Project description:Characterizing the impact of pharmacological and shRNA-mediated silencing of EAG2 in medulloblastoma. Medulloblastoma (MB) is the most common pediatric CNS malignancy. Previously, we demonstrated that overexpression of the ion channel EAG2, identified in a subset of histological and molecular subtypes of this disease, functionally contributes to tumor progression (PMID: 22855790). Here, we demonstrate the evolutionarily conserved function of EAG2 potassium channel in promoting brain tumor growth and metastasis, delineate downstream pathways and uncover a co-option mechanism for different potassium channels to regulate mitotic cell volume and tumor progression. We show that EAG2 potassium channel is enriched at the trailing edge of migrating MB cells to regulate local cell volume dynamics, thereby facilitating cell motility. We identify the FDA- approved antipsychotic drug thioridazine as an EAG2 channel blocker that reduces xenografted MB growth and metastasis, and present a case report of repurposing thioridazine for treating a human patient. Our findings thus illustrate the potential of targeting ion channels in cancer treatment.
Project description:miRNAs are small, non-coding RNAs that regulate gene expression post-transcriptionally. We used small RNA sequencing to identify tissue-specific miRNAs in the adult brain, thorax, gut and fat body of Drosophila melanogaster. One of the most brain-specific miRNAs that we identified was miR-210, an evolutionarily highly conserved miRNA implicated in the regulation of hypoxia in mammals. In Drosophila, we show that miR-210 is specifically expressed in sensory organs including photoreceptors. miR-210 knock-out mutants are not sensitive towards hypoxia but show progressive degradation of photoreceptor cells, accompanied by decreased photoreceptor potential, demonstrating an important function of miR-210 in photoreceptor maintenance and survival.
Project description:Polycomb group (PcG) proteins are evolutionarily conserved epigenetic regulators that mediate histone modifications and suppress target gene expression, therefore establish and maintain cellular memory during development1-3. Deregulation of PcG genes is associated with various human cancers, but the mechanisms are incompletely understood4. Polyhomeotic (Ph), one of the Drosophila PcG proteins, can act as a tumor suppressor in larval imaginal discs5, 6. Cells mutant for ph overgrow and give rise to neoplastic tumors during larval development6. Here we report an intrinsic tumor-suppression mechanism mediated by the steroid hormone ecdysone in Drosophila. During metamorphosis, ecdysone transforms tumorigenic ph mutant cells into non-tumorigenic cells, thereby suppressing the malignant growth in adult flies. We demonstrate ecdysone exerts its function by inducing the expression of microRNA lethal-7 (let-7), which suppresses its target gene chinmo, to inhibit the tumorigenic growth of ph mutant cells. Furthermore, we show let-7 can also suppress the overgrowth of brain tumors in brain tumor (brat) mutant flies, indicating this intrinsic mechanism is functional in different tissues to suppress neoplastic growth. As let-7 is highly conserved among metazoans, our findings will be relevant for mechanistic studies and therapeutic applications in human cancers.
Project description:Transcriptional profiling of developmentally staged D. mel. Embryos for three genotypes: wild type, eve3 and ftz11 For additional information, please see Liu et al., 2009. Abstract: We constructed a large-scale functional network model in Drosophila melanogaster built around two key transcription factors involved in the process of embryonic segmentation. Analysis of the model allowed the identification of a new role for the ubiquitin E3 ligase complex factor SPOP. In Drosophila, the gene encoding SPOP is a target of segmentation transcription factors. Drosophila SPOP mediates degradation of the Jun-kinase phosphatase Puckered thereby inducing TNF/Eiger dependent apoptosis. In humans we found that SPOP plays a conserved role in TNF-mediated JNK signaling and was highly expressed in 99% of clear cell renal cell carcinoma (RCC), the most prevalent form of kidney cancer. SPOP expression distinguished histological subtypes of RCC and facilitated identification of clear cell RCC as the primary tumor for metastatic lesions. Keywords: 2 channel transcription timecourse
Project description:Transcriptional profiling of developmentally staged D. mel. Embryos for three genotypes: wild type, eve3 and ftz11 For additional information, please see Liu et al., 2009. Abstract: We constructed a large-scale functional network model in Drosophila melanogaster built around two key transcription factors involved in the process of embryonic segmentation. Analysis of the model allowed the identification of a new role for the ubiquitin E3 ligase complex factor SPOP. In Drosophila, the gene encoding SPOP is a target of segmentation transcription factors. Drosophila SPOP mediates degradation of the Jun-kinase phosphatase Puckered thereby inducing TNF/Eiger dependent apoptosis. In humans we found that SPOP plays a conserved role in TNF-mediated JNK signaling and was highly expressed in 99% of clear cell renal cell carcinoma (RCC), the most prevalent form of kidney cancer. SPOP expression distinguished histological subtypes of RCC and facilitated identification of clear cell RCC as the primary tumor for metastatic lesions. Keywords: 2 channel transcription timecourse Developmental timecourse, 3 genotypes, experimental sample vs. common reference.
Project description:This project aimed to identify proteins copurifying with the Kv2.1 potassium channel from lysates prepared from crosslinked mouse brain homogenates. Comparison samples were prepared from Kv2.1 knockout mouse brains. Parallel immunopurifications were perfofmed for the unrelated Kv1.2 potassium channel.
Project description:Stable Binding of the Conserved Transcription Factor Grainy Head to Its Target Genes Throughout Drosophila melanogaster Development