Threonine 149 Phosphorylation Enhances ΔFosB Transcriptional Activity to Control Psychomotor Responses to Cocaine
Threonine 149 Phosphorylation Enhances ΔFosB Transcriptional Activity to Control Psychomotor Responses to Cocaine
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DOI：
10.1523/jneurosci.1611-14.2014
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发表时间：
2014-08-20
影响因子：
5.3
通讯作者：
Robison, Alfred J.
中科院分区：
文献类型：
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作者：
Cates, Hannah M.;Thibault, Mackenzie;Robison, Alfred J.
神经元基因表达的稳定变化作为成瘾状态的介质已被研究。我们特别感兴趣的是转录因子δ FosB，这是一种截断的、稳定的FosB基因产物，其在伏隔核（NAc）中表达，这是一个关键的奖励区域，几乎所有滥用药物的长期暴露都会诱导其表达，并调节其精神运动和奖励作用。Ser（27）位点的磷酸化有助于Delta FosB在反复暴露于药物后的稳定性和积累，我们最近的研究表明，蛋白激酶CaMKII α磷酸化Delta FosB Ser（27）位点并调节其体内稳定性。在这里，我们确定了Delta FosB上另外两个被CaMKII α磷酸化的位点，Thr（149）和Thr(180)，并证明了它们在体内受到慢性可卡因的调节。我们发现，与野生型（WT） Delta FosB相比，Thr(149) （T149D）的拟磷突变显著增加了AP-1的转录活性，而丙氨酸突变不影响转录活性。利用病毒介导的德尔塔FosB- t149d或德尔塔FosB- t149a基因在小鼠NAc中的体内转移，我们确定德尔塔FosB- t149d在NAc中的过度表达比WT德尔塔FosB在初始低剂量可卡因下导致更大的运动活动。而过表达Delta FosB- t149a并不产生过表达WT Delta FosB后对慢性低剂量可卡因的精神运动性致敏，并消除了对照动物在高剂量可卡因下的致敏作用。我们进一步证明，Thr（149）的突变不会影响小鼠NAc中Delta FosB过表达的稳定性，这表明这些突变的行为影响是由它们改变的转录特性驱动的。
Stable changes in neuronal gene expression have been studied as mediators of addicted states. Of particular interest is the transcription factor Delta FosB, a truncated and stable FosB gene product whose expression in nucleus accumbens (NAc), a key reward region, is induced by chronic exposure to virtually all drugs of abuse and regulates their psychomotor and rewarding effects. Phosphorylation at Ser(27) contributes to Delta FosB's stability and accumulation following repeated exposure to drugs, and our recent work demonstrates that the protein kinase CaMKII alpha phosphorylates Delta FosB at Ser(27) and regulates its stability in vivo. Here, we identify two additional sites on Delta FosB that are phosphorylated in vitro by CaMKII alpha, Thr(149) and Thr(180), and demonstrate their regulation in vivo by chronic cocaine. We show that phosphomimetic mutation of Thr(149) (T149D) dramatically increases AP-1 transcriptional activity while alanine mutation does not affect transcriptional activity when compared with wild-type (WT) Delta FosB. Using in vivo viral-mediated gene transfer of Delta FosB-T149D or Delta FosB-T149A in mouse NAc, we determined that overexpression of Delta FosB-T149D in NAc leads to greater locomotor activity in response to an initial low dose of cocaine than does WT Delta FosB, while overexpression of Delta FosB-T149A does not produce the psychomotor sensitization to chronic low-dose cocaine seen after overexpression of WT Delta FosB and abrogates the sensitization seen in control animals at higher cocaine doses. We further demonstrate that mutation of Thr(149) does not affect the stability of Delta FosB overexpressed in mouse NAc, suggesting that the behavioral effects of these mutations are driven by their altered transcriptional properties.