Sema3A secreted by sensory nerve induces bone formation under mechanical loads / 国际口腔科学杂志·英文版

Bone formation and deposition are initiated by sensory nerve infiltration in adaptive bone remodeling. Here, we focused on the role of Semaphorin 3A (Sema3A), expressed by sensory nerves, in mechanical loads-induced bone formation and nerve withdrawal using orthodontic tooth movement (OTM) model. Firstly, bone formation was activated after the 3rd day of OTM, coinciding with a decrease in sensory nerves and an increase in pain threshold. Sema3A, rather than nerve growth factor (NGF), highly expressed in both trigeminal ganglion and the axons of periodontal ligament following the 3rd day of OTM. Moreover, in vitro mechanical loads upregulated Sema3A in neurons instead of in human periodontal ligament cells (hPDLCs) within 24 hours. Furthermore, exogenous Sema3A restored the suppressed alveolar bone formation and the osteogenic differentiation of hPDLCs induced by mechanical overload. Mechanistically, Sema3A prevented overstretching of F-actin induced by mechanical overload through ROCK2 pathway, maintaining mitochondrial dynamics as mitochondrial fusion. Therefore, Sema3A exhibits dual therapeutic effects in mechanical loads-induced bone formation, both as a pain-sensitive analgesic and a positive regulator for bone formation.

Chaperone-mediated Autophagy Regulates Cell Growth by Targeting SMAD3 in Glioma / 神经科学通报·英文版

Previous studies suggest that the reduction of SMAD3 (mothers against decapentaplegic homolog 3) has a great impact on tumor development, but its exact pathological function remains unclear. In this study, we found that the protein level of SMAD3 was greatly reduced in human-grade IV glioblastoma tissues, in which LAMP2A (lysosome-associated membrane protein type 2A) was significantly up-regulated. LAMP2A is a key rate-limiting protein of chaperone-mediated autophagy (CMA), a lysosome pathway of protein degradation that is activated in glioma. We carefully analyzed the amino-acid sequence of SMAD3 and found that it contained a pentapeptide motif biochemically related to KFERQ, which has been proposed to be a targeting sequence for CMA. In vitro, we confirmed that SMAD3 was degraded in either serum-free or KFERQ motif deleted condition, which was regulated by LAMP2A and interacted with HSC70 (heat shock cognate 71 kDa protein). Using isolated lysosomes, amino-acid residues 75 and 128 of SMAD3 were found to be of importance for this process, which affected the CMA pathway in which SMAD3 was involved. Similarly, down-regulating SMAD3 or up-regulating LAMP2A in cultured glioma cells enhanced their proliferation and invasion. Taken together, these results suggest that excessive activation of CMA regulates glioma cell growth by promoting the degradation of SMAD3. Therefore, targeting the SMAD3-LAMP2A-mediated CMA-lysosome pathway may be a promising approach in anti-cancer therapy.