B6.129S7-Ube3a^tm1Alb/J

Stock number: 016590
Product name: B6 E6-AP-
Strain synonyms: BS AS
Research areas: Developmental Biology Research, Neurobiology Research, Research Tools

Description

E6-AP (Ube3a^tm1Alb) is a knock-out allele. In neurons, the paternal Ube3a allele is silenced by the process of genomic imprinting. Heterozygous mice with a maternally-inherited Ube3a^tm1Alb knock-out allele display the "Ube3a-null" phenotype in neurons that has characteristics of Angelman syndrome (AS).

Genetic background-dependent differences in the behavioral, EEG activity and seizure phenotypes are observed - see C57BL/6 Ube3a maternal deletion mice ("B6 AS" ; Stock No. 016590) and 129 Ube3a maternal deletion mice ("129 AS" ; Stock No. 004477).

Detailed description

E6-AP (Ube3a^tm1Alb) is a knock-out allele. Mice that are heterozygous for the targeted mutation are viable and fertile, but exhibit a phenotype dependent upon their maternal/paternal inheritance of the knock-out allele.

In neurons, the paternal Ube3a allele is silenced by the process of genomic imprinting. Heterozygous mice with a paternally-inherited Ube3a^tm1Alb knock-out allele do not exhibit any neuronal phenotype.

Heterozygous mice with a maternally-inherited Ube3a^tm1Alb knock-out allele display the "Ube3a-null" phenotype in neurons that has characteristics of Angelman syndrome (AS). Specifically, they exhibit a 64-73% reduction in protein levels in heart, liver, and kidney tissues. In situ hybridization reveals no detectable expression in hippocampal neurons and Purkinje cells. They develop fewer dopaminergic neurons in the substantia nigra, display reduced motor coordination (tremor, ataxia), impaired long-term potentiation, defective neocortical plasticity, fluid consumption defects (abnormal licking behavior), and context-dependent learning abnormalities. They have increased Purkinje cell cytoplasmic levels of TRP53 (transformation related protein 53), elevated levels of PML (promyelocytic leukemia tumor suppressor) protein in multiple tissues and an increased susceptibility to tonic clonic seizures induced by handling.

Homozygous offspring (from heterozygous parents) have slightly reduced viability prior to weaning for mice on the hybrid B6;129 background. Surviving homozygotes can display delayed growth, motor dysfunction and reduced fertility. No gene product (mRNA) is detected by Northern blot analysis in homozygous ES cells. Homozygous mice have increased Purkinje cell cytoplasmic levels of TRP53 (transformation related protein 53), elevated levels of PML (promyelocytic leukemia tumor suppressor) protein in multiple tissues and an increased susceptibility to tonic clonic seizures induced by handling.

Mice with this Ube3a knock-out mutation are available on different genetic backgrounds - either C57BL/6 (Stock No. 016590) or 129 (Stock No. 004477). Born et al. 2017 Sci Rep. 7:8451 [PMID:28814801] describes genetic background differences in the behavioral, EEG activity and seizure phenotypes for these mutant mice. In summary, C57BL/6 Ube3a maternal deletion mice ("B6 AS") displayed robust behavioral impairments, spontaneous EEG polyspikes, and increased cortical and hippocampal power primarily driven by delta and theta frequencies. 129 Ube3a maternal deletion mice ("129 AS") demonstrated limited behavioral abnormalities, performed poorly on wire hang and contextual fear conditioning and exhibited a lower seizure threshold and altered spectral power. See that publication for more specific details.

Development

A targeting vector containing neomycin resistance and herpes simplex virus thymidine kinase genes and a loxP site was used to disrupt a 3 kb sequence including exon 2. The construct was electroporated into 129S7/SvEvBrd-Hprt^b-m2 derived AB2.2 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric animals were crossed to 129 mice. The mice were backcrossed to C57BL/6 for at least 5 generations and then backcrossed to C57BL/6J for 2 generations prior to transfer to the Repository. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.

Allele

Symbol: Ube3a^tm1Alb
Name: targeted mutation 1, Arthur L Beaudet
MGI accession ID: MGI:2181811
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Ube3a
Marker name: ubiquitin protein ligase E3A
Chromosome: 7
Strain of origin: 129S7/SvEvBrd-Hprt1^b-m2
Molecular note: A 3kb genomic region including exon 2 was replaced with a neo-loxP-hprt cassette via homologous recombination, resulting in deletion of 100 N-terminal amino acids in the encoded protein and a frameshift inactivating all putative protein isoforms. Homozygous mutant animals were identified by Southern blot and PCR genotype analysis.