Inhibitory Effects of a Novel PPAR-γ Agonist MEKT1 on Pomc Expression/ACTH Secretion in AtT20 Cells.

IF 3.5 3区医学 Q2 MEDICINE, RESEARCH & EXPERIMENTAL PPAR Research Pub Date : 2018-04-23 eCollection Date: 2018-01-01 DOI:10.1155/2018/5346272

Rehana Parvin, Erika Noro, Akiko Saito-Hakoda, Hiroki Shimada, Susumu Suzuki, Kyoko Shimizu, Hiroyuki Miyachi, Atsushi Yokoyama, Akira Sugawara

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引用次数: 4

Abstract

Although therapeutic effects of the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists rosiglitazone and pioglitazone against Cushing's disease have been reported, their effects are still controversial and inconsistent. We therefore examined the effects of a novel PPAR-γ agonist, MEKT1, on Pomc expression/ACTH secretion using murine corticotroph-derived AtT20 cells and compared its effects with those of rosiglitazone and pioglitazone. AtT20 cells were treated with either 1 nM~10 μM MEKT1, rosiglitazone, or pioglitazone for 24 hours. Thereafter, their effects on proopiomelanocortin gene (Pomc) mRNA expression were studied by qPCR and the Pomc promoter (-703/+58) activity was demonstrated by luciferase assay. Pomc mRNA expression and promoter activity were significantly inhibited by MEKT1 at 10 μM compared to rosiglitazone and pioglitazone. SiRNA-mediated PPAR-γ knockdown significantly abrogated MEKT1-mediated Pomc mRNA suppression. ACTH secretion from AtT20 cells was also significantly inhibited by MEKT1. Deletion/point mutant analyses of Pomc promoter indicated that the MEKT1-mediated suppression was mediated via NurRE, TpitRE, and NBRE at -404/-383, -316/-309, and -69/-63, respectively. Moreover, MEKT1 significantly suppressed Nur77, Nurr1, and Tpit mRNA expression. MEKT1 also was demonstrated to inhibit the protein-DNA interaction of Nur77/Nurr1-NurRE, Tpit-TpitRE, and Nur77-NBRE by ChIP assay. Taken together, it is suggested that MEKT1 could be a novel therapeutic medication for Cushing's disease.

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新型PPAR-γ激动剂MEKT1对at20细胞Pomc表达/ACTH分泌的抑制作用

虽然已报道过氧化物酶体增殖物激活受体γ (PPAR-γ)激动剂罗格列酮和吡格列酮对库欣病的治疗效果，但其效果仍存在争议和不一致。因此，我们研究了一种新型PPAR-γ激动剂MEKT1对小鼠促肾上腺皮质激素来源的AtT20细胞Pomc表达/ACTH分泌的影响，并将其与罗格列酮和吡格列酮的作用进行了比较。at20细胞分别用1 nM~10 μM MEKT1、罗格列酮或吡格列酮处理24小时。随后，采用qPCR方法研究其对促黑素皮质素基因(proopiomelanocortin gene, Pomc) mRNA表达的影响，并通过荧光素酶测定证实Pomc启动子(-703/+58)的活性。与罗格列酮和吡格列酮相比，10 μM MEKT1显著抑制Pomc mRNA表达和启动子活性。sirna介导的PPAR-γ敲低显著消除了mekt1介导的Pomc mRNA抑制。at20细胞的ACTH分泌也被MEKT1显著抑制。Pomc启动子的缺失/点突变分析表明，mekt1介导的抑制分别在-404/-383、-316/-309和-69/-63位点通过NurRE、TpitRE和NBRE介导。此外，MEKT1显著抑制Nur77、Nurr1和Tpit mRNA的表达。通过ChIP实验，MEKT1也被证明可以抑制Nur77/Nurr1-NurRE、Tpit-TpitRE和Nur77- nbre的蛋白- dna相互作用。综上所述，MEKT1可能成为库欣病的一种新型治疗药物。

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来源期刊

PPAR Research MEDICINE, RESEARCH & EXPERIMENTAL-

CiteScore

6.20

自引率

3.40%

发文量

审稿时长

12 months

期刊介绍： PPAR Research is a peer-reviewed, Open Access journal that publishes original research and review articles on advances in basic research focusing on mechanisms involved in the activation of peroxisome proliferator-activated receptors (PPARs), as well as their role in the regulation of cellular differentiation, development, energy homeostasis and metabolic function. The journal also welcomes preclinical and clinical trials of drugs that can modulate PPAR activity, with a view to treating chronic diseases and disorders such as dyslipidemia, diabetes, adipocyte differentiation, inflammation, cancer, lung diseases, neurodegenerative disorders, and obesity.