STOCK Astn2^em2Hatn/J

Stock number: 039948
Product name: Astn2 KO

Research areas: Neurobiology Research

Description

Astn2 KO mice carry a knock-out allele in which about 3 kb of the promoter and exon 1 of the mouse astrotactin 2 (Astn2) gene have been excised. These mice provide a genetic model for studying the role of the cerebellum in autism spectrum disorder (ASD)-related behaviors as well as the role of ASTN2 in cerebellar circuit function.

Also available are Astn2^flox mice (Stock No. 039947), in which about 3 kb of the promoter and exon 1 of the mouse Astn2 gene are flanked by loxP sites, which are a Cre recombinase-inducible functional knock-out strain.

Detailed description

Astrotactin 2 (ASTN2) is a transmembrane neuronal protein highly expressed in the cerebellum that functions in receptor trafficking and modulates cerebellar Purkinje cell (PC) synaptic activity. Individuals with ASTN2 mutations exhibit neurodevelopmental disorders, including autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), learning difficulties, and language delay.

Astn2 KO mice carry a CRISPR/Cas9-generated knock-out allele of the mouse Astn2 gene in which 3 kb of the promoter and exon 1 have been excised. No functional protein is produced from the targeted allele, as determined by Western blot. The donating laboratory reports that expression of truncated protein was not assessed due to the lack of additional appropriate antibodies (December 2024).

Astn2 KO homozygous mice exhibit strong ASD-related behavioral phenotypes, including a marked decrease in separation-induced pup ultrasonic vocalization calls, hyperactivity, repetitive behaviors, altered behavior in the three-chamber test, and impaired cerebellar-dependent eyeblink conditioning. They do not show defects in cerebellar gross morphology or in the ultrastructure of the synapses, and there are no abnormalities in cerebellar granule cell proliferation or migration. Heterozygotes appear normal overall, however they have some ultrasonic vocalization deficits.

Also available are Astn2^flox mice (Stock No. 039947), in which about 3 kb of the promoter and exon 1 of the mouse Astn2 gene are flanked by loxP sites, which are a Cre recombinase-inducible functional knock-out strain.

Development

Around 3 kb of the promoter and exon 1 of the mouse Astn2 gene were excised from C57BL/6J embryos using CRISPR/Cas9 methodologies. The donating investigator reports the resultant mice were backcrossed to C57BL/6J for at least 5 generations (to help remove any off-target mutations) prior to sending males to The Jackson Laboratory in 2024 (see SNP results below). Upon arrival, sperm was cryopreserved. To establish a live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

In 2024, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 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 males sent to The Jackson Laboratory Repository. This showed two of the 43 markers throughout the genome segregating for allele-type other than C57BL/6J, as well as one of the C57BL/6 substrain markers (could be C57BL/6N;BALB;C3H;DBA;FVB etc). Taken together, these data suggest the mice sent to The Jackson Laboratory were on a mixed genetic background consisting predominantly of C57BL/6 with other contributions at 2-3 other locations.

Allele

Symbol: Astn2^em2Hatn
Name: endonuclease-mediated mutation 2, Mary E Hatten
MGI accession ID: MGI:7786605
Generation method: Endonuclease-mediated
Attributes: Null/Knockout
Synonyms: Astn2^-
Marker symbol: Astn2
Marker name: astrotactin 2
Marker synonyms: 1d8; Astnl; bA67K19.1
Chromosome: 4
Strain of origin: C57BL/6J
Molecular note: Using CRISPR/Cas9 methodologies ~3 kb of the promoter and exon 1, encoding the ATG start codon of the mouse Astn2 gene, was excised in C57BL/6J embryos.