Effect of Flammulina velutipes polysaccharides on endoplasmic reticulum stress‐mediated apoptosis by activating PLC–IP3 pathway in HepG2 cells

Abstract

Flammulina velutipes polysaccharides (FVP) have been proven to induce apoptosis in HepG2 cells. It is well known that endoplasmic reticulum stress (ERS) is involved in apoptosis. However, ERS mediates FVP-induced apoptosis in HepG2 cells remains unclear. In our study, the results indicated that FVP caused ERS in HepG2 cells. They showed that FVP were water-soluble polysaccharides with the weight average molecular weight of 1972 kDa, which were mainly composed of mannose, gluconic acid, glucose, galactose, xylose and fructose in a molar ratio of 6.6 : 1.3 : 79.9 : 7.4 : 3.4 : 1.5. After FVP treatment, the expression levels of genes and proteins related to ERS were upregulated. The inhibition of ERS by 4-phenylbutyric acid (4-PBA) pretreatment could significantly reduce the role of FVP in inducing apoptosis. We further found the results of immunofluorescence and flow cytometry showing that Ca 2+ in the ERS leaked out, and the intracellular Ca 2+ concentration increased after FVP treatment. The pretreatment with the phospholipase C (PLC) inhibitor U73122 proved that FVP caused excessive intracellular Ca 2+ concentration by activating the phospholipase C-inositol-1,4,5-triphosphate (PLC-IP3) pathway, resulting in ERS, and ultimately leading to apoptosis. In summary, our results indicated that FVP induced ERS-mediated apoptosis by activating PLC-IP3 pathway in HepG2 cells.

Electroacupuncture Ameliorates Gastrointestinal Motility in Rats with Functional Dyspepsia Via PLC/IP3 Signaling

“…PLC inhibitor (U73122) and IP 3 inhibitor (Xestospongin C) can differentially inhibit the contraction of gastric smooth muscles induced by contractile hormones in rats 50 . Pretreatment with U73122 reduced the high intracellular Ca 2+ concentration induced by the PLC-IP 3 pathway 51 . Our results suggest that EA and U73122 + EA upregulate PDGFRα and the expression of P-PLC, PLC, and IP 3 in cells and increase GI motility in FD rats.…”