how does agouti gene work

Full Answer

What is the agouti gene in horses?

Phenotype: The agouti gene controls the distribution of black pigment, and determines whether a horse will have a bay or black base coat color. Alleles: A = Dominant agouti allele (responsible for bay), a = Recessive agouti allele (causes black)

What is the function of the Agouti signaling protein?

The agouti signaling protein interacts with the melanocortin 1 receptor to switch between black and red pigments, creating a banding pattern in individual hairs. Mutations in the agouti signaling protein gene (ASIP) prevent this switch from occurring, resulting in hairs of uniform color.

What is agouti and how does it work?

Agouti works with extension to regulate the color of melanin which is produced in hairs. The agouti protein causes red to yellow pheomelanin to be produced, while the competing molecule α-MSH signals production of brown to black eumelanin.

What does it mean when a mouse is agouti?

All mammals have a gene called agouti. When a mouse's agouti gene is completely unmethylated, its coat is yellow and it is obese and prone diabetes and cancer. When the agouti gene is methylated (as it is in normal mice), the coat color is brown and the mouse has a low disease risk.

What is the function of the agouti gene?

The agouti (a ) gene normally functions to control the differential production of melanin pigments in the skin that gives rise to the true wild-type coat color of mice.

How is the agouti gene regulated?

The Agouti gene in mice controls hair color and is under the control of a developmentally regulated hair cycle-specific promoter in exon 2. As a result, the gene switched ON at a specific time during hair follicle cell development to produce an agouti coat with a yellow stripe in otherwise dark hair [162].

How does the agouti gene work in horses?

“The agouti gene determines where the black will appear on the horse. A dominant agouti means that the black will be restricted to the points—tail, ears, mane—and the body of the horse will likely be a brown color. This color combination is called a bay.

How is agouti fur inherited?

Cats with A/a genotype will have agouti banded hair. They will transmit this agouti variant to 50% of their offspring, and the offspring of an A/a genotype cat can be agouti or non-agouti depending on the genotype of the mate. Cats with a/a genotype will have self-colored (solid) hair.

Do humans have agouti?

The human agouti gene, named Agouti Signaling Protein (ASP), encodes a 132 amino acid protein, the mRNA for which is expressed in testis, ovary, and heart, and at lower levels in liver, kidney, and foreskin.

Which allele is responsible for agouti coat Colour?

The Agouti has two alleles “A” Agouti, and “a” non-Agouti. Dominant “A” produces the banding of hair we recognize as Agouti. Recessive “a” produces solid colored hairs. Many coat color mutations appear in Agouti rats bred in captivity: albino, black, hooded, and others.

Can a black horse carry agouti?

The agouti (allele A) is a modifier that regulates the distribution of black pigment. Put simply, it limits the black on a black horse to the points (ears, legs, mane, and tail). A red based horse (see "color recipes") can carry the agouti without showing it, as the agouti does not affect red pigment.

Is agouti dominant in horses?

Agouti (Bay/Black) The dominant allele A restricts black pigment to the points of the horse (mane, tail, lower legs and ear rims), as seen, for example, in bays and buckskins.

How do you tell what colour your foal will be?

Making an Educated Guess on Foal Coat ColorFor the most basic colors – such as sorrel or chestnut, bay, palomino or black – guessing is fairly simple. Check the Color-Cross Chart to find the color possibilities for your foal.The parent's specific genetic makeup will make a difference in what colors it can produce.

Are all tabby cats agouti?

All cats have a tabby pattern! Right, but while they are not agouti (they don't have any agouti hairs), they still genetically carry a tabby pattern! In fact, there are different genes at play in tabby cats: one that determines if the cat is agouti or solid, and others that determine the tabby pattern of the cat.

What is the agouti gene in dogs?

The agouti gene (A Locus) determines the base coat color in dogs that are ky/ky for dominant black. Dogs must be ky/ky in order to express any alleles on the A locus. The color of the dog can still be modified by other genes, such as by the B locus or D locus, however.

What dogs have agouti?

It's a gene inherited from the wolf, and can be seen on many breeds which are considered to be close to wolves (e.g. Czech Wolfdogs, Saarloos Wolfhonds), as well as some Northern spitz-type breeds (Keeshond, Elkhound). In its normal form, agouti can be very similar to shaded sable.

What effect does methylation or non methylation have on the agouti gene?

