Inflammation and insulin resistance induced by trans-10, cis-12 conjugated linoleic acid depend on intracellular calcium levels in primary cultures of human adipocytes |
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Authors: | Arion Kennedy Kristina Martinez Soonkyu Chung Kathy LaPoint Robin Hopkins Soren F. Schmidt Kenneth Andersen Susanne Mandrup Michael McIntosh |
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Affiliation: | *Department of Nutrition, University of North Carolina at Greensboro, Greensboro, NC;†Department of Wake Forest University School of Medicine, Winston-Salem, NC;§Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark |
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Abstract: | We previously demonstrated that trans-10, cis-12 (10,12) conjugated linoleic acid (CLA) induced inflammation and insulin resistance in primary human adipocytes by activating nuclear factor κB (NFκB) and extracellular signal-related kinase (ERK) signaling. In this study, we demonstrated that the initial increase in intracellular calcium ([Ca2+]i) mediated by 10,12 CLA was attenuated by TMB-8, an inhibitor of calcium release from the endoplasmic reticulum (ER), by BAPTA, an intracellular calcium chelator, and by D609, a phospholipase C (PLC) inhibitor. Moreover, BAPTA, TMB-8, and D609 attenuated 10,12 CLA–mediated production of reactive oxygen species (ROS), activation of ERK1/2 and cJun-NH2-terminal kinase (JNK), and induction of inflammatory genes. 10,12 CLA–mediated binding of NFκB to the promoters of interleukin (IL)-8 and cyclooxygenase (COX)-2 and induction of calcium-calmodulin kinase II (CaMKII) β were attenuated by TMB-8. KN-62, a CaMKII inhibitor, also suppressed 10,12 CLA–mediated ROS production and ERK1/2 and JNK activation. Additionally, KN-62 attenuated 10,12 CLA induction of inflammatory and integrated stress response genes, increase in prostaglandin F2α, and suppression of peroxisome proliferator activated receptor γ protein levels and insulin-stimulated glucose uptake. These data suggest that 10,12 CLA increases inflammation and insulin resistance in human adipocytes, in part by increasing [Ca2+]i levels, particularly calcium from the ER. |
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Keywords: | cell signaling fatty acid reactive oxygen species |
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