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:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
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:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
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