Expression of agouti is regulated through methylation of nine CpG sites within its promoter; increased methylation silences expression, while decreased methylation promotes transcription. The readout of expression is simply the coat color of the mouse.

What is the gene that is permanently on in the obese rats?

Abstract. A responsible gene of genetically obese (ob/ob) mouse has recently been isolated. Genetic disruption of ob gene causes massive obesity. To elucidate the pathophysiological regulation of ob gene, we examined the gene expression in fat tissues of a non-genetical obese model, VMH-lesioned rats.

What causes agouti mice?

Transient A expression in hair follicles during a specific stage of hair growth results in a sub-apical yellow band on each black hair shaft, causing the brown agouti coat color of wild-type mice.

What can be deduced about the effect of DNA methylation levels on expression of the agouti gene?

What can be deduced about the effect of DNA methylation levels on expression of the Agouti gene? Greater levels of methylation resulted in darker coat color.

What gene controls the color of a horse's base coat?

The agouti gene controls the distribution of black pigment, and determines whether a horse will have a bay or black base coat color. Horse with bay coat color. Phenotype: The agouti gene controls the distribution of black pigment, and determines whether a horse will have a bay or black base coat color. Mode of Inheritance: Autosomal dominant.

What is the gene for black horses?

Breeders interested in producing black horses need to have breeding stock carrying the a allele, in addition to the E allele of the Extension gene . Testing for the agouti gene allows breeders to identify animals that carry or have two copies of the recessive (a) allele and can transmit this allele to produce offspring with a black base coat.

Which allele is unable to restrict pigment to the points of the horse?

The dominant agouti allele (A) functions normally to restrict black pigment to the points of the horse, and the recessive (a) allele is unable to restrict pigment to the points of the horse and results in a uniform distribution of black pigment across the body.

What mutation causes black horses?

The mutation causing an all black phenotype is an 11 base pair deletion in exon 2 of the gene agouti-signaling protein (abbreviated as ASIP but also commonly called agouti for short). This deletion is notated as (c.191_201del). This mutation is considered to be a loss of function mutation, meaning that the recessive (a) allele causes the resulting protein to be non functional. The dominant agouti allele (A) functions normally to restrict black pigment to the points of the horse, and the recessive (a) allele is unable to restrict pigment to the points of the horse and results in a uniform distribution of black pigment across the body. Breeders interested in producing black horses need to have breeding stock carrying the a allele, in addition to the E allele of the Extension gene.

Where is the mouse agouti gene located?

The mouse agouti gene is found on chromosome 2.

When did Agouti first appear?

The nonagouti allele is estimated to have first appeared before 1700. Agouti is linked to the wideband gene, with about a 30% crossover rate. Like white bellied agouti mice, rabbits with wildtype agouti produce transcripts with different untranslated 5' ends that have different dorsal and ventral expression.

What does Agouti A look like?

Agouti A looks like AW but the belly is dark like the back. Black and tan at causes a black back with a tan belly. A/at heterozygotes look like AW mice. Nonagouti a mice are almost completely black, with only a few yellow hairs around the ears and the genitals.

What protein causes red to yellow pheomelanin?

The agouti protein causes red to yellow pheomelanin to be produced, while the competing molecule α-MSH signals production of brown to black eumelanin. In wildtype mice, alternating cycles of agouti and α-MSH production cause agouti coloration.

Is Ay dominant or heterozygous?

Ay is incompletely dominant to at, so that heterozygous individuals have more black sabling, especially as puppies and Ayat can resemble the awaw phenotype. Other genes also affect how much black is in the coat.

Who discovered the A gene?

In 1951, zoologist Miguel Odriozola published "A los colores del caballo" in which he suggested four possible alleles for the "A" gene, A+, A, At, and a, in order of most dominant to least. This was accepted until the 1990s, when a new theory became popular.

Is Extreme Nonagouti ae black?

Extreme nonagouti ae mice are fully black, and is recessive to all other alleles in the series.

What is the phenotype of non-agouti cats?

Phenotype: Non-agouti cats do not have alternating pigments in their hair and appear solid aka self-colored. Mode of Inheritance: Autosomal recessive. Alleles: A = agouti, a = non-agouti. Breeds appropriate for testing: Most breeds.

What protein is responsible for the hair color of non-agouti cats?

Quick Summary. The agouti signaling protein interacts with the melanocortin 1 receptor to switch between black and red pigments, creating a banding pattern in individual hairs. Mutations in the agouti signaling protein gene (ASIP) prevent this switch from occurring, resulting in hairs of uniform color. Phenotype: Non-agouti cats do not have ...

