A Neutral Polysaccharide from Spores of Ophiocordyceps gracilis Regulates Oxidative Stress via NRF2/FNIP1 Pathway

Bacillus amyloliquefaciens SC06 alleviates LPS-induced intestinal damage by inhibiting endoplasmic reticulum stress and mitochondrial dysfunction in piglets

Endoplasmic reticulum stress (ERS) and mitochondrial dysfunction play an important role in the pathogenesis of intestinal diseases. Our studies investigated the effects of Bacillus amyloliquefaciens SC06 on jejunal mitochondria and ER in piglets under the LPS-induced intestinal injury model. Eighteen piglets (male, 21 days old) were randomly assigned to three treatments: CON (basal diet), LPS (basal diet +100 μg/kg LPS), and SC06 + LPS (basal diet +1 × 108 cfu/kg SC06 + 100 μg/kg LPS). Compared to the LPS group, administration of SC06 improved jejunal morphology and barrier function. In addition, SC06 reduced reactive oxygen species (ROS) and MDA generation in the jejunum by activating the Nrf2/keap1 pathway, which increased the activity of CAT, GSH and SOD in LPS-challenged pigs. In addition, SC06 reduced LPS-induced mitochondrial dysfunction and ERS as evidenced by a decrease in ROS, an improvement in mitochondrial membrane potential and an increase in adenosine triphosphate levels. The results of in vitro IPEC-J2 cell experiments also indicate that SC06 can reduce LPS-induced oxidative stress, mitochondrial dysfunction, ERS, and intestinal barrier function damage by activating the Nrf2/keap1 signaling pathway. Finally, treatment with the Nrf2-specific inhibitor ML-385 inhibited the upregulated effect of SC06 on antioxidant capacity and intestinal barrier function in IPEC-J2 cells. In conclusion, SC06 ameliorated intestinal damage and mitochondrial dysfunction and attenuated endoplasmic reticulum stress via activation of the Nrf2/keap1 signaling pathway in LPS-challenged piglets.

The relationship between polysaccharide structure and its antioxidant activity needs to be systematically elucidated

Polysaccharides have a wide range of applications due to their excellent antioxidant activity. However, the low purity and unclear structure of polysaccharides have led some researchers to be skeptical about the antioxidant activity of polysaccharides. The current reports on the structure-activity relationship of polysaccharides are sporadic, so there is an urgent need to systematically summarize the antioxidant effects of polysaccharides with clear structures and the relationships between the structures to provide a scientific basis for the development and application of polysaccharides. This paper will systematically elucidate the structure-activity relationship of antioxidant polysaccharides, including the molecular weight, monosaccharide composition, glycosidic linkage, degree of branching, advanced conformation and chemical modification. For the first time, the antioxidant activity of polysaccharides is related to their chemical structure through histogram and radar map, and further studies using principal component analysis and cluster analysis. We critically discussed how the source, chemical structure and chemically modified groups of polysaccharides significantly contribute to their antioxidant activity and summarized the current research status and shortcomings of the structure-activity relationship of antioxidant polysaccharides. This review provides a theoretical basis and new perspective for further research on the structure-activity relationship of antioxidant polysaccharides and the development of natural antioxidants.

A recurrent missense variant in the E3 ubiquitin ligase substrate recognition subunit FEM1B causes a rare syndromic neurodevelopmental disorder

PURPOSE

Fem1 homolog B (FEM1B) acts as a substrate recognition subunit for ubiquitin ligase complexes belonging to the CULLIN 2-based E3 family. Several biological functions have been proposed for FEM1B, including a structurally resolved function as a sensor for redox cell status by controlling mitochondrial activity, but its implication in human disease remains elusive.

METHODS

To understand the involvement of FEM1B in human disease, we made use of Matchmaker exchange platforms to identify individuals with de novo variants in FEM1B and performed their clinical evaluation. We performed functional validation using primary neuronal cultures and in utero electroporation assays, as well as experiments on patient's cells.

RESULTS

Five individuals with a recurrent de novo missense variant in FEM1B were identified: NM_015322.5:c.377G>A NP_056137.1:p.(Arg126Gln) (FEM1BR126Q). Affected individuals shared a severe neurodevelopmental disorder with behavioral phenotypes and a variable set of malformations, including brain anomalies, clubfeet, skeletal abnormalities, and facial dysmorphism. Overexpression of the FEM1BR126Q variant but not FEM1B wild-type protein, during mouse brain development, resulted in delayed neuronal migration of the target cells. In addition, the individuals' cells exhibited signs of oxidative stress and induction of type I interferon signaling.

CONCLUSION

Overall, our data indicate that p.(Arg126Gln) induces aberrant FEM1B activation, resulting in a gain-of-function mechanism associated with a severe syndromic developmental disorder in humans.

Insights into the molecular mechanisms, structure-activity relationships and application prospects of polysaccharides by regulating Nrf2-mediated antioxidant response

The occurrence and development of many diseases are closely related to oxidative stress. In this context, accumulating evidence suggests that Nrf2, as the master switch of cellular antioxidant signaling, plays a central role in controlling the expression of antioxidant genes. The core molecular mechanism of polysaccharides treatment of oxidative stress-induced diseases is to activate Keap1/Nrf2/ARE signaling pathway, promote nuclear translocation of Nrf2, and up-regulate the expression of antioxidant enzymes. However, recent studies have shown that other signaling pathways in which polysaccharides exert antioxidant effects, such as PI3K/Akt/GSK3β, JNK/Nrf2 and NF-κB, have complex crosstalk with Keap1/Nrf2/ARE, may have direct effects on the nuclear translocation of Nrf2. This suggests a new strategy for designing polysaccharides as modulators of Nrf2-dependent pathways to target the antioxidant response. Therefore, in this work, we investigate the crosstalk between Keap1/Nrf2/ARE and other antioxidant signaling pathways of polysaccharides by regulating Nrf2-mediated antioxidant response. For the first time, the structural-activity relationship of polysaccharides, including molecular weight, monosaccharide composition, and glycosidic linkage, is systematically elucidated using principal component analysis and cluster analysis. This review also summarizes the application of antioxidant polysaccharides in food, animal production, cosmetics and biomaterials. The paper has significant reference value for screening antioxidant polysaccharides targeting Nrf2.