(taken from the application) We propose to test the role of the transcription factor PDX1 in the control of islet and acinar cell differentiation, and to determine its model of action and its target genes. We have identified the homeodomain partners (PBX1b and MRG1) that form a functional complex with PDX1 in acinar cell lines, but not in Beta-cell lines. By creating a tissue- specific conditional knock-out of the Pbx1 gene that will be deleted only when and where PDX1 is expressed, we will test the role of the complex in acinar and islet cell development (Specific Aim 1). We will test directly of PDX1 to control the formation of the endocrine (Beta-cell) and exocrine (acinar cell) tissues of the pancreas by placing a mouse Pdx1 transgene under the control of a tetracycline-regulated promoter. In mouse embryos and cultured pancreatic rudiments from embryos in which the endogenous Pdx1 gene has been inactivated, the only source of PDX1 will be the regulated transgene (Specific Aim 2). We will identify the genes activated by PDX1 in early development by creating a library of cDNA clones of mRNAs expressed in pancreatic rudiments when they are released from the developmental block caused by the absence of PDX1, but which they are not present in the blocked rudiments prior to PDX1 induction (Specific Aim 3A). We will also identify genes whose promoters normally are bound by PDX1 in Beta- or acinar cell lines (Specific Aim 3B). We will analyze the role of selected PDX1 target genes likely to be important in early pancreatic development or in the differentiation of Beta-cells (Specific Aim 4).

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK055266-03
Application #
6177394
Study Section
Special Emphasis Panel (ZDK1-GRB-8 (O1))
Program Officer
Sato, Sheryl M
Project Start
1998-09-30
Project End
2003-08-31
Budget Start
2000-09-30
Budget End
2001-08-31
Support Year
3
Fiscal Year
2000
Total Cost
$245,727
Indirect Cost
Name
University of Texas Sw Medical Center Dallas
Department
Biochemistry
Type
Schools of Medicine
DUNS #
City
Dallas
State
TX
Country
United States
Zip Code
75390
Hori, Kei; Cholewa-Waclaw, Justyna; Nakada, Yuji et al. (2008) A nonclassical bHLH Rbpj transcription factor complex is required for specification of GABAergic neurons independent of Notch signaling. Genes Dev 22:166-78
Beres, Thomas M; Masui, Toshihiko; Swift, Galvin H et al. (2006) PTF1 is an organ-specific and Notch-independent basic helix-loop-helix complex containing the mammalian Suppressor of Hairless (RBP-J) or its paralogue, RBP-L. Mol Cell Biol 26:117-30
Holland, Andrew M; Gonez, L Jorge; Naselli, Gaetano et al. (2005) Conditional expression demonstrates the role of the homeodomain transcription factor Pdx1 in maintenance and regeneration of beta-cells in the adult pancreas. Diabetes 54:2586-95
Hale, Michael A; Kagami, Hideaki; Shi, Ling et al. (2005) The homeodomain protein PDX1 is required at mid-pancreatic development for the formation of the exocrine pancreas. Dev Biol 286:225-37
Liu, Y; MacDonald, R J; Swift, G H (2001) DNA binding and transcriptional activation by a PDX1.PBX1b.MEIS2b trimer and cooperation with a pancreas-specific basic helix-loop-helix complex. J Biol Chem 276:17985-93
Rose, S D; Swift, G H; Peyton, M J et al. (2001) The role of PTF1-P48 in pancreatic acinar gene expression. J Biol Chem 276:44018-26
Viswanath, R L; Rose, S D; Swift, G H et al. (2000) A binary mechanism for the selective action of a pancreatic beta -cell transcriptional silencer. J Biol Chem 275:40273-81
Swift, G H; Peyton, M J; MacDonald, R J (2000) Assessment of RNA quality by semi-quantitative RT-PCR of multiple regions of a long ubiquitous mRNA. Biotechniques 28:524, 526, 528, 530-1