Unraveling the role of PIEZO mediated mechanosensory signaling in pediatric clubfoot deformity repair

Project Summary Clubfoot deformity is the most common musculoskeletal birth defect (1-4 in every 1,000 live births) in which a baby's foot turns inward so severely that the bottom of the foot faces sideways or even upward, leading to lifelong pain and seriously limited activity. While clubfoot clinicians, including those on our team, have noted the increased force exerted by medial muscles likely due to aberrant neural development, little work has been done to elucidate this neural-tendon interaction. To offload the aberrant force caused by clubfoot deformity, 90% of kids require surgical cutting of the Achilles tendon shortly after birth followed by 2 years of splinting to further decrease mechanical strain on the foot. Despite these interventions, over 30% of kids develop recurrent clubfoot deformity leading to arthritis and pain requiring further surgical interventions. Post-tenotomy recurrence is the most common and most debilitating complication in kids with clubfoot deformity and no prevention or therapeutic strategies exist. Recent studies from our teams have uncovered an increase in PIEZO2 and TAZ signaling in clubfoot patients who suffer from recurrence. These observations have led to our central hypothesis that excessive PIEZO2 signaling activates aberrant TAZ signaling causing post-tenotomy recurrence seen in clubfoot patients and that FDA approved therapies and dietary modifications inhibiting PIEZO and TAZ signaling will mitigate post-tenotomy recurrence and enhance extremity function in kids treated for clubfoot deformity. Aim 1: Define the role of PIEZO2 as a critical upstream regulator of TAZ signaling in controlling post- tenotomy clubfoot recurrence in pediatric clubfoot patients and in a clinically relevant mouse model. We will map the neuro-tendon interactions in human pediatric clubfoot patients who developed post-tenotomy recurrence using scRNA seq and histologic analyses. Additionally, we will perform an Achilles tenotomy in our mouse clubfoot deformity model (PvalbCre;R26TdTom;Piezo2E2799del/wt) with a therapeutic TAZ inhibitor to mimic care of clubfoot patients. Our hypotheses are; 1) pathologic overexpression of PIEZO2 mediates TAZ signaling in clubfoot patients who suffer from post-tenotomy repair recurrence and that; 2) human and mouse nerve/tendon multi-tissue seq will map the neuro-tendon interactome and predict mechanisms for future study. Aim 2: Modulate mechanosensory signaling to mitigate post-tenotomy recurrence using FDA-approved therapies and dietary modifications in a clinically relevant mouse clubfoot model. Our Aim 2 hypothesis is that pharmacologic or dietary mechanosensory and PIEZO inhibition will prevent post-tenotomy recurrence in a mouse model of clubfoot deformity. To prevent post-tenotomy recurrence, we will target mechanosensory nerves (Botox) and PIEZO signaling pharmacologically (GsMTx4) as well as using a dietary supplement (w-3 poly-unsaturated fatty acid eicosapentaenoic acid; EPA).