To investigate the Role of RPN3, a proteasomal subunit component, in Border Cell Migration using mutant analysis

Majhi, Bikram (2022) To investigate the Role of RPN3, a proteasomal subunit component, in Border Cell Migration using mutant analysis. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Bikram Majhi (17MS185)) 17MS185_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

The ability of a group of cells to migrate together as clusters, strands, sheets, or ducts using actin and myosin-mediated protrusions and guidance by external chemoattractant and mechanical cues is referred to as collective migration. Cell migration as a cohesive group includes tissue remodelling processes that drives embryonic morphogenesis, wound healing, immunosurveillance, and cancer invasion. Despite the fact that proteasomes have been linked to regulation of cellular movement and that proteasomal inhibitors are widely employed to treat cancers, the underlying molecular mechanism as to how they modulate cell migration is still unclear. We used the migration of Border Cells (BC) during Drosophila oogenesis as a model to investigate how proteasomes modulate cell movement. Protein degradation is required by all living organisms to terminate various biological processes and to eliminate damaged or misfolded proteins. One such machinery to degrade proteins inside the cell is the 26S proteasome, a compartmentalised barrel-shaped multicatalytic protease including two cap like structure known as 19S regulatory subunit responsible for substrate recognition. Being an essential part for maintaining cellular proteostasis, it has remained conserved throughout the evolution. 19S Regulatory Particle (RP), which is made up of several subunits that constitute the Lid and the Base. Rpn3 is part of 19S lid complex. Cell cycle arrest and apoptosis have been reported to happen when Rpn3 is knocked out (REF). In this thesis, I explored the role of Rpn3 mutants on BC migration through mutant analysis. I hypothesised that reducing Src activity in border cell clusters would rescue the phenotype. To test my hypothesis, I used p-Src inhibitor to inhibit Src activity. Indeed, I observed that p-Src treatment was rescuing migration defect caused by Rpn3 knockdown. Through mutant analysis, I show that the Ubiquitin-Proteasome system is required for border cell movement. I also found pathways in which it may not regulate border cell migration. All these, I believe this will help us understanding how proteosome regulate collective cell migration such as tumour metastasis.

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