Adiponectin inhibits palmitate-induced apoptosis through suppression of reactive oxygen species in endothelial cells: involvement of cAMP/protein kinase A and AMP-activated protein kinase

Abstract

The present study examined whether adiponectin can inhibit palmitate-induced apoptosis, and also the associated mechanisms and signal transduction pathways in human umbilical vein endothelial cells. Cells treated with 500 mM palmitate for 48 h increased reactive oxygen species (ROS) generation and induced apoptosis. Treatment with antioxidant N-acetyl-L-cysteine (1 mM) and globular adiponectin (5 mg/ml) inhibited palmitate-induced ROS generation and apoptosis. The AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide-1-b-D-ribofuranoside (AICAR; 1 mM), and cAMP activators forskolin (10 mM) and cholera toxin (200 ng/ml) also displayed the same effects. The inhibitory effects of adiponectin on ROS generation and apoptosis were reversed by the AMPK inhibitor compound C (40 mM), cAMP inhibitor SQ22536 (50 mM), and protein kinase A (PKA) inhibitor H-89 (10 mM). The inhibitory effect of forskolin on palmitateinduced apoptosis was reversed by compound C, whereas the inhibitory effect of AICAR was not reversed by SQ22536 and H-89. AICAR and forskolin could not inhibit palmitate-induced apoptosis in cells treated with dominantnegative AMPK. Forskolin increased phosphorylated AMPK at both Thr-172 and Ser-485/491. These results suggest that adiponectin inhibits palmitate-induced apoptosis by suppression of ROS generation via both the cAMP/PKA and AMPK pathways. Interaction between cAMP/PKA and AMPK pathways may be involved.

Globular Adiponectin Attenuated H2O2-Induced Apoptosis in Rat Chondrocytes by Inducing Autophagy Through the AMPK/ mTOR Pathway

“…To further investigate the role of autophagy induced by gAPN in the suppression of H 2 O 2 -induced apoptosis, we pretreated chondrocytes with 10 mM 3-MA (3-methyladenine, Chondrocytes were pretreated with 0.5 µg/ mL gAPN for 24 Fig. 5.…”

Palmitate-induced inflammatory pathways in human adipose microvascular endothelial cells promote monocyte adhesion and impair insulin transcytosis

“…Long-term exposure to high concentrations of saturated fatty acids have previously been found to trigger apoptosis in cells in culture. In endothelial cells, most studies on viability and lipotoxic effects of palmitate used exposure of more than 24 h and doses more than 0.3 mM often with a high palmitate/BSA ratio (24,30,44,53). Moreover, the apoptosis induced by high concentrations of PA in aortic cells is independent of NF-B activation, dissociating the proinflammatory effects of saturated fatty acids from their toxicity at high concentrations (12).…”

IGFBP5 mediates high glucose-induced cardiac fibroblast activation

“…The antibody for IGFBP5 was from Upstate Biotechnology (Lake Placid, NY, USA), glyceraldehyde 3-phosphate dehydrogenase was from Santa Cruz Biotechnology, and TATA-binding factor (TFIIB) was from BD Biosciences (San Jose, CA, USA). Total protein extraction and western blotting were performed as described previously (Kim et al 2010). Briefly, the cells were harvested by trypsinization and resuspended in lysis buffer, and protein concentrations were determined by a Bradford assay (Sigma-Aldrich).…”

“…Apoptosis was determined by flow cytometry using annexin V conjugated with FITC, as described previously (Kim et al 2010). In brief, 1!10 5 cells/100 ml binding buffer were transferred to a tube and incubated with 5 ml annexin V-FITC (BD Biosciences) containing 0.01 M HEPES, pH 7.4, 0.14 M NaCl, and 2.5 mM CaCl for 15 min at room temperature.…”