An update on extra-oral bitter taste receptors

Abstract

Bitter taste-sensing type 2 receptors (TAS2Rs or T2Rs), belonging to the subgroup of family A G-protein coupled receptors (GPCRs), are of crucial importance in the perception of bitterness. Although in the first instance, TAS2Rs were considered to be exclusively distributed in the apical microvilli of taste bud cells, numerous studies have detected these sensory receptor proteins in several extra-oral tissues, such as in pancreatic or ovarian tissues, as well as in their corresponding malignancies. Critical points of extra-oral TAS2Rs biology, such as their structure, roles, signaling transduction pathways, extensive mutational polymorphism, and molecular evolution, have been currently broadly studied. The TAS2R cascade, for instance, has been recently considered to be a pivotal modulator of a number of (patho)physiological processes, including adipogenesis or carcinogenesis. The latest advances in taste receptor biology further raise the possibility of utilizing TAS2Rs as a therapeutic target or as an informative index to predict treatment responses in various disorders. Thus, the focus of this review is to provide an update on the expression and molecular basis of TAS2Rs functions in distinct extra-oral tissues in health and disease. We shall also discuss the therapeutic potential of novel TAS2Rs targets, which are appealing due to their ligand selectivity, expression pattern, or pharmacological profiles.

Extra-Oral Taste Receptors—Function, Disease, and Perspectives

“…Other tissues shown to express taste receptors are the reproductive tract ( 8 ), urethra ( 9 ), skin ( 10 – 12 ), brain ( 13 ), heart ( 14 , 15 ), pancreas ( 16 , 17 ) and blood cells ( 18 – 22 ). For the sake of space, we will focus in this mini-review on the gastrointestinal (GI) tract and refer the interested reader to a number of comprehensive recent review articles for further reading ( 23 – 25 ). Before discussing the function of taste receptors in the GI tract, we will briefly introduce the receptors, their signaling elements and cells in their “original” environment, the taste system.…”

“…The first hints that some of these responses may involve components of the taste transduction system came from the detection of α-gustducin, a Gα-subunit first identified in the rodent gustatory system ( 47 ), in brush cells of the stomach and small intestine ( 48 ). Nowadays, sweet, umami and bitter taste receptors and all canonical taste signaling components have been detected in GI tissues from stomach to colon ( 23 – 25 ). Moreover, a variety of GI cell types expressing the taste signaling molecules including enteroendocrine cells, brush cells, goblet cells, and Paneth cells have been discovered and nutrient sensing mechanisms involving taste-like signaling molecules were proposed ( 23 – 25 ).…”

“…Nowadays, sweet, umami and bitter taste receptors and all canonical taste signaling components have been detected in GI tissues from stomach to colon ( 23 – 25 ). Moreover, a variety of GI cell types expressing the taste signaling molecules including enteroendocrine cells, brush cells, goblet cells, and Paneth cells have been discovered and nutrient sensing mechanisms involving taste-like signaling molecules were proposed ( 23 – 25 ).…”

Diet and Respiratory Infections: Specific or Generalized Associations?

“…Many of these effects are likely mediated by caffeine’s ability to antagonize adenosine receptors [ 43 ]. Caffeine is also a ligand of several taste 2 receptor (TAS2R) subtypes, which mediate bitter taste perception but also have other newly realized roles in extra-oral physiological processes impacting respiratory health and both innate and adaptive immunity [ 44 , 45 ]. Coffee and tea also have unique profiles of other constituents that may impact immunity differently [ 46 , 47 , 48 ].…”

Correction to: An update on extra-oral bitter taste receptors

“…After publication of the original article [ 1 ] the authors noticed the following error: The author names were listed as “Tuzim Kamila and Korolczuk Agnieszka”. The correct author names are Kamila Tuzim and Agnieszka Korolczuk.…”