Date of Award
Open Access Master's Thesis
Master of Science in Biological Sciences (MS)
Administrative Home Department
Department of Biological Sciences
Committee Member 1
Committee Member 2
The Dp, Retinoblastoma, E2F, And MuvB (DREAM) complex mediates transcriptional repression and is highly conserved throughout a number of species, including vertebrates, Drosophila melanogaster, and Caenorhabditis elegans. Differing from mammalian DREAM, C.elegans DRM, appears to act solely in a repressive role, with the MuvB subcomplex (LIN-9, LIN-37, LIN-52, LIN-53, and LIN-54) playing a key role in the repression of genes. In this study, we use the auxin-inducible degron (AID) system, an effective, fast-acting, tool used in the degradation of degron-tagged proteins to individually deplete two key proteins of the MuvB subcomplex, LIN-9 and LIN-54, in C. elegans. The AID system relies on the expression of the F-box protein, transport inhibitor response 1 (TIR1), which in the presence of auxin acts as the substrate recognition component for the SKP1-CUL1-F-box (SCF) E3 ubiquitin ligase complex, leading to the degradation of tagged proteins. In degron-tagged LIN-54 worms, using a 6-hour auxin time course, we observed that DREAM target genes become significantly upregulated. Expression of DREAM target genes increased with longer exposure to auxin, indicating that LIN-54 plays a key role in the regulation of DREAM target genes. However, in both a 6-hour and 24-hour auxin time course experience, degron-tagged LIN-9 worms showed no uniform nor significant upregulation of DREAM target genes compared to ethanol vehicle control. These results demonstrate that LIN-54, the sole DNA-binding protein of MuvB, plays a more important role in MuvB’s repression of genes than the core protein of MuvB, LIN-9. We recommend further study into these two proteins using the AID system to further explore their roles in MuvB and DREAM complex function.
Chosa, Karli E., "AUXIN-INDUCED DEGRADATION OF DREAM PROTEINS, LIN-9 AND LIN-54, IN CAENORHABDITIS ELEGANS", Open Access Master's Thesis, Michigan Technological University, 2021.