Adenosine monophosphate-activated protein kinase–mechanistic target of rapamycin–autophagy signaling axis (AMPK–mTOR–autophagy axis)

The AMPK–mTOR–autophagy signaling axis is a fundamental regulatory network that integrates cellular energy sensing with the control of protein synthesis and degradation. At the core of this axis, the adenosine monophosphate-activated protein kinase (AMPK) functions as a metabolic rheostat, becoming activated in response to low ATP levels to restore energy balance (Hardie et al., 2012, Chem Biol). Once active, AMPK suppresses the mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of cell growth, while simultaneously activating the Unc-51 like autophagy activating kinase 1 (ULK1) to initiate autophagy (Kim et al., 2011, Nat Cell Biol). This coordinated response allows cells to survive nutrient deprivation by recycling internal components and halting energy-intensive anabolic processes. Dysfunctions in this signaling cascade are linked to a wide array of human diseases, including type 2 diabetes, various cancers, and neurodegenerative disorders like Alzheimer's disease (Mizushima & Komatsu, 2011, Cell). Consequently, pharmacological agents that target components of this axis—such as the AMPK activator metformin or mTOR inhibitors like rapamycin—are extensively studied for their potential to treat metabolic syndrome and extend lifespan (Saxton & Sabatini, 2017, Cell). However, the role of autophagy in disease is context-dependent, as it can serve as a survival mechanism for established tumor cells, presenting a significant challenge for therapeutic intervention.

Other names

AMPK/mTOR/ULK1 pathwayAMPK-mTOR signaling cascadeEnergy-sensing autophagy pathwayAMPK-mTOR-autophagy axis

Modulation of the axis occurs through the activation of AMPK or the inhibition of mTORC1, both of which lead to the downstream activation of the ULK1 complex and the induction of autophagy (Kim et al., 2011, Nat Cell Biol).