PT  - JOURNAL ARTICLE
AU  - Papkoff, J
AU  - Rubinfeld, B
AU  - Schryver, B
AU  - Polakis, P
TI  - Wnt-1 regulates free pools of catenins and stabilizes APC-catenin complexes.
AID  - 10.1128/MCB.16.5.2128
DP  - 1996 May 01
TA  - Molecular and Cellular Biology
PG  - 2128--2134
VI  - 16
IP  - 5
4099  - http://mcb.asm.org/content/16/5/2128.short
4100  - http://mcb.asm.org/content/16/5/2128.full
SO  - Mol. Cell. Biol.1996 May 01; 16
AB  - The Wnt-1 proto-oncogene induces the accumulation of beta-catenin and plakoglobin, two related proteins that associate with and functionally modulate the cadherin cell adhesion proteins. Here we have investigated the effects of Wnt-1 expression on the tumor suppressor protein APC, which also associates with catenins. Expression of Wnt-1 in two different cell lines greatly increased the stability of APC-catenin complexes. The steady-state levels of both catenins and APC were elevated by Wnt-1, and the half-lives of both beta-catenin and plakoglobin associated with APC were also markedly increased. The stabilization of catenins by Wnt-1 was primarily the result of a selective increase in the amount of uncomplexed, monomeric beta-catenin and plakoglobin, detected both by affinity precipitation and size-exclusion chromatography of cell extracts. Exogenous expression of beta-catenin was possible in cells already responding to Wnt-1 but not in the parental cells, suggesting that Wnt-1 inhibits an essential regulatory mechanism for beta-catenin turnover. APC has the capacity to oppose this Wnt-1 effect in experiments in which overexpression of the central region of APC significantly reduced the size of the monomeric pool of beta-catenin induced by Wnt-1. Thus, the Wnt-1 signal transduction pathway leads to the accumulation of monomeric catenins and stabilization of catenin complex formation with both APC and cadherins.