B6;129-Nrxn3^tm2Sud Nrxn1^tm2Sud Nrxn2^tm2Sud/J

Stock number: 008416
Product name: NBR
Research areas: Neurobiology Research

Description

These conditional targeted mutation mice carry loxP sites on either side of the first unique coding exon of the neurexin beta promoter isoforms of Nrxn1 (neurexin I), Nrxn2 (neurexin II), and Nrxn3 (neurexin III). These exons correspond to exon 18 of Nrxn1 (neurexin I), exon 17 of Nrxn2 (neurexin II), and exon 17 of Nrxn3 (neurexin III). When crossed with a Cre recombinase-expressing strain, this strain is useful in eliminating tissue-specific expression of the beta isoforms of the gene(s). This strain may be useful in studies of neuronal synaptic vesicle exocytosis.

Note: The original curations for this strain indicated that exon 1 of the Nrxn1, Nrxn2, and Nrxn3 genes were modified. Subsequent published information (Anderson, 2015) clarified that it was the first exon of the beta promoter isoforms that were targeted. (September, 2019)

Detailed description

These conditional targeted mutation mice carry loxP sites on either side of the first unique coding exon of the neurexin beta promoter isoforms of Nrxn1 (neurexin I), Nrxn2 (neurexin II), and Nrxn3 (neurexin III). These exons correspond to exon 18 of Nrxn1 (neurexin I), exon 17 of Nrxn2 (neurexin II), and exon 17 of Nrxn3 (neurexin III). These exons have been further modified to include green fluorescent protein (GFP) (neurexins 1 and 3), or hemagglutinin (HA) protein (neurexin 2). The GFP and HA inserts don't affect the expression of the beta neurexin genes, but it is very difficult to detect signals in the tissue by immunohistochemistry or direct fluorescence. The single, double and triple homozygous floxed mutants are fully viable, fertile, normal in size, and do not display any gross physical or behavioral abnormalities. When crossed with a Cre recombinase-expressing strain, this strain is useful in eliminating tissue-specific expression of the beta isoforms of the gene(s). This strain may be useful in studies of neuronal synaptic vesicle exocytosis.

Homozygous deletion of the beta neurexin 3 floxed segment mediated through Cre excision generates pups with normal viability and fertility; triple knockout mice are viable, but are infertile and smaller in size (~70% of wild-type in body weight).

Note: The original curations for this strain indicated that exon 1 of the Nrxn1, Nrxn2, and Nrxn3 genes were modified. Subsequent published information (Anderson, 2015) clarified that it was the first exon of the beta promoter isoforms that were targeted. (September, 2019).

Development

Each of the three targeted genes were modified by the insertion of a loxP site in the 5' UTR, and an Frt-flanked neomycin cassette with a 3' loxP site in the first unique coding exon of the neurexin beta promoter isoforms of Nrxn1 (neurexin I), Nrxn2 (neurexin II), and Nrxn3 (neurexin III). These exons correspond to exon 18 of Nrxn1 (neurexin I), exon 17 of Nrxn2 (neurexin II), and exon 17 of Nrxn3 (neurexin III). These exons have been further modified to include green fluorescent protein (GFP) (neurexins 1 and 3), or hemagglutinin (HA) protein (neurexin 2).

The GFP and HA inserts don't affect the expression of beta neurexin genes, but it is very difficult to detect GFP and HA signals in the tissue by immunohistochemistry or direct fluorescence. The genes were independently targeted in (129X1/SvJ x 129S1/Sv)F1- Kitl⁺-derived R1 embryonic stem (ES) cells. Resultant germline mutant mice were crossed with a transgenic flipase (FLP) strain on a mixed C57BL/6 and 129 background to remove the neomycin cassettes. The three mutations were intercrossed and backcrossed three or more times to C57BL/6.

Note: The original curations for this strain indicated that exon 1 of the Nrxn1, Nrxn2, and Nrxn3 genes were modified. Subsequent published information (Anderson, 2015) clarified that it was the first exon of the beta promoter isoforms that were targeted. (September, 2019).

Allele

Symbol: Nrxn3^tm2Sud
Name: targeted mutation 2, Thomas C Sudhof
MGI accession ID: MGI:3797484
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Synonyms: Nrxn3beta cKO
Marker symbol: Nrxn3
Marker name: neurexin III
Chromosome: 12
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Molecular note: A loxP site was inserted into the 5' end of a modified exon 17, which contains an EGFP reporter gene followed by a FRT-flanked neomycin resistance cassette and a loxP site. Flp-mediated recombination removed the selection cassette and left the modified exon 17 floxed. The GFP insert does not affect the expression of neurexin 3 gene, but it is very difficult to detect GFP signals in the tissue by immunohistochemistry or direct fluorescence.

Allele

Symbol: Nrxn1^tm2Sud
Name: targeted mutation 2, Thomas C Sudhof
MGI accession ID: MGI:3797417
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Synonyms: Nrxn1beta cKO
Marker symbol: Nrxn1
Marker name: neurexin I
Chromosome: 17
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Molecular note: A loxP site was inserted into the 5' end of a modified exon 18, which contains an EGFP reporter gene followed by FRT-flanked neomycin resistance cassette and a loxP site. Flp-mediated recombination removed the selection cassette and left the modified exon 18 floxed. The GFP insert does not affect the expression of neurexin 1 gene, but it is very difficult to detect GFP signals in the tissue by immunohistochemistry or direct fluorescence.

Allele

Symbol: Nrxn2^tm2Sud
Name: targeted mutation 2, Thomas C Sudhof
MGI accession ID: MGI:3797418
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Synonyms: Nrxn2beta cKO
Marker symbol: Nrxn2
Marker name: neurexin II
Chromosome: 19
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Molecular note: A loxP site was inserted into the 5' end of a modified exon 17, which contains an hemagglutinin (HA) reporter tag followed by a FRT-flanked neomycin resistance cassette and a loxP site. Flp-mediated recombination removed the selection cassette and left the modified exon 17 floxed. The HA insert does not affect the expression of neurexin 2 gene, but it is very difficult to detect GFP signals in the tissue by immunohistochemistry.