Figure 4. Effect of TLE1ΔQ expression on ventral spinal cord Pax6+ and Nkx2.2+ progenitor populations and neuronal fate acquisition.

(A) Schematic representation of TLE1ΔQ, compared to TLE1 and AES, depicting the lack of the Q domain but retention of the WDR domain in TLE1ΔQ. (B) Coimmunoprecipitation experiments performed using lysates from chick embryo spinal cords electroporated with plasmid encoding FLAG-TLE1ΔQ. Immunoprecipitation (IP) was performed using anti-FLAG antibody, followed by Western blotting (WB) analysis of input lysate (10%) and immunoprecipitated material using a panTLE antibody that recognizes all full-length TLE proteins and also TLE1ΔQ because it is directed against the WDR domain [19]. Endogenous TLE did not coimmunoprecipitate with exogenous TLE1ΔQ. (C) Quantification of the number of GFP+ cells expressing Nkx2.2 [in either the ventricular zone (VZ) or marginal zone (MZ)], Pax6, Hb9, or Isl1 in chick embryos electroporated with GFP alone or together with TLE1 or TLE1ΔQ. Expression of TLE1ΔQ resulted in an increase in the number of Pax6+ progenitor cells as well as Hb9+ and Isl1+ MNs compared to the control conditions. These effects were opposite to the effects of TLE1. See Figure S5 for double-labeling immunohistochemical analysis of electroporated embryos. (D) Quantification of the number of GFP+ cells expressing Pax6 in chick embryo spinal cord electroporated with GFP alone or together with TLE1, TLE1ΔQ, or TLE1 and TLE1ΔQ together, as indicated. Data in (C and D) are expressed as mean ± SEM (*p<0.05; **p<0.01; n.s., not significant).