Phenotypic Mutation 'sposh' (pdf version)
Mutation Type missense
Coordinate104,059,150 bp (GRCm39)
Base Change A ⇒ G (forward strand)
Gene Ednrb
Gene Name endothelin receptor type B
Synonym(s) ETR-b, Sox10m1, ETb
Chromosomal Location 104,052,061-104,081,838 bp (-) (GRCm39)
MGI Phenotype FUNCTION: This gene encodes a member of the G-protein coupled receptor family. It encodes a receptor for endothelins, peptides that are involved in vasocontriction. The encoded protein activates a phosphatidylinositol-calcium second messenger system and is required for the development of enteric neurons and melanocytes. Gene disruption causes pigmentation anomalies, deafness, and abnormal dilation of the colon due to defects of neural crest-derived cells. Mutations in this gene are found in the piebald mouse, and mouse models of Hirschsprung's disease and Waardenburg syndrome type 4. Renal collecting duct-specific gene deletion causes sodium retention and hypertension. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2013]
PHENOTYPE: Mice homozygous for null mutations have pigmentation limited to small patches on the head and rump and die from megacolon resulting from impaired neural crest migration and aganglionosis. Heterozygotes for a null allele show improved cardiac tolerance to hypoxia. [provided by MGI curators]
Accession Number

NCBI RefSeq: NM_007904.4, NM_001276296.1, NM_001136061.2; MGI: 102720

Amino Acid Change Phenylalanine changed to Serine
Institutional SourceBeutler Lab
Gene Model predicted gene model for protein(s): [ENSMUSP00000022718] [ENSMUSP00000126057] [ENSMUSP00000154806]
AlphaFold P48302
SMART Domains Protein: ENSMUSP00000022718
Gene: ENSMUSG00000022122
AA Change: F292S

signal peptide 1 26 N/A INTRINSIC
Pfam:7TM_GPCR_Srx 109 329 2.3e-6 PFAM
Pfam:7TM_GPCR_Srsx 112 401 7.3e-11 PFAM
Pfam:7tm_1 118 387 8.5e-44 PFAM
Predicted Effect probably damaging

PolyPhen 2 Score 0.974 (Sensitivity: 0.76; Specificity: 0.96)
(Using ENSMUST00000022718)
SMART Domains Protein: ENSMUSP00000126057
Gene: ENSMUSG00000022122
AA Change: F292S

signal peptide 1 26 N/A INTRINSIC
Pfam:7TM_GPCR_Srx 109 328 1.9e-6 PFAM
Pfam:7TM_GPCR_Srsx 112 401 7.3e-11 PFAM
Pfam:7tm_1 118 387 4.2e-40 PFAM
Predicted Effect probably damaging

PolyPhen 2 Score 0.974 (Sensitivity: 0.76; Specificity: 0.96)
(Using ENSMUST00000172237)
Predicted Effect probably damaging

PolyPhen 2 Score 0.974 (Sensitivity: 0.76; Specificity: 0.96)
(Using ENSMUST00000227824)
Meta Mutation Damage Score 0.7425 question?
Is this an essential gene? Possibly essential (E-score: 0.716) question?
Phenotypic Category Unknown
Candidate Explorer Status loading ...
Single pedigree
Linkage Analysis Data
Alleles Listed at MGI

All mutations/alleles(48) : Chemically and radiation induced(2) Chemically induced (ENU)(2) Chemically induced (other)(11) Radiation induced(18) Spontaneous(4) Targeted(11)

