Ribonucleoproteins (RNP) condensates often contain intrinsically disordered proteins (IDPs) able to confer an exceptional multifunctionality necessary for gene expression, a process that defines cell types and enables cellular adaptation in metazoans. Centosomes, the microtubule-organizing centers of animal cells, are particularly enriched in disordered proteins but the role of RNPs surrounding the centrosome and the ciliary basal body remains largely unknown. By refining and integrating the existing protein-protein interaction network, spatial proteomics and transcriptomic data, we here report the subcellular and genomic proximity between the spliceosome, a huge nuclear RNP complex that removes introns from a transcribed pre-mRNA, and centrosome/cilia components. We present a comprehensive map of pre-RNA processing factors and other RNA-binding proteins playing a role in the regulation of splicing but localized to the centrosome and cilia. Protein-protein interactions studies reveal that a large number of spliceosome components interact with both centrosome linker and centriolar satellites elements, necessary for cellular division and ciliogenesis. RNAseq data from mouse Embryonic Stem Cells (mESC) and human tissues revealed a co-transcriptional coordination program of splicing and centrosome-related genes with relevance to tissue-specific neurosensory disorders and cancer types. Additionally, we found that centrosome and spliceosome genes form linearly and spatially colocalized genomic loci (CEP250, RBBM39, DHX35, and CTNNBL1) conserved in human and mouse genome, then explaining similarities in co-modification and subcellular distribution. Our results suggest that centrosome and cilia constitute cytoplasmic sites for the exchange of molecular machinery with nucleus, storage of RNA splicing and spliceosome condensates previously unrecognized. These complexes in response to external signals, could play an integral part in ciliogenesis and nuclear division to establish and maintain cellular identity in metazoans.

Nucleolin is an RNA binding protein that is involved in many post-transcriptional regulation steps of messenger RNAs in addition to its nucleolar role in ribosomal RNA transcription and assembly in pre-ribosomes. Acetylated nucleolin was found to be associated with nuclear speckles and to co-localize with the splicing factor SC35. Previous nuclear pull down of nucleolin identified several splicing components and factors involved in RNA polymerase II transcription associated with nucleolin. In this report, we show that these splicing components are specifics of the pre-catalytic A and B spliceosomes, while proteins recruited in the Bact, C and P complexes are absent from the nucleolin interacting proteins. Furthermore, we show that acetylated nucleolin co-localized with P-SF3B1, a marker of co-transcriptional active spliceosomes. P-SF3B1 complexes can be pulled down with nucleolin specific antibodies. Interestingly, the alternative splicing of Fibronectin at the IIICS and EDB sites was affected by nucleolin depletion. These data are consistent with a model where nucleolin could be a factor bridging RNA polymerase II transcription and assembly of pre-catalytic spliceosome similarly to its function in the co-transcriptional maturation of pre-rRNA.

The retinoblastoma (RB) transcriptional corepressor 1 (RB1) is a critical tumor suppressor gene, governing diverse cellular processes implicated in cancer biology. Dysregulation or deletion in RB1 contributes to the development and progression of various cancers, making it a prime target for therapeutic intervention. RB1's canonical function in cell cycle control and DNA repair mechanisms underscores its significance in restraining aberrant cell growth and maintaining genomic stability. Understanding the complex interplay between RB1 and cellular pathways is beneficial to fully elucidate its tumor-suppressive role across different cancer types and for therapeutic development. As a result, investigating vulnerabilities arising from RB1 deletion-associated mechanisms offers promising avenues for targeted therapy. Recently, several findings highlighted multiple methods as a promising strategy for combating tumor growth driven by RB1 loss, offering potential clinical benefits in various cancer types. This review summarizes the multifaceted role of RB1 in cancer biology and its implications for targeted therapy.