HnRNPL phase separation activates PIK3CB transcription and promotes glycolysis in ovarian cancer (hnRNPL RNAseq)
Ontology highlight
ABSTRACT: Ovarian cancer has the highest mortality rate among gynecologic tumors worldwide, with unclear underlying mechanisms of pathogenesis. RNA-binding proteins (RBPs) primarily direct post-transcriptional regulation through modulating RNA metabolism. Recent evidence demonstrates that RBPs are also implicated in transcriptional control. However, the role and mechanism of RBP-mediated transcriptional regulation in tumorigenesis remain largely unexplored. Here, we show that the RBP heterogeneous ribonucleoprotein L (hnRNPL) interacts with chromatin and regulates gene transcription by forming phase-separated condensates in ovarian cancer. hnRNPL phase separation activates PIK3CB transcription and glycolysis, thus promoting ovarian cancer progression. Notably, we observe that the PIK3CB promoter is transcribed to produce a non-coding RNA which interacts with hnRNPL and promotes hnRNPL condensation. Furthermore, hnRNPL is significantly amplified in ovarian cancer, and its high expression predicts poor prognosis for ovarian cancer patients. By using cell-derived xenograft and patient-derived organoid models, we show that hnRNPL knockdown suppresses ovarian tumorigenesis. Together, our study reveals that phase separation of the chromatin-associated RBP hnRNPL promotes PIK3CB transcription and glycolysis to facilitate tumorigenesis in ovarian cancer. The formed hnRNPL-PIK3CB-AKT axis depending on phase separation can serve as a potential therapeutic target for ovarian cancer.
Project description:Ovarian cancer has the highest mortality rate among gynecologic tumors worldwide, with unclear underlying mechanisms of pathogenesis. RNA-binding proteins (RBPs) primarily direct post-transcriptional regulation through modulating RNA metabolism. Recent evidence demonstrates that RBPs are also implicated in transcriptional control. However, the role and mechanism of RBP-mediated transcriptional regulation in tumorigenesis remain largely unexplored. Here, we show that the RBP heterogeneous ribonucleoprotein L (hnRNPL) interacts with chromatin and regulates gene transcription by forming phase-separated condensates in ovarian cancer. hnRNPL phase separation activates PIK3CB transcription and glycolysis, thus promoting ovarian cancer progression. Notably, we observe that the PIK3CB promoter is transcribed to produce a non-coding RNA which interacts with hnRNPL and promotes hnRNPL condensation. Furthermore, hnRNPL is significantly amplified in ovarian cancer, and its high expression predicts poor prognosis for ovarian cancer patients. By using cell-derived xenograft and patient-derived organoid models, we show that hnRNPL knockdown suppresses ovarian tumorigenesis. Together, our study reveals that phase separation of the chromatin-associated RBP hnRNPL promotes PIK3CB transcription and glycolysis to facilitate tumorigenesis in ovarian cancer. The formed hnRNPL-PIK3CB-AKT axis depending on phase separation can serve as a potential therapeutic target for ovarian cancer.
Project description:Ovarian cancer has the highest mortality rate among gynecologic tumors worldwide, with unclear underlying mechanisms of pathogenesis. RNA-binding proteins (RBPs) primarily direct post-transcriptional regulation through modulating RNA metabolism. Recent evidence demonstrates that RBPs are also implicated in transcriptional control. However, the role and mechanism of RBP-mediated transcriptional regulation in tumorigenesis remain largely unexplored. Here, we show that the RBP heterogeneous ribonucleoprotein L (hnRNPL) interacts with chromatin and regulates gene transcription by forming phase-separated condensates in ovarian cancer. hnRNPL phase separation activates PIK3CB transcription and glycolysis, thus promoting ovarian cancer progression. Notably, we observe that the PIK3CB promoter is transcribed to produce a non-coding RNA which interacts with hnRNPL and promotes hnRNPL condensation. Furthermore, hnRNPL is significantly amplified in ovarian cancer, and its high expression predicts poor prognosis for ovarian cancer patients. By using cell-derived xenograft and patient-derived organoid models, we show that hnRNPL knockdown suppresses ovarian tumorigenesis. Together, our study reveals that phase separation of the chromatin-associated RBP hnRNPL promotes PIK3CB transcription and glycolysis to facilitate tumorigenesis in ovarian cancer. The formed hnRNPL-PIK3CB-AKT axis depending on phase separation can serve as a potential therapeutic target for ovarian cancer.
Project description:RNA-binding proteins (RBPs) are crucial factors of post-transcriptional gene regulation and their modes of action are intensely investigated. At the center of attention are RNA motifs that guide where RBPs bind. However, sequence motifs recognized by RBPs are typically a poor predictor of RBP-RNA interactions in vivo. It is hence believed that many RBPs recognize RNAs as complexes, to increase specificity and regulatory potential. To probe the potential for RBP–RBP complex formation, we assembled a library of 978 mammalian RBPs and used rec-Y2H screening to detect direct interactions between RBPs, sampling >1M possible interactions. We discovered 1994 new interactions and demonstrate that our interaction screening discovers RBP pairs that bind RNAs adjacently. We further find that the mRNA binding region preferences of an RBP can deviate, depending on its adjacently binding interaction partner. Finally, we reveal novel RBP–RBP interaction networks among major RNA processing steps and show that RBP mutations observed in cancer rewire spliceosomal interaction networks.
