STOCK Pdx1^tm1Macd/J

Stock number: 005701
Product name: Pdx1^tTA KI
Research areas: Endocrine Deficiency Research, Metabolism Research, Research Tools

Description

These knock-in mice express a transactivator protein (tTA) from the endogenous promoter/enhancer elements of the Pdx1 gene in the pancreas.

Detailed description

Mice homozygous for the targeted mutation fail to develop a pancreas. Heterozygous mice have normal pancreas development but partially impaired glucose tolerance in adulthood. The substitution of the targeted gene with tTA_off inactivates the endogenous allele and places tTA_off expression under the control of the endogenous transcriptional regulatory sequences. tTA expression from the modified locus is identical to that of the normal allele; tTA mRNA is detectable in the pancreas but not in other visceral organs or salivary glands. This mutant may be useful in studies of pancreatic endocrine/exocrine function and diabetes. Heterozygotes also can be bred with transgenic mice that express a target gene under the regulation of a tetracycline-responsive element (TRE; tetO) for pancreas-specific applications.

This mutant was originally designed to be mated with mutant mice with a TRE-controlled transgene coding for the endogenous Pdx1 (Ipf1) gene along with a reporter (EGFP or beta-galactosidase gene, (see Stock No. 005699 and 005728 respectively).

Development

A targeting vector containing a tetracycline-responsive tet-repressor/VP16 fusion transactivator (tTA_off) and the neomycin-resistance gene flanked with 4.5-kb upstream and 1.3-kb downstream homology domains was used to replace the entire coding region (both exons and the intron) of the endogenous Pdx1 locus. The construct was electroporated into the (129X1/SvJ x 129S1/Sv)F1-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric males were bred with C57BL/6 females to generate heterozygotes. At some point, mutant mice were bred to B6SJL hybrid transgenic mice. The transgene was selected against in subsequent breedings, and strain is now maintained as heterozygous for the Pdx1 targeted mutation.

Allele

Symbol: Pdx1^tm1Macd
Name: targeted mutation 1, Raymond J MacDonald
MGI accession ID: MGI:2388676
Generation method: Targeted
Attributes: Transactivator
Marker symbol: Pdx1
Marker name: pancreatic and duodenal homeobox 1
Chromosome: 5
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Expressed genes: tTA,tetracycline-controlled transactivator,E. coli
Site of expression: Expresses tTA in pancreas.
Molecular note: Exons 1 and 2, which encompass the entire coding region, were replaced with a cassette containing a tetracycline transactivator (tTA) and a neo resistance gene. RT-PCR showed tTA expression in adult pancreas tissue but not in other visceral organs or salivary glands.