Loss of Capicua alters early T cell development and predisposes mice to T cell lymphoblastic leukemia/lymphoma
Ontology highlight
ABSTRACT: Thymic lymphomas were dissected from Cic adult knockout mice or wildtype mice transplanted with Cic adult knockout progenitors. Tissues were snap-frozen in liquid nitrogen until further analysis. RNAs were purified using the AllPrep DNA/RNA mini kit (Qiagen).
Project description:CIC is a HMG box-containing transcriptional repressor evolutionarily conserved from C. elegans to human. It's known to associate with various types of cancer but physiological function of CIC remain largely unknown. In this study, we characterized Cic hypomorphic (Cic-L-/-) mice and identified critical roles for of CIC in drug metabolism and bile acid homeostasis. Total RNA obtained from isolated liver tissue of Cic-L-/- mouse compared to liver tissue of normal mouse
Project description:Analysis of cerebella from Capicua (Cic) mutant mice and wild-type controls at 28 days of age (P28). Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by expansion of a translated CAG repeat in Ataxin-1 (ATXN1). The transcriptional repressor Cic binds directly to Atxn1 and plays a key role in SCA1 pathogenesis. Two isoforms of Cic, long (Cic-L) and short (Cic-S), are transcribed from alternative promoters. Using embryonic stem cells in which the Cic locus was targeted by an insertion of a genetrap cassette between exon 1 of the Cic-L isoform and exon 1 of the Cic-S isoform, we generated mice that carried this allele and backcrossed these onto a Swiss Webster (CD-1) strain for >6 generations. The resulting Cic-L-/- mice completely lack the Cic-L isoform with ~10% of Cic-S remaining. These data were used to compare with previous microarray data to determine the Cic-depedent pathogenic mechanisms in SCA1. Total RNA from cerebella of wild-type (n=4) and Capicua mutant mice (n=4) at 28 days of age was prepared and labeled according the manufacturer's protocols for the Affymetrix Mouse Gene 1.0 ST Array.
Project description:CIC is a HMG box-containing transcriptional repressor evolutionarily conserved from C. elegans to human. It's known to associate with various types of cancer but physiological function of CIC remain largely unknown. In this study, we characterized Cic hypomorphic (Cic-L-/-) mice and identified critical roles for of CIC in drug metabolism and bile acid homeostasis.
Project description:We identified genome-wide binding patterns of CIC in several different cell types and find that CIC target genes are enriched for MAPK effector genes involved in cell cycle regulation and proliferation. CIC binding to its target genes is abolished by high MAPK activity, which leads to hyperacetylation and their transcriptional activation. Inhibition of MAPK signaling via MEK inhibition leads to recruitment of CIC to its target genes. ChIP-seq data of G144 cells after MEK inhibition and CIC knockout is available under accession E-MTAB-6682
Project description:Analysis of cerebella from Capicua (Cic) mutant mice and wild-type controls at 28 days of age (P28). Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by expansion of a translated CAG repeat in Ataxin-1 (ATXN1). The transcriptional repressor Cic binds directly to Atxn1 and plays a key role in SCA1 pathogenesis. Two isoforms of Cic, long (Cic-L) and short (Cic-S), are transcribed from alternative promoters. Using embryonic stem cells in which the Cic locus was targeted by an insertion of a genetrap cassette between exon 1 of the Cic-L isoform and exon 1 of the Cic-S isoform, we generated mice that carried this allele and backcrossed these onto a Swiss Webster (CD-1) strain for >6 generations. The resulting Cic-L-/- mice completely lack the Cic-L isoform with ~10% of Cic-S remaining. These data were used to compare with previous microarray data to determine the Cic-depedent pathogenic mechanisms in SCA1.
