Transcriptomic and Epigenomic Profiles of CIC-knockout and IDH1 mutant cells [histone_chip]
Ontology highlight
ABSTRACT: Capicua (CIC)’s transcriptional repressor function is implicated in neurodevelopment and in oligodendroglioma (ODG) aetiology. However, CIC’s role in these contexts remains obscure, primarily from our currently limited knowledge regarding its biological functions. Moreover, CIC mutations in ODG invariably co-occur with a neomorphic IDH1/2 mutation, yet the functional relationship between these two genetic events is unknown. Here, we analysed models derived from an E6/E7/hTERT-immortalized (i.e. p53- and RB-deficient) normal human astrocyte cell line. To examine the consequences of CIC loss, we compared transcriptomic and epigenomic profiles between CIC wildtype and knockout cell lines, with and without mutant IDH1 expression. Our analyses revealed dysregulation of neurodevelopmental genes in association with CIC loss. CIC ChIP-seq was also performed to expand upon the currently limited ensemble of known CIC target genes. Among the newly identified direct CIC target genes were EPHA2 and ID1, whose functions are linked to neurodevelopment and the tumourigenicity of in vivo glioma tumour models. NFIA, a known mediator of gliogenesis, was discovered to be uniquely overexpressed in double mutant cells (CIC-knockout + IDH1-mutant). These results identify neurodevelopment and specific genes within this context as candidate targets through which CIC alterations may contribute to the progression of IDH-mutant gliomas.
Project description:Capicua (CIC)’s transcriptional repressor function is implicated in neurodevelopment and in oligodendroglioma (ODG) aetiology. However, CIC’s role in these contexts remains obscure, primarily from our currently limited knowledge regarding its biological functions. Moreover, CIC mutations in ODG invariably co-occur with a neomorphic IDH1/2 mutation, yet the functional relationship between these two genetic events is unknown. Here, we analysed models derived from an E6/E7/hTERT-immortalized (i.e. p53- and RB-deficient) normal human astrocyte cell line. To examine the consequences of CIC loss, we compared transcriptomic and epigenomic profiles between CIC wildtype and knockout cell lines, with and without mutant IDH1 expression. Our analyses revealed dysregulation of neurodevelopmental genes in association with CIC loss. CIC ChIP-seq was also performed to expand upon the currently limited ensemble of known CIC target genes. Among the newly identified direct CIC target genes were EPHA2 and ID1, whose functions are linked to neurodevelopment and the tumourigenicity of in vivo glioma tumour models. NFIA, a known mediator of gliogenesis, was discovered to be uniquely overexpressed in double mutant cells (CIC-knockout + IDH1-mutant). These results identify neurodevelopment and specific genes within this context as candidate targets through which CIC alterations may contribute to the progression of IDH-mutant gliomas.
Project description:Capicua (CIC)’s transcriptional repressor function is implicated in neurodevelopment and in oligodendroglioma (ODG) aetiology. However, CIC’s role in these contexts remains obscure, primarily from our currently limited knowledge regarding its biological functions. Moreover, CIC mutations in ODG invariably co-occur with a neomorphic IDH1/2 mutation, yet the functional relationship between these two genetic events is unknown. Here, we analysed models derived from an E6/E7/hTERT-immortalized (i.e. p53- and RB-deficient) normal human astrocyte cell line. To examine the consequences of CIC loss, we compared transcriptomic and epigenomic profiles between CIC wildtype and knockout cell lines, with and without mutant IDH1 expression. Our analyses revealed dysregulation of neurodevelopmental genes in association with CIC loss. CIC ChIP-seq was also performed to expand upon the currently limited ensemble of known CIC target genes. Among the newly identified direct CIC target genes were EPHA2 and ID1, whose functions are linked to neurodevelopment and the tumourigenicity of in vivo glioma tumour models. NFIA, a known mediator of gliogenesis, was discovered to be uniquely overexpressed in double mutant cells (CIC-knockout + IDH1-mutant). These results identify neurodevelopment and specific genes within this context as candidate targets through which CIC alterations may contribute to the progression of IDH-mutant gliomas.
