Two proteins involved in oral taste detection have a crucial role in sperm development, say researchers.
"This paper highlights a connection between the taste system and male reproduction," lead author Bedrich Mosinger, MD, PhD, a molecular biologist at Monell Center, said.
"It is one more demonstration that components of the taste system also play important roles in other organ systems," Mosinger said.
While breeding mice for taste-related studies, the researchers discovered that they were unable to produce offspring that were simultaneously missing two taste-signaling proteins.
As reported the critical proteins were TAS1R3, a component of both the sweet and umami (amino acid) taste receptors, and GNAT3, a molecule needed to convert the oral taste receptor signal into a nerve cell response.
Breeding experiments determined that fertility was affected only in males. Both taste proteins had previously been found in testes and sperm, but until now, their function there was unknown.
In order to explore the reproductive function of the two proteins, the research team engineered mice that were missing genes for the mouse versions of TAS1R3 and GNAT3 but expressed the human form of the TAS1R3 receptor. These mice were fertile.
However, when the human TAS1R3 receptor was blocked in the engineered mice by adding the drug clofibrate to the rodents' diet, thus leaving the mice without any functional TAS1R3 or GNAT3 proteins, the males became sterile due to malformed and fewer sperm.
The research is published online in the Proceedings of the National Academies of Sciences.