Sustained Nrf2 Overexpression-Induced Metabolic Deregulation Can Be Attenuated by Modulating Insulin/Insulin-like Growth Factor Signaling.

The modulation of insulin/insulin-like growth factor signaling (IIS) is associated with altered nutritional and metabolic states. The genome encodes eight insulin-like peptides, whose activity is regulated by a group of secreted factors, including Ecdysone-inducible gene L2 (), which acts as a potent IIS inhibitor. We recently reported that cncC (cncC/Nrf2), the fly ortholog of Nrf2, is a positive transcriptional regulator of ImpL2, as part of a negative feedback loop aiming to suppress cncC/Nrf2 activity. This finding correlated with our observation that sustained cncC/Nrf2 overexpression/activation (; a condition that signals organismal stress) deregulates IIS, causing hyperglycemia, the exhaustion of energy stores in flies' tissues, and accelerated aging. Here, we extend these studies in by assaying the functional implication of ImpL2 in -mediated metabolic deregulation. We found that knockdown (KD) in flies partially reactivated IIS, attenuated hyperglycemia and restored tissue energetics. Moreover, KD largely suppressed -mediated premature aging. In support, pharmacological treatment of flies with Metformin, a first-line medication for type 2 diabetes, restored (dose-dependently) IIS functionality and extended flies' longevity. These findings exemplify the effect of chronic stress in predisposition to diabetic phenotypes, indicating the potential prophylactic role of maintaining normal IIS functionality.