August 30, 2019

BCMB student highlight

Eugene Nyamugenda

Eugene is a Ph.D. Student in his 5th year in the Biochemistry and Molecular Biology Department in the laboratory of Dr. Giulia Baldini.

He has a B.A. in Biochemistry and Molecular Biology from Hendrix College.

Research Interest Statement

The hypothalamus plays a central role in maintaining healthy energy homeostasis. The arcuate nucleus (ARC) of the hypothalamus receives anorexigenic signals from the periphery mediated by increased circulating leptin and insulin, which bind to receptors expressed by proopiomelanocortin (POMC) neurons in the ARC. When activated, POMC neurons release α-Melanocyte stimulating hormone (α-MSH). In the paraventricular nucleus (PVN), α-MSH binds to the melanocortin-4 receptor (MC4R) to signal decreased food intake and increased energy expenditure. Single-minded-1 (Sim1) neurons in the PVN include the population of MC4R neurons. My research uses mice to study the effect of obesity by a high-fat (HF) diet on the PVN neurons expressing Sim1 transcription factor and MC4R.  When mice are fed HF diet, they have increased body weight as a result of increased caloric intake. We found that exposure to HF diet induces loss of Sim1 neurons in the PVN and, in male mice, loss of POMC neurons and α-MSH abundance.  Because there are no reliable commercial antibodies that can detect MC4R, we generated a knock-in mouse line expressing HA-tagged MC4R (MC4R-HA) by using CRISPR/Cas9 technology to detect MC4R protein. We found that HF diet induces injury to MC4R neurons in the PVN as indicated by loss of MC4R protein, decreased mitochondrial abundance, and mitochondrial network size. The data suggest that HF diet induces loss of MC4R protein rather than of MC4R neurons, suggesting that expression of MC4R could be a target for anti-obesity therapy.

Something Notable about Time as a Graduate Student

Overall my time in graduate school has been excellent. I would say that I happened to fall into the right group of people. The life lesson I learned is never to translate a joke. The chances are either the joke is not funny, none understands it, or you will offend someone.

Career Goals

I want to do a postdoctoral fellowship for a few years and look for opportunities in biotech and pharmaceutical companies.

Experiment or Technique You Would Most Like to Do

I like to do many experiments. I love making DNA constructs. It excites me. If my labmates wanted to subclone anything, I would volunteer to do it.

Fun fact

When I grew up, my mother treated every ailment with a specific type of food (she still does). When I got sick in boarding school, I asked permission to go home. She would cook food for me, and the next day I would feel better and go back to school. Food is still my over-the-counter medicine today.  If you see me sick, the first treatment to give me is food (enough of it).

Publications

Nyamugenda E, Cox AB, Pierce JB, Banning RC, Huynh ML, May C, Marshall S, Turkal CE, Duina AA. Charged residues on the side of the nucleosome contribute to normal Spt16-gene interactions in budding yeast. Epigenetics. 2018; 13(1):1-7. doi: 10.1080/15592294.2017.1418132. Epub 2018 Feb 8. PMID: 29271283

Nyamugenda E, Trentzsch M, Russell S, Miles T, Boysen G, Phelan KD, Baldini G. Injury to hypothalamic Sim1 neurons is a common feature of obesity by exposure to a high-fat diet in male and female mice. J Neurochem. 2019 Apr; 149(1):73-97. doi: 10.1111/jnc.14662. Epub 2019 Feb 11. PMID: 30615192

Awards

Rwanda Presidential Scholarship