Genetic Analysis of Rb Family Loss in G2-S Transit Regulation
Description
Retinoblastoma (Rb) and its family members, p107 and p130 are tumour suppressor genes that regulate the G1/S restriction point when cells transition from growth factor dependent to independent cell cycle progression. G1 arrest is crucial for cell differentiation during embryonic development. Rb family dysfunction can lead to premature cell cycle entry. Deletion of all three Rb family members causes lethality at ~E9, earlier than lethality at ~E14.5 caused by placental deficit associated with Rb loss. The cause of Rb family lethality at ~E9 remains unknown, as triple knockout (TKO) embryos appear physically normal. The Rb family regulates the interface between proliferation and differentiation across cell types during embryogenesis. To investigate potential causes of lethality in Rb TKO embryos, we analyzed WT and conditional TKO embryos from embryonic days 6.5-9.5 using single cell RNA sequencing and Seurat to identify differences in the cell cycle across embryonic cell types. We will validate cell cycle defects by quantifying EDU incorporation across genotypes. Our analysis suggests that multiple cell types have a higher proportion of cycling cells in the Rb TKO embryos while others show increased G1 arrest. These defects could contribute to early embryonic lethality, providing further insight into the role of Rb genes in development. Since Rb is a tumour suppressor, the study of its loss could also offer clues about cancer initiation specifically in tissues where Rb related cancers arise.
Genetic Analysis of Rb Family Loss in G2-S Transit Regulation
Retinoblastoma (Rb) and its family members, p107 and p130 are tumour suppressor genes that regulate the G1/S restriction point when cells transition from growth factor dependent to independent cell cycle progression. G1 arrest is crucial for cell differentiation during embryonic development. Rb family dysfunction can lead to premature cell cycle entry. Deletion of all three Rb family members causes lethality at ~E9, earlier than lethality at ~E14.5 caused by placental deficit associated with Rb loss. The cause of Rb family lethality at ~E9 remains unknown, as triple knockout (TKO) embryos appear physically normal. The Rb family regulates the interface between proliferation and differentiation across cell types during embryogenesis. To investigate potential causes of lethality in Rb TKO embryos, we analyzed WT and conditional TKO embryos from embryonic days 6.5-9.5 using single cell RNA sequencing and Seurat to identify differences in the cell cycle across embryonic cell types. We will validate cell cycle defects by quantifying EDU incorporation across genotypes. Our analysis suggests that multiple cell types have a higher proportion of cycling cells in the Rb TKO embryos while others show increased G1 arrest. These defects could contribute to early embryonic lethality, providing further insight into the role of Rb genes in development. Since Rb is a tumour suppressor, the study of its loss could also offer clues about cancer initiation specifically in tissues where Rb related cancers arise.
https://scholar.uwindsor.ca/we-spark-conference/2025/postersessions/15