PERFORM Colloquium: When a calorie is not a calorie

This talk will describe some of the history behind this field of research: some of the key discoveries, and some of the ongoing controversies. Then the mechanisms through which cellular energy substrate supply and oxidation are balanced, and how they become disordered in disease will be reviewed.

Discussion will be focused largely on tissues that have high metabolic flexibility, including skeletal muscle, brown adipose and cardiac muscle. The uncoupling of oxidative phosphorylation decreases fuel transduction efficiency (i.e., the cost of ATP synthesis) and reactive oxygen species (ROS) production. The costs and benefits of uncoupling will be discussed. An overview of the key findings in mouse models, and in our research with patients in the Ottawa Hospital Weight Management clinic will be reviewed.

Our research in obese diet-sensitive and obese diet resistant adults reveals that muscle structure and metabolic functions are distinctly different, and may in part explain differences in weight loss propensities on hypocaloric diets.

Find out more about the PERFORM Colloquium Series.

Speaker Bio

Dr. Mary-Ellen Harper is a Professor at the University of Ottawa in the Department of Biochemistry, Microbiology and Immunology since 2010. After doing a bachelor degree in Nutrition from the University of Guelph, Dr. Harper went on to do her PhD in biochemistry at the University of Ottawa. She did a first Post-Doctorate in Biochemistry at the University of Cambridge in Cambridge, England. She then did a second postdoctorate at the University of Ottawa in the Department of Biochemistry, Microbiology and Immunology. Presently, Dr. Harper has 135 peer-reviewed publications that have been cited over 8500 times. She recently served as the representative for Canada on the North American Obesity Society, and is currently a Board Member of the Canadian Obesity Network.

Research in Dr. Harper’s laboratory deciphers mechanisms through which cellular energy substrate supply and oxidation are balanced, and how they become disordered in disease. Research focuses mainly on processes in skeletal muscle, brown adipose and cardiac muscle - and mitochondrial events therein. The major phenomenon investigated is the uncoupling of oxidative phosphorylation, which impacts fuel transduction efficiency (i.e., the cost of ATP synthesis) and reactive oxygen species (ROS) production. The uncoupling of oxidative phosphorylation is also referred to as mitochondrial proton leak (or simply, leak), and it can occur through the activation of uncoupling proteins, through the adenine nucleotide translocator and through other as yet poorly understood mechanisms. Approaches and methods used in Dr. Harper’s laboratory spans from molecular in vitro studies, to mouse models, and to integrative studies in patient populations.

Read more about Dr. Harper.