Mitotic gene regulation by the N-MYC-WDR5-PDPK1 nexus
Ontology highlight
ABSTRACT: Background: During mitosis the cell depends on proper attachment and segregation of replicated chromosomes to generate two identical progeny. In cancers defined by overexpression or dysregulation of the MYC oncogene this process becomes impaired, leading to genomic instability and tumor evolution. Recently it was discovered that the chromatin regulator WDR5—a critical MYC cofactor—regulates expression of genes needed in mitosis through a direct interaction with the master kinase PDPK1. However, whether PDPK1 and WDR5 contribute to similar mitotic gene regulation in MYC-overexpressing cancers remains unclear. Therefore, to characterize the influence of WDR5 and PDPK1 on mitotic gene expression in cells with high MYC levels, we performed a comparative transcriptomic analysis in neuroblastoma cell lines defined by MYCN-amplification, which results in high cellular levels of the N-MYC protein. Results: Using RNA-seq analysis, we identify the genes regulated by N-MYC and PDPK1 in multiple engineered CHP-134 neuroblastoma cell lines and compare them to previously published gene expression data collected in CHP-134 cells following inhibition of WDR5. We find that as expected N-MYC regulates a multitude of genes, including those related to mitosis, but that PDPK1 regulates specific sets of genes involved in development, signaling, and mitosis. Analysis of N-MYC- and PDPK1-regulated genes reveals a small group of commonly controlled genes associated with spindle pole formation and chromosome segregation, which overlap with genes that are also regulated by WDR5. We also find that N-MYC physically interacts with PDPK1 through the WDR5-PDPK1 interaction suggesting regulation of mitotic gene expression may be achieved through a N-MYC-WDR5-PDPK1 nexus. Conclusions: Overall, we identify a small group of genes highly enriched within functional gene categories related to mitotic processes that are commonly regulated by N-MYC, WDR5, and PDPK1 and suggest that a tripartite interaction between the three regulators may be responsible for setting the level of mitotic gene regulation in N-MYC amplified cell lines. This study provides a foundation for future studies to determine the exact mechanism by which N-MYC, WDR5, and PDPK1 converge on cell cycle related processes.
Project description:Background: During mitosis the cell depends on proper attachment and segregation of replicated chromosomes to generate two identical progeny. In cancers defined by overexpression or dysregulation of the MYC oncogene this process becomes impaired, leading to genomic instability and tumor evolution. Recently it was discovered that the chromatin regulator WDR5—a critical MYC cofactor—regulates expression of genes needed in mitosis through a direct interaction with the master kinase PDPK1. However, whether PDPK1 and WDR5 contribute to similar mitotic gene regulation in MYC-overexpressing cancers remains unclear. Therefore, to characterize the influence of WDR5 and PDPK1 on mitotic gene expression in cells with high MYC levels, we performed a comparative transcriptomic analysis in neuroblastoma cell lines defined by MYCN-amplification, which results in high cellular levels of the N-MYC protein. Results: Using RNA-seq analysis, we identify the genes regulated by N-MYC and PDPK1 in multiple engineered CHP-134 neuroblastoma cell lines and compare them to previously published gene expression data collected in CHP-134 cells following inhibition of WDR5. We find that as expected N-MYC regulates a multitude of genes, including those related to mitosis, but that PDPK1 regulates specific sets of genes involved in development, signaling, and mitosis. Analysis of N-MYC- and PDPK1-regulated genes reveals a small group of commonly controlled genes associated with spindle pole formation and chromosome segregation, which overlap with genes that are also regulated by WDR5. We also find that N-MYC physically interacts with PDPK1 through the WDR5-PDPK1 interaction suggesting regulation of mitotic gene expression may be achieved through a N-MYC-WDR5-PDPK1 nexus. Conclusions: Overall, we identify a small group of genes highly enriched within functional gene categories related to mitotic processes that are commonly regulated by N-MYC, WDR5, and PDPK1 and suggest that a tripartite interaction between the three regulators may be responsible for setting the level of mitotic gene regulation in N-MYC amplified cell lines. This study provides a foundation for future studies to determine the exact mechanism by which N-MYC, WDR5, and PDPK1 converge on cell cycle related processes.
Project description:JMJD6 is an important oncogene that is upregulated in 17q21-ter gained neuroblastoma.It plays a role in E2F and N-Myc-regulated gene pathways and neuroblastoma tumorigenesis Using ChIP-Seq, We profiled RNA polymerase 2 binding in doxycycline inducible JMJD6 shRNA CHP-134 neuroblastoma cells, treated with either doxycycline or vehicle control. We identified a list of genes with reduced RNA Pol II binding peaks at their gene promoters as a result of the JMJD6 knockdown. GSEA analysis showed that the top four gene sets, with most considerable reduction in RNA Pol II binding peaks at gene promoters, were E2F target genes, G2M checkpoint genes, mitotic spindle genes, and Myc target genes.
