Nur77 is involved in the regulation of obesity-related lower muscle mass by promoting Pten degradation.

Obesity may impair muscle function and is sometimes associated with lower muscle mass. However, the internal regulatory mechanism is still unclear. Nur77 has been reported to improve obesity phenotype by regulating glucose and lipid metabolism and inhibiting the production of inflammatory factors and reactive oxygen species. Concurrently, Nur77 also plays an important role in muscle differentiation and development. We aimed to investigate the role of Nur77 in obesity-related lower muscle mass. Our in vivo and in vitro experiments illustrated that the reduction of obesity-related Nur77 accelerated the occurrence of lower muscle mass by interfering with the signaling pathways involved in the regulation of myoprotein synthesis and degradation. We further demonstrated that Nur77 activates the PI3K/Akt pathway by promoting Pten degradation, which enhances the phosphorylation of the Akt/mTOR/p70S6K pathway and inhibits the expression of skeletal muscle-specific E3 ligases (MAFbx/MuRF1). Nur77 induces Pten degradation by increasing the transcription of its specific E3 ligase Syvn1. Our study confirms that Nur77 is a key factor in ameliorating obesity-related lower muscle mass, providing a new therapeutic target and theoretical basis for the treatment of obesity-related lower muscle mass.

Implications from proteomic studies investigating circadian rhythm disorder-regulated neurodegenerative disease pathology.

Neurodegenerative diseases (NDs) affect 15% of the world's population and are becoming an increasingly common cause of morbidity and mortality worldwide. Circadian rhythm disorders (CRDs) have been reported to be involved in the pathogenic regulation of various neurologic diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis and amyotrophic lateral sclerosis. Proteomic technology is helpful to explore treatment targets for CRDs in patients with NDs. Here, we review the key differentially expressed (DE) proteins identified in previous proteomic studies investigating NDs, CRDs and associated models and the related pathways identified by enrichment analysis. Furthermore, we summarize the advantages and disadvantages of the above studies and propose new proteomic technologies for the precise study of circadian disorder-mediated regulation of ND pathology. This review provides a theoretical and technical reference for the precise study of circadian disorder-mediated regulation of ND pathology.

Nur77 Prevents Osteoporosis by Inhibiting the NF-κB Signalling Pathway and Osteoclast Differentiation.

Inflammation is a major risk factor for osteoporosis, and reducing inflammatory levels is important for the prevention of osteoporosis. Although nuclear receptor 77 (Nur77) protects against inflammation in a variety of diseases, its role in osteoporosis is unknown. Therefore, the main purpose of this study was to investigate the osteoprotective and anti-inflammatory effects of Nur77. The microCT and haematoxylin and eosin staining results indicated that knockout of Nur77 accelerated femoral bone loss in mice. The enzyme-linked immunosorbent assay (ELISA) results showed that knockout of Nur77 increased the serum levels of hsCRP and IL-6. The expression levels of NF-κB, IL-6, TNF-α and osteoclastogenesis factors (TRAP, NFATC1, Car2, Ctsk) in the femurs of Nur77 knockout mice were increased significantly. Furthermore, in vitro, shNur77 promoted the differentiation of RAW264.7 cells into osteoclasts by activating NF-κB, which was confirmed by PDTC treatment. Mechanistically, Nur77 inhibited osteoclast differentiation by inducing IκB-α and suppressing IKK-ß. In RAW264.7 cells, overexpression of Nur77 alleviated inflammation induced by siIκB-α, while siIKK-ß alleviated inflammation induced by shNur77. Consistent with the in vivo studies, we found that compared with control group, older adults with high serum hsCRP levels were more likely to suffer from osteoporosis (OR = 1.76, p < 0.001). Our data suggest that Nur77 suppresses osteoclast differentiation by inhibiting the NF-κB signalling pathway, strongly supporting the notion that Nur77 has the potential to prevent and treat osteoporosis.

[Biological roles of adenosine deaminase acting on RNA and their relationship with human diseases].

RNA editing, especially A-to-I RNA editing, is a common post-transcriptional modification in mammals. Adenosine deaminase acting on RNA (ADAR) is a key protein for A-to-I editing, which converts the adenosine group of a double-stranded RNA to creatinine group by deaminating it, resulting in a change of nucleotide sequence. There are 3 types of ADARs (ADAR1, ADAR2, ADAR3) that have been found in recent years. The abnormalities of ADARs are closely related to many human diseases such as viral infections, metabolic diseases, nervous system diseases, and tumors.