Combined Expression of Pancreatic Duodenal Homeobox 1 and Islet Factor 1 Induces Immature Enterocytes to Produce Insulin
- Hideto Kojima1,
- Takaaki Nakamura2,
- Yukihiro Fujita1,
- Akio Kishi1,
- Mineko Fujimiya2,
- Syu Yamada1,
- Motoi Kudo2,
- Yoshihiko Nishio1,
- Hiroshi Maegawa1,
- Masakazu Haneda1,
- Hitoshi Yasuda1,
- Itaru Kojima3,
- Masaharu Seno4,
- Norman C.W. Wong5,
- Ryuichi Kikkawa1 and
- Atsunori Kashiwagi1
- 1Third Department of Medicine, Shiga University of Medical Science, Shiga, Japan
- 2Department of Anatomy, Shiga University of Medical Science, Shiga, Japan
- 3Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- 4Department of Bioscience and Biotechnology, Faculty of Engineering, Okayama University, Okayama, Japan
- 5Departments 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
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Address correspondence and reprint requests to Atsunori Kashiwagi, MD, PhD, Third Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Otsu, Shiga 520-2192, Japan. E-mail: kasiwagi{at}belle.shiga-med.ac.jp.
Received for publication 11 May 2001 and accepted in revised form 14 January 2002.
H.K. and T.N. contributed equally to this work.
BYK cell, YK cells treated with betacellulin; Cdx-2, caudal-related homeodomain protein 2; DMEM, Dulbecco’s modified Eagle’s medium; FBS, fetal bovine serum; GK, glucokinase; HNF, hepatocyte nuclear factor; Isl-1, islet factor 1; Isl-YK cells, YK cells transfected with Isl-1; Ngn-3, neurogenin 3; PBST, PBS containing 0.3% Triton X; Pdx-1, pancreatic duodenal homeobox 1; RIA, radioimmunoassay; STZ, streptozotocin.
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