The Role of AMPK Pathway in Neuroprotection

Adenosine monophosphate-activated kinase (AMPK) is a highly conserved protein kinase found in all eukaryotic genomes. It exists as heterotrimeric protein consisting of α, β, and γ subunits. AMPK is activated by elevated levels of adenosine mono-phosphate (AMP), which is produced during conditions of low ATP production and perhaps mitochondrial dysfunction. Activation of AMPK has been shown to regulate a large number of downstream pathways. These will either increase energy production such as increase oxidation of fatty acids and glucose, or decrease energy utilization such as inhibiting synthesis of glycogen, fatty acid synthesis, and protein synthesis. In addition, being a key regulator of physiological energy dynamics, AMPK has been demonstrated to play roles in regulating various cellular processes such as mitochondrial biogenesis (Jager et al. Proc Natl Acad Sci U S A 104:12017–12022, 2007), autophagy (Hyttinen et al. Rejuven Res 14:651–660, 2011) and inflammation and immune responses (Giri et al. 2004). Retinal neurons have a high energy demand but have a poor energy storage capacity. Because of this, it is likely that the AMPK signaling pathway plays an important role in maintaining energy balance, and therefore may be a therapeutic target to prevent or delay retinal degeneration.