Aspects of the regulatory mechanisms of PPAR functions: Analysis of a bidirectional response element and regulation by sumoylation
Aspects of the regulatory mechanisms of PPAR functions: Analysis of a bidirectional response element and regulation by sumoylation
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DOI：
10.1007/s11010-005-9052-z
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发表时间：
2006-06-01
影响因子：
4.3
通讯作者：
Osumi, Takashi
中科院分区：
文献类型：
--
作者：
Shimizu, Makoto;Yamashita, Daisuke;Osumi, Takashi
过氧化物酶体增殖物激活受体（PPARs）是核受体超家族的一个亚家族。包括降血脂剂、抗糖尿病药物和长链脂肪酸在内的多种化合物是PPARs的潜在配体。为了探讨PPARs的调控机制，我们在本工作中研究了两个主题。首先，我们在PEX 11 α和围脂蛋白基因之间的间隔区确定了一个功能性的PPAR-binding位点，该基因在小鼠基因组上串联排列。通过基因报告分析和体内以及体外结合试验，我们表明，这些基因的组织选择性调节通过这个共同的结合位点：PEX 11 α基因激活的过氧化物酶体增殖物激活受体α在肝脏中，而perilipin基因的过氧化物酶体增殖物激活受体γ在脂肪组织中。作为第二个主题，我们发现PPAR γ 2与小泛素相关修饰物（SUMO）在氨基末端区域的特定赖氨酸残基上缀合。通过定点突变结合基因报告基因分析和sumoylation分析，我们表明，sumoylation抑制配体独立的反式激活功能，该区域进行，因此负调控整个的PPAR γ 2的反式激活能力。此外，在氨基末端区域的特定位点的磷酸化可能通过增强类小泛素化来抑制PPAR γ 2的反式激活。
Peroxisome proliferator-activated receptors (PPARs) constitute a subfamily of nuclear receptor superfamily. A wide variety of compounds including hypolipidemic agents, antidiabetic drugs, and long-chain fatty acids are the potential ligands of PPARs. To approach the regulatory mechanisms of PPARs, we studied on two subjects in this work. First, we identified a functional PPAR-binding site in the spacer region between the PEX11 alpha and perilipin genes, which are arranged in tandem on the mouse genome. By gene reporter assays and in vivo as well as in vitro binding assays, we show that these genes are regulated tissue-selectively through this common binding site: The PEX11 alpha gene is activated by PPAR alpha in the liver, whereas the perilipin gene by PPAR gamma in the adipose tissue. As the second subject, we found that PPAR gamma 2 is conjugated with small ubiquitin-related modifier (SUMO) at a specific lysine residue in the amino-terminal region. By site-directed mutagenesis combined with gene reporter assays and sumoylation analyses, we show that sumoylation represses the ligand-independent transactivating function carried by this region, and hence negatively regulates the whole transactivating competence of PPAR gamma 2. In addition, phosphorylation at a specific site in the amino-terminal region represses the transactivation by PPAR gamma 2 possibly through enhancing sumoylation.