Physiological mitochondrial ROS regulate diapause by enhancing HSP60/Lon complex stability in Helicoverpa armigera

Diapause is a long-lived stage which has evolved into an important strategy for insects to circumvent extreme environments. In the pupal stage, Helicoverpa armigera can enter diapause, a state characterized by significantly decreased metabolic activity and enhanced stress resistance, to survive cold winters. Previous studies have shown that reactive oxygen species (ROS) can promote the diapause process by regulating a distinct insulin signaling pathway. However, the source of ROS in the diapause-destined pupal brains and mechanisms by which ROS regulate diapause are still unknown. In this study, we showed that diapause-destined pupal brains accumulated high levels of mitochondrial ROS (mtROS) and total ROS during the diapause process, suggesting that mitochondria are the main source of ROS in diapause-destined pupal brains. In addition, injection of 2-deoxy-D-glucose (DOG), a glucose metabolism inhibitor, could delay pupal development by elevating mtROS levels in the nondiapause-destined pupal brains. Furthermore, the injection of a metabolite mixture to increase metabolic activity could avert the diapause process in diapause-destined pupae by decreasing mtROS levels. We also found that ROS could activate HSP60 expression and promote the stability of the HSP60-Lon complex, increasing its ability to degrade mitochondrial transcription factor A (TFAM) and decreasing mitochondrial activity or biogenesis under oxidative stress. Thus, this study illustrated the beneficial function of ROS in diapause or lifespan extension by decreasing mitochondrial activity.