Ixeris dentata decreases ER stress and hepatic lipid accumulation through regulation of ApoB secretion.

Nonalcoholic fatty liver disease (NAFLD) is caused by the hepatic accumulation of saturated fatty acids involving the ER stress mechanism. Secretion of apo lipid carrier proteins and their binding to hepatic TG and cholesterol are affected by ER stress. This study was designed to identify ER stress regulators with potential effects against hepatic lipid accumulation. Ixeris dentata (IXD) is a traditional herbal remedy for indigestion, hepatitis, and diabetes used in Korea, Japan, and China. To examine the regulatory effects of IXD against hepatic lipid accumulation and elucidate its suggested mechanism of ER stress, HepG2 hepatocytes were treated with IXD extract in the presence of palmitate. While palmitate induced an ER stress response in hepatocytes, as indicated by the upregulation of PERK, increased eukaryotic initiation factor 2α (eIF2α) phosphorylation, enhanced expression of GADD153/C/EBP homologous protein (CHOP), and reduced secretion of apoB resulting in hepatic cellular accumulation of triglycerides (TG) and cholesterol, IXD extract significantly inhibited the lipid accumulation and PERK/eIF2α/CHOP-axis of the ER stress response. The inhibition of the PERK/eIF2α/CHOP signaling pathway by IXD in palmitate-treated cells suggests that IXD regulates hepatic dyslipidemia through the regulation of ER stress.

Eucommia ulmoides Oliver extract, aucubin, and geniposide enhance lysosomal activity to regulate ER stress and hepatic lipid accumulation.

Eucommia ulmoides Oliver is a natural product widely used as a dietary supplement and medicinal plant. Here, we examined the potential regulatory effects of Eucommia ulmoides Oliver extracts (EUE) on hepatic dyslipidemia and its related mechanisms by in vitro and in vivo studies. EUE and its two active constituents, aucubin and geniposide, inhibited palmitate-induced endoplasmic reticulum (ER) stress, reducing hepatic lipid accumulation through secretion of apolipoprotein B and associated triglycerides and cholesterol in human HepG2 hepatocytes. To determine how EUE diminishes the ER stress response, lysosomal and proteasomal protein degradation activities were analyzed. Although proteasomal activity was not affected, lysosomal enzyme activities including V-ATPase were significantly increased by EUE as well as aucubin and geniposide in HepG2 cells. Treatment with the V-ATPase inhibitor, bafilomycin, reversed the inhibition of ER stress, secretion of apolipoprotein B, and hepatic lipid accumulation induced by EUE or its component, aucubin or geniposide. In addition, EUE was determined to regulate hepatic dyslipidemia by enhancing lysosomal activity and to regulate ER stress in rats fed a high-fat diet. Together, these results suggest that EUE and its active components enhance lysosomal activity, resulting in decreased ER stress and hepatic dyslipidemia.