baik, Keun-Young Park, Byung-Joon Kim
Journal of Pharmacological Sciences.2012; 118(1): 65. CrossRef
GLP-1 Can Protect Proinflammatory Cytokines Induced Beta Cell Apoptosis through the Ubiquitination
Dong Mee Lim, Ju Young Kim, Kang Woo Lee, Keun Young Park, Byung Joon Kim
Endocrinology and Metabolism.2011; 26(2): 142. CrossRef
Exendin-4 Protects Oxidative Stress-Induced β-Cell Apoptosis through Reduced JNK and GSK3β Activity
Ju-Young Kim, Dong-Mee Lim, Chan Il Moon, Kyung-Jin Jo, Seong-Kyu Lee, Haing-Woon Baik, Ki-Ho Lee, Kang-Woo Lee, Keun-Young Park, Byung-Joon Kim
Journal of Korean Medical Science.2010; 25(11): 1626. CrossRef

PDX-1/VP16 Overexpression Induce the Transdifferentiation of Canine Adult Pancreatic Cells into Beta-cells.: Young Hye You, Sun Cheol Park, Seung Hwan Lee, Heon Seok Park, Dong Sik Ham, Marie Rhee, Ji Won Kim, Ki Ho Song, Kun Ho Yoon; Korean Diabetes J. 2007;31(1):51-62. Published online January 1, 2007; DOI: https://doi.org/10.4093/jkda.2007.31.1.51

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Abstract PDF

BACKGROUND
A major obstacle of islet transplantation is an inadequate supply of insulin-producing tissue. Ad-PDX-1/VP16 overexpression and Exendin-4 treatment have been proved the effects on differentiation and proliferation of pancreatic stem cells. But, the study is insufficient using adult animal pancreatic stem cells. METHODS: Pancreatic cells were prepared from the non-endocrine fraction of canine pancreases. This cells were cultivated free floating state and monolayer culture after dispersion. The floating pancreatic cells were transplanted under the kidney capsule of normoglycaemic nude mice. The dispersed pancreatic cells were infected with Ad-PDX-1/VP16 or Ad-GFP. After infection, those cells were transplanted of nude mice. After transplantation, mice were treated with either 1 nmol/kg exendin-4 or saline solution by intraperitoneal injection for 10 days. RESULTS: The relative volume of the beta-cells in the grafts of the free floating cultured pancreatic cells were 23.4 +/- 13.1% at two weeks and 5.2 +/- 2.0% at eight weeks. At two weeks after transplantation, the relative volume of insulin-positive cells in the grafts of dispersed pancreatic cells were 28 +/- 5.7%, 20.5 +/- 0.7% and 31 +/- 1.4% in control, GFP and PDX-1/VP16 treated groups respectively. At eight weeks after transplantation, the relative volume of insulin-positive cells in the grafts were 11.8 +/- 5.9%, 8 +/- 7.3% and 16.6 +/- 7.4% in control, GFP and PDX-1/VP16 treated groups respectively. Exendin-4 treatment didn't show any additive effects on transdifferentiation of pancreas stem cell into beta-cells. CONCLUSION: The expansion and transdifferentiation were not observed after the transplantation of the free floating cultured pancreatic cells. PDX-1/VP16 overexpression induces the transdifferentiation of adult pancreatic cells into beta-cells. However Exendin-4 treatment hasn't any effects on the expansion and transdifferentiation of the cells in the grafts.

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Generation of Functional Insulin-Producing Cells from Neonatal Porcine Liver-Derived Cells by PDX1/VP16, BETA2/NeuroD and MafA
Dong-Sik Ham, Juyoung Shin, Ji-Won Kim, Heon-Seok Park, Jae-Hyoung Cho, Kun-Ho Yoon, Kathrin Maedler
PLoS ONE.2013; 8(11): e79076. CrossRef
Adenoviruses Expressing PDX-1, BETA2/NeuroD and MafA Induces the Transdifferentiation of Porcine Neonatal Pancreas Cell Clusters and Adult Pig Pancreatic Cells into Beta-Cells
Young-Hye You, Dong-Sik Ham, Heon-Seok Park, Marie Rhee, Ji-Won Kim, Kun-Ho Yoon
Diabetes & Metabolism Journal.2011; 35(2): 119. CrossRef
Transdifferentiation of Enteroendocrine K-cells into Insulin-expressing Cells
Esder Lee, Jun Mo Yu, Min Kyung Lee, Gyeong Ryul Ryu, Seung-Hyun Ko, Yu-Bae Ahn, Sung-Dae Moon, Ki-Ho Song
Korean Diabetes Journal.2009; 33(6): 475. CrossRef

The Role of cAMP/PKA Activation on Exendin-4-Induced Cyclin D1 Expression in INS-1 Cell.: Gyeong Ryul Ryu, Jung Hoon Kang, Hwa In Jang, Seung Hyun Ko, In Kyung Jeong, Duck Joo Rhie, Shin Hee Yoon, Sang June Hahn, Yang Hyeok Jo, Myung Suk Kim, Myung Jun Kim; Korean Diabetes J. 2005;29(4):295-303. Published online July 1, 2005

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Abstract PDF: BACKGROUND
Glucagon-like peptide-1(GLP-1) and exendin-4(EX-4) have been known to induce pancreatic islet proliferation and increases in the betacell mass. Cyclin D1 is a key protein responsible for the entry of the G into the S phase, thereby contributing to cell proliferation. Therefore, the effect of EX-4 on the expression of cyclin D1 in INS-1 cells, a rat pancreatic betacell line, was investigated. The involvement of either mitogen-activated protein kinases(MAPKs) or cyclic adenosine 5'-monophosphate/protein kinase A(cAMP/ PKA) in the EX-4-induced cyclin D1 expression was also examined. METHODS: INS-1 cells were treated with EX-4 (10 nM), and the cyclin D1 protein levels then determined by Western blot. To investigate the involvement of MAPKs in the EX-4- induced cyclin D1 expression, either a combined treatment of MAPKs inhibitors or transient transfection of extracellular signal-regulated kinase-1 (ERK1) was performed. The effect of cAMP on the EX-4-induced cyclin D1 expression was also examined by treatments with forskolin, an adenylyl cyclase activator, and H-89, a PKA inhibitor. RESULTS: EX-4 increased the expression of cyclin D1 protein in a dose-dependent manner. Although EX-4 induced phosphorylation of ERK1/2, the treatment with PD 98059 or the overexpression of ERK1 had no effect on the EX-4-induced cyclin D1 expression. However, forskolin significantly induced the expression of cyclin D1, whereas the pretreatment of H-89 inhibited the EX-4-induced cyclin D1 expression. CONCLUSION: These results suggest that EX-4 induce cyclin D1 expression in INS-1 cells via cAMP/PKA pathway, but this is not due to ERK activation.

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