FVB/NJ-Ap2b1^{Tg(Tyr)427Ove}/EtevJ

Stock number: 016870
Research areas: Cell Biology Research, Developmental Biology Research, Neurobiology Research

Description

These OVE427 mice harbor a knockout of the Ap2b1 gene caused by random insertion of two head-to-tail copies of the tyrosinase minigene transgene. Homozygous mice exhibit complete clefting of the secondary palate (autosomal recessive nonsyndromic cleft palate) and die shortly after birth.

Detailed description

These OVE427 mice harbor a mutation created by random insertion of two head-to-tail copies of the tyrosinase minigene (TYBS) transgene into the Ap2b1 (adaptor protein complex 2 β1 subunit) gene on chromosome 11. This results in a knockout allele; no β2-adaptin mRNA or protein is expressed from the mutant allele. Homozygous OVE427 mice exhibit complete clefting of the secondary palate (autosomal recessive nonsyndromic cleft palate) and die shortly after birth. Coronal cross-sections of the secondary palate of embryonic day (E)17 and E18 homozygous embryos display evidence of palatal shelf elevation and the apparent failure of the shelves to fuse. Ap2β1-deficiency also leads to reduced levels of another adaptor protein-2 (AP-2) complex protein, α-adaptin (Ap2a1). No craniofacial dysmorphology or any anomalies involving the limbs or developing skeleton are reported for OVE427 homozygotes. Other than cleft palate, additional histological examination through serial cross-sections of entire embryos do not reveal differences in major internal organs (heart, brain, lungs, kidneys, gastrointestinal tract) between wildtype and homozygous littermates.

Adaptor protein (AP) complexes are composed of subunits (adaptins) that are involved in the formation of intracellular transport vesicles and in the selection of cargo for incorporation into vesicles. The Ap2β1 (Ap2b1) gene encodes the β2-adaptin protein that, together with the α-adaptin protein (Ap2a1), the μ2 medium chain adaptin (Ap2m1), and the σ2 small chain adaptin (Ap2s1), assemble into the heterotetrameric adaptor protein-2 (AP-2) complex involved in clathrin-dependent endocytosis of receptors from the plasma membrane. These OVE427 mice are useful tools for studying the genetic components of cleft palate; including AP-2 complex assembly/function and defective endocytosis of one or more receptors or other cell surface proteins involved in palatogenesis.

Development

The 4.1 kb tyrosinase minigene (TYBS) transgene was designed by Dr. Paul A. Overbeek (Baylor College of Medicine) with the 2.1 kb BALB/c mouse Tyr promoter region and 2.0 kb Tyr cDNA sequence (including the stop codon polyA sequences). This transgene was injected into one-cell stage FVB/NJ mouse embryos. Expression of the tyrosinase minigene results in melanin synthesis (rescue of the FVB/N albino phenotype); so founder mice (F0) were identified by coat color and eye pigmentation. F0 mice were assigned an OVE number and then bred with FVB/NJ mice. Heterozygous mice of line OVE427 (OVE#427) were viable and fertile with sand/tan coat color and dark pink/rust colored eyes. OVE427 mice were then sent to Dr. Eric T. Everett (University of North Carolina at Chapel Hill) for characterization and further strain maintenance. Homozygous OVE427 mice exhibiting perinatal lethality were identified and shown to have two head-to-tail copies of the TYBS transgene within the Ap2β1 (adaptor protein complex 2 β1 subunit) gene on chromosome 11; with both transgenes in reverse-orientation relative to the disrupted mouse gene. Specifically, the flanking sequences correspond to the intron between exons 1-2, and the intron between exons 14-15 of Ap2β1. Heterozygous OVE427 mice were bred with wildtype mice (white coat color and pink eyes) for more than 20 generations prior to sending to The Jackson Laboratory Repository Facebase collection. Upon arrival, these mice were bred to FVB/NJ inbred mice (Stock No. 001800) for at least one generation to establish the live colony.

Allele

Symbol: Ap2b1^{Tg(Tyr)427Ove}
Name: transgene insertion 427, Paul Overbeek
MGI accession ID: MGI:5295975
Generation method: Transgenic
Attributes: Reporter; Null/Knockout
Marker symbol: Ap2b1
Marker name: adaptor-related protein complex 2, beta 1 subunit
Chromosome: 11
Strain of origin: FVB/NJ
Expressed genes: Tyr,tyrosinase,mouse, laboratory
Molecular note: The 4.1 kb tyrosinase minigene (TYBS) transgene with the 2.1 kb BALB/c mouse Tyr promoter region and 2.0 kb Tyr cDNA sequence (including the stop codon polyA sequences) inserted into chromosome 11 in reverse-orientation with the left arm mapping to intron 1 and the right arm mapping to intron 14. The absence of protein expression was confirmed by western blot analysis on mouse embryonic fibroblasts, brain, and liver extracts.