Establishing the ESCRT-III complex as the executor of Piezo's local inhibition of axon regeneration

PROJECT SUMMARY/ABSTRACT The failure of damaged axons to functionally regenerate can cause the debilitating pain and loss of important sensory and motor functions seen in patients with peripheral and central nervous system injuries. The regenerative response of neurons after axon injury varies greatly across species, with a low capacity seen in most mammals including humans. Unfortunately, there is a dearth of effective treatments for neural injury that provide clinically meaningful recovery. Understanding the genetic and molecular mechanisms that underlie the failure of axons to regenerate is relevant to public health because it may ultimately lead to the development of therapeutics for neural injury. Our understanding of the mechanisms controlling axon regeneration is still fragmentary due to the technical difficulty, cost, and time-consuming nature of studying mammalian axon regeneration in real time. Additionally, mammalian systems do not allow for large-scale genetic studies. Thus, the Song lab has developed a Drosophila melanogaster sensory neuron injury model that displays class specific regeneration properties, with subtypes that either do or do not regenerate spontaneously in the periphery. During growth and regeneration, cells sense their environment and respond to mechanical stimuli. Recent work in the Song lab has revealed that growth cones dynamically probe the environment during regeneration. Mechanical forces applied to the growth cone then activate the mechanosensitive ion channel Piezo which leads to the inhibition of axon regeneration. Multiple gaps in knowledge of how this mechanosensation inhibits regeneration remain: is the localization of Piezo important in its function; what specific regenerative processes are modulated by Piezo; what downstream effectors of Piezo act locally at the axon tip to inhibit regeneration? This proposal aims to answer these questions and gain further insights into novel regeneration regulators, advancing the understanding of axon regeneration and how to foster improved recovery in patient populations suffering from neural injury. The proposed research will also provide the applicant with rigorous training in molecular biology and imaging techniques; rigor and reproducibility; experimental design; as well as leadership and scientific communication. The research and training of the applicant will be supported by a team of experts headed by the sponsor Dr. Yuanquan Song and including Dr. Michael Granato, Dr. Damaris Lorenzo, Dr. Mike Henne, Dr. Andrea Stout, and Dr. Isaac Chen. The resources available at the internationally renowned institutions of the University of Pennsylvania and the Children’s Hospital of Philadelphia will ensure the successful completion of the proposed research and training of the applicant to become an independent research professor of neuroscience.