title: Pro-inflammatory Macrophages suppress PPARγ activity in Adipocytes via S-nitrosylation.
abstract: Peroxisome proliferator-activated receptor-γ (PPARγ) is a ligand-activated nuclear receptor and plays an essential role in insulin signaling. Macrophage infiltration into adipose tissue is a character of metabolic inflammation and closely related to insulin resistance in type 2 diabetes. The mechanism by which pro-inflammatory macrophages cause insulin resistance remains to be elucidated. Here we showed that co-culture with macrophages significantly suppressed the transcriptional activity of PPARγ on its target genes in 3T3-L1 preadipocytes and diabetic primary adipocytes, depending on inducible nitric oxide synthase (iNOS). We further showed that PPARγ underwent S-nitrosylation in response to nitrosative stress. Mass-spectrometry and site-directed mutagenesis revealed that S-nitrosylation at cysteine 168 was responsible for the impairment of PPARγ function. Extended exposure to NO instigated the proteasome-dependent degradation of PPARγ. Consistently, in vivo evidence revealed an association of the decreased PPARγ protein level with increased macrophage infiltration in visceral adipose tissue (VAT) of obese diabetic db/db mice. Together, our results demonstrated that pro-inflammatory macrophages suppressed PPARγ activity in adipocytes via S-nitrosylation, suggesting a novel mechanism linking metabolic inflammation with insulin resistance.
authors.affiliation: Institute of Cardiovascular Science and Diabetes Center, Peking University, Beijing 100191, China.
authors.forename: Ruiying
authors.initials: R
authors.lastname: Yin
authors.affiliation: Institute of Cardiovascular Science and Diabetes Center, Peking University, Beijing 100191, China.
authors.forename: Li
authors.initials: L
authors.lastname: Fang
authors.affiliation: Institute of Cardiovascular Science and Diabetes Center, Peking University, Beijing 100191, China.
authors.forename: Yingjia
authors.initials: Y
authors.lastname: Li
authors.affiliation: Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Xue
authors.affiliation: Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yazi
authors.initials: Y
authors.lastname: Li
authors.affiliation: The Advanced Institute for Medical Sciences, Dalian Medical University, Dalian 116044, China.
authors.forename: Youfei
authors.initials: Y
authors.lastname: Guan
authors.affiliation: National Laboratory of Medical Molecular Biology, Institute of Basic Medical Science, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100005, China.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: changchen@moon.ibp.ac.cn.
authors.forename: Chang
authors.initials: C
authors.lastname: Chen
authors.affiliation: Institute of Cardiovascular Science and Diabetes Center, Peking University, Beijing 100191, China; The Advanced Institute for Medical Sciences, Dalian Medical University, Dalian 116044, China. Electronic address: nanpingwang2003@yahoo.com.
authors.forename: Nanping
authors.initials: N
authors.lastname: Wang
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D007124:Immunoenzyme Techniques; D007249:Inflammation / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D047495:PPAR gamma / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015533:Transcriptional Activation
chemical_list: D007328:Insulin; D047495:PPAR gamma; D012333:RNA, Messenger; D009569:Nitric Oxide
keywords: Adipose tissue; Insulin resistance; Macrophage; PPARγ; S-nitrosylation