Transcriptional And Post-transcriptional Regulation Of RNF220

Sonic hedgehog(Shh)acts as a morphogen to pattern the ventral spinal cord during vertebrate neural development.RNF220,an ubiquitin E3 ligase,expressed at the ventral part of developing hindbrain and spinal cord and involved in ventral spinal cord patterning by modulating the activity of Glis,which are the downstream transcriptional factors for Shh signaling.The transcriptional controlling mechanism for the ventral spinal cord expression pattern of RNF220 and whether RNF220 expression is regulated by the Shh signaling are largely unknown.Here,this thesis identified an ultraconserved element(M280)located in RNF220 genome which is probably responsible for RNF220 transcriptional controlling.This study examined the transcriptional activity of M280 at spinal cord using reporter system electroporation assays in chick embryos.In addition,this thesis found that Shh activation induced ectoptic RNF220 expression in chick spinal cord.As an ubiquitin E3 ligase,whether RNF220 itself is controlled by ubiquitination is also an important issue.This study reports that ubiquitin E3 ligases Smurf1/2 could target RNF220 for polyubiquitination and degradation.This thesis also found that ZC4H2,a small nuclear Zinc finger containing protein,stabilizes RNF220 through inhibiting Smurf1/2 activities.Therefore,this thesis primarily illustrated the mechanism for RNF220 expression at both transcriptional and translational levels.