Neuronatin Promotes SERCA Uncoupling and Its Expression is Inversely Associated with High Fat Diet Induced Weight Gain in vivo

• DOI: 10.1096/fasebj.2021.35.s1.01993
• Publication Date: 2021-06-11T01:05:27Z
• Authors: Jessica Braun; Allen Teng; Mia Geromella; Chantal Ryan; Rachel Fenech; Rebecca MacPherson; Anthony Gramolini; Val Fajardo
• Keywords: SERCA; Phospholamban; HEK 293 cells

Neuronatin (NNAT) is a paternally imprinted gene involved in many aspects of metabolism but the underlying cellular mechanism remains unknown. Its sequence homology with phospholamban (PLN) and sarcolipin (SLN) suggest that NNAT has putative role regulating enzymatic activity sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) striated muscles. Both PLN SLN physically interact functionally inhibit SERCA by lowering its affinity for Ca2+, only unique ability to uncouple SERCA-mediated Ca2+ transport from ATP hydrolysis mouse soleus Uncoupling pump increases energy expenditure may be beneficial combatting imbalances, such as obesity. The objective this study was test our hypothesis like SLN, would also promote uncoupling. In addition, we examined whether expression altered muscles obtained C57BL/6 mice fed high fat diet (HFD). Using human embryonic kidney (HEK) cells co-transfected cDNA, measured coupling ratio using an Indo-1 based fluorometric uptake assay enzyme-linked spectrophotometric ATPase assay. promoted uncoupling both SERCA1a SERCA2a isoforms HEK dose-dependent manner showing increased sensitivity when compared SERCA2a. Western blotting used confirm cell transfection well assess content low (LFD) or HFD (60% kcal) 12 weeks. A ~40% reduction ~50% increase protein observed LFD. Total levels relative (SERCA1a + SERCA2a) were reduced ~45%, respectively LFD mice. Plotting muscle (relative SERCA) against total weight gained after weeks feeding revealed significant inverse relationship (r2=0.49, p=0.01), suggesting higher related vivo. This first demonstrate uncoupler negatively associated induced gain. These findings regulate whole-body balance via