Project description:We identified a Mariner transposase helix-turn-helix (HTH) DNA-binding domain that was captured in the Caenorhabditis genus by a subset of F-box genes, which we refer to as F-box A2 genes. The origin of F-box A2 genes likely occurred through a single transposase capture event, followed by an increase in copy number. We focused on fbxa-215, a F-box A2 gene highly expressed in the C. elegans germline and embryos, and that localizes to germ granules in embryos. The HTH domain of FBXA-215 is required for fertility and displays predominantly a signature of purifying selection, highlighting the importance of this domain. As the HTH domain of FBXA-215 is related to the DNA-binding HTH domain of transposases, we reasoned that FBXA-215 may bind to DNA in C. elegans and thus regulate gene expression at the transcriptional level. We performed mRNA sequencing of young adults and embryos to test this, but found no clear deregulation of protein-coding genes and transposable elements upon complete deletion of fbxa-215.
Project description:We identified a Mariner transposase helix-turn-helix (HTH) DNA-binding domain that was captured in the Caenorhabditis genus by a subset of F-box genes, which we refer to as F-box A2 genes. The origin of F-box A2 genes likely occurred through a single transposase capture event, followed by an increase in copy number. We focused on fbxa-215, a F-box A2 gene highly expressed in the C. elegans germline and embryos, and that localizes to germ granules in embryos. The HTH domain of FBXA-215 is required for fertility and displays predominantly a signature of purifying selection, highlighting the importance of this domain. As the HTH domain of FBXA-215 is related to the DNA-binding HTH domain of transposases, we reasoned that FBXA-215 may bind to DNA in C. elegans and thus regulate gene expression at the transcriptional level. We performed mRNA sequencing of young adults and embryos to test this, but found no clear deregulation of protein-coding genes and transposable elements upon complete deletion of fbxa-215.
Project description:Cell cycle arrest in response to DNA damage is an important anti-tumorigenic mechanism. microRNAs (miRNAs) were shown recently to play key regulatory roles in cell cycle progression. For example, miR-34a is induced in response to p53 activation and mediates G1 arrest by down-regulating multiple cell cycle-related transcripts. Here we show that genotoxic stress promotes the p53-dependent up-regulation of the homologous miRNAs, miR -192 and miR-215. Like miR-34a, activation of miR-192/215 induces cell cycle arrest suggesting that multiple microRNA families operate in the p53 network. Furthermore, we define a downstream gene expression signature for miR-192/215 expression that includes a number of transcripts that regulate G1 and G2 checkpoints. Of these transcripts, 18 transcripts are direct targets of miR-192/215 and the observed cell cycle arrest likely results from a cooperative effect among the modulations of these genes by the miRNAs. Our results demonstrating a role for miR-192/215 in cell proliferation combined with recent observations that these miRNAs are under-expressed in primary cancers support the idea that miR-192 and miR-215 function as tumor-suppressors. Description: Transfection of siRNA luc, miR-192 or miR-215 into HCT116 Dicerex5, compared to mock-transfected cells, with mRNA expression profiled at 10h and 24h post-transfection. Species: Human Tissue: HCT116 Dicerex5 cell line (tissue of origin = human colorectal carcinoma); this cell line is hypomorphic for Dicer gene function. Dye-swap: no Negative control: siRNA luc Replicates per each timepoint: no
Project description:Cell cycle arrest in response to DNA damage is an important anti-tumorigenic mechanism. microRNAs (miRNAs) were shown recently to play key regulatory roles in cell cycle progression. For example, miR-34a is induced in response to p53 activation and mediates G1 arrest by down-regulating multiple cell cycle-related transcripts. Here we show that genotoxic stress promotes the p53-dependent up-regulation of the homologous miRNAs, miR -192 and miR-215. Like miR-34a, activation of miR-192/215 induces cell cycle arrest suggesting that multiple microRNA families operate in the p53 network. Furthermore, we define a downstream gene expression signature for miR-192/215 expression that includes a number of transcripts that regulate G1 and G2 checkpoints. Of these transcripts, 18 transcripts are direct targets of miR-192/215 and the observed cell cycle arrest likely results from a cooperative effect among the modulations of these genes by the miRNAs. Our results demonstrating a role for miR-192/215 in cell proliferation combined with recent observations that these miRNAs are under-expressed in primary cancers support the idea that miR-192 and miR-215 function as tumor-suppressors.