Conditional Gene Targeting in Mouse Pancreatic β-Cells

Analysis of Ectopic Cre Transgene Expression in the Brain

  1. Peter J. Dempsey3,4
  1. 1Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Chicago, Chicago, Illinois;
  2. 2Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee;
  3. 3Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan;
  4. 4Division of Gastroenterology, Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan;
  5. 5Program in Neuroscience, University of Michigan, Ann Arbor, Michigan;
  6. 6Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan;
  7. 7Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee;
  8. 8Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, Tennessee;
  9. 9Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee;
  10. 10Departments of Medicine, Cell and Developmental Biology, the State University of New York Upstate Medical University, Syracuse, New York; and the
  11. 11U.S. Department of Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee.
  1. Corresponding authors: Barton Wicksteed, wicksteed{at}uchicago.edu; Alvin C. Powers, al.powers{at}vanderbilt.edu; and Peter J. Dempsey, petedemp{at}med.umich.edu.
  1. B.W. and M.B. contributed equally to this article.

Abstract

OBJECTIVE Conditional gene targeting has been extensively used for in vivo analysis of gene function in β-cell biology. The objective of this study was to examine whether mouse transgenic Cre lines, used to mediate β-cell– or pancreas-specific recombination, also drive Cre expression in the brain.

RESEARCH DESIGN AND METHODS Transgenic Cre lines driven by Ins1, Ins2, and Pdx1 promoters were bred to R26R reporter strains. Cre activity was assessed by β-galactosidase or yellow fluorescent protein expression in the pancreas and the brain. Endogenous Pdx1 gene expression was monitored using Pdx1tm1Cvw lacZ knock-in mice. Cre expression in β-cells and co-localization of Cre activity with orexin-expressing and leptin-responsive neurons within the brain was assessed by immunohistochemistry.

RESULTS All transgenic Cre lines examined that used the Ins2 promoter to drive Cre expression showed widespread Cre activity in the brain, whereas Cre lines that used Pdx1 promoter fragments showed more restricted Cre activity primarily within the hypothalamus. Immunohistochemical analysis of the hypothalamus from Tg(Pdx1-cre)89.1Dam mice revealed Cre activity in neurons expressing orexin and in neurons activated by leptin. Tg(Ins1-Cre/ERT)1Lphi mice were the only line that lacked Cre activity in the brain.

CONCLUSIONS Cre-mediated gene manipulation using transgenic lines that express Cre under the control of the Ins2 and Pdx1 promoters are likely to alter gene expression in nutrient-sensing neurons. Therefore, data arising from the use of these transgenic Cre lines must be interpreted carefully to assess whether the resultant phenotype is solely attributable to alterations in the islet β-cells.

Footnotes

  • The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

  • See accompanying commentary, p. 2991.

  • Received April 30, 2010.
  • Accepted August 21, 2010.

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  1. Diabetes vol. 59 no. 12 3090-3098
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