Targeting metabolic driving and minimization of by-products synthesis for high-yield production of D-pantothenate in Escherichia coli.

BACKGROUND: d-Pantothenate (DPA) is an important functional chemical that has been widely applied in healthcare, cosmetics, animal food, and feed industries. METHODS AND RESULTS: In this study, a high-yield DPA-producing strain was constructed by metabolic engineering strategies with targeting metabolic driving and by-products minimization. The metabolic driving force of push and pull was firstly obtained to improve the production of DPA via enrichment of precursor pool and synthetic pathway, accumulating 4.29 g L-1 DPA in shake flask fermentation. To eliminate the metabolic pressure on DPA production, an amino throttling system was proposed and successfully attenuated the synthesis of four competitive amino acids by a single-step regulation of gdhA. Further minimization of acetate was carried out by pta deletion, and utilization of ß-alanine was improved via enhancing its uptake system with producing 5.78 g L-1 DPA. Finally, the engineered strain produced 66.39 g L-1 DPA with ß-alanine addition in fermentor under fed-batch fermentation. CONCLUSION: This study paved a foundation for the industrial production of DPA.

Treadmill and wheel exercise protect against JNK/NF-κB induced inflammation in experimental models of knee osteoarthritis.

Osteoarthritis (OA) remains a challenge for clinicians and effective treatments are lacking. In this study, we investigated JNK/NF-κB signaling in knee OA patients. Rats were used to establish an OA model and were divided into six groups; (1) Control (sterile saline injection only); (2) Controls with treadmill exercise (treadmill); (3) Controls with wheel exercise (wheel); (4) OA (MIA injection); (5) OA with treadmill exercise (OA + treadmill); and (6) OA with wheel exercise (OA + wheel). The results showed that, compared to the OA group, the OA + treadmill and OA + wheel groups had lower levels of IL-1ß, IL-6 and TNF-α, and similar levels of p-P65, p-JNK, and P-IκBα. Furthermore, treatment with the JNK agonist anisomycin enhanced the damage to the joint cartilage and increased the levels of IL-1ß, IL-6 and TNF-α. Taken together, these data suggest that treadmill and wheel exercise protect against inflammation through the regulation of JNK/NF-κB signaling in experimental models of knee OA.

Eupatilin protects chondrocytes from apoptosis via activating sestrin2-dependent autophagy.

Cartilage degradation is the main characterization of osteoarthritis (OA). Accumulating evidence suggests that chondrocyte apoptosis and autophagy are associated with cartilage degradation. Thus, we investigated the protective effect and underlying mechanism of eupatilin for treating OA. IL-1ß was used to simulate OA in vitro. Data show that eupatilin treatment attenuated IL-1ß-induced apoptosis of chondrocytes. Autophagy was also activated by eupatilin in a dose-dependent manner. Then, pretreatment with chloroquine (CQ), an autophagic inhibitor, decreased eupatilin-induced autophagy and increased apoptosis in the chondrocytes. To investigate the mechanism of eupatilin, the expressions of sestrin2 and mTOR were measured using Western blot; eupatilin upregulated sestrin2 but downregulated mTOR phosphorylation. The administration of sestrin2-siRNA significantly decreased autophagy and reversed the protective effect of eupatilin against chondrocyte apoptosis and degradation of the cartilage matrix. Thus, eupatilin can inhibit IL-1ß-induced apoptosis via sestrin2-dependent autophagy in chondrocytes.