Multiple forms of PKR present in the nuclei of acute leukemia cells represent an active kinase that is responsive to stress
Multiple forms of PKR present in the nuclei of acute leukemia cells represent an active kinase that is responsive to stress
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DOI：
10.1038/leu.2010.264
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发表时间：
2011-02-01
期刊：
影响因子：
11.4
通讯作者：
Cocco, L.
中科院分区：
文献类型：
--
作者：
Blalock, W. L.;Bavelloni, A.;Cocco, L.
许多癌症具有dsRNA依赖性激酶PKR的组成型活性。这些癌症中PKR的抑制导致肿瘤细胞死亡。我们最近报道了骨髓增生异常综合征（MDS）患者和急性白血病细胞系的临床样本中Thr 451磷酸化PKR（p-T451 PKR）的存在增加。而在低风险患者样品或PTEN阳性急性白血病细胞系中的p-T451 PKR主要是细胞质的，在高风险患者样品和PTEN缺陷的急性白血病细胞系中，p-T451 PKR主要是细胞核的。由于PKR的核活性以前没有被表征，我们研究了急性白血病细胞系中核PKR的状态。利用N-末端、C-末端和激酶结构域的抗体结合蛋白质组学方法，我们发现PKR以不同分子量的形式存在于细胞核中。通过逆转录酶-PCR分析PKR转录物，并通过MS/MS分析PKR衍生肽，表明这些形式是翻译后修饰（PTM）的结果。生化分析表明，核PKR是一种能够响应应激的活性激酶。鉴于PKR与PTEN和Fanconi复合物的相关性，这些结果表明PKR可能在核信号传导中具有其他先前未被认识到的作用，这些作用可能有助于白血病的发展。Leukemia（2011）25，236-245; doi：10.1038/leu.2010.264; 2010年11月12日在线发表
A number of cancers possess constitutive activity of the dsRNA-dependent kinase, PKR. Inhibition of PKR in these cancers leads to tumor cell death. We recently reported the increased presence of PKR phosphorylated on Thr451 (p-T451 PKR) in clinical samples from myelodysplastic syndrome (MDS) patients and acute leukemia cell lines. Whereas p-T451 PKR in low-risk patient samples or PTEN-positive acute leukemia cell lines was mostly cytoplasmic, in high-risk patient samples and acute leukemia cell lines deficient in PTEN, p-T451 PKR was mainly nuclear. As nuclear activity of PKR has not been previously characterized, we examined the status of nuclear PKR in acute leukemia cell lines. Using antibodies to N-terminus, C-terminus and the kinase domain in conjunction with a proteomics approach, we found that PKR exists in diverse molecular weight forms in the nucleus. Analysis of PKR transcripts by reverse transcriptase-PCR, and PKR-derived peptides by MS/MS revealed that these forms were the result of post-translational modifications (PTMs). Biochemical analysis demonstrated that nuclear PKR is an active kinase that can respond to stress. Given the association of PKR with PTEN and the Fanconi complex, these results indicate that PKR likely has other previously unrecognized roles in nuclear signaling that may contribute to leukemic development. Leukemia (2011) 25, 236-245; doi:10.1038/leu.2010.264; published online 12 November 2010