NGF-TrkA signaling in sensory nerves is required for skeletal adaptation to mechanical loads in mice

RE Tomlinson, Z Li, Z Li, L Minichiello… - Proceedings of the …, 2017 - National Acad Sciences
RE Tomlinson, Z Li, Z Li, L Minichiello, RC Riddle, A Venkatesan, TL Clemens
Proceedings of the National Academy of Sciences, 2017National Acad Sciences
Sensory nerves emanating from the dorsal root extensively innervate the surfaces of
mammalian bone, a privileged location for the regulation of biomechanical signaling. Here,
we show that NGF-TrkA signaling in skeletal sensory nerves is an early response to
mechanical loading of bone and is required to achieve maximal load-induced bone
formation. First, the elimination of TrkA signaling in mice harboring mutant TrkAF592A
alleles was found to greatly attenuate load-induced bone formation induced by axial …
Sensory nerves emanating from the dorsal root extensively innervate the surfaces of mammalian bone, a privileged location for the regulation of biomechanical signaling. Here, we show that NGF-TrkA signaling in skeletal sensory nerves is an early response to mechanical loading of bone and is required to achieve maximal load-induced bone formation. First, the elimination of TrkA signaling in mice harboring mutant TrkAF592A alleles was found to greatly attenuate load-induced bone formation induced by axial forelimb compression. Next, both in vivo mechanical loading and in vitro mechanical stretch were shown to induce the profound up-regulation of NGF in osteoblasts within 1 h of loading. Furthermore, inhibition of TrkA signaling following axial forelimb compression was observed to reduce measures of Wnt/β-catenin activity in osteocytes in the loaded bone. Finally, the administration of exogenous NGF to wild-type mice was found to significantly increase load-induced bone formation and Wnt/β-catenin activity in osteocytes. In summary, these findings demonstrate that communication between osteoblasts and sensory nerves through NGF-TrkA signaling is essential for load-induced bone formation in mice.
National Acad Sciences