B6.129S7-Ednrb^tm1Ywa/FrykJ

Stock number: 021933
Research areas: Dermatology Research, Developmental Biology Research, Internal/Organ Research, Mouse/Human Gene Homologs, Neurobiology Research

Description

This Ednrb knock-out exhibits an aganglionic megacolon, skin pigmentation deficiency and lymphoid depletion. They may be used as a model for human Hirschsprung's disease.

Detailed description

Exon 3 is replaced by a neomycin resistance cassette in this knock-out mutant of the endothelin receptor type B (Ednrb) gene. Ednrb encodes a G protein-coupled receptor expressed in vascular endothelial cells where it is involved in vasoconstriction, vasodilation, bronchoconstriction and cell proliferation. In humans, mutations in this gene have been associated with Waardenburg syndrome type 4 (Waardenburg-Shah syndrome) which is characterized by deafness, neural crest defects, pigmentation changes, and Hirschsprung's disease. Hirschsprung's disease is primarily an intestinal disorder in which colon segments of variable length lack ganglion cells resulting in intestinal blockage and megacolon. Homozygous knock-out mice are initially viable but die within the first month. They show a disruption of neural crest lineage development, which is characterized by a lack of hair or skin pigmentation on 90% of their body. Death occurs by sepsis, likely from enterocolitis. Immunosuppression is evidenced by small spleens, bone marrow suppression, and thymic involution caused by the aganglionic megacolon. The phenotype is more severe (earlier onset enterocolitis and shorter life-span) on a congenic C57BL/6J strain than on the B6/129 hybrid background (Stock No. 003295). They also do not breed as well and have smaller litters than the B6/129 line. This mutation is allelic with the piebald lethal spontaneous mutation.

Development

A targeting vector was designed to replace exon 3 of the endothelin receptor type B (Ednrb) gene with a neomycin resistance cassette. The construct was electroporated into 129S7/SvEvBrd-derived JH-1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts and the resulting chimeric males were bred to C57BL/6 females. These mice arrived at The Jackson Laboratory on a mixed background as Stock No. 003295. Some mice were obtained by Dr Philip Frykman, at Cedars-Sinai Medical Center. These mice were bred to C57BL/6J inbred mice (Stock No. 000664) for many generations using a marker-assisted, speed congenic approach to generate this C57BL/6J-congenic strain (Stock No. 021933). Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J mice for at least one generation to establish the colony.

Allele

Symbol: Ednrb^tm1Ywa
Name: targeted mutation 1, Masashi Yanagisawa
MGI accession ID: MGI:1857161
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Ednrb
Marker name: endothelin receptor type B
Chromosome: 14
Strain of origin: 129S7/SvEvBrd
Molecular note: A neomycin resistance cassette replaced a 4.2kb segment of the gene, which contained exon 3. Exon 3 encodes the fourth transmembrane helix of the protein. Functional analysis showed that the allele is null.