Project description:We performed a genome-scale CRISPR screen in a KRAS-mutant pancreatic cancer cell line treated with the MEK inhibitor trametinib, and found that loss of the transcriptional repressor CIC confers resistance to MEK inhibition. We determined that CIC loss also confers resistance to MEK or BRAF inhibition in lung cancer, colorectal cancer, and melanoma cell lines with mutant RAS or BRAF. CIC is a transcriptional repressor that is phosphorylated and inhibited by the MAPK pathway. We hypothesized that inhibition of the MAPK pathway would lead to activation of CIC and repression of CIC target genes. Loss of CIC would therefore restore expression of these genes, conferring drug resistance. To identify the relevant CIC target genes that mediate trametinib resistace, we generated 4 Cas9-expressing cell lines from different lineages and with different RAS or RAF mutations, and generated control (gGFP) or CIC-knockout (gCIC) cell lines. We treated cells with DMSO or trametinib for 24 hours, and performed NRA-seq. We found that trametinib treatment reduces expression of at least one member of the PEA3 family of ETS transcription factors (ETV1, ETV4, and ETV5) in all cell lines assessed, and that loss of CIC results in maintained expression of these genes despite MEK inhibition. We further validated that ETV1, 4, and 5 expression was necessary for resistance mediated by CIC loss; and that ETV1, 4, or 5 expression was sufficient to confer trametinib resistance.
Project description:We identified genome-wide binding patterns of CIC in several different cell types and find that CIC target genes are enriched for MAPK effector genes involved in cell cycle regulation and proliferation. CIC binding to its target genes is abolished by high MAPK activity, which leads to hyperacetylation and their transcriptional activation. Inhibition of MAPK signaling via MEK inhibition leads to recruitment of CIC to its target genes. Expression data of G144 cells after MEK inhibition and CIC knockout is available under accession E-MTAB-6681
Project description:We isolated RNAs from hematopoietic stem and progenitor cells (HSPCs). We compared two groups of mice: Cicflox/flox (control) and UBC-cre/ERT2; Cicflox/flox (knockout), two weeks post tamoxifen treatment. Following RNA isolation, RNAseq was performed and gene expression profiles were compared between controls and conditional knockouts.
Project description:Capicua (CIC) regulates a transcriptional network downstream of the RAS/MAPK signaling cascade. In Drosophila, CIC is important for many developmental processes, including embryonic patterning and specification of wing veins. In humans, CIC has been implicated in neurological diseases, including spinocerebellar ataxia type 1 (SCA1) and a neurodevelopmental syndrome. Additionally, we and others have reported mutations in CIC in several cancers. However, whether CIC is a tumor suppressor remains to be formally tested. In this study, we found that deletion of Cic in adult mice causes T cell acute lymphoblastic leukemia/lymphoma (T-ALL). Using hematopoietic-specific deletion and bone marrow transplantation studies, we show that loss of Cic from hematopoietic cells is sufficient to drive T-ALL. Cic-null tumors show up-regulation of the KRAS pathway as well as activation of the NOTCH1 and MYC transcriptional programs. In sum, we demonstrate that loss of CIC causes T-ALL, establishing it as a tumor suppressor for lymphoid malignancies. Moreover, we show that mouse models lacking CIC in the hematopoietic system are robust models for studying the role of RAS signaling as well as NOTCH1 and MYC transcriptional programs in T-ALL.
Project description:The HMG-box protein Capicua (Cic) is a conserved transcriptional repressor that functions downstream of receptor tyrosine kinase (RTK) signaling pathways in a relatively simple switch: in the absence of signaling, Cic represses RTK-responsive genes by binding to nearly invariant sites in DNA, whereas activation of RTK signaling downregulates Cic activity, leading to derepression of its targets. This mechanism controls gene expression in both Drosophila and mammals, but whether Cic can also function via other regulatory mechanisms remains unknown. Here we characterize an RTK-independent role of Cic in regulating spatially restricted expression of Toll/IL-1 signaling targets in Drosophila embryogenesis. We show that Cic represses those targets by binding to suboptimal DNA sites of lower affinity than its known consensus sites. This binding depends on Dorsal/NF-kB, which translocates into the nucleus upon Toll activation and binds next to the Cic sites. As a result, Cic binds to and represses Toll targets only in regions with nuclear Dorsal. These results reveal a new mode of Cic regulation unrelated to the well-established RTK-Cic depression axis and implicate cooperative binding in conjunction with low-affinity binding sites as an important mechanism of enhancer regulation. Given that Cic plays a role in many developmental and pathological processes in mammals, our results raise the possibility that some of these Cic functions are independent of RTK regulation and may depend on cofactor-assisted DNA binding.