Hedgehog signal transduction proteins: contacts of the Fused kinase and Ci transcription factor with the Kinesin-related protein Costal2

Background Hedgehog signaling proteins play important roles in development by controlling growth and patterning in various animals including Drosophila and mammals. Hedgehog signaling triggers changes in responsive cells through a novel transduction mechanism that ultimately controls the transcription of specific target genes via the activity of zinc finger transcription factors of the Cubitus interruptus /GLI family. In flies, key Hedgehog signal transduction components have been identified including the kinesin-related protein Costal2, the serinethreonine kinase Fused, and the PEST-containing protein Suppressor of Fused. These proteins control Cubitus interruptus cleavage, nucleo-cytoplasmic localization and activation. In fly embryos, Costal2, Fused, Suppressor of Fused and Cubitus interruptus are associated in at least one cytoplasmic complex, which interacts with the microtubules in a Hedgehog-dependent manner.

      Results
      Here we identified and mapped direct interactions between Cos2, Fu, and Ci using an in vitro affinity assay and the yeast two-hybrid system.
    
    
      Conclusions
      Our results provide new insights into the possible mechanism of the cytosolic steps of Hedgehog transduction.