Year: 2013
Type: dissertation
Abstract: The development of an organism requires precise determination of cell fate. The Notch pathway acts as a major coordinator during development, by regulating cell fate in a wide variety of tissues in multicellular organisms. A critical step in activation of Notch signaling is endocytosis of the Notch ligands, Delta and Serrate. Ligand endocytosis is regulated by one of two E3 ubiquitin ligases, Neuralized or Mind bomb. Neuralized (Neur) is composed of a C-terminal RING domain, which is required for Delta ubiquitination, and two Neur homology repeat (NHR) domains. Here, I characterized the two NHR domains. We have previously shown that the NHR1 domain is required for Delta trafficking and I further determined that NHR1 also affects binding and internalization of Serrate. Furthermore, I showed that the NHR2 domain is required for Neur function and that a point mutation in NHR2 (Gly430) abolishes Neur ubiquitination activity, thereby affecting ligand internalization. I also provided evidence that Neur can form oligomers in cultured cells and in fly tissues, which regulates Neur activity, by extension, ligand internalization. Finally, I investigated the role of Neuralized in germline stem cell (GSC) maintenance. Specifically, I found that Neuralized is required for GSC maintenance and the NHR and RING domains are indispensable for this function. Furthermore, I showed that Neuralized is a downstream target of the Jak/Stat pathway in GSC maintenance. Interestingly, I also provided evidence that Notch may not be required for GSC maintenance, suggesting that Neur can function independent of Notch signaling in GSCs. Altogether, my studies demonstrate that Neur plays critical roles in regulating cell fate in different developmental contexts.
Source: TSpace (University of Toronto)
Author: Sili Liu
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2727633597