
- 积分
- 24
- 威望
- 24
- 包包
- 1831
|

β-catenin stabilization results in its higher nuclear levels, but how β-catenin is shuttled to and retained in the nucleus is not well understood Earlier studies suggested that β-catenin enters the nucleus in an NLS (nuclear localization signal)- and importin-independent fashion by interacting directly with nuclear pore proteins 。 β-atenin also exits the nucleus via export involving APC 、Axin,and RanBP3 (Ran binding protein 3), which binds to β-catenin in a Ran-GTP dependent manner . Live cell imaging suggests that while Axin and APC can enrich β-catenin in the cytoplasm and TCF and β-catenin co-activators (BCL9 and Pygopus, see below) increase
1 s4 T9 d3 n# R; ~nuclear β-catenin, they do not accelerate the export or import rate of β-catenin, thereby arguing y( C6 J% D9 o, W0 e
for their roles in β-catenin retention rather than shuttling . Thus β-catenin nuclear and cytoplasmic partitioning is likely the dynamic sum of both shuttling and retention between the two compartments via multiple mechanisms.A recent study argues that Wnt-induced β-catenin stabilization is not sufficient for its nuclear3 M% m6 b/ I3 ^: n
accumulation, but Wnt activation of the Rac1 GTPase is required in parallel . Specifically Rac1, JNK2 (Jun N-terminal kinase 2) and β-catenin form a cytoplasmic complex, and JNK2 phosphorylates β-catenin (at serines 191 and 605) and promotes it nuclear translocation。
* S; [) |8 w1 x' \. S# E |
-
总评分: 威望 + 5
包包 + 10
查看全部评分
|