AUTHOR=Kurgan Nigel , Baranowski Bradley , Stoikos Joshua , MacNeil Adam J. , Fajardo Val A. , MacPherson Rebecca E. K. , Klentrou Panagiota 

TITLE=Characterization of sclerostin’s response within white adipose tissue to an obesogenic diet at rest and in response to acute exercise in male mice

JOURNAL=Frontiers in Physiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.1061715

DOI=10.3389/fphys.2022.1061715

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> It is well established that sclerostin antagonizes the anabolic Wnt signalling pathway in bone, however, its physiological role in other tissues remains less clear. This study examined the effect of a high-fat diet (HFD) on sclerostin content and downstream markers of the Wnt signaling pathway (GSK3β and β-catenin) within subcutaneous inguinal white adipose tissue (iWAT), and visceral epididymal WAT (eWAT) depots at rest and in response to acute aerobic exercise.</p><p><bold>Methods:</bold> Male C57BL/6 mice (<italic>n</italic> = 40, 18 weeks of age) underwent 10 weeks of either a low-fat diet (LFD) or HFD. Within each diet group, mice were assigned to either remain sedentary (SED) or perform 2 h of endurance treadmill exercise at 15 m min<sup>−1</sup> with 5° incline (EX), creating four groups: LFD + SED (<italic>N</italic> = 10), LFD + EX (<italic>N</italic> = 10), HFD + SED (<italic>N</italic> = 10), and HFD + EX (<italic>N</italic> = 10). Serum and WAT depots were collected 2 h post-exercise.</p><p><bold>Results</bold>: Serum sclerostin showed a diet-by-exercise interaction, reflecting HFD + EX mice having higher concentration than HFD + SED (+31%, <italic>p</italic> = 0.03), and LFD mice being unresponsive to exercise. iWAT sclerostin content decreased post-exercise in both 28 kDa (−31%, <italic>p</italic> = 0.04) and 30 kDa bands (−36%, main effect for exercise, <italic>p</italic> = 0.02). iWAT β-catenin (+44%, <italic>p</italic> = 0.03) and GSK3β content were higher in HFD mice compared to LFD (+128%, main effect for diet, <italic>p</italic> = 0.005). Monomeric sclerostin content was abolished in eWAT of HFD mice (−96%, main effect for diet, <italic>p</italic> &lt; 0.0001), was only detectable as a 30 kDa band in LFD mice and was unresponsive to exercise. β-catenin and GSK3β were both unresponsive to diet and exercise within eWAT.</p><p><bold>Conclusion</bold>: These results characterized sclerostin’s content to WAT depots in response to acute exercise, which appears to be specific to a reduction in iWAT and identified a differential regulation of sclerostin’s form/post-translational modifications depending on diet and WAT depot.</p>