Xin Wan, University of Utah
Life Sciences
Endothelial dysfunction exists in individuals with diet-induced obesity (DIO) and type 2 diabetes (T2DM). Markers of endothelial dysfunction include reduced phosphorylation (p) of endothelial nitric oxide (NO) synthase (eNOS) to total eNOS (p-eNOS:eNOS), and attenuated endothelium-dependent vasorelaxation. Free fatty acids (FFAs) are elevated in individuals with DIO and T2DM. Our laboratory has shown that when: (i) endothelial cells are incubated with saturated FFA palmitate; (ii) mice are infused with lard-oil; and/or (iii) when mice are fed with high-fat diet, protein phosphatase 2A (PP2A) binds directly with eNOS. When this occurs, the association among Akt-Hsp90-eNOS is disrupted, p-eNOS:eNOS is impaired, and endothelium-dependent dysfunction occurs. This is prevented using pharmacological and genetic approaches that limit production of FFA metabolite ceramide. It is unknown whether PP2A inhibition per se is protective. We hypothesized that arterial dysfunction in obese vs. lean mice is prevented by PP2A inhibition. Seven-week-old, male, C57B16 mice consumed standard (CON, n=20) or high-fat (HF, n=20) chow for 12-weeks. Subgroups (n=10) of CON and HF mice received IP injections of saline (vehicle; V) or Lixte Biotechnology 100 (LB1, 1 mg/kg/day) for the last 14-days. Preliminary experiments verified that LB1-treatment for 3 and 21 days decreases (p<0.05) arterial PP2A activity. HF mice gained weight and developed peripheral glucose intolerance vs. CON mice regardless of LB1 treatment. Endothelium-dependent vasorelaxation was impaired (p<0.05) in HF-V vs. CON-V mice, but dysfunction was less severe (p<0.05) in HF-LB1 mice. p-eNOS:eNOS was reduced (p<0.05) in arteries from HF-V vs. CON-V mice, but p-eNOS:eNOS was similar in arteries from HF-LB1 and CON-LB1 mice. Akt and Hsp90 co-immunoprecipitation with eNOS was impaired (p<0.05) in HF-V vs. HF-CON mice, but this was not observed in arteries from HF-LB1 and CON-LB1 mice. These findings suggest that PP2A activity suppression in vivo is sufficient to preserve endothelial function in obese mice.