Investigating the roles of primary cilium in Gli protein activation and Hedgehog signaling pathway using Sufu/Gli ciliary recruitment system

Open Access
Author:
Yang, Xiaoxu
Graduate Program:
Molecular, Cellular and Integrative Biosciences
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
September 26, 2017
Committee Members:
  • Aimin Liu, Thesis Advisor
  • Xiong Na, Committee Member
  • Adam Bleier Glick, Committee Member
Keywords:
  • Hh signaling
  • Sufu
  • Gli2
  • primary cilia
Abstract:
The Hedgehog (Hh) signaling pathway is crucial for various developmental processes such as proliferation, differentiation and cell migration. Primary cilia are critical for Hh signaling transduction in vertebrate. Major Hh pathway components are transported and accumulated in cilia throughout pathway activity. Hh activation inhibits Sufu and Gli phosphorylation, and induces their ciliary accumulation at the tips, where full length Gli is processed into Gli activator. However, the molecular role of cilia in Gli protein activation is not completely established. Recent study in the lab has shown that lacking of Gli2 ciliary localization in Gli2∆CLR mutant resulted in the loss of its response to Hh activation while still remaining its intrinsic transcriptional activity. In this thesis study, we used the ciliary target sequence (CTS) of fibrocystin and three different ciliary proteins Arl13b, Sstr3 and 5HT6 to target Sufu and recruit Gli2∆CLR into the cilia. Other than CTS targeted Sufu, which failed to localize into the cilia, both C-terminus and N-terminus fused Arl13b, Sstr3 and 5HT6 are able to target Sufu into the whole cilia. And both Arl13b and Sstr3 targeted Sufu can recruit Gli2∆CLR into the cilia. Overall, we successfully established the ciliary target Sufu system, which can recruit Gli2∆CLR into the cilia through Sufu/Gli interaction and will help improve our understanding of the cilia-dependent regulation of Hh signaling.