Can a non-agouti be a homozygous?

Offspring can be agouti or non-agouti depending on the genetics of the mating. a/a. Homozygous for non-agouti (solid colored). If bred to a non-agouti, only non-agouti offspring will be produced.

How many amino acids are in the agouti protein?

The primary amino acid sequence of the agouti protein was predicted from the nucleotide sequence of the cDNA. The agouti protein is 131 amino acids in length and contains four noteworthy features: 1 ) an amino-terminal signal presequence that is important for entry into the secretory pathway, 2 ) a central region where 16 out of 29 amino acids are basic arginine or lysine residues, 3 ) a poly-proline stretch that follows the basic region, and 4 ) a cysteine-rich carboxy-terminal domain. The carboxy-terminal domain was shown to be as biologically active as the full-length protein in cell-based in vitro assays ( Kiefer et al. 1997, Willard et al. 1995 ). The most remarkable feature of the carboxy-terminus is that the 10 cysteine residues are spaced similarly to the conserved ordering of cysteines in a large group of neurotoxins found in the venom of the primitive hunting spiders and cone snails (reviewed in Olivera et al. 1994 ). Direct analysis of the cysteine oxidation state in recombinant agouti protein indicates that all 10 cysteines are disulfide bonded in a pattern ( Willard et al. 1995) that is consistent with the pattern of disulfides in the agatoxins ( Olivera et al. 1994 ).

How many alleles are there in the mouse agouti locus?

Molecular genetic characterization of six recessive viable alleles of the mouse agouti locus.

What enzymes are involved in de novo fatty acid synthesis and desaturation?

Additional analysis of the yellow agouti mutants revealed that the expression of two key enzymes involved in de novo fatty acid synthesis and desaturation, fatty acid synthetase (FAS) and stearoyl-CoA desaturase were elevated in the liver and adipose tissue ( Jones et al. 1996 ). Similarly, recombinant agouti protein stimulates both the expression and activity of FAS and causes an increase in triglyceride accumulation in 3T3-L1 adipocytes. This effect can either be completely prevented by Ca 2+ channel blockade ( Jones et al. 1996) or mimicked with Ca 2+ agonists ( Zemel et al. 1995a ), suggesting that alterations in Ca 2+ influx, without complementary alterations in Ca 2+ efflux, may mediate these lipogenic effects of agouti. The soleus muscle of Avy mice also exhibited an elevation in steady-state levels of intracellular free Ca 2+ and increases in Ca 2+ influx rate ( Zemel et al. 1995b ). A similar effect has been observed in both primary and cultured skeletal myocytes after treatment with recombinant agouti protein. These findings suggest that perturbations in calcium signaling and calcium homeostasis by extracellular agouti protein may contribute substantially to the insulin resistance and lipogenic bias in the yellow obese mice. Possible mechanisms include a G-protein–mediated coupling between melanocortin receptors and Ca 2+ channels, direct stimulation of Ca 2+ channels by extracellular agouti protein, or an indirect effect on Ca 2+ channels by blocking voltage-gated or ATP-gated potassium channels.

How early can you get hyperinsulinemia in Avy mice?

Hyperinsulinemia is evident in Avy mice at ∼6 wk of age (compared with 10 and 15 d for Leprdb and Lepob mutant mice, respectively) ( Frigeri et al. 1983 ), and can become as high as 20-fold over lean controls by 6 mo of age ( Gill and Yen 1991 ). Because insulin promotes nutrient partitioning into adipose tissue and stimulates adipocyte growth and development (reviewed in Bray 1996 ), the hyperinsulinemia in the yellow agouti mutants may contribute to their obesity and possibly to other traits of the pleiotropic syndrome ( Wolff et al. 1986 ). A positive temporal relationship has been established between the hyperinsulinemia and the activity of hepatic lipogenic enzymes in yellow Avy / a mice ( Yen et al. 1976 ), and pancreatic β-cell hyperplasia is evident in Avy males at 21 d of age before any detectable weight gain or changes in insulin or glucagon levels ( Warbritton et al. 1994 ). However, the relationships among hyperinsulinemia, insulin resistance and obesity are complex; currently, it is not possible to attribute the obesity in the yellow agouti mutants to the hyperinsulinemia alone (reviewed in Yen et al. 1994 ).

