Notch Signaling Regulates Pupal Development In Helicoverpa Armigera

In order to guarantee population exists, creates evolve varieties of strategies to against the harsh environments through longtime natural selection. Insects mainly through diapause pass bad condition. Helicoverpa armigera can recognize the change of photoperiod and temperature in larval phase and enter diapause in pupal stage. They keep pupal morph until environment improvement to enough for living, then break diapause and restart development to complish generation cycles. During diapause process, H. armigera increases resistance and declines metabolic activity.According to research on E.elegan, Notch signal pathway can maintain Dauer phenomenon which is alike to insect diapause. Based on that we decided to survey Notch signal pathway work or not work in the diapause of H. armigera.In this study, Western Blot outcome shows Notch protein expresses higher in non-diapause type than diapause type and the expression gradually decreases in diapause type in pupal brain. The outcome is equal to c-Myc protein expression in two type pupal brain. And cells experiment outcome also indicates that Notch can regulate c-Myc gene transcription and expression.Though ChIP experiment, we fond c-Myc protein bind to the TFAM gene promotor sequence in pupal brain. We overexpressed Notch protein and disposed HzAml cells with Notch inhibitor LY411575, the experiment outcomes also show Notch can regulate TFAM gene promotor activity and its expression. So we thought Notch can regulate transcription and expression of TFAM gene across c-Myc.As the mitochondria transcription factor, TFAM protein is crucial for of mitochondrial DNA and mitochondrial activity. Based on the experiment outcomes, the mitochondrial DNA levels rose when Notch protein was overexpressed. The opposite outcomes are obtained when inhibitor LY411575 was added and Notch protein was interfered. On the other side, cytochrome c oxidase is very important for mitochondrion to carry on the function on energy transformation. So we decided to use COX activity to represent the mitochondrial activity. After Notch protein was interfered, the COX activity was depressed. It demonstates Notch can regulate mitochondria activity.So we think Notch signal through Notch-c-Myc-TFAM pathway to influence mitochondrial activity in the pupal brain of H. armigera. In non-diapause type pupal brain, high expression of Notch enhances mitochondrial activity and accelerates development. On the contrary, low expression of Notch in diapause type pupal brain depresses mitochondrial activity and maintains diapause.