Quercetin, a flavonoid found in natural medicines, has shown a role in disease prevention and health promotion. Moreover, because of its recently identified contribution in regulating bone homeostasis, quercetin may be considered a promising agent for improving bone health. This study aimed to elucidate the role of quercetin in androgen deprivation therapy-induced osteoporosis in mice. C57BL/6 mice were subjected to orchiectomy, followed by quercetin treatment (75 and 150 mg/kg/d) for 8 weeks. Bone microstructure was then assessed by micro-computed tomography, and a three-point bending test was used to evaluate the biomechanical parameters. Hematoxylin and eosin (H&E) staining was used to examine the shape of the distal femur, gastrocnemius muscle, and liver. The balance motion ability in mice was evaluated by gait analysis, and changes in the gastrocnemius muscle were observed via Oil red O and Masson’s staining. ELISA and biochemical analyses were used to assess markers of the bone, glucose, and lipid metabolism. Western blotting analyses of glucose and lipid metabolism-related protein expression was performed, and expression of the GPCR6A/AMPK/mTOR signaling pathway-related proteins was also assessed. After 8 weeks of quercetin intervention, quercetin-treated mice showed increased bone mass, bone strength, and improved bone microstructure. Additionally, gait analysis, including stride length and frequency, were significantly increased, whereas a reduction of the stride length and gait symmetry was observed. H&E staining of the gastrocnemius muscle showed that the cross-sectional area of the myofibers had increased significantly, suggesting that quercetin improves balance, motion ability, and muscle mass. Bone metabolism improvement was defined by a reduction of serum levels of insulin, triglycerides, total cholesterol, and low-density lipoprotein, whereas levels of insulin-like growth factor-1 and high-density lipoprotein were increased after quercetin treatment. Expression of proteins involved in glucose uptake was increased, whereas that of proteins involved in lipid production was decreased. Moreover, the GPRC6A and the phospho-AMPK/AMPK expression ratio was elevated in the liver and tibia tissues. In contrast, the phospho-mTOR/mTOR ratio was reduced in the quercetin group. Our findings indicate that quercetin can reduce the osteoporosis induced by testosterone deficiency, and its beneficial effects might be associated with the regulation of glucose metabolism and inhibition of lipid metabolism via the GPCR6A/AMPK/mTOR signaling pathway.

Jisuikang (JSK) is an herbal formula composed of many kinds of traditional Chinese medicine, which has been proved to be effective in promoting the rehabilitation of patients with spinal cord injury (SCI) after more than ten years of clinical application. However, the mechanisms of JSK promoting nerve regeneration are yet to be clarified. The aim of this study was to investigate the effects of JSK protecting neurons, specifically the regulation of NgR/RhoA/ROCK signal pathway. The motor function of rats was evaluated by the BBB score and inclined plate test, Golgi staining and transmission electron microscope were used to observe the microstructure of nerve tissue, and fluorescence double-labeling method was used to detect neuronal apoptosis. In this study, we found that JSK could improve the motor function of rats with SCI, protect the microstructure (mitochondria, endoplasmic reticulum, and dendritic spine) of neurons, and reduce the apoptosis rate of neurons in rats with SCI. In addition, JSK could inhibit the expression of Nogo receptor (NgR) in neurons and the NgR/RhoA/ROCK signal pathway in rats with SCI. These results indicated JSK could improve the motor function of rats with SCI by inhibiting the NgR/RhoA/ROCK signal pathway, which suggests the potential applicability of JSK as a nerve regeneration agent.

