👤 Ryo Nakamichi

Amyloid-beta (Aβ) oligomers, formed by Aβ aggregation, are the causative agent of Alzheimer's disease and induce the hyperphosphorylation of tau protein (Tau) and neurotoxicity. The antioxidant ergothioneine (ERGO) is transferred to the brain after oral ingestion and protects against Aβ- induced neurotoxicity and cognitive dysfunction. However, the impact of ERGO on Aβ oligomer-induced Tau phosphorylation remains unclear. To investigate the effects of ERGO on Aβ-induced Tau phosphorylation and their mechanism in neurons. SH-SY5Y cells differentiated into cholinergic neuron-like cells or primary cultured neurons derived from the murine hippocampus were pretreated with ERGO and exposed to Aβ Differentiated SH-SY5Y cells exhibited increased neurite outgrowth and mRNA expression of ERGO may suppress the increased expression of p-Tau and proteins involved in Aβ production induced by Aβ oligomers by inactivating GSK-3β, thereby mitigating neurotoxicity. Show less

The WW domain-containing protein 2 (Wwp2) gene, the host gene of miR-140, codes for the Wwp2 protein, which is an HECT-type E3 ubiquitin ligases abundantly expressed in articular cartilage. However, its function remains unclear. Here, we show that mice lacking Wwp2 and mice in which the Wwp2 E3 enzyme is inactivated (Wwp2-C838A) exhibit aggravated spontaneous and surgically induced osteoarthritis (OA). Consistent with this phenotype, WWP2 expression level is downregulated in human OA cartilage. We also identify Runx2 as a Wwp2 substrate and Adamts5 as a target gene, as similar as miR-140. Analysis of Wwp2-C838A mice shows that loss of Wwp2 E3 ligase activity results in upregulation of Runx2-Adamts5 signaling in articular cartilage. Furthermore, in vitro transcribed Wwp2 mRNA injection into mouse joints reduces the severity of experimental OA. We propose that Wwp2 has a role in protecting cartilage from OA by suppressing Runx2-induced Adamts5 via Runx2 poly-ubiquitination and degradation. Show less