Avil^{tm1(HBEGF)Phep}

Exon 2 of the sensory neuron-specific Avril gene and 66 bp of DNA upstream thereof have been replaced by the Cre recombinase-inducible "iDTR cassette," which contains a loxP-flanked transcriptional/translational STOP cassette blocking expression of the open reading frame of the simian heparin binding EGF like growth factor (HBEGF) cDNA; unlike the mouse protein, primate HBEGF is a diphtheria toxin receptor (DTR). The loxP-flanked segment contains two SV40 polyadenylation signals p[A], a frt-flanked neo cassette, and the STOP cassette (comprising 550 bp of 3' sequence from the S. cerevisiae His3 gene, an SV40 p[A], and a sequence containing a false translation initiation codon (ATG) immediately followed by a splice donor sequence). Deletion of the STOP cassette by Cre recombinase allows expression of HBEGF under control of the endogenous Avil promoter, which renders Avil-expressing sensory neurons susceptible to ablation by diphtheria toxin. Immunohistochemical analysis of dorsal root ganglion (DRG) sections from mice bearing this allele in the absence of Cre using goat anti-human HB-EGF antibody detected no expression of DTR. In mice also expressing Cre recombinase in somatostatin-positive neurons, DTR was detected in a small subset of IB4- DRG neurons; no signal was seen in sections taken from mice following DT administration. (J:118365, J:131076, J:234423)