Project description:Post-transcriptional modifications of tumor suppressors, including microRNA-mediated downregulation, are important events in tumor progression. To identify microRNAs involved in oncogenic transformation, we examined global microRNA profiles of three ras transgenic zebrafish models. Four microRNAs are upregulated in all transgenic systems. Analysis of the predicted targets shows that three of them target Jmjd6, and overexpression of Jmjd6 in ras transformed melanocytes blocks proliferation and melanoma development. We found that Jmjd6 functions to regulate splicing of the tumor suppressor cdkn1a/p21. Truncated cdkn1a/p21 transcripts, lacking the PCNA binding domain, accumulate in ras-expressing melanocytes during melanoma development. These findings implicate Jmjd6 in a novel mechanism for inactivation of a major tumor suppressor pathway in melanoma.
Project description:p53-mediated cell cycle arrest during DNA damage is dependent on the induction of p21 protein, encoded by the CDKN1A gene. p21 inhibits cyclin-dependent kinases required for cell cycle progression to guarantee accurate repair of DNA lesions. Hence, fine-tuning of p21 levels is crucial to preserve genomic stability. Currently, the multilayered regulation of p21 levels during DNA damage is not fully understood. Herein, we identified the human RNA binding motif protein 42 (RBM42) as a novel regulator of p21 levels during DNA damage. Genome-wide transcriptome and interactome analysis revealed that RBM42 alters the expression of p53-regulated genes during DNA damage. Specifically, we demonstrated that RBM42 facilitates CDKN1A splicing by counteracting the splicing inhibitory effect of RBM4 protein. Unexpectedly, we also show that RBM42, underpins translation of various splicing targets, including CDKN1A. Concordantly, transcriptome-wide mapping of RBM42-RNA interactions using eCLIP further substantiates the dual function of RBM42 in regulating splicing and translation of its target genes, including CDKN1A. Collectively, our data show that RBM42 couples splicing and translation machineries to fine-tune gene expression during DNA damage response.
Project description:Dysregulated pre-mRNA splicing and metabolism are two hallmarks of MYC-driven cancers. Pharmacological inhibition of both processes has been extensively investigated as potential therapeutic avenues in preclinical and clinical studies. However, how pre-mRNA splicing and metabolism are orchestrated in response to oncogenic stress and therapies is poorly understood. Here, we demonstrate that Jumonji Domain Containing 6, Arginine Demethylase and Lysine Hydroxylase, or JMJD6, acts as a hub connecting splicing and metabolism in MYC-driven neuroblastoma. JMJD6 cooperates with MYC in cellular transformation by physically interacting with RNA binding proteins involved in pre-mRNA splicing and protein homeostasis. Notably, JMJD6 controls the alternative splicing of two isoforms of glutaminase (GLS), namely kidney-type glutaminase (KGA) and glutaminase C (GAC), which are rate-limiting enzymes of glutaminolysis in the central carbon metabolism in neuroblastoma. Further, we show that JMJD6 is correlated with the anti-cancer activity of indisulam, a “molecular glue” that degrades splicing factor RBM39, which complexes with JMJD6. The indisulam-mediated cancer cell killing is at least partly dependent on the glutamine-related metabolic pathway mediated by JMJD6. Our findings reveal a cancer-promoting metabolic program is coupled with alternative pre-mRNA splicing through JMJD6, providing a rationale to target JMJD6 as a therapeutic avenue for treating MYC-driven cancers.
Project description:Chromosome 17q gain occurs frequently in MYC-driven tumors including high-risk neuroblastoma. However, the biological consequences of this genetic event remain elusive. Here we show that JMJD6, frequently amplified at the chromosome 17q25 locus, is one of the essential genes to neuroblastoma cells that are engaged in pathways of mitochondrial metabolism, RNA processing and protein homeostasis. JMJD6 cooperates with MYC in cellular transformation and promotes cancer cell proliferation and tumor growth. Mechanistically, JMJD6 physically interacts with RNA-processing machinery to regulate the alternative splicing and protein synthesis. Notably, JMJD6 controls the alternative splicing of glutaminase (GLS), kidney-type glutaminase (KGA) and glutaminase C (GAC), a rate-limiting enzyme of glutaminolysis, and, consequently, the central carbon metabolism in neuroblastoma. Our findings indicate that JMJD6 coordinates with MYC in tumorigenesis by regulating cancer-promoting metabolic programs through an alternative pre-mRNA splicing mechanism.
Project description:Zebrafish are an important model organism with inherent advantages that have the potential to make zebrafish a widely applied model for the study of energy homeostasis and obesity. The small size of zebrafish allows for assays on embryos to be conducted in a 96- or 384-well plate format, Morpholino and CRISPR based technologies promote ease of genetic manipulation, and drug treatment by bath application is viable. Moreover, zebrafish are ideal for forward genetic screens allowing for novel gene discovery. Given the relative novelty of zebrafish as a model for obesity, it is necessary to develop tools that fully exploit these benefits. Herein, we describe a method to measure energy expenditure in thousands of embryonic zebrafish simultaneously. We have developed a whole animal microplate platform in which we use 96-well plates to isolate individual fish and we assess cumulative NADH2 production using the commercially available cell culture viability reagent alamarBlue. In poikilotherms the relationship between NADH2 production and energy expenditure is tightly linked. This energy expenditure assay creates the potential to rapidly screen pharmacological or genetic manipulations that directly alter energy expenditure or alter the response to an applied drug (e.g. insulin sensitizers).
Project description:TAF15 (formerly TAFII68) is a member of the TET family of RNA and DNA binding proteins whose genes are frequently translocated in sarcomas. Consistent with a functional role in cell viability, TAF15 depletion had a growth-inhibitory effect and increased apoptosis. Interestingly, one of the genes affected by TAF15 depletion is CDKN1A/p21, a key regulator of cell cycle. Here we show that TAF15 down-regulates CDKN1A/p21 expression through a pathway involving miRNAs.
Project description:The p21 protein, encoded by CDKN1A, plays a vital role in the induction of senescence, and its transcriptional control by p53 tumour supressor is well-established. However, p21 can also be regulated in a p53-independent manner, by mechanisms that remain poorly understood. Therefore, we here used a chromatin-directed proteomic approach and identified ZNF84 as a novel regulator of p21 in various p53-deficient cell lines.