The pluripotency rheostat Nanog functions as a dimer

Nicholas P Mullin , Adam Yates , Arthur J Rowe , Bianca Nijmeijer , Douglas Colby , Paul N Barlow , Malcolm D Walkinshaw , Ian Chambers (1)

1 Institute for Stem Cell Research

The defining activity of the homeodomain protein Nanog is the ability to confer cytokine-independent self-renewal upon embryonic stem (ES) cells in which it is overexpressed. However, the biochemical basis by which Nanog achieves this function remains unknown. Here we show that Nanog dimerises through a functionally critical domain. Co-immunoprecipitation of Nanog molecules tagged with distinct epitopes demonstrates that Nanog self-associates through a region in which every fifth residue is tryptophan. In vitro binding experiments establish that this region participates directly in self-association. Moreover, analytical ultracentrifugation indicates that, in solution, Nanog is in equilibrium between monomeric and dimeric forms with a Kd of 3 μM. The functional importance of Nanog dimerisation is established by ES cell colony-forming assays in which deletion of the tryptophan repeat region eliminates the capacity of Nanog to direct LIF-independent self-renewal.

Mots clés: Life Sciences

Nicholas P Mullin, Adam Yates, Arthur J Rowe, Bianca Nijmeijer, Douglas Colby, et al.. The pluripotency rheostat Nanog functions as a dimer. Biochemical Journal, 2008, 411 (2), pp.227-231. ⟨10.1042/BJ20080134⟩. ⟨hal-00478956⟩