Globular Adiponectin Exerts a Pro-Inflammatory Effect via IκB/NF-κB Pathway Activation and Anti-Inflammatory Effect by IRAK-1 Downregulation
Kyoung-Hee Lee1,3, Jiyeong Jeong1,3, Jisu Woo1, Chang-Hoon Lee1,2, Chul-Gyu Yoo1,2,*
1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Hospital, Seoul 03080, Korea, 2Department of Internal Medicine, Seoul National University College of Medicine, Seoul 03080, Korea, 3These authors contributed equally to this work.
*Correspondence: cgyoo@snu.ac.kr
Received January 2, 2018; Revised June 8, 2018; Accepted June 20, 2018.; Published online July 30, 2018.
© Korean Society for Molecular and Cellular Biology. All rights reserved.

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ABSTRACT
Adiponectin, a hormone produced by adipose tissue, is very abundant in plasma, and its anti- and pro-inflammatory effects are reported. However, the mechanisms of these proand anti-inflammatory effects are not fully defined. Herein, we evaluated the dual inflammatory response mechanism of adiponectin in macrophages. Short-term globular adiponectin (gAd) treatment induced IκBα degradation, NF-κB nuclear translocation, and TNF-α production in RAW 264.7 cells. Polymyxin B pretreatment did not block gAd-induced IκBα degradation, and heated gAd was unable to degrade IκBα, suggesting that the effects of gAd were not due to endotoxin contamination. gAd activated IKK and Akt, and inhibition of either IKK or Akt by dominant-negative IKKβ (DN-IKKβ) or DN-Akt overexpression blocked gAd-induced IκBα degradation, suggesting that short-term incubation with gAd mediates inflammatory responses by activating the IκB/NF-κB and PI3K/Akt pathways. Contrastingly, long-term stimulation with gAd induced, upon subsequent stimulation, tolerance to gAd, lipopolysaccharide, and CpG-oligodeoxynucleotide, which is associated with gAd-induced downregulation of IL-receptorassociated kinase-1 (IRAK-1) due to IRAK-1 transcriptional repression. Conclusively, our findings demonstrate that the pro-proand anti-inflammatory responses to gAd in innate immune cells are time-dependent, and mediated by the activation of the IκB/NF-κB pathway, and IRAK-1 downregulation, respectively.
Keywords: globular adiponection, NF-κB, IRAK-1


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31 July 2018 Volume 41,
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