The sense of taste is an important sensation that, along with sight, hearing, smell, and touch, constitutes the 'five senses.' Experiencing taste is directly linked to quality of life. This has been proven through research showing that eating delicious food triggers the release of a hormone called dopamine in the brain, which induces feelings of pleasure. It is no coincidence that one of Korea's traditional 'Obok (五福)'?the five blessings passed down orally?includes having strong teeth.
However, a person's sense of taste can decline due to aging or external factors such as illness, medication, or radiation therapy. A representative example is patients infected with COVID-19 who have experienced temporary loss of taste and smell. This loss of taste typically occurs due to the loss of taste receptor cells on the tongue. If these cells can be regenerated, the sense of taste can be restored. Recently, a domestic research team has attracted academic attention by uncovering the regeneration mechanism of taste receptor cells.
Professor Hanseong Jeong from the Department of Oral Biology at Yonsei University College of Dentistry, researcher Anish Adpaika, dental student Hyeyeon Cho, and Professor Jongmin Lee from the BK21 Creative Dental Convergence Education and Research Group recently revealed the regeneration mechanism of taste receptor cells, confirming new possibilities for treating taste loss.
The small projections on the tongue surface called papillae contain taste receptor cells that perceive taste. Groups of 50 to 150 of these cells form a taste bud. Within a single taste bud, some taste receptor cells detect sweet, bitter, and umami flavors, while others receive salty and sour tastes. Each cell has an average lifespan of about two weeks, and when they reach the end of their life, they are replaced by new cells in a lifelong regeneration process. However, this function can decline due to external factors or aging, causing an inability to properly perceive taste.
Previously, it was only known in academia that taste stem cells outside the taste buds express a gene called 'Lgr5' to regenerate taste receptor cells, and there were few studies fully elucidating the regeneration mechanism of taste receptor cells that cause taste function loss. The research team focused on whether there might be another regeneration mechanism for these taste receptor cells. To investigate this, they experimented to see if taste receptor cells inside the papillae could regenerate when the nerves outside the taste buds were damaged.
Professor Jeong Han-seong of the Department of Oral Biology, Yonsei University College of Dentistry, Researcher Anish Adpaika, Dental student Cho Hye-yeon, and Professor Lee Jong-min of the BK21 Creative Dental Convergence Education and Research Group (from left to right). [Photo by Yonsei Medical Center]
The research team severed the glossopharyngeal nerve, which controls taste, in experimental mice to remove taste buds and then observed the regenerating cells. As a result, they discovered a phenomenon called 'dedifferentiation,' where some of the remaining taste receptor cells in the papillae reverted to an early developmental stage to regenerate the taste buds. During this process, multiple proteins such as 'K14' were expressed, producing new taste receptor cells. This was the first confirmation of the existence of another type of cell involved in taste bud regeneration, in addition to the previously known taste stem cells that regenerate taste receptor cells.
Professor Hanseong Jeong stated, "We revealed that the 'dedifferentiation phenomenon' during the differentiation process of epithelial cells in the mouth induces cell regeneration," adding, "This is expected not only to improve treatment outcomes for patients with taste disorders but also to aid research on stem cell principles in other organs." This study was published in the international journal Experimental and Molecular Medicine (IF 12.172).
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