PTEN enters the nucleus by diffusion
PTEN enters the nucleus by diffusion
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DOI：
10.1002/jcb.20525
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发表时间：
2005-10-01
影响因子：
4
通讯作者：
Ross, AH
中科院分区：
文献类型：
--
作者：
Liu, FH;Wagner, S;Ross, AH
尽管有很多证据表明磷脂酰肌醇磷酸（PIP）在细胞核中触发信号通路，但对这些蛋白质的水平和活性如何调节的了解甚少。作为阐明这个问题的第一步，我们确定了10号染色体上缺失的磷酸酶和张力蛋白同源物（PTEN）是否通过被动扩散或主动转运进入细胞核。我们在tsBN 2、HeLa、LNCaP和U87 MG细胞中表达了各种PTEN融合蛋白，并确定最大的PTEN融合蛋白显示很少或没有核定位。由于通过核孔的扩散仅限于60，000 Da或更小的蛋白质，这表明PTEN的核易位通过扩散发生。我们研究了PTEN突变体，试图确定一个核定位信号（NLS）的PTEN。K13和R14的突变降低了核定位，但这些氨基酸似乎不是NLS的一部分。我们使用光漂白后的荧光恢复（FRAP）来证明GFP-PTEN可以被动地通过核孔。对于显示减少的核定位的PTEN突变体，细胞质中的扩散被延迟。我们的结论是，PTEN通过扩散进入细胞核。此外，PTEN在细胞质中的隔离可能限制PTEN核转位。
Despite much evidence for phosphatidylinositol phosphate (PIP)-triggered signaling pathways in the nucleus, there is little understanding of how the levels and activities of these proteins are regulated. As a first step to elucidating this problem, we determined whether phosphatase and tensin homolog deleted on chromosome 10 (PTEN) enters the nucleus by passive diffusion or active transport. We expressed various PTEN fusion proteins in tsBN2, HeLa, LNCaP, and U87MG cells and determined that the largest PTEN fusion proteins showed little or no nuclear localization. Because diffusion through nuclear pores is limited to proteins of 60,000 Da or less, this suggests that nuclear translocation of PTEN occurs via diffusion. We examined PTEN mutants, seeking to identify a nuclear localization signal (NLS) for PTEN. Mutation of K13 and R14 decreased nuclear localization, but these amino acids do not appear to be part of an NLS. We used fluorescence recovery after photobleaching (FRAP) to demonstrate that GFP-PTEN can passively pass through nuclear pores. Diffusion in the cytoplasm is retarded for the PTEN mutants that show reduced nuclear localization. We conclude that PTEN enters the nucleus by diffusion. In addition, sequestration of PTEN in the cytoplasm likely limits PTEN nuclear translocation.