While cigarette smoking is a common-knowledge way to stay lean, it has long been known as a risk factor for diabetes and obesity. Here we establish that smoking causes fat gain and metabolic disruption in mice, effects which are exacerbated by a high-fat, high-sugar diet. We found that smoke exposure increases levels of ceramide—the lipid responsible for diet-induced insulin resistance—and that blocking ceramide production with the pharmacological inhibitor myriocin restored insulin sensitivity, stopped weight gain, and rescued mitochondrial respiration in vivo and in vitro.We also sought to assess the impact of the RAGE ligand HMGB1 on skeletal muscle metabolism. We found that respiration between vehicle and HMGB1-injected red gastrocnemius was comparable. In myotubes, adding myriocin treatment to the HMGB1 cells increased respiration above HMGB1 treatment alone. HMGB1 increased oxidative stress in cultured myotubes and increased the transcript levels of Spt2, the enzyme responsible for the rate-limiting step in ceramide synthesis, although transcript levels of markers of mitochondrial fission and fusion leave us unsure of HMGB1's impact on mitochondrial dynamics. HMGB1, even at an exceptionally low dose over only 2 weeks, did cause significant impairment in glucose and insulin tolerance tests. Considering HMGB1's accessibility as a therapeutic target, its involvement in metabolic disruption is worth pursuing further.
College and Department
Life Sciences; Physiology and Developmental Biology
BYU ScholarsArchive Citation
Thatcher, Mikayla Orton, "HMGB1 and Ceramides: Potential Mediators of Cigarette Smoke-induced Metabolic Dysfunction" (2015). Theses and Dissertations. 6041.
ceramide, HMGB1, RAGE, cigarette smoking, metabolic dysfunction, myriocin