A dominant-negative peroxisome proliferator-activated receptor γ (PPARγ) mutant is a constitutive repressor and inhibits PPARγ-mediated adipogenesis
A dominant-negative peroxisome proliferator-activated receptor γ (PPARγ) mutant is a constitutive repressor and inhibits PPARγ-mediated adipogenesis
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DOI：
10.1074/jbc.275.8.5754
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发表时间：
2000-02-25
影响因子：
4.8
通讯作者：
Chatterjee, VKK
中科院分区：
文献类型：
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作者：
Gurnell, M;Wentworth, JM;Chatterjee, VKK
核受体过氧化物酶体增殖激活受体γ (PPAR γ)促进脂肪细胞分化，在单核细胞/巨噬细胞中发挥致动脉粥样硬化和抗炎作用，并被认为介导抗糖尿病噻唑烷二酮配体的胰岛素增敏作用。由于迄今为止还没有完整的PPAR γ拮抗剂，我们构建了一个显性阴性突变受体来抑制野生型PPAR γ的作用。配体结合域第12螺旋高度保守的疏水和带电残基（Leu（468）和Glu(471)）突变为丙氨酸。这种化合物PPAR γ突变体保留配体和DNA结合，但由于共激活因子（cAMP-response element-binding protein，结合蛋白和类固醇受体共激活因子- 1）的募集受损，显着降低了转激活。出乎意料的是，突变受体沉默基础基因转录，比野生型PPAR γ更强烈地招募核心压力因子（类维生素a和甲状腺受体的沉默介质以及核辅抑制因子），并表现出延迟的配体依赖性辅抑制因子释放，它是一种强大的显性阴性共转染野生型受体作用抑制剂。此外，当使用重组腺病毒在原代人前脂肪细胞中表达时，这种PPAR γ突变体阻断了噻唑烷二酮诱导的分化，这为PPAR γ介导脂肪形成提供了直接证据。我们的观察结果表明，在其他核受体突变情况下（急性早幼粒细胞白血病，甲状腺激素抵抗），PPAR γ的显性负抑制与异常的辅抑制因子相互作用有关。腺病毒表达这种突变受体是对抗PPAR γ信号的一种有价值的手段。
The nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) promotes adipocyte differentiation, exerts atherogenic and anti-inflammatory effects in monocyte/macrophages, and is believed to mediate the insulin-sensitizing action of antidiabetic thiazolidinedione ligands. As no complete PPAR gamma antagonists have been described hitherto, we have constructed a dominant-negative mutant receptor to inhibit wild-type PPAR gamma action. Highly conserved hydrophobic and charged residues (Leu(468) and Glu(471)) in helix 12 of the ligand-binding domain were mutated to alanine. This compound PPAR gamma mutant retains ligand and DNA binding, but exhibits markedly reduced transactivation due to impaired coactivator (cAMP-response element-binding protein-binding protein and steroid receptor coactivator-l) recruitment. Unexpectedly, the mutant receptor silences basal gene transcription, recruits core pressors (the silencing mediator of retinoid and thyroid receptors and the nuclear corepressor) more avidly than wild-type PPAR gamma, and exhibits delayed ligand-dependent corepressor release, It is a powerful dominant-negative inhibitor of cotransfected wild-type receptor action. Furthermore, when expressed in primary human preadipocytes using a recombinant adenovirus, this PPAR gamma mutant blocks thiazolidinedione-induced differentiation, providing direct evidence that PPAR gamma mediates adipogenesis. Our observations suggest that, as in other mutant nuclear receptor contexts (acute promyelocytic leukemia, resistance to thyroid hormone), dominant-negative inhibition by PPAR gamma is linked to aberrant corepressor interaction. Adenoviral expression of this mutant receptor is a valuable means to antagonize PPAR gamma signaling.