Akt is a highly regulated serine/threonine kinase involved in stress response and cell survival. Stress response pathways
must cope with increasing chronic stress susceptibility with age. We found an age-related lesion in Akt activity via loss
of phosphorylation on Ser473. In hepatocytes from old rats, basal phospho-Ser473 Akt is 30% lower when compared to young,
but basal phospho-Thr308 Akt is unchanged. (
R)-α-lipoic acid (LA), a dithiol compound with antioxidant properties, is effective against age-related increases in oxidative
stress and has been used to improve glucose utilization through insulin receptor (IR) pathway-mediated Akt phosphorylation.
Treatment with physiologically relevant doses of LA (50 μM) provided a 30% increase in phospho-Ser473. Furthermore, two phosphatases
that antagonize Akt, PTEN and PP2A, were both partially inhibited by LA. Thus, LA may be a nutritive agent that can remediate
loss of function in the Akt pathway and aid in the survival of liver cells.
Keywords PKB/Akt - PI3 kinase - Aging - Alpha-lipoic acid - Phosphatase - Oxidative stress