Project description:In the current project with aim to unequivocally characterize a novel splicing-regulatory network that proves to be a central mediator of endothelial barrier function and vascular integrity. At the core of this network is the endothelial enriched lncRNA NTRAS (annotated as RP11-354k1.1) is shown to control alternative splicing decisions in HUVECs through interplaying with splicing factor hnRNPL. Specifically, in the project we show that NTRAS sequesters the splicing factor hnRNPL through a CA dinucleotide motif, to enhance TJP1 exon 20 usage, thereby TJP1α+ isoform. In turn disrupting TJP1α+ isoform expression impaired endothelial barrier function. Collectively, this splicing-regulatory network might prove fundamental in unlocking new interventions strategic to prevent or reverse vascular leakage.
Project description:Long noncoding RNAs (lncRNAs) can regulate the activity of interacting RNA binding proteins (RBPs), but how lncRNAs efficiently compete against other transcripts to bind and regulate RBP activity is poorly understood. This problem is exemplified by NORAD, a lncRNA that maintains genomic stability by inhibiting PUMILIO (PUM) proteins. Here we show that NORAD is able to out-compete other PUM-binding transcripts by nucleating the formation of phase-separated PUM condensates, termed NP bodies. Dual mechanisms of PUM recruitment, involving multivalent PUM-NORAD and PUM-PUM interactions, enable NORAD to sequester a super-stoichiometric amount of PUM in these condensates. Accordingly, synthetic RNAs that induce PUM phase separation rescue genome instability in NORAD-deficient cells. These results illuminate mechanisms of RBP regulation by RNA-driven phase separation and uncover an essential role for this process in genome maintenance.
Project description:Circular RNAs (circRNAs) are covalently closed transcripts involved in the regulation of different cellular processes, and their dysregulation has been frequently observed in cancer. In this study, we investigated the role of circCDYL, a circRNA generated from the CDYL gene, in modulating alternative splicing (AS) and isoform switching in breast cancer cells. Analysis of circRNA profiles in breast cancer cells showed that circCDYL expression increased in estrogen receptor alpha (ERα)-downregulated cells, suggesting a potential link between circCDYL-mediated regulation and ERα signaling pathways. RNA-Sequencing analysis following circCDYL knock-down in MCF-7 cells revealed significant alterations in the splicing pattern, with over 2,900 splicing events significantly affected. Through RNA immunoprecipitation and RNA pull-down assays, we found evidence of an association between circCDYL and the splicing factor hnRNPL. To explore the consequences of this association, we performed AS and isoform switching analysis after circCDYL and hnRNPL silencing, revealing significant effects on AS and a weaker modulation of isoform switching events. Furthermore, we observed that circCDYL and hnRNPL modulated CDYL isoform expression, as confirmed by isoform-specific qRT-PCR analysis. Chromatin immunoprecipitation assays also indicated changes in chromatin marks at the CDYL locus upon knock-down of circCDYL and hnRNPL. These results suggested a possible association between circCDYL and hnRNPL, which contributed to the regulation of alternative splicing in breast cancer cells and may be involved in the modulation of isoform expression and chromatin dynamics of CDYL gene.
Project description:Analysis of RNA expression in LNCaP prostate cancer cells treated with different siRNAs to define the regulatory effect of HNRNPL and LARP on RNA expression.
Project description:RNA binding proteins (RBPs) bind RNAs through specific RNA-binding domains, generating multi-molecular complexes known as ribonucleoproteins (RNPs). Various post-translational modifications (PTMs) have been described to regulate RBP structure, subcellular localization and interactions with other proteins or RNAs. Recent proteome-wide experiments showed that RBPs are the most representative group within the class of arginine (R)-methylated proteins; moreover, emerging evidence suggests that this modification plays a major role in the regulation of RBP-RNA interaction. Nevertheless, a systematic analysis of how changes in protein-R-methylation can affect globally RBPs-RNA interactions has not yet been carried out. We describe here a quantitative proteomics approach to profile global changes of RBP-RNA interactions upon the modulation of protein arginine methyltransferases PRMT1 and PRMT5. By coupling the recently described Orthogonal Organic Phase Separation (OOPS) with SILAC labelling and pharmacological modulation of PRMT1 and PRMT5 enzyme, we describe the RNA-binding protein dynamics in dependence of protein-R-methylation.
Project description:Analysis of circular RNA expression in LNCaP prostate cancer cells treated with different siRNAs to define the regulatory effect of HNRNPL and LARP on circular RNA expression.