Rational: Senescence is a major aging process that contributes to the development of cardiovascular diseases, but the underlying molecular mechanisms remain largely unknown. One reason is due to the lack of suitable animal models. We aimed to generate a cardiomyocyte (CM)-specific senescent animal model, uncover the underlying mechanisms, and develop new therapies for aging associated cardiac dysfunction. Methods:The gain/loss of circHIPK3 approach was used to explore the role of circHIPK3 in cardiomyocyte (CM) senescence. To investigate the mechanisms of circHIPK3 function in cardiac senescence, we generated CM-specific tamoxifen-induced circHIPK3 knockout (CKO) mice. We also applied various analyses including PCR, Western blot, nuclear and cytoplasmic protein extraction, immunofluorescence, echocardiography, RNA immunoprecipitation assay, RNA-pulldown assay, and co-immunoprecipitation. Results: Our novel CKO mice exhibited worse cardiac function, decreased circHIPK3 expression and telomere length shortening in the heart. The level of the senescence-inducer p21 in the hearts of CKO mice was significantly increased and survival was poor compared with control mice. In vitro, the level of p21 in CMs was significantly decreased by circHIPK3 overexpression, but increased by circHIPK3 silencing. We showed that circHIPK3 was a scaffold for p21 mRNA-binding protein HuR and E3 ubiquitin ligase β-TrCP. circHIPK3 silencing weakened the interaction between HuR and β-TrCP, reduced HuR ubiquitination, and enhanced the interaction between HuR and p21 mRNA. Moreover, we found that mice injected with human umbilical cord mesenchymal stem cell-derived exosomes (UMSC-Exos) showed increased circHIPK3 levels, decreased levels of p21, longer telomere length, and good cardiac function. However, these beneficial effects exerted by UMSC-Exos were inhibited by silencing circHIPK3. Conclusions: We successfully generated CM-specific CKO mice for aging research. Our results showed that deletion of circHIPK3 led to exaggerated CM senescence and decreased cardiac function. As a scaffold, circHIPK3 enhanced the binding of E3 ubiquitin ligase β-TrCP and HuR in the cytoplasm, leading to the ubiquitination and degradation of HuR and reduced p21 activity. In addition, UMSC-Exos exerted an anti-senescence and cardio-protective effect by delivering circHIPK3. These findings pave the way to the development of new therapies for aging associated cardiac dysfunction.

Recent studies have shown that the hydrogels formed by composite biomaterials are better choice than hydrogels formed by single biomaterial for tissue repair. We explored the feasibility of the composite hydrogel formed by silk fibroin (SF) and silk sericin (SS) in tissue repair for the excellent mechanical properties of SF, and cell adhesion and biocompatible properties of SS. In our study, the SF SS hydrogel was formed by SF and SS protein with separate extraction method (LiBr dissolution for SF and hot alkaline water dissolution for SS), while SF-SS hydrogel was formed by SF and SS protein using simultaneous extraction method (LiBr dissolution for SF and SS protein). The effects of the two composite hydrogels on the release of inflammatory cytokines from macrophages and the wound were analyzed. Moreover, two hydrogels were used to encapsulate and deliver human umbilical cord mesenchymal stem cell derived exosomes (UMSC-Exo). Both SF SS and SF-SS hydrogels promoted wound healing, angiogenesis, and reduced inflammation and TNF-α secretion by macrophages. These beneficial effects were more significant in the experimental group treated by UMSC-Exo encapsulated in SF-SS hydrogel. Our study found that SF-SS hydrogel could be used as an excellent alternative to deliver exosomes for tissue repair.

Macrophages play an essential role in the pathogenesis of most inflammatory diseases. Recent studies have shown that mechanical load can influence macrophage function, leading to excessive and uncontrolled inflammation and even systemic damage, including cardiovascular disease and knee osteoarthritis. However, the molecular mechanism remains unclear. In this study, murine RAW264.7 cells were treated with mechanical stretch (MS) using the Flexcell-5000T Tension System. The expression of inflammatory factors and cytokine release were measured by RT-qPCR, ELISA, and Western blotting. The protein expression of NF-κB p65, Iκb-α, p-Iκb-α, RhoA, ROCK1, and ROCK2 was also detected by Western blotting. Then, Flow cytometry was used to detect the proportion of macrophage subsets. Meanwhile, Y-27632 dihydrochloride, a ROCK inhibitor, was added to knockdown ROCK signal transduction in cells. Our results demonstrated that MS upregulated mRNA expression and increased the secretion levels of proinflammatory factors iNOS, IL-1β, TNF-α, and IL-6. Additionally, MS significantly increased the proportion of CD11b+CD86+ and CD11b+CD206+ subsets in RAW264.7 macrophages. Furthermore, the protein expression of RhoA, ROCK1, ROCK2, NF-κB p65, and IκB-α increased in MS-treated RAW264.7 cells, as well as the IL-6 and iNOS. In contrast, ROCK inhibitor significantly blocked the activation of RhoA-ROCK and NF-κB pathway, decreased the protein expression of IL-6 and iNOS, reduced the proportion of CD11b+CD86+ cells subpopulation, and increased the proportion of CD11b+CD206+ cell subpopulation after MS. These data indicate that mechanical stretch can regulate the RAW264.7 macrophage polarization and enhance inflammatory responses in vitro, which may contribute to activation the RhoA-ROCK/NF-κB pathway.