Period circadian clock 3 inhibits palmitic acid-induced oxidative stress and inflammatory factor secretion in podocytes / 中南大学学报(医学版)

OBJECTIVES@#High fat-induced podocyte injury is one of the important factors leading to obesity related nephropathy (ORG), but the mechanism is not clear. This study aims to explore the mechanism of period circadian clock 3 (PER3) in the oxidative stress and inflammation induced by palmitic acid (PA) in podocytes.@*METHODS@#The C57BL/6J mice were fed with chow and high-fat diet for 16 weeks. The PER3 expression in kidney tissues were detected in the normal body weight group and the obesity group. The PER3 mRNA and protein expression were detected after the podocytes were induced with different concentrations (0, 50, 150 and 300 μmol/L) of PA for 48 h. The PER3 mRNA and protein expression were detected after the podocytes were induced with 150 μmol/L PA for 0, 24, 36, and 48 h. Triglyceride (TG) levels were examined in the PA group, the adenovirus (ad)-PER3+PA group, and the siRNA-PER+PA group after the podocytes were transfected by Ad-PER3 or small interfering RNA (siRNA)-PER3 for 48 h and subsequently were induced with 150 μmol/L PA for 48 h. The differential gene expression was detected using RNA sequencing (RNA-seq) after podocytes were transfected by siRNA-PER3 (siRNA-PER3 group) and siRNA-control (siRNA-control group), respectively. The mRNA levels of nephrin, podocin, podocalyxin, podoplanin, superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), catalase (CAT), and the levels of malondialdehyde (MDA), glutathione (GSH), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and interleukin-2 (IL-2) were detected after podocytes were transfected with Ad-PER3 or Ad-control for 48 h and then they were induced by 150 μmol/L PA for 48 h.@*RESULTS@#The PER3 was down-regulated in the obesity group compared with the normal body weight group (@*CONCLUSIONS@#PER3 can decrease the PA-induced oxidative stress and inflammatory factor secretion via inhibiting the lipogenesis in podocytes.

Guanxin Zhitong Capsules attenuate human endothelial cell damage induced by palmitic acid via MAPK signaling pathway / 中国中药杂志

The present study observed the effect of Guanxin Zhitong Capsules(GXZT) on the lipotoxicity of vascular endothelial cells and investigated the mechanism of GXZT in atherosclerosis treatment. The lipotoxicity model in human umbilical vein endothelial cells(HUVECs) was induced by palmitic acid(PA) stimulation. These cells were divided into a normal control group(NC, 15% normal serum), a model group(PA, 0.6 mmol·L~(-1) PA+15% normal serum), a high-dose GXZT group(GXZT-H, 0.6 mmol·L~(-1) PA+15% GXZT-medicated serum), a medium-dose GXZT group(GXZT-M, 0.6 mmol·L~(-1) PA+10% GXZT-medicated serum+5% normal serum) and a low-dose GXZT group(GXZT-L, 0.6 mmol·L~(-1) PA+5% GXZT-medicated serum+10% normal serum). HUVECs were detected for cell viability by cell counting kit-8(CCK-8) assay, apoptosis by flow cytometry, mitochondrial membrane potential(MMP) by JC-1 labeled laser scanning confocal microscopy, and total and phosphorylated proteins of p38, ERK1/2, and JNK1/2 in the mitogen-activated protein kinases(MAPK) signaling pathway by Western blot. The phosphorylated level was calcula-ted. Compared with the NC group, the PA group showed decreased cell viability and MMP(P<0.01, P<0.01), elevated apoptosis(P<0.01), and up-regulated phosphorylated levels of p38, ERK1/2, and JNK1/2(P<0.01, P<0.01, P<0.01). Compared with the PA group, the GXZT-H, GXZT-M, and GXZT-L groups showed increased cell viability and MMP(P<0.01, P<0.01, P<0.01), reduced apoptosis(P<0.01), and down-regulated protein expression and phosphorylated levels of p38, ERK1/2 and JNK1/2 in the MAPK signaling pathway(P<0.01, P<0.01, P<0.01). In conclusion, the results suggest that GXZT functions via blocking MAPK signaling pathway to relieve the damage of HUVECs induced by PA.

Palmitic acid-induced lipotoxicity promotes a novel interplay between Akt-mTOR, IRS-1, and FFAR1 signaling in pancreatic ß-cells

BACKGROUND: Free fatty acid receptor 1 (FFAR1) is G-protein coupled receptor predominantly expressed in pancreatic ß-cells that is activated by a variety of free fatty acids (FFAs). Once activated, it promotes glucose-stimulated insulin secretion (GSIS). However, increased levels of FFAs lead to lipotoxicity, inducing loss of ß-cell function. FFAR1 plays a key role in the development of type 2 diabetes (T2D), and previous studies have indicated the importance of developing anti-diabetic therapies against FFAR1, although its role in the regulation of ß-cell function remains unclear. The present study investigated the role of FFAR1 under lipotoxic conditions using palmitic acid (PA). The rat insulinoma 1 clone 832/13 (INS-1 832/13) cell line was used as a model as it physiologically resembles native pancreatic ß-cells. Key players of the insulin signaling pathway, such as mTOR, Akt, IRS-1, and the insulin receptor (INSR1ß), were selected as candidates to be analyzed under lipotoxic conditions. RESULTS: We revealed that PA-induced lipotoxicity affected GSIS in INS-1 cells and negatively modulated the activity of both IRS-1 and Akt. Reduced phosphorylation of both IRS-1 S636/639 and Akt S473 was observed, in addition to decreased expression of both INSR1ß and FFAR1. Moreover, transient knockdown of FFAR1 led to a reduction in IRS-1 mRNA expression and an increase in INSR1ß; mRNA. Finally, PA affected localization of FFAR1 from the cytoplasm to the perinucleus. CONCLUSIONS: In conclusion, our study suggests a novel regulatory involvement of FFAR1 in crosstalk with mTOR-Akt and IRS-1 signaling in ß-cells under lipotoxic conditions.