Hyperphosphorylation of the retinoid X receptor α by activated c-Jun NH2-terminal kinases
Hyperphosphorylation of the retinoid X receptor α by activated c-Jun NH2-terminal kinases
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DOI：
10.1074/jbc.274.27.18932
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发表时间：
1999-07-02
影响因子：
4.8
通讯作者：
Rochette-Egly, C
中科院分区：
文献类型：
--
作者：
Adam-Stitah, S;Penna, L;Rochette-Egly, C
核受体小鼠视黄醇X受体α(mRXRα)在其NH2末端的A/B区被结构性地磷酸化，该区域含有潜在的Pro/Ser/Thr激酶的磷酸化位点，每个可能的位点都产生了突变体，并在COS-1细胞中过表达。经胰酶定位的磷酸化残基包括位于RXRα1亚型A1区的丝氨酸22，应激激活的蛋白激酶c-Jun NH2末端蛋白1和2(JNK1和JNK2)的过度表达和紫外线激活，过度磷酸化的RXRα，导致其凝胶迁移率显著降低。RXRαB区有3个残基(丝氨酸61、75和苏氨酸87)，配基结合区(E区)有1个残基(丝氨酸265)。体外与纯化的重组蛋白的结合实验表明，JNKs不与RXRα相互作用，但与其异源二聚体、维甲酸受体α和γ(RARα和RARγ)结合。JNKs的过度磷酸化不影响RXRα同源二聚体或RXRα/RARα异源二聚体在转基因细胞中的反式激活特性。
The nuclear receptor mouse retinoid X receptor alpha (mRXR alpha) was shown to be constitutively phosphorylated in its NH2-terminal A/B region, which contains potential phosphorylation sites for proline-directed Ser/Thr kinases, Mutants for each putative site were generated and overexpressed in transfected COS-1 cells. Constitutively phosphorylated residues identified by tryptic phosphopeptide mapping included serine 22 located in the A1 region that is specific to the RXR alpha 1 isoform, Overexpression and UV activation of the stress-activated kinases, c-Jun NH2-terminal kinases 1 and 2 (JNK1 and JNK2), hyperphosphorylated RXR alpha, resulting in a marked decrease in its electrophoretic mobility. This inducible hyperphosphorylation involved three residues (serines 61 and 75 and threonine 87) in the B region of RXR alpha and one residue (serine 265) in the ligand binding domain (E region). Binding assays performed in vitro with purified recombinant proteins demonstrated that JNKs did not interact with RXR alpha but bound to its heterodimeric partners, retinoic acid receptors alpha and gamma (RAR alpha and RAR gamma). Hyperphosphorylation by JNKs did not affect the transactivation properties of either RXR alpha homodimers or RXR alpha/RAR alpha heterodimers in transfected cultured cells.