The dynamic role of TRIM8, a novel ciliary protein, during various stages of mitosis.

Abstract

TRIM8 is an E3 ubiquitin ligase that functions as both a tumour suppressor and an oncoprotein. Earlier, we reported that TRIM8 interacts with key regulators of mitotic spindle assembly, and that TRIM8 knockdown results in mitotic delay and aneuploidy. In this study, we implemented an omics strategy with differential transcriptomic (single-cell RNA sequencing or scRNA-seq), translatomic (polysome profiling with RNA-seq), and proteomic (LC-MS/MS) approaches to elucidate the involvement of TRIM8 in different levels (transcription, translation, post-translation) and stages (G0/G1, S, G2/M) of mitotic cell cycle regulation and progression. With the aid of differential transcriptomic and proteomic approaches, we show that depletion of TRIM8 perturbs the canonical 'Cell Cycle Control of Chromosomal Replication' pathway. Furthermore, TRIM8 downregulation induces alterations in the translation activity of cells and results in the upregulation of polysome-bound MALAT1 lncRNA by means of significant changes in polysome profiling coupled with RNA-sequencing. Moreover, we unveil for the first time endogenous TRIM8 as a novel ciliary protein that localizes with CEP170 at centrosome. Cilia analysis revealed a significant reduction in the number of ciliated cells, along with shorter cilia, in TRIM8-silenced ARPE-19 cells. Our study is the first to demonstrate the dynamic role of a TRIM family protein across multiple stages of mitosis and to define TRIM8 as a novel ciliary protein.