Project description:Aberrations in Capicua (CIC) have recently been implicated as a negative prognostic factor in a multitude of cancer types through activation of the MAPK signalling cascade and derepression of oncogenic ETS transcription factors. The Ataxin-family protein ATXN1L has previously been reported to interact with CIC in developmental and disease contexts to facilitate the repression of CIC target genes. To further investigate this relationship, we performed functional in vitro studies utilizing ATXN1LKO and CICKO human cell lines and characterized a reciprocal functional relationship between CIC and ATXN1L.
Project description:CIC has recently been implicated as a negative prognostic factor in multiple cancers. CIC and ATXN1L have been reported as interactors in several cellular contexts including development and disease state. To investigate the relationship between CIC and ATXN1L on a transcriptomic level, CIC-KO and ATXN1L-KO cell lines were generated. Gene expression profiling of CIC-KO and ATXN1L-KO cell lines was performed by microarray and differentially expressed genes were compared. We found a high degree of overlap in differentially expressed genes in CIC-KO and ATXN1L-KO suggesting loss of either interacting partner to lead to similar transcriptomic changes.
Project description:CIC has recently been implicated as a negative prognostic factor in multiple cancers. CIC and ATXN1L have been reported as interactors in several cellular contexts including development and disease state. To investigate the relationship between CIC and ATXN1L on a transcriptomic level, CIC-KO and ATXN1L-KO cell lines were generated. Gene expression profiling of CIC-KO and ATXN1L-KO cell lines was performed by microarray and differentially expressed genes were compared. We found a high degree of overlap in differentially expressed genes in CIC-KO and ATXN1L-KO suggesting loss of either interacting partner to lead to similar transcriptomic changes.
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: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:Many neurological diseases attack specific brain regions despite widespread expression of the disease-related protein. Spinocerebellar ataxia type 1 (SCA1) primarily affects the cerebellum, though Ataxin-1 (ATXN1) is widely expressed. We previously showed that intensified interaction between mutant ATXN1 and Capicua (CIC) drives SCA1 pathogenesis in the cerebellum, whereas ATXN1 loss augments amyloid beta production in the hippocampus and cortex. CIC, however, forms a complex with ATXN1 and its paralog, Ataxin-1-like (ATXN1L)—yet knockout of either yields completely different phenotypes. To determine whether this could be due to CIC having two isoforms, we generated mice bearing either the long (CIC-L) or short (CIC-S) isoform. Loss of CIC-L led to cognitive deficits, whereas loss of CIC-S caused perinatal lethality, phenocopying, ATXN1 and ATXN1L knockout mice, respectively. Furthermore, CIC-L preferentially interacts with ATXN1, and CIC-S with ATXN1L. Our data underscore the importance of isoform–paralog interplay in studying regional vulnerability in neurodegenerative diseases.
Project description:The receptor tyrosine kinase (RTK)/Extracellular Signal-Regulated Kinase (ERK) signaling pathway controls cell proliferation, differentiation, and survival. How ERK activation is relayed to its phosphorylation targets is not well understood. The transcriptional repressor Capicua (Cic) has emerged as a key target for ERK-mediated downregulation in Drosophila and mammals, and mutations in human CIC result in cancer and neurological diseases. Phosphorylation by ERK is critical for Cic downregulation, but the identities of phosphosites in Drosophila Cic are unknown. Here, we identify sites of phosphorylation in Cic that are directly targeted by ERK and validate their developmental functions in vivo using mutant Cic variants. Cic phosphosites are distributed throughout the length of the protein, and a group of centrally located sites appears to have a primary role in Cic downregulation. Cic mutated in 20 high-confidence sites behaves as a “super-repressor” in vivo that is largely insensitive to ERK-mediated downregulation, despite fully retaining the ability to bind to ERK. No single site is sufficient to turn off Cic activity; instead, we find that ERK must phosphorylate multiple sites in Cic simultaneously to achieve full downregulation. This multisite phosphorylation likely targets phosphodegrons that are recognized by ubiquitin ligases such as Ago/FBXW7 and contributes to Cic degradation. This study advances our understanding of the molecular mechanisms of signal interpretation downstream of the RTK/ERK signaling network.