CGC Bibliography Paper 4885

The divergent Caenorhabditis elegans beta-catenin proteins BAR-1, WRM-1 and HMP-2 make distinct protein interactions but retain functional redundancy in vivo.

Natarajan L, Witwer NE, Eisenmann DM

Medline:

11560894

Citation:

Genetics 159: 159-172 2001

Type:

ARTICLE

Genes:

bar-1 egl-27 hmp-2 wrm-1

Abstract:

beta -Catenins function both in cell adhesion as part of the cadherin/catenin complex and in Writ signal transduction as transcription factors. Vertebrates express two related proteins, beta -catenin and plakoglobin, while Drosophila has a single family member, Armadillo. Caenorhabditis elegans expresses three beta -catenin-related proteins, BAR-1, HMP-2, and WRM-1, which are quite diverged sequence from each other and other beta -catenins. While BAR-1 and WRM-1 are known to act in Wnt-mediated processes, and HMP-2 acts in a complex with cadherin/alpha -catenin homologs, it is unclear whether all three proteins retain the other functions of beta -catenin. Here we show that BAR-1, like vertebrate beta -catenin, has redundant transcription activation domains in its amino- and carboxyl-terminal regions but that HMP-2 and WRM-1 also possess the ability to activate transcription. We show via yeast two-hybrid analysis that these three proteins display distinct patterns of protein interactions. Surprisingly, we find that both WRM-1 and HMP-2 can substitute for BAR-1 in C. elegans when expressed from the bar-1 promoter. Therefore, although their mutant phenotypes and protein interaction patterns strongly suggest that the functions of beta -catenin in other species have been segregated among three diverged proteins in C. elegans, these proteins still retain sufficient similarity to display functional