Nuclear Protein Tyrosine Phosphatase Shp-2 Is One Important Negative Regulator of Nuclear Export of Telomerase Reverse Transcriptase
Nuclear Protein Tyrosine Phosphatase Shp-2 Is One Important Negative Regulator of Nuclear Export of Telomerase Reverse Transcriptase
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DOI：
10.1074/jbc.m805138200
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发表时间：
2008-11-28
影响因子：
4.8
通讯作者：
Haendeler, Judith
中科院分区：
文献类型：
--
作者：
Jakob, Sascha;Schroeder, Peter;Haendeler, Judith
衰老是许多疾病的主要危险因素之一。端粒酶逆转录酶（TERT）在衰老和细胞凋亡中起着重要作用。以前，我们证明，抑制氧化应激诱导的Src激酶家族依赖的细胞核输出的TERT的结果在延迟复制衰老和细胞凋亡的敏感性降低。因此，本研究的目的是研究抑制TERT核输出的机制。首先，我们证明了H2 O2诱导的TERT核输出在Src，Fyn和Yes缺陷的胚胎成纤维细胞中被废除。接下来，我们想确定这种出口过程的一个潜在的负调节器。一个候选者是蛋白酪氨酸磷酸酶Shp-2（Shp-2），其可以抵消Src激酶家族的活性。事实上，Shp-2均匀分布在细胞核和细胞质之间。核Shp-2与内皮细胞中的TERT结合，并在其核输出之前与TERT解离。过表达Shp-2 wt抑制H2 O2诱导的TERT输出。过表达的催化失活，显性负性Shp-2突变体（Shp 2（C459 S））减少内源性以及过表达的核端粒酶蛋白和端粒酶活性，而它对端粒酶（Y 707 F）没有影响。与TERTwt相比，TERT（Y 707 F）与Shp-2的结合减少。Shp-2表达的消融仅导致TERTwt的酪氨酸磷酸化增加，但不导致TERT（Y 707 F）的酪氨酸磷酸化增加。此外，Shp-2表达减少会降低核端粒酶活性，而Shp-2过表达的内皮细胞核端粒酶活性则增加。总之，Shp-2通过调节酪氨酸707磷酸化将TERT保留在细胞核中。
Aging is one major risk factor for numerous diseases. The enzyme telomerase reverse transcriptase ( TERT) plays an important role for aging and apoptosis. Previously, we demonstrated that inhibition of oxidative stress-induced Src kinase family-dependent nuclear export of TERT results in delayed replicative senescence and reduced apoptosis sensitivity. Therefore, the aim of this study was to investigate mechanisms inhibiting nuclear export of TERT. First, we demonstrated that H2O2 induced nuclear export of TERT was abolished in Src, Fyn, and Yes-deficient embryonic fibroblasts. Next, we wanted to identify one potential negative regulator of this export process. One candidate is the protein tyrosine phosphatase Shp-2 (Shp-2), which can counteract activities of the Src kinase family. Indeed, Shp-2 was evenly distributed between the nucleus and cytosol. Nuclear Shp-2 associates with TERT in endothelial cells and dissociates from TERT prior to its nuclear export. Overexpression of Shp-2 wt inhibited H2O2-induced export of TERT. Overexpression of the catalytically inactive, dominant negative Shp-2 mutant (Shp2(C459S)) reduced endogenous as well as overexpressed nuclear TERT protein and telomerase activity, whereas it had no influence on TERT(Y707F). Binding of TERT( Y707F) to Shp-2 is reduced compared with TERTwt. Ablation of Shp-2 expression led only to an increased tyrosine phosphorylation of TERTwt, but not of TERT( Y707F). Moreover, reduced Shp-2 expression decreased nuclear telomerase activity, whereas nuclear telomerase activity was increased in Shp-2-overexpressing endothelial cells. Inconclusion, Shp-2 retains TERT in the nucleus by regulating tyrosine 707 phosphorylation.