Posttranscriptional regulation of α-Catenin expression is required for wnt signaling in L cells

Nobuyuki Takahashi, Satoru Ishihara, Shinji Takada, Shoichiro Tsukita, Akira Nagafuchi

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

α-Catenin is an essential component of the cadherin-catenin cell-cell adhesion complex. An excess amount of α-catenin also affects the Wnt signaling pathway probably through its direct binding to β-catenin. Here, we examined the molecular mechanisms of the posttranscriptional regulation of α-catenin expression. We constructed an expression vector with α-catenin cDNA lacking the 5'-untranslated sequence. In L cell transfectants stably expressing mRNA derived from this vector, the amount of exogenous α-catenin protein was about 10-fold higher than that of the endogenous protein. The expression level of the exogenously expressed α-catenin mRNA, however, was about 80% of that of endogenous molecule. Most of the endogenous and exogenous α-catenin protein in cadherin-negative cells was degraded 5 h after inhibition of protein synthesis. Although α-catenin contains the PEST sequence, various proteasome and calpain inhibitors did not affect the level of expression of endogenous α-catenin protein in L cells. Overexpressed α-catenin showed cytoplasmic localization, disturbed the nuclear localization of stabilized β-catenin, and inhibited TCF-4-responsive transactivation after Wnt-3a treatment. These results suggested that the low-efficiency of translation and unidentified degradation mechanisms maintained the low levels of α-catenin expression in the cytoplasm as a necessary condition for the Wnt signaling pathway. (C) 2000 Academic Press.

Original languageEnglish
Pages (from-to)691-698
Number of pages8
JournalBiochemical and Biophysical Research Communications
Volume277
Issue number3
DOIs
Publication statusPublished - 02-11-2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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