Differential modification of p27Kip1 controls its cyclin D-cdk4 inhibitory activity (Publication with Expression of Concern)
Differential modification of p27Kip1 controls its cyclin D-cdk4 inhibitory activity (Publication with Expression of Concern)
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DOI：
10.1128/mcb.02171-06
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发表时间：
2008-01-01
影响因子：
5.3
通讯作者：
Blain, Stacy W.
中科院分区：
文献类型：
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作者：
James, Melissa K.;Ray, Arpita;Blain, Stacy W.
p27是否是细胞周期蛋白D-cdk 4/6抑制剂仍有争议，它如何在这两种模式之间转换尚不清楚。争论的两个状态的机制，我们表明，p27结合细胞周期蛋白D-cdk4可以是抑制性和非抑制性的，由于其差异生长状态依赖的酪氨酸磷酸化。我们发现，p27从增殖的细胞是非抑制性的，但从被捕的细胞p27是抑制性的，从绑定的非抑制剂到绑定的抑制剂的过渡是不是由于p27浓度的增加。相反，两个酪氨酸残基（Y88和Y89）在p27的cdk相互作用结构域的磷酸化优先在增殖细胞，这转化为p27的非抑制剂。一致地，这些位点的突变使得p27对磷酸化具有抗性，并在体内和体外将其锁定为结合抑制剂模式。Y88在体外被酪氨酸激酶Abl直接磷酸化，将p27转化为cdk4结合的非抑制剂。这些数据表明，p27的生长状态依赖性酪氨酸磷酸化调节其在体内的抑制活性。
Whether p27 is a cyclin D-cdk4/6 inhibitor or not is controversial, and how it might switch between these two modes is unknown. Arguing for a two-state mechanism, we show that p27 bound to cyclin D-cdk4 can be both inhibitory and noninhibitory, due to its differential-growth-state-dependent tyrosine phosphorylation. We found that p27 from proliferating cells was noninhibitory but that p27 from arrested cells was inhibitory, and the transition from a bound noninhibitor to a bound inhibitor was not due to an increase in p27 concentration. Rather, two tyrosine residues (Y88 and Y89) in p27's cdk interaction domain were phosphorylated preferentially in proliferating cells, which converted p27 to a noninhibitor. Concordantly, mutation of these sites rendered p27 resistant to phosphorylation and locked it into the bound-inhibitor mode in vivo and in vitro. Y88 was directly phosphorylated in vitro by the tyrosine kinase Abl, which converted p27 to a cdk4-bound noninhibitor. These data show that the growth-state-dependent tyrosine phosphorylation of p27 modulates its inhibitory activity in vivo.