Combined Expression of Pancreatic Duodenal Homeobox 1 and Islet Factor 1 Induces Immature Enterocytes to Produce Insulin

Combined Expression of Pancreatic Duodenal Homeobox 1 and Islet Factor 1 Induces Immature Enterocytes to Produce Insulin Hideto Kojima 1 , Takaaki Nakamura 2 , Yukihiro Fujita 1 , Akio Kishi 1 , Mineko Fujimiya 2 , Syu Yamada 1 , Motoi Kudo 2 , Yoshihiko Nishio 1 , Hiroshi Maegawa 1 , Masakazu Haneda 1 , Hitoshi Yasuda 1 , Itaru Kojima 3 , Masaharu Seno 4 , Norman C.W. Wong 5 , Ryuichi Kikkawa 1 and Atsunori Kashiwagi 1 1 Third Department of Medicine, Shiga University of Medical Science, Shiga, Japan 2 Department of Anatomy, Shiga University of Medical Science, Shiga, Japan 3 Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan 4 Department of Bioscience and Biotechnology, Faculty of Engineering, Okayama University, Okayama, Japan 5 Departments of Medicine and Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada Abstract Immature rat intestinal stem cells (IEC-6) given the ability to express the transcription factor, pancreatic duodenal homeobox 1 (Pdx-1), yielded YK cells. Although these cells produced multiple enteroendocrine hormones, they did not produce insulin. Exposure of YK cells to 2 nmol/l betacellulin yielded BYK cells that showed the presence of insulin expression in cytoplasm and that secreted insulin into culture media. By examining the mechanism of differentiation in BYK cells, we found that another transcription factor, islet factor 1 (Isl-1) was newly expressed with the disappearance of Pax-6 expression in those cells after exposure to betacellulin. These results indicated that combined expression of Pdx-1 and Isl-1 in IEC-6 cells was required for the production of insulin. In fact, overexpression of both Pdx-1 and Isl-1 in IEC-6 cells (Isl-YK-12, -14, and -15 cells) gave them the ability to express insulin without exposure to betacellulin. Furthermore, implantation of the Isl-YK-14 cells into diabetic rats reduced the animals’ plasma glucose levels; glucose levels dropped from 19.4 to 16.9 mmol/l 1 day after the injection of cells. As expected, the plasma insulin concentrations were 2.7 times higher in the diabetic rats injected with Isl-YK-14 cells compared to in controls. In summary, our results indicated that immature intestinal stem cells can differentiate into insulin-producing cells given the ability to express the transcription factors Pdx-1 and Isl-1. Footnotes Address correspondence and reprint requests to Atsunori Kashiwagi, MD, PhD, Third Department of Medicine, Shiga U