Atypical Mowat-Wilson patient confirms the importance of the novel association between ZFHX1B/SIP1 and NuRD corepressor complex

G. Verstappen, L. A. van Grunsven, C. Michiels, T. Van de Putte, J. Souopgui, J. Van Damme, E. Bellefroid, J. Vandekerckhove, D. Huylebroeck
2008 Human Molecular Genetics  
Mutations in ZFHX1B cause Mowat -Wilson syndrome (MWS) but the precise mechanisms underlying the aberrant functions of mutant ZFHX1B proteins (also named Smad-interacting protein-1, SIP1) in patients are unknown. Using mass spectrometry analysis, we identified subunits of the NuRD corepressor complex in affinity-purified Zfhx1b complexes. We find that Zfhx1b associates with NuRD through its N-terminal domain, which contains a previously postulated NuRD interacting motif. Interestingly, this
more » ... restingly, this motif is substituted by an unrelated sequence in a recently described MWS patient. We show here that such aberrant ZFHX1B protein is unable to recruit NuRD subunits and displays reduced transcriptional repression activity on the XBMP4 gene promoter, a target of Zfhx1b. We further demonstrate that the NuRD component Mi-2b is involved in repression of the Zfhx1b target gene E-cadherin as well as in Zfhx1b-induced neural induction in animal caps from Xenopus embryos. Thus, NuRD and Zfhx1b functionally interact, and defective NuRD recruitment by mutant human ZFHX1B can be a MWS-causing mechanism. This is the first study providing mechanistic insight into the aberrant function of a single domain of the multi-domain protein ZFHX1B/SIP1 in human disease.
doi:10.1093/hmg/ddn007 pmid:18182442 fatcat:w3hs53zbw5hghjwos7nhujmcmu