Targeting TFEB to promote bridge Schwann cell function in peripheral nerve gap repair - PROJECT SUMMARY Traumatic peripheral nerve injuries that create nerve gaps remain a major clinical challenge. Autologous nerve grafts, the current gold standard, are limited by donor nerve availability, additional morbidity, and diminished Schwann cell function with age or increasing gap length. Acellular nerve conduits offer an alternative, but their success is severely limited for long-gap injuries because host bridge Schwann cells (bSCs), the specialized repair SCs that migrate from the cut nerve ends, often fail to expand, migrate, or survive within the hypoxic, nutrient-poor gap. When bSCs lose viability or stall, regenerating axons lose their cellular scaffold and retract, leading to poor functional outcomes. Strategies that enhance bSC generation, motility, and metabolic resilience represent a critical unmet need for improving long-gap nerve repair. Our preliminary findings identify TFEB as a promising regulator of bSC biology. TFEB is rapidly activated after nerve injury and controls gene networks involved in plasticity, mesenchymal transition, proliferation, and autophagy, processes that closely match the cellular demands placed on bSCs. TFEB promotes Schwann cell migration, increases N-cadherin expression, and is required for induction of Sox2, a driver of the bSC migratory phenotype. Because bSCs operate within a metabolically stressed environment, TFEB-mediated metabolic adaptation may be essential for their survival. The overall objective of this study is to define how TFEB regulates bSC generation, migration, and survival, and to determine whether augmenting TFEB activity enhances regeneration across long nerve gaps. Aim 1 will use inducible Schwann cell–specific TFEB/TFE3 loss-of-function mice combined with in vivo lineage tracing (ROSA-tdTomato) and scRNA-seq to define TFEB-dependent transcriptional programs and determine how TFEB regulates bSC expansion, migration, autophagy, and survival during gap repair. Aim 2 will use Schwann cell–specific TFEB gain-of-function mice to determine whether TFEB activation enhances bSC metabolic capacity, stress resilience, motility, and long-gap regeneration in a clinically relevant collagen conduit model. Successful completion of this work will establish TFEB as a master regulator of bSC biology and provide mechanistic insight into how bSCs regenerate severed nerves. These findings will enable new therapeutic strategies to enhance endogenous repair or improve the performance of engineered nerve conduits, reducing reliance on autografts.