Project description:The WIN site of WDR5 is a druggable pocket that is crucial for WDR5 protein function and carries therapeutic potential for treating cancer. This study evaluates the protein interactions affected by small molecule blockade of the WIN site of WDR5. We find that PDPK1 directly binds the WIN site of WDR5, and we investigate this newfound interaction through proteomic, biochemical, and genomic methods.
Project description:The highly conserved WD40-repeat protein WDR5 is part of multiple functional complexes both inside and outside the nucleus, interacting with the MLL/SET1 histone methyltransferases that catalyze histone H3 lysine 4 (H3K4) di- and tri-methylation (me2,3), and KIF2A, a member of the Kinesin-13 family of microtubule depolymerase. It is currently unclear whether, and how, the distribution of WDR5 between complexes is regulated. Here, we show that an unannotated microprotein dually encoded in the human SCRIB gene regulates the association of WDR5 with epigenetic and KIF2A complexes. We propose to name this alt-protein EMBOW, or microprotein that is the epigenetic to mitotic binder of WDR5. Loss of EMBOW decreases WDR5 interaction with KIF2A, displaces WDR5 from the spindle pole during G2/M phase, and shortens the spindle length, hence prolonging G2/M phase and delaying cell proliferation. On the other hand, loss of EMBOW increases WDR5 interaction with epigenetic complexes, including KMT2A/MLL1, and promotes WDR5 association with chromatin and binding to the target genes, hence increasing H3K4me3 levels of target genes. Together, these results implicate EMBOW as a regulator of WDR5 that switches it between epigenetic and mitotic regulatory roles during cell cycle, explaining how mammalian cells can temporally control the multifunctionality of WDR5.
Project description:The oncoprotein transcription factor MYC is overexpressed in the majority of human cancers. Key to its oncogenic activity is the ability of MYC to bind chromatin and regulate broad gene expression patterns that drive and maintain the tumorigenic state. The interaction of MYC with chromatin is absolutely dependent on interaction with MAX, but may also be facilitated by additional chromatin-resident proteins such as WDR5. If the role of these additional proteins can be understood, they could serve as novel focal points for therapeutically targeting MYC. To stringently challenge the role of WDR5 in MYC function, we developed a Burkitt's Lymphoma system that allows inducible and quantitative exchange of wild-type for mutant forms of MYC defective for interaction with WDR5 or MAX. Using this system, we show that WDR5 recruits MYC to a small cohort of genes, enriched in those encoding ribosome protein subunits, and demonstrate that disrupting the MYC-WDR5 interaction is as effective as disrupting interaction with MAX at preventing tumor initiation and promoting tumor regression in vivo. These findings show that WDR5 is connected to a central tumorigenic function of MYC and forecast that small molecule WDR5 inhibitors could be broadly effective anti-cancer agents.
Project description:The highly conserved WD40-repeat protein WDR5 is part of multiple functional complexes both inside and outside the nucleus, interacting with the MLL/SET1 histone methyltransferases that catalyze histone H3 lysine 4 (H3K4) di- and tri-methylation (me2,3), and KIF2A, a member of the Kinesin-13 family of microtubule depolymerase. It is currently unclear whether, and how, the distribution of WDR5 between complexes is regulated. Here, we show that an unannotated microprotein dually encoded in the human SCRIB gene regulates the association of WDR5 with epigenetic and KIF2A complexes. We propose to name this alt-protein EMBOW, or microprotein that is the epigenetic to mitotic binder of WDR5. Loss of EMBOW decreases WDR5 interaction with KIF2A, displaces WDR5 from the spindle pole during G2/M phase, and shortens the spindle length, hence prolonging G2/M phase and delaying cell proliferation. On the other hand, loss of EMBOW increases WDR5 interaction with epigenetic complexes, including KMT2A/MLL1, and promotes WDR5 association with chromatin and binding to the target genes, hence increasing H3K4me3 levels of target genes. Together, these results implicate EMBOW as a regulator of WDR5 that switches it between epigenetic and mitotic regulatory roles during cell cycle, explaining how mammalian cells can temporally control the multifunctionality of WDR5.
Project description:We report a comparison of the genome-wide binding patterns of MYC and WDR5, and the effects of a mutation in MYC (WBM) that disrupt the MYC-WDR5 interaction.
Project description:The WIN site of WDR5 is a druggable pocket that impairs WDR5 protein function and carries therapeutic potential for treating cancer. This study evaluates the protein interactions affected by small molecule blockade of this surface on WDR5. Inhibited and uninhibited WDR5-containing complexes from HEK293 cells were quantitatively compared by SILAC-based proteomics. Of the high confidence proteins affected by this inhibition, one protein, PDPK1, was investigated further by mass spectrometry for identification of post translational modifications that could influence binding to WDR5.