Phenotypic Mutation 'garfield'

• Allele: garfield
• Chromosome: 2
• Gene: a
• Gene Name: nonagouti
• Synonym(s): agouti, As, ASP, agouti signal protein
• Chromosomal Location: 154,792,519-154,892,932 bp (+) (GRCm39)
• MGI Phenotype: FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] In mice, the agouti gene encodes a paracrine signaling molecule that causes hair follicle melanocytes to synthesize pheomelanin, a yellow pigment, instead of the black or brown pigment, eumelanin. Pleiotropic effects of constitutive expression of the mouse gene include adult-onset obesity, increased tumor susceptibility, and premature infertility. This gene is highly similar to the mouse gene and encodes a secreted protein that may (1) affect the quality of hair pigmentation, (2) act as a pharmacological antagonist of alpha-melanocyte-stimulating hormone, (3) play a role in neuroendocrine aspects of melanocortin action, and (4) have a functional role in regulating lipid metabolism in adipocytes. [provided by RefSeq, Jul 2008] ; PHENOTYPE: Agouti acts in the hair follicles, primarily affecting the relative amount and distribution of yellow pigment (phaeomelanin) and black pigment (eumelanin) in hairs of the coat. Some alleles show lethal effects or are associated with obesity. [provided by MGI curators]
• Mapped: No
• Institutional Source: Beutler Lab
• Ref Sequences:
  Ensembl: ENSMUSP00000105319
• Gene Model: not available
• AlphaFold: Q03288
• Meta Mutation Damage Score: Not available
• Is this an essential gene?: Probably nonessential (E-score: 0.213)
• Phenotypic Category: Unknown
• Mode of Inheritance: Unknown
• Local Stock: Sperm
• Last Updated: 2021-10-06 11:53 AM by Diantha La Vine
• Record Created: unknown
• Record Posted: 2014-05-22
• Science Writers: Anne Murray
• Illustrators: Peter Jurek
• Authors: Celine Eidenschenk, Bruce Beutler

Accession Number

NCBI RefSeq: NM_015770; MGI:87853

Alleles Listed at MGI

All alleles(401) : Targeted(1) Gene trapped(296) Spontaneous(58) Chemically induced(16) Radiation induced(30) Other(1)

Repository

none

Phenotypic Description

The index garfield mouse is a female that arose within the stock of the MCMV-susceptible aki strain. The mouse has a brownish coat color (instead of black) and lighter pigmentation ventrally (Figure 1).

Nature of Mutation

The coat color phenotype of garfield mice strongly suggested a mutation of agouti; this has not been verified by complementation testing and the nature of the mutation is not known.

Protein Prediction

Figure 2. The domain structure of agouti signaling protein (ASP). ASP has a cleavable signal peptide (SIG; amino acids 1-22), a hydrophobic region (HYD; amino acids 40-50), a lysine/arginine-rich basic domain (BASIC; amino acids 57-85), and a cysteine-rich C-terminus (CYS; amino acids 92-131). Asparagine 39 is predicted to be N-linked glycosylated. Regions 1, 2 and 3 are described on the yellowbelly page.

The agouti (a; alternatively, nonagouti) gene encodes the 131-amino acid secreted agouti signaling protein (ASP) (Figure 2). ASP functions in pigment type switching in melanocytes by inhibiting the function of the melanocortin 1 receptor (MC1R), subsequently promoting the production of pheomelanin (red/yellow pigment).

For more information about a, please see the record yellowbelly.

Putative Mechanism

The garfield mice exhibit a similar phenotype to the tanoid mouse (a^td ; MGI:1855942), with flecked brown dorsal hair and abnormal (tan) ventral coat pigmentation (1). The belly color phenotype of the a^td mouse is similar to the black and tan model (a^t; MGI:1855941); most a expression in the a^t  mouse is controlled by regulatory elements that direct ventral expression of a. We predict that the garfield mutation permits ventral-specific expression of a, but that dorsal expression normally regulated by a hair cycle-specific promoter is moderately impaired, resulting in residual a expression to give brown hair.

Primers

Primers cannot be located by automatic search.

References

1. Loosli, R. (1963) Tanoid--a New Agouti Mutant in the Mouse. J. Hered. 54, 26-29.