Lab Alleles
AlleleSourceChrCoordTypePredicted EffectPPH Score
IGL00531:Ednrb APN 14 104057455 missense probably damaging 1.00
IGL01433:Ednrb APN 14 104080626 missense probably damaging 0.98
IGL01631:Ednrb APN 14 104080661 missense probably benign 0.02
IGL01696:Ednrb APN 14 104060625 missense probably benign 0.00
IGL01974:Ednrb APN 14 104058254 missense probably damaging 1.00
IGL02749:Ednrb APN 14 104060495 missense possibly damaging 0.63
IGL03277:Ednrb APN 14 104080735 missense probably benign 0.00
gus-gus UTSW 14 104057449 missense probably damaging 1.00
pongo UTSW 14 104060710 splice site probably null
R0284:Ednrb UTSW 14 104057449 missense probably damaging 1.00
R0591:Ednrb UTSW 14 104060710 splice site probably null
R2072:Ednrb UTSW 14 104054535 missense probably benign 0.27
R2080:Ednrb UTSW 14 104080536 missense probably damaging 1.00
R2102:Ednrb UTSW 14 104058350 nonsense probably null
R2118:Ednrb UTSW 14 104059204 missense probably benign 0.42
R2119:Ednrb UTSW 14 104059204 missense probably benign 0.42
R2124:Ednrb UTSW 14 104059204 missense probably benign 0.42
R2851:Ednrb UTSW 14 104059110 missense probably benign 0.04
R2852:Ednrb UTSW 14 104059110 missense probably benign 0.04
R3708:Ednrb UTSW 14 104054516 missense probably damaging 1.00
R4887:Ednrb UTSW 14 104057447 missense possibly damaging 0.95
R5626:Ednrb UTSW 14 104080564 missense probably damaging 0.98
R5688:Ednrb UTSW 14 104060831 missense probably damaging 1.00
R5802:Ednrb UTSW 14 104059150 missense probably damaging 0.97
R5834:Ednrb UTSW 14 104058313 missense probably damaging 1.00
R7212:Ednrb UTSW 14 104080444 missense probably damaging 0.96
R7368:Ednrb UTSW 14 104057453 missense probably benign 0.01
R7766:Ednrb UTSW 14 104080725 missense probably benign 0.12
R7866:Ednrb UTSW 14 104080738 missense probably benign
R8170:Ednrb UTSW 14 104060640 missense possibly damaging 0.92
R8220:Ednrb UTSW 14 104059141 missense probably damaging 1.00
R8299:Ednrb UTSW 14 104060936 missense probably damaging 1.00
R8375:Ednrb UTSW 14 104057383 missense probably damaging 1.00
R8431:Ednrb UTSW 14 104080633 missense probably benign 0.00
R9035:Ednrb UTSW 14 104080665 missense probably benign 0.00
R9128:Ednrb UTSW 14 104080528 missense probably damaging 1.00
R9546:Ednrb UTSW 14 104080459 missense probably benign
R9547:Ednrb UTSW 14 104080459 missense probably benign
Mode of Inheritance Unknown
Local Stock Live Mice
Last Updated 2019-09-04 9:38 PM by Anne Murray
Record Created 2018-01-30 2:48 PM by Jamie Russell
Record Posted 2018-03-28
Phenotypic Description

Figure 1. Sposh mice exhibited variable white belly spotting.

The sposh phenotype was identified among N-ethyl-N-nitrosourea (ENU)-induced G3 mice of the pedigree R5802, some of which showed variable white belly spotting (Figure 1).

Nature of Mutation

Figure 2. Linkage mapping of the pigmentation phenotype using a recessive model of inheritance. Manhattan plot shows -log10 P values (Y-axis) plotted against the chromosome positions of 63 mutations (X-axis) identified in the G1 male of pedigree R5802. Binary phenotype data are shown for single locus linkage analysis without consideration of G2 dam identity. Horizontal pink and red lines represent thresholds of P = 0.05, and the threshold for P = 0.05 after applying Bonferroni correction, respectively.

Whole exome HiSeq sequencing of the G1 grandsire identified 63 mutations. The pigmentation phenotype was linked to a mutation in Ednrb: a T to C transition at base pair 103,821,714 (v38) on chromosome 14, or base pair 22,763 in the GenBank genomic region NC_000080 encoding Ednrb. Linkage was found with a recessive model of inheritance (P = 0.000234), wherein six affected mice were homozygous (N = 5) or heterozygous (N = 1) for the variant allele, and 31 unaffected mice were either heterozygous (N = 22) or homozygous for the reference allele (N = 9) (Figure 2).

The mutation corresponds to residue 1,286 in the mRNA sequence NM_001136061.2 within exon 5 of 8 total exons.

287  -A--I--T--A--V--F--Y--T--L--M--T-

The mutated nucleotide is indicated in red.  The mutation results in a phenylalanine to serine substitution at amino acid 292 (F292S) in both endothelin receptor type B (ETBR) isoforms.

