B6.Cg-Tg(Gfap-cre)77.6Mvs/2J

Stock number: 024098
Product name: GFAP-Cre line 77.6
Research areas: Developmental Biology Research, Neurobiology Research, Research Tools

Description

GFAP-Cre transgenic mice from founder line 77.6 have Cre recombinase expression directed to astrocytes in the brain and spinal cord by the mouse glial fibrillary acidic protein promoter. These GFAP-Cre line 77.6 mice may be useful for studying astrocytes in the brain and spinal cord.

Detailed description

Mice hemizygous for the Gfap-cre transgene are viable and fertile, with a mouse glial fibrillary acidic protein (mGfap) promoter sequence directing expression of Cre recombinase. When GFAP-Cre line 77.6 mice are bred with mice containing a loxP-flanked sequence, Cre-mediated recombination is expected to result in deletion of the floxed sequences in the Cre recombinase-expressing tissues of the offspring.

Specifically, Cre recombinase activity (as defined by expression of a floxed-STOP reporter gene) is targeted to most astrocytes throughout healthy brain and spinal cord tissues, and to essentially all astrocytes following central nervous system (CNS) injury. Some germline expression is observed (see below).

These GFAP-Cre line 77.6 mice (Stock No. 024098) also have Cre recombinase activity in a subpopulation of adult neural stem cells in the subventricular zone. In contrast to GFAP-Cre line 73.12 (Stock No. 012886), GFAP-Cre line 77.6 mice are reported to have no Cre recombinase activity in postnatal or adult neural stem cells (or their progeny) from the hippocampus or other brain regions. As such, GFAP-Cre line 77.6 mice are particularly useful for selective targeting of astrocytes. Additionally, the donating investigator reports GFAP-Cre lines 73.12 and 77.6 have cre expression in the male germline, and suggests breeding GFAP-Cre females with floxed males for Cre-lox experiments.

Furthermore, Luo et al. 2020 Neuron 106:37 Table 1 shows germline recombination in offspring (F2) of Cre;floxed double mutant (F1) mice bred to floxed and/or wildtype mice. The authors also note that in general, the frequency of recombination in Cre;floxed double mutant germline cells appears to be considerably higher than in zygotes produced by breeding Cre mice to floxed mice.
This reports that GFAP-Cre line 77.6;floxed double mutant males bred to floxed females produced some offspring with germline deletion of the floxed allele [observed from several cohorts (including up to 100% in a few litters)]. As such, for Cre-lox experiments and to avoid/minimize germline deletion of the floxed allele, researchers may consider breeding GFAP-Cre line 77.6 females to floxed males.

If the recombinase activity pattern of this allele is further characterized by the Genetic Resource Science group at The Jackson Laboratory, such findings will be reported on the Mouse Genome Informatics (MGI) Allele Detail entry. This same information may also be found searching the MGI Recombinase Activity and MGI Gene Expression + Recombinase Activity Comparison Matrix.

Development

The mGFAP-Cre transgene was designed by Dr. Michael V. Sofroniew (University of California, Los Angeles) with the entire mouse glial fibrillary acidic protein gene (Gfap) sequences directing expression of Cre recombinase. The construct has a small fragment of the Gfap first exon removed to prevent GFAP expression from the transgene. The transgene was microinjected into fertilized (BALB/c x C57BL/6NHsd)F1 oocytes. Transgenic founders were bred to C57BL/6 mice, and founder line 77.6 was identified. The GFAP-Cre line 77.6 colony was backcrossed onto the C57BL/6 genetic background for at least 15-20 generations. In 2014, Dr. Sofroniew sent female mice to The Jackson Laboratory Repository as Stock No. 024098. Upon arrival, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish our live colony.

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 4 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Tg(Gfap-cre)77.6Mvs
Name: transgene insertion 77.6, Michael V Sofroniew
MGI accession ID: MGI:3838840
Generation method: Transgenic
Attributes: Recombinase-expressing
Marker symbol: Tg(Gfap-cre)77.6Mvs
Marker name: transgene insertion 77.6, Michael V Sofroniew
Chromosome: UN
Strain of origin: (BALB/c x C57BL/6NHsd)F1
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: Cre recombinase activity is is observed in most astrocytes throughout the healthy brain and spinal cord and to essentially all astrocytes after Central Nervous System (CNS) injury. Cre recombinase activity is also observed in a subpopulation of the adult stems in the subventricular zone. In contrast to Tg(Gfap-cre)73.12Mvs, there is no targeting of postnatal or adult neural stem cells or their progeny in the hippocampus or other brain regions in Tg(Gfap-cre)77.6Mvs.
Molecular note: The bacterial Cre recombinase gene was inserted into the first exon of an expression cassette (clone 445) that contains all the introns, promoter regulatory elements, exons, and 2.5 kb of 5' and 2 kb of 3' flanking DNA of the astroglia-specific mouse glial fibrillary acidic protein gene. GFAP is not expressed from the transgene due to deletion of part of exon 1. Cre expression was detected in a small population of cells within the subependymal zone in the adult brain. No Cre expression or activity was detected during embryonic development or in the hippocampus.