α-Amyrin induces GLUT4 translocation mediated by AMPK and PPARδ/γ in C2C12 myoblasts

alpha-Amyrin, a natural pentacyclic triterpene, has an antihyperglycemic effect in mice and dual PPAR delta/gamma action in 3T3-L1 adipocytes, and potential in the control of type 2 diabetes (T2D). About 80% of glucose uptake occurs in skeletal muscle cells, playing a significant role in insulin resistance (IR) and T2D. Peroxisome-proliferator activated receptors (PPARs), in particular PPAR delta and PPAR gamma, are involved in the regulation of lipids and carbohydrates and, along with adenosine-monophosphate (AMP) - activated protein kinase (AMPK) and protein kinase B (Akt), are implicated in translocation of glucose transporter 4 (GLUT4); however, it is still unknown whether alpha-amyrin can affect these pathways in skeletal muscle cells. Our objective was to determine the action of alpha-amyrin in PPAR delta, PPAR gamma, AMPK, and Akt in C2C12 myoblasts. The expression of PPAR delta, PPAR gamma, fatty acid transporter protein (FATP), and GLUT4 was quantified using reverse transcription quantitative PCR and Western blot. alpha-Amyrin increased these markers along with phospho-AMPK (p-AMPK) but not p-Akt. Molecular docking showed that alpha-amyrin acts as an AMPK-allosteric activator, and may be related to GLUT4 translocation, as evidenced by confocal microscopy. These data support that alpha-amyrin could have an insulin-mimetic action in C2C12 myoblasts and should be considered as a bioactive molecule for new multitarget drugs with utility in T2D and other metabolic diseases.