It has become evident how vital Hh signaling is during development, if mutated, can cause birth defects. (Xiong Y., 2014) According to the Hh concentration, the signals act over long ranges and conducts distinct downstream reactions. To maintain its activities, the Hh are lipid modified and form soluble protein complexes. Proteins such as Ptc (patched) and Smo (smoothened) are effected by the presence of Hh. The Ptc releases an inhibitory effect on Smo, which prompts the translocation from the cytoplasm to plasma membrane. Ci gene is induced and translocated into the nucleus to regulate downstream gene expression (Xiong Y., …show more content…
Ci protein also shares a high degree of homology with the GLI family; elegans sex determination gene, and the Xenopus transcriptional factor TFIIIA. GLI proteins are found in humans and possess the same characteristics of mutations of the Ci protein. The Sonic Hedgehog (Shh) signaling play a vital role in limb development and call death in the nervous system during development. Although it is not quite clear what the purpose of PKA is but it does play an essential role in Drosophila embryonic development and the Hh signaling cascade. If absent, the level of the full-length Ci155 increases and the dpp, wg, and ptc gene expressions are induced. Due to the negative feedback inhibition, PKA play a dual role of activation the wg and ptc genes by the Hh