The Hidden One: What We Know About Bitter Taste Receptor 39

Abstract

Over thousands of years of evolution, animals have developed many ways to protect themselves. One of the most protective ways to avoid disease is to prevent the absorption of harmful components. This protective function is a basic role of bitter taste receptors (TAS2Rs), a G protein-coupled receptor family, whose presence in extraoral tissues has intrigued many researchers. In humans, there are 25 TAS2Rs, and although we know a great deal about some of them, others are still shrouded in mystery. One in this latter category is bitter taste receptor 39 (TAS2R39). Besides the oral cavity, it has also been found in the gastrointestinal tract and the respiratory, nervous and reproductive systems. TAS2R39 is a relatively non-selective receptor, which means that it can be activated by a range of mostly plant-derived compounds such as theaflavins, catechins and isoflavones. On the other hand, few antagonists for this receptor are available, since only some flavones have antagonistic properties (all of them detailed in the document). The primary role of TAS2R39 is to sense the bitter components of food and protect the organism from harmful compounds. There is also some indication that this bitter taste receptor regulates enterohormones and in turn, regulates food intake. In the respiratory system, it may be involved in the congestion process of allergic rhinitis and may stimulate inflammatory cytokines. However, more thorough research is needed to determine the precise role of TAS2R39 in these and other tissues.

Tas2R signaling enhances mouse neutrophil migration via a ROCK-dependent pathway

“…Currently, little is known about Tas2R signaling ( 32 ). Our results indicate that arbutin facilitates neutrophil migration via a Tas2R126/143–ROCK2–MLC2 pathway, which is consistent with findings that bitter taste substances induce ROCK-dependent smooth muscle contraction and MLC phosphorylation in smooth muscle cells ( 26 , 27 ).…”

Improving taste sensitivity in healthy adults using taste recall training: a randomized controlled trial

“…Additionally, while olfaction can detect an object from an odor, taste identifies the tastes of various raw materials as similar taste qualities 25 , 26 . Moreover, while humans have about 400 odorant receptor genes, there is almost one type of sensor for sweetness, umami, sourness, saltiness, and about 25 types of sensors for bitterness 27 , 28 . Since taste is thus identified by a small number of types of sensors on the surface of the tongue, it is difficult for the tongue to identify a huge variety of foods in detail with such a small number of sensors.…”

The roles of type 1 and type 2 taste receptors in bone remodeling: A literature review

“…ATP, released from the taste cells as a neurotransmitter, activates afferent nerves, resulting in the perception of taste in the brain. 7,11,13,22 In addition, we can assume that the Ca 2+ -mediated response pathways may regulate cell differentiation in several cells including bone cells, although it has not been confirmed and further investigation is needed.…”