Experimental control of pancreatic development and maintenance

To investigate the role of the HOX-like homeoprotein PDX1 in the formation and maintenance of the pancreas, we have genetically engineered mice so that the only source of PDX1 is a transgene that can be controlled by the application of tetracycline or its analogue doxycycline. In these mice the coding region for the tetracycline-regulated transactivator (tTAoff) has replaced the coding region of the endogenous Pdx1 gene to ensure correct temporal and spatial expression of the regulatable transactivator. In the absence of doxycycline, tTAoff activates the transcription of a bicistronic transgene encoding PDX1 and an enhanced green fluorescent protein reporter, which acts as a visual marker of transgene expression in living cells. Expression of the transgene-encoded PDX1 rescues the Pdx1-null phenotype; the pancreata of these mice develop and function normally. The rescue is conditional; doxycycline-mediated repression of the transgenic Pdx1 throughout gestation recapitulates the Pdx1 null phenotype. Moreover, application of doxycycline at mid-pancreogenesis blocks further development. Adult animals of the rescue genotype that were treated with doxycycline for 3 weeks shut off Pdx1 expression, decreased insulin production, and lost the ability to maintain glucose homeostasis. These results demonstrate the feasibility of controlling the formation of an organ during embryogenesis in utero and the maintenance of the mature organ through the experimental manipulation of a key developmental regulator.

[1]  Kathleen M. Scully,et al.  Pituitary Development: Regulatory Codes in Mammalian Organogenesis , 2002, Science.

[2]  V. Schwitzgebel.  Programming of the pancreas , 2001, Molecular and Cellular Endocrinology.

[3]  J. Habener,et al.  Development of diabetes mellitus in aging transgenic mice following suppression of pancreatic homeoprotein IDX-1. , 2001, The Journal of clinical investigation.

[4]  O. Madsen,et al.  Improved glucose tolerance and acinar dysmorphogenesis by targeted expression of transcription factor PDX-1 to the exocrine pancreas. , 2001, Diabetes.

[5]  R. Walther,et al.  The Tet-On system in transgenic mice: inhibition of the mouse pdx-1 gene activity by antisense RNA expression in pancreatic β-cells , 2001, Journal of Molecular Medicine.

[6]  Deepak Srivastava,et al.  A genetic blueprint for cardiac development , 2000, Nature.

[7]  P. Holland,et al.  Evidence for 14 homeobox gene clusters in human genome ancestry , 2000, Current Biology.

[8]  R. Bretzel,et al.  Pancreatic exocrine function in patients with type 1 and type 2 diabetes mellitus , 2000, Acta Diabetologica.

[9]  S. Tilghman,et al.  The temporal requirement for endothelin receptor-B signalling during neural crest development , 1999, Nature.

[10]  L. Larsson.  On the development of the Islets of Langerhans , 1998, Microscopy research and technique.

[11]  S. Rose,et al.  An Endocrine-Exocrine Switch in the Activity of the Pancreatic Homeodomain Protein PDX1 through Formation of a Trimeric Complex with PBX1b and MRG1 (MEIS2) , 1998, Molecular and Cellular Biology.

[12]  W. Garrard,et al.  A targeted kappa immunoglobulin gene containing a deletion of the nuclear matrix association region exhibits spontaneous hyper-recombination in pre-B cells. , 1998, Molecular immunology.

[13]  H. Edlund,et al.  beta-cell-specific inactivation of the mouse Ipf1/Pdx1 gene results in loss of the beta-cell phenotype and maturity onset diabetes. , 1998, Genes & development.

[14]  S. Bonner-Weir,et al.  Regulatory factor linked to late-onset diabetes? , 1998, Nature.

[15]  R. Hammer,et al.  Dual genetic pathways of endothelin-mediated intercellular signaling revealed by targeted disruption of endothelin converting enzyme-1 gene. , 1998, Development.

[16]  R. Stein,et al.  Hepatocyte nuclear factor 3beta is involved in pancreatic beta-cell-specific transcription of the pdx-1 gene , 1997, Molecular and cellular biology.

[17]  H. Edlund,et al.  The morphogenesis of the pancreatic mesenchyme is uncoupled from that of the pancreatic epithelium in IPF1/PDX1-deficient mice. , 1996, Development.

[18]  B. Hogan,et al.  PDX-1 is required for pancreatic outgrowth and differentiation of the rostral duodenum. , 1996, Development.

[19]  J. Slack.  Developmental biology of the pancreas. , 1995, Development.

[20]  R. Stein,et al.  Expression of murine STF-1, a putative insulin gene transcription factor, in beta cells of pancreas, duodenal epithelium and pancreatic exocrine and endocrine progenitors during ontogeny. , 1995, Development.

[21]  H. Edlund,et al.  Insulin-promoter-factor 1 is required for pancreas development in mice , 1994, Nature.

[22]  J. Habener,et al.  IDX‐1: a new homeodomain transcription factor expressed in rat pancreatic islets and duodenum that transactivates the somatostatin gene. , 1994, The EMBO journal.

[23]  H. Ohlsson,et al.  IPF1, a homeodomain‐containing transactivator of the insulin gene. , 1993, The EMBO journal.

[24]  J. Roder,et al.  Derivation of completely cell culture-derived mice from early-passage embryonic stem cells. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[25]  R. Hammer,et al.  Hypercholesterolemia in low density lipoprotein receptor knockout mice and its reversal by adenovirus-mediated gene delivery. , 1993, The Journal of clinical investigation.

[26]  S. Jang,et al.  Construction of a bifunctional mRNA in the mouse by using the internal ribosomal entry site of the encephalomyocarditis virus , 1992, Molecular and cellular biology.

[27]  M. Gossen,et al.  Tight control of gene expression in mammalian cells by tetracycline-responsive promoters. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[28]  J. Jami,et al.  Polyclonal origin of pancreatic islets in aggregation mouse chimaeras. , 1991, Development.

[29]  D. Andrews,et al.  Both the 5' untranslated region and the sequences surrounding the start site contribute to efficient initiation of translation in vitro , 1991, Molecular and cellular biology.

[30]  M. Meisler,et al.  Regulation of amylase gene expression in diabetic mice is mediated by a cis-acting upstream element close to the pancreas-specific enhancer. , 1990, Genes & development.

[31]  R. James,et al.  Bovine serum albumin density gradient isolation of rat pancreatic islets. , 1987, Transplantation.

[32]  M. Meisler,et al.  Tissue-specific and insulin-dependent expression of a pancreatic amylase gene in transgenic mice , 1987, Molecular and cellular biology.

[33]  J. Chirgwin,et al.  Isolation of RNA using guanidinium salts. , 1987, Methods in enzymology.

[34]  R. Palmiter,et al.  Factors affecting the efficiency of introducing foreign DNA into mice by microinjecting eggs. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[35]  R. Hammer,et al.  Tissue-specific expression of the rat pancreatic elastase I gene in transgenic mice , 1984, Cell.

[36]  W. Rutter,et al.  Pancreatic islet-acinar cell interaction: amylase messenger RNA levels ar determined by insulin. , 1981, Science.

[37]  R H Williams,et al.  An ultrastructural analysis of the developing embryonic pancreas. , 1972, Developmental biology.

[38]  N. K. Wessells,et al.  Early Pancreas Organogenesis: Morphogenesis, Tissue Interactions, and Mass Effects. , 1967, Developmental biology.