Red cats are very present in our collective imagination, whether through Garfield or Azraël in The Smurfs. But the scientific community has long been unable to explain the genetic mutation responsible for their color. Two research teams, independent of each other, believe they have lifted the veil on this mystery.
In most mammals, including humans, red hair results from mutations in a protein called Mc1r. This protein tells melanocytes to produce either a dark pigment or a light pigment with red-yellow highlights. When it is less active, these pigment cells in the skin are limited to producing a light pigment with a red-yellow tint, thus giving rise to red hair.
But, in cats, the gene coding for the Mc1r protein does not appear to be the cause of their amber coat, with the majority of orange cats not having a mutation in the Mc1r protein. “It’s a genetic mystery, an enigma,” Greg Barsh, a professor of genetics and pediatrics at Stanford University, told Science magazine.
Professor Barsh and his colleagues attempted to understand the genetic mechanisms that give cats the ginger color by taking skin samples from eight cat fetuses, four orange and four non-orange, from sterilization clinics. By analyzing the RNA produced by melanocytes, researchers identified the genes activated in these cells. They noticed that the melanocytes of orange cats produced thirteen times more RNA coming from a specific gene, Arhgap36, located on the X chromosome. A discovery which could explain the origin of the orange color, as they explain in an article published on the prepublication platform bioRxiv.
However, when looking in more detail at the Arhgap36 gene, researchers found that it did not have any mutations that could account for the orange color of some cats. However, they identified an anomaly in a DNA sequence located just upstream of this gene, likely to influence the pigmentation of the skin or hair.
These results were corroborated by the team of Professor Hiroyuki Sasaki, from Kyushu University, who also highlighted the role of the Arhgap36 gene in the red coloring of the coat of certain cats. Although crucial, this discovery will need to be the subject of additional research. Either way, it helps to deepen our knowledge of these fascinating felines that are cats.
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