出版社:American Society for Biochemistry and Molecular Biology
摘要:Diacylglycerol kinases (DGK) convert diacylglycerol to phosphatidic acid, which has been reported to stimulate calcium release from the endoplasmic reticulum. Based on our published data showing that trans -10, cis -12 conjugated linoleic acid (t10,c12 CLA)-mediated intracellular calcium accumulation is linked to inflammation and insulin resistance, we hypothesized that inhibiting DGKs with R59022 would prevent t10,c12 CLA-mediated inflammatory signaling and insulin resistance in human adipocytes. Consistent with our hypothesis, R59022 attenuated t10,c12 CLA-mediated i ) increased gene expression and protein secretion of interleukin (IL)-8, IL-6, and monocyte chemoattractant protein-1 (MCP-1); ii ) increased activation of extracellular signal-related kinase (ERK), cJun-NH2-terminal kinase (JNK), and cJun; iii ) increased intracellular calcium levels; iv ) suppressed mRNA or protein levels of peroxisome proliferator activated receptor γ, adiponectin, and insulin-dependent glucose transporter 4; and v ) decreased fatty acid and glucose uptake and triglyceride content. DGKη was targeted for investigation based on our findings that i ) DGKη was highly expressed in primary human adipocytes and time-dependently induced by t10,c12 CLA and that ii ) t10,c12 CLA-induced DGKη expression was dose-dependently decreased with R59022. Small interfering RNA (siRNA) targeting DGKη decreased t10,c12 CLA-induced DGKη, IL-8, and MCP-1 gene expression, as well as activation of JNK and cJun. Taken together, these data suggest that DGKs mediate, in part, t10,c12 CLA-induced inflammatory signaling in primary human adipocytes.