Diabetes & Metabolism Journal

Original Articles

Activin A Converts Pancreatic Ductal Cells into Insulin-Secreting Cells.: Kyoung Hee Lee, Mi Kyung Park, Han Wook Kang, Hyun Jin Kim, In Kyung Jeong, Hyung Joon Yoo, Jae Hoon Jeong, Yong Ki Min, Myung Shik Lee, Kwang Won Kim, Moon Kyu Lee; Korean Diabetes J. 2004;28(1):20-27. Published online February 1, 2004

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Abstract PDF: BACKGROUND
Islet transplantation as a potential treatment for diabetes has been investigated extensively over the past years. One of the major limitations to successful islet transplantation is shortage of insulin-producing tissue, which has stimulated the search for alternative sources, and recently, attention has been focused on the possible use of controlled differentiation of stem cells to obtain specialized cells useful in treating many diseases. It is currently believed that pancreatic progenitor or stem cells exist in the ductal cell population. Activin A is a member of the TGFbeta superfamily, which can block the exocrine pancreatic development and potentiate the endocrine development of the pancreas. In this study, whether activin A could expand and/or differentiate the ductal cells into insulin-producing cells was examined. METHODS: From a collagenase P digested pancreas, ductal tissue was cultured under conditions that allowed expansion as a monolayer, where the cells were overlaid with a rat tail collagen I-coated dish. Activin A cDNA was transfected into rat ductal cells by using Lipofectamine, and the insulin secretion, content and differentiation markers examined. RESULT: The clumps of ductal tissue adhered to the dish 24 hr later, and formed a complete monolayer after 3 days of culture. Activin A overexpression significantly increased both the insulin secretion and content from the ductal cells. The glucose(16.7mM)-induced insulin secretion was also significantly increased. Immunohistochemistry and RT-PCR analyses revealed expression of PDX-1, as well as insulin & GLUT2. CONCLUSION: Activin A overexpression could potentiate the differentiation of pancreatic ductal cells, which might provide a potential new source of cinsulin- producing cells for transplantation

Development of Proinsulin-secreting Non-endocrine Cell.: Do Jun Yoon, Seok Hyun Kim, Jae Woo Kim, Yu Kyong Kim, Young Duk Song, Yong Ho Ahn; Korean Diabetes J. 1998;22(4):467-474. Published online January 1, 2001

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Abstract PDF: BACKGROUND
Recently, the advent of genetic engineering technics enabled. us to transfer foreign genes of interests into various cells and establish an "artificial b-cells" capable of secreting insulin in response to plasma glucose level. In this study, we have designed a study to establish an "artificial b-cells" by transfecting liver/pancreatic b-cell type glucose transporter 2(GLUT2) cDNA and genomic DNA of proinsulin into non-endocrine cell. Because GLUT2 molecules on the plasma membranes act as a sensor of glucose outside the cell and promote the secretion of proinsulin from the cells, cotransfection of GLUT2 cDNA along with insulin gene will translate the GLUT2 molecules necessary for glucose transport into the cells and hence leading to insulin secretion. METHODS: We have subcloned GLUT2 cDNA and proinsulin gene into separate eukaryotic expression vectors and transfected them to Chinese hamster ovary cells. The stable cell lines harboring GLUT2 cDNA and proinsulin gene were selected by G418, neomycin analogue. The surviving clones were harvested and subjected to Southem blot analysis by digesting the chromosomal DNA either with BamHI for insulin gene detection or Xho I/Sma I double digestion for GLUT2 gene detection. The amount of proinsulin secretion into the medium was measured by the insulin radioimmunoassay(DPC, Coat-A-Count insulin, LA, USA) which detected proinsulin with 40% cross-reactivity. RESULTS: 1) We were able to find out 3 clones positive for both GLUT2 gene and insulin gene. 2) Of these clones, clone 5 cells secreted proinsulin 3 times as much as that of the control CHO cells. CONCLUSION: There was some increase of proinsulin secretion in artificial g-cells compared to control cells. But this increased proinsulin secretion was not enough to be used as therapeutics. We need more expriments to find out more efficient way of proinsulin secretion and to identify the glucose-regulated insulin secretion in these artificial b-cells.

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