A research group led by Professor Nakamura Motonao of Okayama University of Science has discovered for the first time in the world that bitter taste receptors identical to those found on the tongue are present in the keratinocytes of the skin and that they play an important role in detecting and expelling invading harmful substances.
Bitterness serves as a warning that a substance is harmful, and bitter taste receptors in the taste cells of the tongue detect harmful substances in food as bitter and reject them, preventing them from entering the mouth. However, harmful substances can enter the body not only through the mouth, but also through the skin.
Although we do not sense bitterness in the skin, bitter taste receptors are deployed in the keratinocytes, the first line of defense, to protect the body from harmful substances that enter the body. They are truly "gatekeepers" that protect the body. Bitter taste receptors are localized in the endoplasmic reticulum inside keratinocytes. These receptors are activated when they sense (bind to) harmful substances that have entered the keratinocyte, and they "turn on" the switch that activates the efflux pump, thereby expelling the harmful substances from the cell. This is the first time that we have clarified this series of biological defensive roles of bitter taste receptors in the skin.
Some harmful substances cannot be detected by bitter taste receptors, and in such cases the harmful substances accumulate inside cells, triggering skin disorders and inflammation. The results of this research suggest that such harmful substances accumulated inside cells can be expelled from the cells by artificially activating bitter taste receptors and turning on the excretion mechanism. Non-harmful drugs that can activate receptors are promising as skin protectants and anti-inflammatory drugs.
Paper information:[FASEB BioAdvances] Intracellular TAS2Rs act as a gatekeeper for the excretion of harmful substances via ABCB1 in keratinocytes
