Deletion of Nf2 in neural crest-derived tongue mesenchyme alters tongue shape and size, Hippo signalling and cell proliferation in a region- and stage-specific manner

Hippo/YAP1 promotes osteoporotic mice bone defect repair via the activating of Wnt signaling pathway

BACKGROUND

This study is to investigate the role and mechanism of Hippo/YAP1 in the repair of osteoporotic bone defects in aged mice, both in vivo and in vitro.

METHODS

We investigated the expression differences of the Hippo signaling in young and aged individuals both in vivo and in vitro. By manipulating the expression of Lats1/2 and Yap1, we investigated the role of Hippo/YAP1 in regulating osteogenic differentiation in aged BMSCs. In vivo, by intervening in the local and systemic expression of Lats1/2 and Yap1 respectively, we sought to demonstrate whether Hippo/YAP1 promotes the repair of bone defects in aged osteoporotic conditions. Finally, we delved into the underlying mechanisms of Hippo/YAP1 in regulating osteogenic differentiation.

RESULTS

We observed differences in the expression of the Hippo signaling between young and aged individuals. After knocking out Lats1/2 in aged BMSCs, we observed that the upregulation of endogenous YAP1 promotes cellular osteogenic differentiation and proliferation capacity. Through interference with Yap1 expression, we provided strong evidence for the role of Hippo/YAP1 in promoting osteogenic differentiation in aged BMSCs. In vivo, we confirmed that Hippo/YAP1 promotes the repair of bone defects in aging osteoporosis. Moreover, we discovered an interaction relationship among YAP1, β-catenin, and TEAD1.

CONCLUSION

This study elucidates the role of Hippo/YAP1 in promoting the repair of osteoporotic bone defects in aged mice. Mechanistically, YAP1 functions by activating the Wnt/β-catenin pathway, and this process is not independent of TEAD1.

Andrographolide inhibits the activation of spinal microglia and ameliorates mechanical allodynia

Andrographolide (Andro), a labdane diterpene, possesses anti-inflammatory properties and has been used to treat numerous inflammatory diseases. Novel findings revealed that Andro might be vital in regulating pain. However, the contribution of Andro to chronic inflammatory pain has yet to be determined, and its underlying mechanism of action remains unknown. In this study, we observed that Andro attenuated mechanical allodynia in inflammatory pain mice induced by injecting complete Freund's adjuvant (CFA) into the right hind paws. This analgesic effect of Andro is mainly dependent on its inhibition of microglial overactivation and the release of proinflammatory cytokines (TNF and IL-1β) in lumbar spinal cords of inflammatory pain model mice. More importantly, our data in vivo and in vitro revealed a negative role for Andro in regulating the TLR4/NF-κB signaling pathway, which might contribute to the inhibition of spinal microglial activation and proinflammatory cytokines production, and the improvement of paw withdrawal thresholds in a mouse model of chronic inflammatory pain evoked by CFA. We further found the potential interaction of Andro with TLR4/myeloid differentiation factor 2 heterodimer using molecular modeling, implying that TLR4 might be a potential target for Andro to exert an analgesic effect. Taken together, our findings demonstrated that the modulation of spinal microglial activation by Andro might be substantially conducive to managing chronic pain triggered by neuroinflammation.

Taste papilla cell differentiation requires the regulation of secretory protein production by ALK3-BMP signaling in the tongue mesenchyme

Taste papillae are specialized organs, each of which comprises an epithelial wall hosting taste buds and a core of mesenchymal tissue. In the present study, we report that during early taste papilla development in mouse embryos, bone morphogenetic protein (BMP) signaling mediated by type 1 receptor ALK3 in the tongue mesenchyme is required for epithelial Wnt/β-catenin activity and taste papilla differentiation. Mesenchyme-specific knockout (cKO) of Alk3 using Wnt1-Cre and Sox10-Cre resulted in an absence of taste papillae at E12.0. Biochemical and cell differentiation analyses demonstrated that mesenchymal ALK3-BMP signaling governed the production of previously unappreciated secretory proteins, i.e. it suppressed those that inhibit and facilitated those that promote taste papilla differentiation. Bulk RNA-sequencing analysis revealed many more differentially expressed genes (DEGs) in the tongue epithelium than in the mesenchyme in Alk3 cKO versus control. Moreover, we detected downregulated epithelial Wnt/β-catenin signaling and found that taste papilla development in the Alk3 cKO was rescued by the GSK3β inhibitor LiCl, but not by Wnt3a. Our findings demonstrate for the first time the requirement of tongue mesenchyme in taste papilla cell differentiation.