Lean Phenotype Induced by Methionine Restriction in Mice is Associated with Proteomic Changes in Perivascular Adipose Tissue

Perivascular adipose tissue (PVAT) surrounds blood vessels, is thermogenic, and secretes adipokines that can be vasoprotective. During aging and obesity, PVAT loses its thermogenic capacity, shows increased inflammation, and secretes proatherogenic cytokines. Our collaborative research has previously shown that dietary methionine restriction (MetR) in mice can decrease adiposity, improve glucose sensitivity, and induce PVAT to become more thermogenic. To identify initiating signals from PVAT that correspond to thermogenic conversion, we challenged male C57BL/6 mice with a high fat diet (HFD, 60 kcal% fat, 0.86% methionine) until they weighed \u3e45g (~12 weeks of age). Weight matched mice were then either maintained on this diet or switched to a high fat, methionine restricted diet (60 kcal% fat, 0.12% methionine). We collected PVAT after 3, 5, or 10 days, and analyzed tissues by mass spectrometry using Sequential Window Acquisition of all Theoretical Spectra (SWATH) to identify proteomic signatures. When compared to control, PVAT from methionine restricted conditions exhibited significant differences (p\u3c0.05) in 624, 313, and 502 proteins on days 3, 5, and 10 respectively. Overall, we observed a significant increase in proteins involved in mitochondrial network formation, such as GRP75, a heat-shock protein that our previous data indicate may be a potentially novel thermogenic marker in PVAT. Our study identifies unique protein signatures that are responsive to dietary methionine concentration and are associated with a lean phenotype, despite a HFD. These profiles can be used to identify pathways that may initiate the thermogenic phenotype in PVAT, which is predicted to suppress cardiovascular disease