Serine 220 phosphorylation of the Merkel cell polyomavirus large T antigen crucially supports growth of Merkel cell carcinoma cells
Serine 220 phosphorylation of the Merkel cell polyomavirus large T antigen crucially supports growth of Merkel cell carcinoma cells
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默克尔细胞多瘤病毒大 T 抗原的丝氨酸 220 磷酸化对默克尔细胞癌细胞的生长至关重要
DOI：
10.1002/ijc.29862
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发表时间：
2015
影响因子：
6.4
通讯作者：
Houben R
中科院分区：
文献类型：
--
作者：
Schrama D;Hesbacher S;Angermeyer S;Schlosser A;Haferkamp S;Adam C;Weber A;Schmidt M;Houben R
默克尔细胞多瘤病毒（MCPyV）被认为是默克尔细胞癌（MCC）的主要致病因子。事实上，MCPyV阳性MCC细胞的肿瘤细胞生长依赖于具有完整视网膜母细胞瘤蛋白（RB）结合位点的截短病毒大T抗原（LT）的表达。在这里，我们通过质谱法确定了MCC特有的截短MCPyV-LT的磷酸化模式，揭示了MCPyV-LT是在几个丝氨酸和苏氨酸残基处磷酸化的多磷酸蛋白。值得注意的是，大多数这些磷酸化位点的破坏并不影响其在MCC细胞中拯救内源性T抗原敲低的能力，表明相应氨基酸的磷酸化对于MCPyV-LT的生长促进功能不是必需的。然而，丝氨酸220变为丙氨酸完全消除了MCPyV-LT支持MCC细胞增殖的能力。相反，通过将丝氨酸220突变为谷氨酸来模拟磷酸化状态导致了完全功能性的LT。此外，MCPyV-LTS 220 A在免疫共沉淀实验中表现出与RB的结合减少，以及MCC细胞中RB靶基因的诱导减弱。总之，我们提供的证据表明，丝氨酸220的磷酸化是必需的有效的RB失活在MCC，因此可能是一个潜在的目标，为未来的治疗方法。
Merkel cell polyomavirus (MCPyV) is regarded as a major causal factor for Merkel cell carcinoma (MCC). Indeed, tumor cell growth of MCPyV‐positive MCC cells is dependent on the expression of a truncated viral Large T antigen (LT) with an intact retinoblastoma protein (RB)‐binding site. Here we determined the phosphorylation pattern of a truncated MCPyV‐LT characteristically for MCC by mass spectrometry revealing MCPyV‐LT as multi‐phospho‐protein phosphorylated at several serine and threonine residues. Remarkably, disruption of most of these phosphorylation sites did not affect its ability to rescue knockdown of endogenous T antigens in MCC cells indicating that phosphorylation of the respective amino acids is not essential for the growth promoting function of MCPyV‐LT. However, alteration of serine 220 to alanine completely abolished the ability of MCPyV‐LT to support proliferation of MCC cells. Conversely, mimicking the phosphorylated state by mutation of serine 220 to glutamic acid resulted in a fully functional LT. Moreover, MCPyV‐LTS220Ademonstrated reduced binding to RB in co‐immunoprecipitation experiments as well as weaker induction of RB target genes in MCC cells. In conclusion, we provide evidence that phosphorylation of serine 220 is required for efficient RB inactivation in MCC and may therefore be a potential target for future therapeutic approaches.
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DOI：
--
发表时间：
2000
期刊：
Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research.
影响因子：
--
作者：
Chien,WM;Parker,JN;Schmidt-Grimminger,DC;Broker,TR;Chow,LT
通讯作者：
Chow,LT
影响因子：
14.5
作者：
Cheng J;DeCaprio JA;Fluck MM;Schaffhausen BS
通讯作者：
Schaffhausen BS
影响因子：
5.4
作者：
Chemes, Lucia B.;Sanchez, Ignacio E.;de Prat-Gay, Gonzalo
通讯作者：
de Prat-Gay, Gonzalo
影响因子：
6.4
作者：
LEONARD, JH;DASH, P;BELL, JR
通讯作者：
BELL, JR
影响因子：
15.9
作者：
Shuda, Masahiro;Kwun, Hyun Jin;Moore, Patrick S.
通讯作者：
Moore, Patrick S.