What is the long-range restriction map surrounding the mouse agouti locus?

The long-range restriction map surrounding the mouse agouti locus reveals a disparity between physical and genetic distances.

What mutation is associated with the pleiotropic phenotype of mice?

Molecular basis of the pleiotropic phenotype of mice carrying the hypervariable yellow ( Ahvy) mutation at the agouti locus.

What receptors are disrupted in obesity?

Targeted disruption of the melanocortin-4 receptor results in obesity in mice.

How does the epigenome help us?

Formed through a lifetime of experiences beginning in the womb, our epigenome may provide a wealth of information about how to eat better. Enter the future field of nutrigenomics, where nutritionists take a look at your methylation pattern and design a personalized nutrition plan. While we're not quite to that point yet, your doctor can already tell a lot about the your disease risk by looking at your family health history.

What is the pathway that extracts nutrients from food?

The nutrients we extract from food enter metabolic pathways where they are manipulated, modified, and molded into molecules the body can use. One such pathway is responsible for making methyl groups - important epigenetic tags that silence genes.

What is the key gene in royal jelly?

In a series of experiments, scientists determined that royal jelly silences a key gene ( Dnmt3 ), which codes for an enzyme that silences a group of queen genes. When Dnmt3 is turned "on," the queen genes are epigenetically silenced, and the larvae develop into the default "worker" variety. But when royal jelly turns Dnmt3 "off," the queen genes jump into action, turning the larvae into queens.

What are the components of the methyl-making pathway?

Familiar nutrients like folic acid, B vitamins, and SAM-e (S-Adenosyl methionine, a popular over-the-counter supplement) are key components of this methyl-making pathway. Diets high in these methyl-donating nutrients can rapidly alter gene expression, especially during early development when the epigenome is first being established.

How does diet affect epigenome?

Your mother's diet during pregnancy and your diet as an infant can affect your epigenome in ways that stick with you into adulthood. Animal studies have shown that a diet with too little methyl-donating folate or choline before or just after birth causes certain regions of the genome to be under-methylated for life.

Does BPA cause agouti?

In the laboratory, BPA appears to reduced methylation of the agouti gene. In the strain of mice that was studied, yellow mothers give birth to pups with a range of coat colors from yellow to brown. When mothers were fed BPA, their babies were more likely to be yellow and obese—like the one shown on the left.

What is the role of the agouti gene in hair?

In mice, the agouti gene encodes a paracrine signalling molecule that causes hair follicle melanocytes to synthesize the yellow pigment pheomelanin 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 an inverse agonist 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.

What is the function of Agouti?

It is responsible for the distribution of melanin pigment in mammals. Agouti interacts with the melanocortin 1 receptor to determine whether the melanocyte (pigment cell) produces phaeomelanin (a red to yellow pigment), or eumelanin (a brown to black pigment). This interaction is responsible for making distinct light and dark bands in the hairs ...

What would happen if the same mother had eaten a methyl-rich diet supplemented with zinc, vitamin?

If the same mother had eaten a methyl-rich diet supplemented with zinc, vitamin B12, and folic acid then the offspring's agouti gene would likely become methylated, it wouldn't be expressed , and the coat color would be brown instead.

What is the epigenetic state of an IAP?

The epigenetic state of the IAP element is determined by the level of methylation, as individuals show a wide range of phenotypes based on their degree of DNA methylation.

What is the yellow vy mutation?

The viable yellow (A vy) mutation is due to a change in the mRNA length of agouti, as the expressed gene becomes longer than the normal gene length of agouti. This is caused by the insertion of a single intracisternal A particle (IAP) retrotransposon upstream to the start site of agouti transcription.

What is the cause of the yellow mutation?

The lethal yellow (A y) mutation is due to an upstream deletion at the start site of agouti transcription. This deletion causes the genomic sequence of agouti to be lost, except the promoter and the first non-encoding exon of Raly, a ubiquitously expressed gene in mammals.

What is the aguouti signaling protein?

From Wikipedia, the free encyclopedia. Agouti-signaling protein is a protein that in humans is encoded by the ASIP gene. It is responsible for the distribution of melanin pigment in mammals. Agouti interacts with the melanocortin 1 receptor to determine whether the melanocyte (pigment cell) produces phaeomelanin (a red to yellow pigment), ...

Overview

Mice

Dogs

Cats

Horses

Rabbits

Further reading