Metabolic dysfunction and insulin resistance are common underlying factors in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), and many age-related diseases, including obesity and type 2 diabetes. CB4211 is a novel peptide analog of MOTS-c, a mitochondrially encoded peptide with a potential role in metabolic homeostasis. CB4211 reduces free fatty acid release from cultured adipocytes, improves NAFLD activity score (NAS) in STAM® mice, and selectively decreases fat mass in DIO mice. We investigated the mechanism of action (MOA) of CB4211 in regulating fatty acid metabolism, glucose homeostasis, and insulin sensitivity. CB4211 potentiated insulin mediated inhibition of lipolysis in isoproterenol stimulated adipocyte cultures without changing maximal response, while CB4211 alone had no effect. Inhibitors of IR auto-phosphorylation (GSK183705A) or downstream PI3K/Akt signaling pathway components (wortmannin, Akti-1/2) abolished the antilipolytic effects of insulin alone and in combination with CB4211. Further supporting sensitization of insulin signaling, CB4211 enhanced insulin mediated phosphorylation of IR, IRS-1, and Akt, without affecting IGF mediated phosphorylation of IGF-1R. Consistent with activity through IR, CB4211 potentiated insulin induced reduction in glucose production in H4-IIE cells. The acute in vivo effect of CB4211 on insulin tolerance was determined in fasted DIO mice. Administration of CB4211 with insulin enhanced insulin sensitivity, prolonging the reduction in blood glucose levels compared to insulin alone.
In conclusion, CB4211 potentiates insulin effects on fatty acid metabolism and glucose homeostasis by acting at the level of IR. The observed MOA of CB4211 therefore supports its potential utility for treatment of NASH, obesity, type 2 diabetes, and other metabolic disorders.
K. Grindstaff: Employee; Self; CohBar, Inc.. R. Magnan: None. R. Shang: Employee; Self; CohBar Inc. E. Stenger: Employee; Self; CohBar, Inc.. J.S. Holland: None. D. Perez-Tilve: Research Support; Self; Novo Nordisk A/S, Cohbar. K.C. Cundy: Employee; Self; CohBar, Inc.. Stock/Shareholder; Self; CohBar, Inc..