Project description:Capicua (CIC)’s transcriptional repressor function is implicated in neurodevelopment and in oligodendroglioma (ODG) aetiology. However, CIC’s role in these contexts remains obscure, primarily from our currently limited knowledge regarding its biological functions. Moreover, CIC mutations in ODG invariably co-occur with a neomorphic IDH1/2 mutation, yet the functional relationship between these two genetic events is unknown. Here, we analysed models derived from an E6/E7/hTERT-immortalized (i.e. p53- and RB-deficient) normal human astrocyte cell line. To examine the consequences of CIC loss, we compared transcriptomic and epigenomic profiles between CIC wildtype and knockout cell lines, with and without mutant IDH1 expression. Our analyses revealed dysregulation of neurodevelopmental genes in association with CIC loss. CIC ChIP-seq was also performed to expand upon the currently limited ensemble of known CIC target genes. Among the newly identified direct CIC target genes were EPHA2 and ID1, whose functions are linked to neurodevelopment and the tumourigenicity of in vivo glioma tumour models. NFIA, a known mediator of gliogenesis, was discovered to be uniquely overexpressed in double mutant cells (CIC-knockout + IDH1-mutant). These results identify neurodevelopment and specific genes within this context as candidate targets through which CIC alterations may contribute to the progression of IDH-mutant gliomas.
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 encodes a transcriptional repressor inactivated by loss-of-function mutations in several cancer types, indicating that it may function as a tumor suppressor. Recent data indicate that CIC may regulate cell cycle genes in humans; however, a thorough investigation of this proposed role has not yet been reported. Here, we used single-cell RNA sequencing technology to provide evidence that inactivation of CIC in human cell lines resulted in transcriptional dysregulation of genes involved in cell cycle control. We also mapped CIC’s protein-protein and genetic interaction networks, identifying interactions between CIC and members of the Switch/Sucrose Non-Fermenting (SWI/SNF) complex, as well as novel candidate interactions between CIC and cell cycle regulators. We further showed that CIC loss was associated with an increased frequency of mitotic defects in human cell lines and a mouse model. Overall, our study positions CIC as a cell cycle regulator and indicates that CIC loss can lead to mitotic errors, consistent with CIC’s emerging role as a tumor suppressor of relevance in several cancer contexts.
Project description:Through development of an in vivo orthotopic lung cancer model, we reveal an unanticipated pathway driving spontaneous metastasis that is orchestrated by the developmentally-regulated transcriptional repressor, Capicua (CIC). RNAseq and DNA copy number analysis of H1975 (EGFR-mutant lung adenocarcinoma) cells in the context of drug resistance to erlotinib
Project description:Type I low-grade gliomas (LGGs), characterized by 1p/19q co-deletions and IDH1/2 mutations, show superior overall survival compared to other gliomas. Approximately 70% of cases harbour mutations in the Capicua (CIC) gene, whose product is a transcriptional repressor whose transcriptional network has yet to be extensively studied in human cells. To address this, we developed CIC knockout cell lines and used transcriptome analyses to study the consequences of CIC loss. Results were further compared to data for Type I LGGs and stomach adenocarcinomas from The Cancer Genome Atlas (TCGA). We find that CIC appears to regulate the expression of genes involved in cell-cell adhesion and nervous system development. CIC deficiency is also found to be associated with a MEK activation transcriptional signature and to act as an effector of MEK signalling. Loss of CIC may thus present a novel mechanism for the dysregulation of this and other oncogenic pathways.
Project description:CIC encodes a transcriptional repressor and MAPK signalling effector that is inactivated by loss-of-function mutations in several cancer types, consistent with a role as a tumour suppressor. Here, we used bioinformatic, genomic, and proteomic approaches to investigate CIC’s interaction networks. We observed both previously identified and novel candidate interactions between CIC and SWI/SNF complex members, as well as novel interactions between CIC and cell cycle regulators and RNA processing factors. We found that CIC loss is associated with an increased frequency of mitotic defects in human cell lines and an in vivo mouse model and with dysregulated expression of mitotic regulators. We also observed aberrant splicing in CIC-deficient cell lines, predominantly at 3′ and 5′ untranslated regions of genes, including genes involved in MAPK signalling, DNA repair, and cell cycle regulation. Our study thus characterises the complexity of CIC’s functional network and describes the effect of its loss on cell cycle regulation, mitotic integrity, and transcriptional splicing, thereby expanding our understanding of CIC’s potential roles in cancer. In addition, our work exemplifies how multi-omic, network-based analyses can be used to uncover novel insights into the interconnected functions of pleiotropic genes/proteins across cellular contexts.
Project description:A better understanding of oligodendroglioma biology is needed to develop new specific targeted therapies. We show here that CIC mutations are associated with negative outcome and upregulation of proliferative pathways. Our data also suggest that CIC mutations result in CIC inactivation. Finally our data suggest a synergistic negative impact of the CIC mutations and P16 alterations on survival, pointing out to CyclinD1 as key effector of oligodendrogliomas.
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.