Advances in the novel functions of insect prophenoloxidase

As a core component of the insect innate immune system, prophenoloxidase (PPO) also plays a pivotal role in various physiological processes. Since the last century, the pioneering work conducted by Professor Kenneth Söderhäll and other distinguished research groups has led to a deeper understanding of the insect PPO expression and activation mechanisms, significantly contributing to our knowledge of insect innate immunity. In the context of immunity, PPO not only mediates defense responses against bacteria, fungi, parasites, and viruses through melanization but also interacts with immune pathways such as Toll and IMD, thereby integrating cellular immunity into a coordinated response. Recently, a substantial body of research indicates that insect PPO possesses several other critical functions. Studies on non-immune functions have demonstrated that PPO is involved in critical physiological processes, including the detoxification, cuticular sclerotization, development, and oxygen transport. Interestingly, targeted strategies developed based on the regulatory mechanisms of PPO have exhibited substantial potential for pest control. Looking ahead, further in-depth investigations into the functional roles of PPO will be highly significant. Such studies will not only elucidate the molecular mechanisms underlying insect physiological regulation but also provide a theoretical foundation for the development of novel targeted pesticides and ecological control strategies.