Open Close
Uhler, J., Zhang, H., Syu, L.J., Mellerick, D.M. (2007). The Nk-2 box of the Drosophila homeodomain protein, Vnd, contributes to its repression activity in a Groucho-dependent manner.  Mech. Dev. 124(1): 1--10.
FlyBase ID
Publication Type
Research paper

The transcription factor, Vnd, is a dual regulator that specifies ventral neuroblast identity in Drosophila by both repressing and activating target genes. Vnd and its homologues have a conserved amino acid sequence, the Nk-2 box or Nk specific domain, as well a conserved DNA-binding homeodomain and an EhI-type Groucho interaction domain. However, the function of the conserved Nk-2 box has not been fully defined. To explore its function, we deleted the Nk-2 box and compared the regulatory activity of mutant Vnd in transgenic over-expression assays to that of the wild-type protein. We were unable to assign regulatory activity to the Nk-2 box using an over-expression assay, because the mutant protein activated expression of endogenous Vnd, masking a requirement for the Nk-2 box. However, in transgenic rescue assays, Vnd lacking the Nk-2 box repressed ind expression at 30% lower levels than the wild-type protein. Moreover, in transient transfection assays using Gal4 DNA-binding domain-Vnd chimeras, the repression activity of Vnd lacking the Nk-2 box was compromised. Because Vnd represses target gene expression in conjunction with Groucho, we asked whether the Nk-2 box affects Vnd's ability to interact with this co-repressor. Vnd lacking the Nk-2 box binds Groucho 30% less efficiently than wild-type Vnd in co-immunoprecipitations. These data suggest that the Nk-2 box contributes to the repression activity of Vnd by stabilizing its interaction with the co-repressor, Groucho.

PubMed ID
PubMed Central ID
Associated Information
Associated Files
Other Information
Secondary IDs
    Language of Publication
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Mech. Dev.
    Mechanisms of Development
    Publication Year
    Data From Reference
    Genes (5)
    Physical Interactions (1)