The transactivating function of peroxisome proliferator-activated receptor γ is negatively regulated by SUMO conjugation in the amino-terminal domain
The transactivating function of peroxisome proliferator-activated receptor γ is negatively regulated by SUMO conjugation in the amino-terminal domain
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DOI：
10.1111/j.1365-2443.2004.00786.x
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发表时间：
2004-11-01
期刊：
影响因子：
2.1
通讯作者：
Osumi, T
中科院分区：
文献类型：
--
作者：
Yamashita, D;Yamaguchi, T;Osumi, T
过氧化物酶体增殖激活受体(PPAR)-gamma2是核激素受体超家族的成员，在脂肪细胞分化中起关键作用。其氨基末端区具有与配体无关的基因激活功能AF-1，由激活域和抑制域组成。我们在体内发现PPARgamma2及其异构体PPARgamma1在抑制区域的赖氨酸残基处被小泛素相关修饰物(SUMO)-1修饰。在报告者实验中，PPARgamma2的summoylylation缺陷的K107R突变体比野生型表现出更强的反激活，与抑制域缺失的突变体相当。在使用PPARgamma2中SUMO基序突变和SUMO偶联酶Ubc9的显性负突变体进行的分析中，观察到PPARgamma2的SUMO化水平与PPARgamma2的转激活之间存在密切的负相关。对磷酸化缺陷突变体的研究表明，PPARgamma2的S112位点磷酸化可促进K107的磷酸化，而后者具有更强的抑制作用。K107R突变体PPARgamma2用病毒载体感染NIH3T3细胞时，比野生型更有效地促进了脂肪细胞的分化。这些观察结果提供了证据，表明sumo化参与了PPARgamma2反激活功能的负调控。
Peroxisome proliferator-activated receptor (PPAR)-gamma2, a member of the nuclear hormone receptor superfamily, plays a key role in adipocyte differentiation. Its amino-terminal region carries a ligand-independent gene-activating function, AF-1, and is composed of activation as well as repression domains. We have found PPARgamma2 and its isoform, PPARgamma1, to be modified by small ubiquitin-related modifier (SUMO)-1 in vivo, at a lysine residue in the repression domain. In reporter assays, a sumoylation-defective K107R mutant of PPARgamma2 exhibited much stronger transactivation than the wild-type, comparable with that of a mutant deleted for the repression domain. A close inverse correlation was observed between the levels of sumoylation and transactivation by PPARgamma2, in analyses employing PPARgamma2 forms with mutations in the sumoylation motif and a dominant-negative mutant of the SUMO conjugating enzyme, Ubc9. Studies with phosphorylation-defective mutants suggested that phosphorylation at S112 of PPARgamma2 promotes K107 sumoylation, and this latter exerts the more potent repressive effects. The K107R mutant PPARgamma2, when infected into NIH3T3 cells with a viral vector, promoted differentiation into adipocytes more efficiently than the wild-type. These observations provide evidence that sumoylation is involved in negative regulation of the transactivating function of PPARgamma2.