Engineering of triterpene metabolism and overexpression of the lignin biosynthesis gene PAL promotes ginsenoside Rg3 accumulation in ginseng plant chassis

The ginsenoside Rgfound in Panax species has extensive pharmacological properties,in particular anti-cancer effects.However,its natural yield in Panax plants is limited.Here,we report a multimodular strategy to improve yields of Rgin a Panax ginseng chassis,combining engineering of triterpene metabolism and overexpression of a lignin biosynthesis gene,phenylalanine ammonia lyase(PAL).We first performed semi-rational design and site mutagenesis to improve the enzymatic efficiency of Pq3-O-UGT2,a glycosyltransferase that directly catalyzes the biosynthesis of Rgfrom Rh.Next,we used clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9)gene editing to knock down the branch pathway of protopanaxatriol-type ginsenoside biosynthesis to enhance the metabolic flux of the protopanaxadiol-type ginsenoside Rg.Overexpression of PAL accelerated the formation of the xylem structure,significantly improving ginsenoside Rgaccumulation(to 6.19-fold higher than in thecontrol).Wecombinedoverexpression of the ginsenoside aglycon synthetic genes squalene epoxidase,Pq3-O-UGT2,and PAL with CRISPR/Cas9-based knockdown of CYP716A53v2 to improve ginsenoside Rgaccumulation.Finally,we produced ginsenoside Rgat a yield of 83.6 mg/L in a shake flask(7.0 mg/g dry weight,21.12-fold higher than with wild-type cultures).The highproduction system established in this study could be a potential platform to produce the ginsenoside Rgcommercially for pharmaceutical use.

A shedding soluble form of interleukin-17 receptor D exacerbates collagen-induced arthritis through facilitating TNF-α-dependent receptor clustering

Rheumatoid arthritis(RA)is exacerbated by TNF-alpha signaling.However,it remains unclear whether TNF-α-activated TNFR1 and TNFR2 are regulated by extracellular factors.Here,we showed that soluble glycosylated interleukin-17 receptor D(sIL-17RD),which was produced by proteolytic cleavage,enhanced TNF-α-induced RA.We revealed that IL-17RD shedding was induced by the proteolytic enzyme TACE and enhanced by TNF-αexpression in macrophages.Intriguingly,sIL-17RD was elevated in the sera of arthritic mice and rats.Recombinant sIL-17RD significantly enhanced the TNF-α-induced proinflammatory response by promoting TNF-α-TNFR-sIL-17RD complex formation and receptor clustering,leading to the accelerated development of collagen-induced arthritis.Our observations revealed that ectodomain shedding of IL-17RD occurred in RA to boost the TNF-α-induced inflammatory response.Targeting sIL-17RD may provide a new strategy for the therapy of RA.