STAT3 Acetylation and Deacetylation in Metastasis

描述（由申请人提供）：信号转导子和转录激活子（STAT）的激活和失活受蛋白酪氨酸激酶（即，JAK）和蛋白酪氨酸磷酸酶（即，SHP-2）活动。C-末端区域磷酸化的STAT二聚化并易位到细胞核中，在那里它结合DNA进行转录激活。为了达到最大的转录活性，STAT需要与其他核因子相互作用。来自我们实验室的证据表明，p300/CBP和HDAC家族成员都能够与STAT3形成复合物，但对STAT3依赖性转录产生相反的作用：虽然p300/CBP增强了STAT3的转录活性，但在293T细胞中过表达HDAC家族成员HDAC3在阻断STAT3依赖性转录方面非常有效。因此，p300/CBP和HDAC活性可能在调节STAT3活性中起关键作用。近年来，研究发现STAT3在调节细胞迁移和肿瘤转移中发挥重要作用，但其具体机制尚不清楚。在这方面，STAT3组成性磷酸化已在转移性和非转移性细胞中广泛检测到。因此，STAT3似乎需要额外的翻译后修饰事件来调节与转移表型获得相关的基因转录。在该提议中待检验的总体假设是STAT活性分别受HAT和HDAC介导的乙酰化和去乙酰化的控制。进一步假设，组成型STAT3乙酰化可能在转移的发展中起核心作用。为了充分验证这些假设，实验将使用我们的抗体阵列技术、特异性基因缺陷和/或下调以及质谱，以便：（1）探索HAT/HDAC作为STAT3信号复合物的组分;（2）测试STAT3二聚化中的STAT3乙酰化和抵抗失活/降解;（3）验证STAT3乙酰化在转移相关基因调控中发挥作用以及组成性STAT3乙酰化是体内转移表型的原因这一假设。这些互补的方法将阐明不受控制的STAT3乙酰化/脱乙酰化在引起癌细胞侵袭和转移中的作用。

DESCRIPTION (provided by applicant): Signal transducer and activator of transcription (STAT) activation and inactivation are controlled by protein tyrosine kinase (i.e., JAK) and protein tyrosine phosphatase (i.e., SHP-2) activities, respectively. C-terminal region phosphorylated STAT dimerize and translocate into nuclei where it binds to DNA for transcriptional activation. To achieve maximum transcriptional activity, STAT needs to interact with other nuclear factors. Evidence from our laboratory shows that both p300/CBP and HDAC family members are capable of forming complexes with STAT3 but exert opposite effects on STAT3-dependent transcription: while p300/CBP enhances STATS's activity in transcription, overexpression of the HDAC family member HDAC3 in 293T cells was highly effective in blocking STAT3-dependent transcription. Thus, p300/CBP and HDAC activities may play key roles in regulating STAT3 activity. Recently, STAT3 has been found to play an important role in regulating cell migration and tumor metastasis although the mechanism has yet to be determined. In this regard, STAT3 constitutive phosphorylation has been widely detected in both metastatic and non-metastatic cells. Thus, an additional post-translational modification event seems to be required for STAT3 to regulate gene transcription relevant to acquisition of the metastatic phenotype. The overarching hypothesis to be tested in this proposal is that STAT activity is under the control of acetylation and deacetylation mediated by HAT and HDAC, respectively. It is hypothesized further that constitutive STAT3 acetylation may play a central role in development of metastasis. To fully test these hypotheses, experiments will use our antibody array technology, specific gene-deficiency and/or down regulation, and mass-spectroscopy in order to: (1) explore HAT/HDAC as components of STAT3 signaling complex; (2) test STAT3 acetylation in STAT3 dimerization and resisting to inactivation/degradation; and (3) test the hypothesis that STAT3 acetylation plays a role in metastasis-related gene regulation and constitutive STAT3 acetylation is responsible for metastatic phenotype in vivo. These complimentary approaches will elucidate the role of uncontrolled STAT3 acetylation/deacetylation in causing cancer cell invasion and metasasis.