Fig. 8

Targeted depletion of Hmga2-Citrine in zebrafish embryos.

(a) mRNA of wild type Ab-SPOP or mutant Ab(mut)-SPOP (deletion of CDR3 region of the vhhGFP4 nanobody), was injected into one-cell stage zebrafish embryos expressing Hmga2-Citrine protein (homozygous ct29a^GT). TagRFP mRNA was co-administered as an injection control. Ab-SPOP expression abolishes Hmga2-Citrine, resulting in early developmental defects such as abnormal cell division during cleavage, delayed cell migration during epiboly and ultimately embryonic death. In contrast, embryos injected with Ab(mut)-SPOP mRNA did not affect Hmga2-Citrine level or disrupt embryonic development, suggesting that Ab-SPOP activity directly promotes degradation of Hmga2-Citrine protein resulting in developmental phenotypes. (b) The toxicity of Ab-SPOP was tested by injecting Ab-SPOP mRNA into wild type embryos (AB line). Embryonic development was normal. ‘n’ represents the total number of embryos from several injection experiments.