Ciliary recruitment of the Dynein-2 motor and its role in C. elegans sensory functions

• Autor(a) principal: Castro, Ana Rita Gonçalves de
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/16677
• topic: Ciliopatias; Recrutamento; Complexo dineína-2; Transporte intraflagelar; WDR-60; Zona de transição; Domínio/Área Científica::Ciências Médicas::Outras Ciências Médicas

Cilia are specialized organelles present in most mammalian cells to detect multiple environmental cues, important to regulate cell proliferation, differentiation, and function. Defects in these structures can cause innumerous severe disorders known as ciliopathies. During ciliogenesis, the ciliary base attaches to the plasma membrane and forms a Transition Zone (TZ) that acts as a specialized ciliary gate. The microtubule-based ciliary axoneme then extends forming the Middle and the Distal Segments, surrounded by a receptor-rich ciliary membrane. Building of all types of cilia depends on the efficient bidirectional transport of different components from the ciliary base and tip, known as Intraflagellar Transport (IFT). Kinesin-II motors transport cargo to the tip, while dynein-2 retrieves signaling molecules and other IFT components to the base. The dynein-2 motor is a large multi-subunit complex composed of several dimers of Heavy Chains (HC), Light Intermediate Chains (LIC), Intermediate Chains (IC) and Light Chains (LC). However, most aspects of dynein-2 subunit recruitment and function are still poorly understood. To determine the mechanisms that control dynein-2 recruitment and activity inside cilia, and increase our understanding on how mutations in dynein-2 subunits cause developmental ciliopathies, I used live fluorescence microscopy to directly monitor the dynamics of dynein-2 subunits in Caenorhabditis elegans. In this study, I showed the importance of dynein-2 IC (WDR-60) and LIC (XBX-1) for the ciliary recruitment of the dynein-2 HC (CHE-3). I also found that loss of WDR-60 results in severe defects in IFT kinetics and CHE-3 accumulations near the TZ. Strikingly, by disrupting TZ components, I was able to rescue the accumulation of these particles, revealing that, in addition to contributing to dynein-2 activity, WDR-60 is critical for the passage of IFT particles through the TZ to exit cilia. Thus, the results from this study have important implications for the better understanding of WDR60-associated ciliopathies.