In this study, supplementation with Panax notoginseng (PN) in obese mice reversed excessive weight gain, improved glucose homeostasis and insulin sensitivity, and significantly reversed hepatic steatosis. Concurrently, PN treatment normalized the intestinal microecosystem, reflected in a decreased Firmicutes-to-Bacteroidetes ratio (F/B ratio) and an enrichment of the commensal species Enterocloster clostridioformis (EC). Of particular note, oral administration of EC alone largely reproduced the major beneficial phenotypes observed with PN—namely, reduced fat mass, improved glycaemic regulation, and attenuated hepatic triglyceride deposition. Mechanistically, EC intervention suppressed the pathological overactivation of the hepatic insulin receptor substrate (IRS)-phosphatidylinositol-3 kinase (PI3K)-AKT kinase (AKT) pathway and inhibited the phosphorylation of IRS. This recalibration of the insulin signaling cascade improved insulin sensitivity and effectively counteracted the metabolic disturbances provoked by the high-fat diet (HFD). Taken together, these results suggest that the anti-obesity effects of PN are at least partially mediated by gut microbiota-driven EC enrichment, with consequent modulation of the IRS-PI3K-AKT pathway. Collectively, our findings identify EC as a potential candidate commensal bacterium and highlight the importance of the PN-EC-IRS-PI3K-AKT regulatory axis in counteracting obesity and its associated comorbidities.
Alisma plantago-aquatica L. is a traditional Chinese medicinal herb used to treat urinary disorders. Acylated protostane-type tetracyclic triterpenes such as alisol B 23-acetate and alisol C 23-acetate are its major bioactive components and have been reported to exhibit improved antiviral activities. However, the content of these compounds is relatively low in plants, and the enzyme that catalyzes this acetylation process has not yet been identified. In this study, we constructed a transcriptome dataset for A. plantago-aquatica. Using co-expression analysis and enzyme activity screening, we successfully identified a benzyl alcohol O-acetyltransferase, anthocyanin O-hydroxycinnamoyltransferase, anthranilate N-hydroxycinnamoyl/benzoyltransferase, deacetylvindoline 4-O-acetyltransferase (BAHD), ApAT2. This enzyme catalyzes the acetylation of alisol B and alisol C but does not exhibit any catalytic activity toward alisol A. Molecular docking and site-directed mutagenesis confirmed that the M412 residue of ApAT2 played a critical role in its substrate specificity. Phylogenetic analysis suggests that the active pocket of ApAT2 possibly diverged via lineage-specific evolution, conferring specificity for protostane-type tetracyclic triterpenes. Furthermore, we established a semi-biosynthetic platform in Escherichia coli expressing ApAT2 to produce alisol B 23-acetate from alisol B. In conclusion, we identified the BAHD enzyme responsible for the acetylation of protostane-type tetracyclic triterpenes, thus providing new systems to produce these valuable compounds. We also identified a new molecular basis for the recognition and modification of diverse substrates by the BAHD family during plant evolution.
β-Catenin/CTNNB1 is the key intracellular effector of the canonical Wnt signaling. While zygotic CTNNB1 is essential for gastrulation in mouse embryos, maternal CTNNB1 is thought to be dispensable for development to the blastocyst stage. Besides, it remains controversial whether maternal CTNNB1 is activated during preimplantation stages. In this study, we report that maternal CTNNB1 is required for activating canonical Wnt signaling after fertilization and sustaining robust blastocyst formation. Loss of maternal CTNNB1 causes developmental delay, impaired compaction, reduced trophectoderm (TE) cell number, and developmental defects at E18.5. Transcriptome profiling highlights widespread dysregulation of cell-cycle, MAPK/ERK, and apoptosis pathways. Treatment with basic fibroblast growth factor (bFGF) or overexpression of Ctnnb1, Erk2, or Ccnd1 can partially rescue preimplantation defects in maternal Ctnnb1 (MCtnnb1) mutant embryos. Mechanistically, maternal CTNNB1 promotes nuclear accumulation of phosphorylated ERK1/2 (pERK1/2) and transcription of Ccnd1 to sustain TE proliferation and robust blastocyst formation. Taken together, our findings shed light on the role of maternal CTNNB1 signaling in supporting preimplantation embryo quality in mammals.
