The pan-AMPK activator MK-8722 outperforms the AMPK activators SC4 and A-769662 in human endothelial cells

Abstract AMP-activated protein kinase (AMPK), a heterotrimeric serine/threonine protein kinase consisting of the catalytic α-subunit and regulatory β- and γ-subunits, regulates endothelial homeostasis. Consequently, it has emerged as a target for pharmacological activators in the treatment of endothelial dysfunction. However, the efficiency of these agonists may differ depending on the expression of different AMPK subunit isoforms in different cells and tissues, as these isoforms may form AMPK complexes with distinct activation profiles. The present study compares the effects of three direct AMPK activators in endothelial cells: MK-8722, a pan-AMPK activator; SC4, an intermediate activator with preference for AMPKα2; and A-769662, a β1-specific compound. We demonstrate that MK-8722 (0.1 to 10 μM) induces a robust and sustained, short- and long-term activation of AMPK, as evidenced by the phosphorylation of acetyl-CoA carboxylase and the inhibition of the mechanistic target of rapamycin complex 1 pathway. On an equimolar basis, MK-8722 was significantly more potent than SC4 and A-769662. This was associated with a significant antiviral effect of MK-8722 against herpes simplex virus type 1, whereas SC4 and A-769662 had no effect. At 10 μM, MK-8722 led to energy depletion and increased formation of mitochondrial and cytosolic reactive oxygen species due to inhibition of mitochondrial complex I. Under these conditions, liver kinase B1-mediated AMPK activation was observed but was not functionally relevant. We propose that the strong activation of AMPK by MK-8722 is related to the presence of different AMPK heterotrimers in endothelial cells. Therefore, targeting endothelial dysfunction pharmacologically may require pan-AMPK activators.