Illustration of Mutations in
Gene & Protein
Protein Prediction
Figure 3. The topography and domain structure of ETBR. (A) ETBR is a G-protein coupled receptor with seven transmembrane (TM) domains. Shown are the locations of the signal peptide and ET-1-induced cleavages of the N-terminus. The post-translational modifications that occur on ETBR are also shown: N-linked glycosyaltion at N60, disulfide bond formation between C174 and C255, palmitoylation at C402, C403, and C405, the 13 phosphorylation (Ps) sites, and the location of Gcoupling. (B) The domain structure of ETBR. Abbreviations: TM, transmembrane domain; SP, signal peptide; CT, C-terminus, Ps, phosphorylation.

Ednrb encodes endothelin receptor type B (ETBR), a member of the endothelin (ET) receptor family of rhodopsin-like G protein-coupled receptors (GPCRs; see the record for Bemr3) (1;2). The rhodopsin-like GPCRs have seven helical transmembrane domains, three extracellular and three intracellular loops, an extracellular N-terminus, and a cytoplasmic C-terminus (Figure 3). The sposh mutation results in a phenylalanine to serine substitution at amino acid 292 in both endothelin receptor type B (ETBR) isoforms; amino acid 292 is within the fifth transmembrane domain.

Please see the record gus-gus for more information on Ednrb.
Putative Mechanism

ET-associated signaling (ET-1/ETAR and ET-3/ETBR) is essential for neural crest (NC) cell proliferation, migration, differentiation, and transformation (3-5). The embryonic NC gives rise to pluripotent cells that migrate to different locations within the embryo during development (6). The NC cells subsequently differentiate into several cell types including adrenomedullary cells, craniofacial skeletal tissue, glia and some neurons of the peripheral nervous system, enteric neurons and glia, and melanocytes of the skin, hair and inner ear. ET-3/ETBR-associated signaling is required between embryonic day (E)10-E12.5 in the mouse for the survival and migration of enteric ganglion neurons and melanocytes derived from trunk/vagal NC cells (4;5;7-11). Other studies indicate that ETBR signaling may also stimulate melanocyte proliferation in the epidermis (11). Mice homozygous for targeted as well as naturally occurring Ednrb null mutations (e.g., MGI:1856148, MGI:1856149, MGI:1857161, and MGI:3795226) exhibit a piebald appearance due to the absence of NC-derived melanocytes in the epidermis (7;9;12-14). Ednrb null mice also exhibit an absence of choroidal melanocytes; neuroectoderm-derived pigment epithelium melanocytes develop normally (7). Ednrb null mice display early postnatal lethality [from ~postnatal day 15 to up to seven weeks after birth; (7;12;14)]. The sposh mice exhibit variable white belly spotting. The Ednrb knockout mouse models have established that the observed pigmentation defects are due to the absence of NC-derived melanocytes in the hair bulbs of non-pigmented areas (7;9;12-14).

Primers PCR Primer

Sequencing Primer

PCR program

1) 94°C 2:00
2) 94°C 0:30
3) 55°C 0:30
4) 72°C 1:00
5) repeat steps (2-4) 40x
6) 72°C 10:00
7) 4°C hold

The following sequence of 564 nucleotides is amplified (chromosome 14, - strand):

1   gtagatatgg cccacgaaac cctatacagt acatatatgg aagatgttac aaaataattg
61  tcctttgatg aatatggcat ttgtaattga catttgatac atatggggtt ttttaaagca
121 gaagatatta atcataaaaa ttctttcttc cccatagttt tacaagacag ccaaagattg
181 gtggctgttc agtttctact tctgcttgcc gctagccatc actgcagtct tttataccct
241 gatgacctgc gaaatgctca ggaagaagag cggtatgcag attgctttga atgatcactt
301 aaagcaggta agagaatgga agaagctagt agagtatagc cataattatg gtcagatcta
361 agtcatgatg atgatgatga catgatgatg atatgatgag ctaattttac acactagaac
421 atattttcac tttcttcatt ctgttcctgt aacaaaaaaa ttttatatta cttacttaga
481 gagtatatca tctataatga tctagagaga atcattgact tttgttgttg attcctttta
541 agatggaatc tcgattagcc tagg

Primer binding sites are underlined and the sequencing primers are highlighted; the mutated nucleotide is shown in red.

Science Writers Anne Murray
Illustrators Diantha La Vine
AuthorsLauren Prince, Jamie Russell, and Bruce Beutler