Phosphorylation state of Ser165 in α-tubulin is a toggle switch that controls proliferating human breast tumors.
Phosphorylation state of Ser165 in α-tubulin is a toggle switch that controls proliferating human breast tumors.
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α-微管蛋白中 Ser165 的磷酸化状态是控制增殖的人类乳腺肿瘤的切换开关。
DOI：
10.1016/j.cellsig.2018.08.021
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发表时间：
2018
影响因子：
4.8
通讯作者：
Rotenberg,SusanA
中科院分区：
文献类型：
--
作者：
Markovsky,Ela;deStanchina,Elisa;Itzkowitz,Aryeh;Haimovitz-Friedman,Adriana;Rotenberg,SusanA
已知蛋白激酶Cα（PKCα）的工程过表达可磷酸化α-微管蛋白中的Ser 165，从而刺激微管动力学和细胞运动，并激活未转化的人乳腺细胞中的上皮-间充质转化（EMT）。本文显示，在两种转移性乳腺细胞系MDA-MB-231-LM 2 -4175和MDA-MB-468中，在PKC磷酸化位点检测到天然α-微管蛋白的内源性磷酸化。模拟磷酸化（S165 D）或非磷酸化（S165 N）状态的α-微管蛋白突变体在MDA-MB-231-LM 2 -4175细胞中稳定表达。S165 D-α-微管蛋白突变体引起EMT生物标志物N-钙粘蛋白的表达，而S165 N-α-微管蛋白抑制N-钙粘蛋白并诱导E-钙粘蛋白表达，揭示了“钙粘蛋白开关”。S165 N-α-tubulin使细胞周期更快地通过，诱导更短的梭形纤维，并表现出更快的增殖。在注射MDA-MB-231-LM 2 -4175细胞的裸鼠中，表达S165 N-α-微管蛋白的细胞（而不是S165 D突变体）产生了过度增殖的肺肿瘤，肿瘤发生率增加，Ki 67表达更高。这些结果暗示α-微管蛋白中Ser 165的磷酸化状态作为PKC调节的分子开关，导致乳腺细胞表现出EMT特征或过度增殖。对人类肿瘤基因组数据库的评估加强了这些发现的临床意义。
Engineered overexpression of protein kinase Cα (PKCα) is known to phosphorylate Ser165in α-tubulin resulting in stimulated microtubule dynamics and cell motility, and activation of an epithelial-mesenchymal transition (EMT) in non-transformed human breast cells. Here it is shown that endogenous phosphorylation of native α-tubulin in two metastatic breast cell lines, MDA-MB-231-LM2–4175 and MDA-MB-468 is detected at PKC phosphorylation sites. α-Tubulin mutants that simulated phosphorylated (S165D) or non-phosphorylated (S165 N) states were stably expressed in MDA-MB-231-LM2–4175 cells. The S165D-α-tubulin mutant engendered expression of the EMT biomarker N-cadherin, whereas S165 N-α-tubulin suppressed N-cadherin and induced E-cadherin expression, revealing a ‘cadherin switch’. S165 N-α-tubulin engendered more rapid passage through the cell cycle, induced shorter spindle fibers and exhibited more rapid proliferation. In nude mice injected with MDA-MB-231-LM2–4175 cells, cells expressing S165 N-α-tubulin (but not the S165D mutant) produced hyper-proliferative lung tumors with increased tumor incidence and higher Ki67 expression. These results implicate the phosphorylation state of Ser165in α-tubulin as a PKC-regulated molecular switch that causes breast cells to exhibit either EMT characteristics or hyper-proliferation. Evaluation of genomic databases of human tumors strengthens the clinical significance of these findings.