A role for Hsc70 in regulating nucleocytoplasmic transport of a temperature-sensitive p53 (p53Val-135)
A role for Hsc70 in regulating nucleocytoplasmic transport of a temperature-sensitive p53 (p53Val-135)
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DOI：
10.1074/jbc.m100200200
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发表时间：
2001-05-04
影响因子：
4.8
通讯作者：
Horinouchi, S
中科院分区：
文献类型：
--
作者：
Akakura, S;Yoshida, M;Horinouchi, S
小鼠温度敏感型p53（Val-135）在32℃时积聚在细胞核中，并作为“野生型”发挥作用，而在37℃时则被隔离在细胞质中。细胞质p53（Val-135）在37度核输出被抑制后重新定位到细胞核中，而主要的二部核定位信号（NLS）的突变引起了组成性的细胞质定位，这表明它通过自身的核输出信号和NLS在细胞质和细胞核之间穿梭，而不是被束缚在细胞质结构上。虽然全长p53（Val-135）不能在37度处与输入受体结合，但缺少326-390残基的c端截断的p53（Val-135）可以与它结合。分子伴侣如Hsc70在37°c时与p53（Val-135）相关，而在32°c时与p53无关。当核输出被leptomycin B阻断时，只有一小部分缺乏Hsc70特异性地在细胞核中积累。网状细胞裂解液中Hsc70的免疫缺失导致p53（Val-135）与输入受体结合。这种结合可以通过提供含有Hsc70的细胞提取物来阻断，但不能通过单独添加重组Hsc70来阻断。我们认为，与含hsc70复合物的结合可以阻止NLS在37°c时通过p53的c端区域（Val-135）进入输入受体，而在32°c时它的解离允许快速的核输入。
Mouse temperature-sensitive p53(Val-135) accumulates in the nucleus and acts as a "wild-type" at 32 degreesC while it is sequestered in the cytoplasm at 37 degreesC. The cytoplasmic p53(Val-135) relocalized into the nucleus upon inhibition of the nuclear export at 37 degreesC, whereas a mutation in a major bipartite nuclear localization signal (NLS) caused constitutive cytoplasmic localization, indicating that it shuttled between the cytoplasm and the nucleus by its own nuclear export signal and NLS rather than tethered to cytoplasmic structures. Although the full-length p53(Val-135) did not bind the import receptor at 37 degreesC, a C-terminally truncated p53(Val-135) lacking residues 326-390 did bind it. Molecular chaperones such as Hsc70 were associated with p53(Val-135) at 37 degreesC but not at 32 degreesC. When the nuclear export was blocked by leptomycin B, only a fraction lacking Hsc70 was specifically accumulated in the nucleus. Immunodepletion of Hsc70 from the reticulocyte lysate caused p53(Val-135) to bind the import receptor. This binding was blocked by supplying the cell extract containing Hsc70 but not by the addition of recombinant Hsc70 alone. We suggest that the association with the Hsc70-containing complex prevents the NLS from the access of the import receptor through the C-terminal region of p53(Val-135) at 37 degreesC, whereas its dissociation at 32 degreesC allows rapid nuclear import.