Expression and function of agouti signaling protein in cattle

ABSTRACT Agouti signaling protein (ASIP) is involved in the regulation of pigmentation in mammals by downregulating melanocortin 1 receptor (MC1R) activity. In wild type mice, ASIP is expressed in skin and testes. Widespread tissue expression of ASIP has been found in humans and cattle. Reverse transcription with subsequent real‐time polymerase chain reaction was used to measure ASIP expression levels in skin and five additional tissues from four cattle breeds. The expression of each sample was represented as a percentage of the expression of the housekeeping gene b‐actin . No significant difference was found in the expression levels in skin from Red Holstein, Simmental (red), Holstein (black) and Brown Swiss (brown/gray) breeds, which were all in the range of 0.2–0.3%. Expression in other tissues varied greatly between individuals, ranging from 196% in the heart of a Red Holstein animal to 0% in the liver samples of all four breeds. Additionally, we showed that expression of bovine ASIP in cell culture reduces cyclic adenosine monophosphate production in cells expressing MC1R, suggesting that bovine agouti is able to downregulate MC1R signaling.