Long non-coding RNA Hsr-omega provides scaffolding for the nuclear domain B-body

<p>The structural organization of the cell nucleus poses many intriguing questions. One of them is the organization of nuclear domains (ND), sharp-bordered nuclear compartments concentrating a range of nuclear proteins. In this study, we used the recently discovered B-body as a model to investigate the mechanisms governing the formation of NDs. The nuclear B-body forms in the cellular precursors of flight muscles in developing <em>Drosophila</em> pupae. Prior to myoblast fusion, the splicing factor Bruno (Bru) concentrates into a single, large B-body but transitions into multiple smaller speckles in a diffused nuclear pattern after the commencement of myogenesis. We hypothesized that the B-body must contain an RNA scaffold because Bru association with B-bodies is RNase-sensitive. Using Immuno-FISH, we identified a lncRNA co-localizing with the B-body; this RNA is the <em>heat shock RNA omega</em> (<em>hsrω</em>). Next, we tested the requirement of protein and RNA components for the integrity of the B-body. Genetic knockdown of the protein Bru did not perturb the size of B-body, as revealed by <em>hsrω</em> FISH. In contrast, when <em>hsrω</em> was removed via chromosomal deletions, the structural stability of the B-body was severely affected. Since <em>hsrω</em> is expressed in a broader range of tissues than Bru, we conducted a misexpression study to test if it is possible to reconstitute the B-body outside flight muscles. Nuclei of the midgut epithelium are similar to the polyploid nuclei to flight muscle progenitors that express <em>hsrω</em>; however, ectopically expressed Bru did not accumulate to form a B-body in them. Lastly, we found that flies with reduced <em>hsrω</em> showed normal IFM development, flight ability, and viability similar to their wild-type counterparts. In summary, our study demonstrates the importance of an RNA scaffolding for the B-body and highlights the importance of an additional mechanism to enable protein trafficking and accumulation at B-bodies. Meanwhile, the functional significance of B-bodies remains elusive and will require additional studies.</p>

Name thesis:degree_name

Master of Science in Integrative Biology (MSIB)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2023

Author dc:creator

• An, SooBin

Contributors dc:contributor

• Brandon Carpenter
• Susan M. Smith
• Carol Chrestensen

• nuclear domains
• B-body
• Bruno
• Drosophila
• nucleus
• muscle development
• lncRNA

Repository record dc:identifier

https://digitalcommons.kennesaw.edu/integrbiol_etd/95

OAI identifier oai:identifier

oai:digitalcommons.kennesaw.edu:integrbiol_etd-1097