Evolution and Endocrinology

What can sharks and rays teach us about human hormones and stress response? Quite a lot, according to Robert Dores, a professor in DU’s Department of Biological Sciences.

In April, Dores will attend the Endocrine Society’s annual meeting in Orlando, Fla., to present research on evolutionary processes that resulted in cartilaginous fish possessing a hormone receptor with properties that are distinct from the corresponding receptors in humans and other bony vertebrates. Not only does the research add to our knowledge of evolution, it also could shine light on adrenal gland disorders and treatments.

“I always wanted to work on diverse groups of organisms, and endocrinology ties it all together,” Dores says. “It’s a complex field within physiology that requires you to be a puzzle solver.”

Dores has been studying endocrinology for more than 40 years. His focus is on a specific protein receptor, called MC2R, found in the adrenal gland. This protein enables the body to produce the hormone cortisol. When the body experiences different types of stress, the adrenal gland releases cortisol into the bloodstream, which enables physiological systems to return to equilibrium.

For MC2R to function, it must be expressed with an accessory protein. Bony vertebrates — a category that includes mammals, reptiles, amphibians and fish with skeletons of bone — are all dependent upon this accessory protein. Meanwhile, cartilaginous fish — which includes sharks and rays — do not require the accessory protein.

“During the evolutionary process, something happened on the bony fish line that didn't happen on the cartilaginous line,” Dores explains.

In his lab, Dores and a team of students use tissue culture procedures to study how MC2R reacts with the accessory protein and the mechanisms that allow the receptor to function.

Collaborating with students has long been one of his top priorities. With support from the Dewey L. and Deborah C. Long Endowment, Dores is able to guide undergrads through research projects that benefit his own research while providing exceptional learning experiences for students.

“I get the students involved in projects for which I’d like to know the answer, and it becomes a process of discovery for both of us,” Dores says. “I get to live out my research fantasies, and the students are totally engaged.”

Senior Alexa Thomas has been working in Dores’ lab since her sophomore year. She’s currently looking at protein receptors in chickens and rainbow trout to learn how they react with hormones.

“It’s like a lock and key system,” she explains. “The hormone fits into the receptor and opens the door, while the accessory protein affects how easily the key fits into the receptor.”

Thomas, who will attend medical school next year, likes the fact that the research is broad and expansive. “It’s really interesting to focus on one specific organism, such as a chicken, and study how its endocrine system works, because the same receptors are found in so many other organisms,” she says.

Megan Deyarmond, also a senior, will attend the Endocrine Society annual meeting to present her poster on MC2R in elephant sharks and stingrays. Like Thomas, she’s also headed to medical school next year.

She says that her experience working in the lab will benefit her path into medicine. “With endocrinology, you can focus on one organism and get to know it, but the research applies to other organisms. So it has applications to human health.”

Both students credit Dores for his ability as a mentor.

“I really like the fact that Dr. Dores doesn’t just give us things to do without making sure that we understand the research,” Deyarmond says. “He mentors us and helps us develop critical-thinking skills.”

A core mission of DU’s Division of Natural Sciences and Mathematics is to offer students unprecedented access to research opportunities. By working alongside distinguished faculty mentors in state-of-the-art facilities, undergraduate and graduate students are able to apply their knowledge to research that changes lives and challenges ideas.