The pBi-Noggin-eGFP transgene has a bidirectional tetracycline-inducible promoter controlling expression of noggin and eGFP. No transgenic noggin or eGFP expression is reported in the absence of tetracycline-controlled transactivator protein (tTA). When bred to other mice expressing tTA or reverse tetracycline-controlled transactivator protein (rtTA), simultaneous noggin and eGFP expression in the resulting double mutant offspring can be regulated by tetracycline or its analog doxycycline (dox).
Mice from founder line 53 were found to have the highest and most stable expression of transgenic noggin and eGFP after dox administration, with the lowest background expression levels. When induced, eGFP expression is readily observed via immunohistochemical detection, but direct eGFP fluorescence is very faint. FVB.pBi-Noggin-eGFP line 53 hemizygotes are viable and fertile, with no reported phenotypic abnormalities. The donating investigator reports the transgene copy number and genomic integration site of the transgene is unknown. The donating investigator also reports that homozygous mice are viable and fertile, with behavior and gene expression the same as hemizygous animals.
When FVB.pBi-Noggin-eGFP line 53 mice are bred to mice expressing rtTA in central nervous system (Nestin-rtTA; see Stock No. 004127), the resulting double mutant offspring may be useful in mobilizing endogenous neural stem cell populations to replace neurons and oligodendrocytes lost as a result of disease, injury, and normal or pathological aging. Immunohistochemical localization of nestin and eGFP in sections of doxycycline-induced brain also showed complete overlap. In the absence of doxycycline, noggin over-expression is not observed.
