A better bitter blocker: Dr. Prashen Chelikani’s research into taste & chemical-sensing receptors

When Dr. Prashen Chelikani talks about bitterness, he’s not referring to the emotion. Rather, the UofM professor of Oral Biology in the Dr. Gerald Niznick College of Dentistry is speaking about one of the five senses; specifically, taste. Science has shown that humans can detect five basic tastes:  sweet, sour, salt, umami and bitter. Of these five, Chelikani has chosen to focus on bitter sensation, and its’ unique role in humans.

“Sensing bitterness is considered a survival response, as some of the natural and plant-derived toxins taste very bitter. The bitter sensation is detected by bitter taste receptors present predominantly on the tongue. It enables humans to distinguish bitter molecules from nutritionally important substances such as sugars (detected by sweet and umami taste receptors) present in food. Therefore, it is not surprising that there are 25 bitter taste receptors (Type 2 Receptors, or T2Rs) in humans to detect bitterness, while there are only three taste receptors (Type 1 Receptors, or T1Rs) to detect energy-rich sweet and umami compounds.”

“Taste” is actually a misnomer for these receptors, as research has shown that T2Rs are found throughout the body, acting as “chemical sensing” receptors. In the lungs, they detect bitter compounds including nicotine (from cigarette smoke) and bacterial signals to cause protective reflexes, and in certain scenarios help to relax the airways. In the gut, they stimulate the release of peptides that tell the stomach wall how hard to contract, intestinal cells how well to absorb nutrients, and brains how full we feel.

Chelikani’s team is studying the role of genetic variations in T2Rs, which are associated with diseases such as cystic fibrosis, rheumatoid arthritis, breast cancer and early childhood tooth decay. Additionally, Chelikani wants to find a way to manipulate T2R’s so as to control the strength and duration of their signal. He and his team are trying to discover substances that will bind to T2Rs and block signals to the brain that allow the perception of bitterness. The discovery would mean the creation of better bitter taste blockers, which are regarded by many in today’s global food industry as the ultimate discovery in taste research. They would allow manufacturers to alter their current methods of blocking bitter taste:  adding large quantities of sugar or multiple chemical blockers.

Due to the great interest in his research, Chelikani has become a popular source for various media outlets over the past few years, especially as an expert opinion on the subject. In May 2018, his team’s paper (published in the American Chemical Society’s Journal of Agricultural and Food Chemistry) garnered much attention for its’ description of the discovery of peptides acting as blockers of bitter receptors.  A dozen news outlets from America to Asia picked up the article, entitled “Beef Protein-Derived Peptides as Bitter Taste Receptor T2R4 Blockers”. Other publications including Maclean’s, WIRED and Metronews also contacted Chelikani for his expert opinion on taste research.

It’s certainly a far cry from his early days at the U of M, when Chelikani arrived in Winnipeg from Vishakhapatnam, India to pursue his PhD. Under the supervision of Dr. Peter Loewen, then Head of the Department of Microbiology, Chelikani learned from his advisor’s example of hard work and passion for research. It was also during that period that he and his fellow grad students bonded over their shared love of the outdoors: “The annual Micro graduate student camping and canoe trips in the Whiteshell [were a highlight]. Each summer, 15-20 graduate students in Micro used to go on a two-day camping and canoeing trip … I really miss those fun times.”

After completing his doctorate, he moved to the Massachussetts Institute of Technology in late 2003 to pursue a post-doc in the lab of Nobel Laureate Dr. Gobind Khorana, whose work in the field of biochemistry Chelikani found truly inspiring. Khorana’s failing health and resultant lab closure forced Chelikani to move yet again in 2007, but not before gaining valuable experience from the distinguished and visionary researcher. 

In 2007, Chelikani moved back to Winnipeg, taking up an assistant professorship in the Department of Oral Biology. After initially applying for grants on B2-AR, he switched focus to his current area of research on T2Rs. Since that time, he has received a variety of prestigious awards, including the Allen Rouse Basic Science Career Award from the Manitoba Medical Service Foundation, the Dean’s Graduate Teaching Award from the Faculty of Dentistry and a New Investigator Award from the Heart and Stroke Foundation of Canada. In 2015, he founded the Manitoba Chemosensory Biology (MCSB) Research Group, whose goal is to bring together researchers in Manitoba with common interests in studying the human chemical senses.

Over the past decade, he and his lab have made great progress in gaining a clearer understanding of bitter taste signal transduction in humans. Chelikani credits his team of “talented, motivated and highly productive” grad students and post-docs, for inroads made in such varied disciplines as pharmacology, physiology, nutritional sciences, microbiology and biochemistry. “Busy” doesn’t do justice to describe Chelikani’s life right now.

“In Winnipeg, we just started a CIHR funded study to look at how genetic variants in T2Rs influence the oral microbiome and oral health in children (currently recruiting 800 children), and in adults with rheumatoid arthritis.”

When asked what he enjoys most about his profession, this expert on bitterness isn’t short on sweet answers:

“Discovering, or trying to discover new things. Training students, fellows, talking to them and sharing my experiences. Writing grants and manuscripts (sometimes reviewing, too). Learning from colleagues. Most importantly, the opportunity and freedom to do all these.”

By Jo Davies

2019 Faculty of Science Alumni Awards Event

Recognizing graduates who have made remarkable contributions to discovering the unknown, inventing the future, and advancing the well-being of society.

January, 31, 2019
Marshall McLuhan Hall (University Centre)
University of Manitoba, Fort Garry Campus
3:30 pm- 5:00 pm

The event includes a Careers in Science Panel Discussion and Q&A where our distinguished guests will share their experiences and offer advice to students about selecting areas of study, navigating career paths, and using their degrees in sometimes unconventional ways.

A reception will follow. Everyone is welcome to attend.