The RNA-Binding Function of Ribosomal Proteins and Ribosome Biogenesis Factors in Human Health and Disease
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ABSTRACT:
SUBMITTER: Catalanotto C
PROVIDER: S-EPMC10669870 | biostudies-literature | 2023 Nov
REPOSITORIES: biostudies-literature
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Project description:Aminoacridines, used for decades as antiseptic and antiparasitic agents, are prospective candidates for therapeutic repurposing and new drug development. Although the mechanisms behind their biological effects are not fully elucidated, they are most often attributed to the acridines' ability to intercalate into DNA. Here, we characterized the effects of 9-aminoacridine (9AA) on pre-rRNA metabolism in cultured mammalian cells. Our results demonstrate that 9AA inhibits both transcription of the ribosomal RNA precursors (pre-rRNA) and processing of the already synthesized pre-rRNAs, thereby rapidly abolishing ribosome biogenesis. Using a fluorescent intercalator displacement assay, we further show that 9AA can bind to RNA in vitro, which likely contributes to its ability to inhibit post-transcriptional steps in pre-rRNA maturation. These findings extend the arsenal of small-molecule compounds that can be used to block ribosome biogenesis in mammalian cells and have implications for the pharmacological development of new ribosome biogenesis inhibitors.
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Project description:IntroductionIn addition to the well-known cartilage extracellular matrix-related expression of Sox9, we demonstrated that chondrogenic differentiation of progenitor cells is driven by a sharply defined bi-phasic expression of Sox9: an immediate early and a late (extracellular matrix associated) phase expression. In this study, we aimed to determine what biological processes are driven by Sox9 during this early phase of chondrogenic differentiation.MaterialsSox9 expression in ATDC5 cells was knocked down by siRNA transfection at the day before chondrogenic differentiation or at day 6 of differentiation. Samples were harvested at 2 h and 7 days of differentiation. The transcriptomes (RNA-seq approach) and proteomes (Label-free proteomics approach) were compared using pathway and network analyses. Total protein translational capacity was evaluated with the SuNSET assay, active ribosomes were evaluated with polysome profiling, and ribosome modus was evaluated with bicistronic reporter assays.ResultsEarly Sox9 knockdown severely inhibited chondrogenic differentiation weeks later. Sox9 expression during the immediate early phase of ATDC5 chondrogenic differentiation regulated the expression of ribosome biogenesis factors and ribosomal protein subunits. This was accompanied by decreased translational capacity following Sox9 knockdown, and this correlated to lower amounts of active mono- and polysomes. Moreover, cap- versus IRES-mediated translation was altered by Sox9 knockdown. Sox9 overexpression was able to induce reciprocal effects to the Sox9 knockdown.ConclusionHere, we identified an essential new function for Sox9 during early chondrogenic differentiation. A role for Sox9 in regulation of ribosome amount, activity, and/or composition may be crucial in preparation for the demanding proliferative phase and subsequent cartilage extracellular matrix production of chondroprogenitors in the growth plate in vivo.
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