PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of molcellbPermissionsJournals.ASM.orgJournalMCB ArticleJournal InfoAuthorsReviewers
 
Mol Cell Biol. May 1997; 17(5): 2920–2932.
PMCID: PMC232144
Heterodimerization of Msx and Dlx homeoproteins results in functional antagonism.
H Zhang, G Hu, H Wang, P Sciavolino, N Iler, M M Shen, and C Abate-Shen
Graduate Program in Microbiology and Molecular Genetics, UMDNJ-Robert Wood Johnson Medical School, Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey 08854, USA.
Abstract
Protein-protein interactions are known to be essential for specifying the transcriptional activities of homeoproteins. Here we show that representative members of the Msx and Dlx homeoprotein families form homo- and heterodimeric complexes. We demonstrate that dimerization by Msx and Dlx proteins is mediated through their homeodomains and that the residues required for this interaction correspond to those necessary for DNA binding. Unlike most other known examples of homeoprotein interactions, association of Msx and Dlx proteins does not promote cooperative DNA binding; instead, dimerization and DNA binding are mutually exclusive activities. In particular, we show that Msx and Dlx proteins interact independently and noncooperatively with homeodomain DNA binding sites and that dimerization is specifically blocked by the presence of such DNA sites. We further demonstrate that the transcriptional properties of Msx and Dlx proteins display reciprocal inhibition. Specifically, Msx proteins act as transcriptional repressors and Dlx proteins act as activators, while in combination, Msx and Dlx proteins counteract each other's transcriptional activities. Finally, we show that the expression patterns of representative Msx and Dlx genes (Msx1, Msx2, Dlx2, and Dlx5) overlap in mouse embryogenesis during limb bud and craniofacial development, consistent with the potential for their protein products to interact in vivo. Based on these observations, we propose that functional antagonism through heterodimer formation provides a mechanism for regulating the transcriptional actions of Msx and Dlx homeoproteins in vivo.
Full Text
The Full Text of this article is available as a PDF (1.3M).
Articles from Molecular and Cellular Biology are provided here courtesy of
American Society for Microbiology (ASM)