Project description:Malignant glioma is the most common type of primary brain tumor diagnosed annually in 16,000 individuals in the United States. We performed a systematic large-scale transcriptomics data mining study of 9,783 Affymetrix samples from the GeneSapiens database in order to identify those genes that are most glioma-specific as compared to other cancers and normal tissues. We searched for genes that are highly expressed in 322 glioblastoma multiforme tissue samples and 66 anaplastic astrocytomas as compared to 425 samples from histologically normal central nervous system. Transcription cofactor HES6 (Hairy and Enhancer of Split 6) emerged as one of the most glioma-specific genes. In immunostaining of a tissue microarray series, HES6 was expressed in 335 (98.8%) out of the 339 clinical glioma samples. Recurrent grade 2 astrocytomas and grade 2-3 oligodendrogliomas showed higher levels of HES6 immunoreactivity than the corresponding primary tumors. Functional studies implied a critical role for HES6 in supporting survival of glioma cells, as evidenced by 60% reduced cancer cell viability and induction of Caspase 3/7 activity after HES6 silencing by RNA interference in A172 and LN405 cells. The biological role and consequences of HES6 silencing and overexpression was explored with genome-wide analyses, which indicated a key role for HES6 in e.g. p53, c-myc, and NF-?B transcriptional networks. We conclude that HES6 has a critical role in sustaining glioma cell growth, survival, migration and possibly angiogenesis. HES6 is a potential therapeutic target and biomarker for glioma. A172 and LN405 cells (240 000 per well on 6-well plates) were transfected for 12-24 h with siHES6 pool, or three individual siRNAs (HES6_1, HES6_2, HES6_3 from Qiagen) or AllStars negative control siRNA (Qiagen) at 30 nM using SiLentFect (Bio-Rad Laboratories, Hercules, CA). One to two biological replicate transfections were performed. LN405 cells were also used for creating stable cell lines by transfecting either pEYFP-C1-mock or pEYFP-HES6 with Fugene6 (Roche) and selecting the positive cells with 600ug/ml of G418 (Sigma). The cells were kept in culture in the presence of 400ug/ml of G418. Total RNA was isolated with RNeasy (Qiagen) or MiRVana? Total RNA Isolation kit (Ambion). RNA quality was evaluated by using an Agilent 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA).

Project description:The basic helix-loop-helix factor Myod initiates skeletal muscle differentiation by directly and sequentially activating sets of muscle differentiation genes, including those encoding muscle contractile proteins. We hypothesize that Pbx homeodomain proteins direct Myod to a subset of its transcriptional targets, in particular fast twitch muscle differentiation genes, thereby regulating the competence of muscle precursor cells to differentiate. We have previously shown that Pbx proteins bind with Myod on the promoter of the zebrafish fast muscle gene mylpfa and that Pbx proteins are required for Myod to activate mylpfa expression and the fast-twitch muscle-specific differentiation program in zebrafish embryos. Here we have investigated the interactions of Pbx with another muscle fiber-type regulator, Prdm1a, a SET-domain DNA-binding factor that directly represses mylpfa expression and fast muscle differentiation. The prdm1a mutant phenotype, early and increased fast muscle differentiation, is the opposite of the Pbx-null phenotype, delayed and reduced fast muscle differentiation. To determine whether Pbx and Prdm1a have opposing activities on a common set of genes, we used RNA-seq analysis to globally assess gene expression in zebrafish embryos with single- and double-losses-of-function for Pbx and Prdm1a. We find that the levels of expression of certain fast muscle genes are increased or approximately wild type in pbx2/4-MO;prdm1a-/- embryos, suggesting that Pbx activity normally counters the repressive action of Prdm1a for a subset of the fast muscle program. However, other fast muscle genes require Pbx but are not regulated by Prdm1a. Thus, our findings reveal that subsets of the fast muscle program are differentially regulated by Pbx and Prdm1a. Our findings provide an example of how Pbx homeodomain proteins act in a balance with other transcription factors to regulate subsets of a cellular differentiation program. Total RNA samples were genotyped and pooled for 4 sample types: control-MO;prdm1+/+; control-MO;prdm1-/-; pbx2/4-MO;prdm1+/+; and pbx2/4-MO;prdm1-/- embryos at the 10 somite (s) stage from three independent sets of egg collections/injections.

Project description:Occupational exposure to crystalline silica results in serious health effects, most notably, silicosis and cancer. A proper understanding of the mechanism(s) underlying the initiation and progression of silica-induced pulmonary toxicity is critical for the intervention and/or prevention of the adverse health effects associated with crystalline silica exposure. Rats were exposed to crystalline silica by inhalation at a concentration of 15 mg/m3, 6 hours/day, 5 days/week for 3, 6 or 12 weeks. At the end of each exposure time point, toxicity and global gene expression changes were determined in the lungs. In general, silica exposure resulted in pulmonary toxicity that was dependent on the duration of silica exposure. A significant and silica exposure time-dependent increase in lactate dehydrogenase activity and accumulation of alveolar macrophages and infiltrating neutrophils in the bronchoalveolar lavage fluid suggested crystalline silica-induced pulmonary toxicity in the rats. Histological changes indicative of pulmonary toxicity were detectable only in the lungs of rats that were exposed to silica for 6- or 12-weeks. Minimal, sub-acute pulmonary inflammation consisting mainly of macrophage accumulation and infiltration of neutrophils was seen in 2 out of 8 rats in the 6-week silica exposure group. Chronic active inflammation, type II pneumocyte hyperplasia, and fibrosis were detected following 12-weeks of silica exposure in all rat lungs. In addition, crystalline silica was visible in the lungs of the rats belonging to the 12-week exposure group. A significant increase in the number of neutrophils seen in the blood indicated silica-induced systemic inflammation in the rats. Microarray analysis of the global gene expression profiles of the rat lungs detected significant differential expression (FDR p <0.05 and fold change >1.5) of 38, 77 and 99 genes in the rats exposed to silica for 3-, 6- and 12-weeks, respectively, compared to the time-matched controls. Bioinformatics analysis of the differentially expressed genes identified significant enrichment of functions, networks and pathways related to inflammation, cancer, oxidative stress, fibrosis and tissue remodeling in the lungs of the silica exposed rats. Collectively, the results of our study provided insights into the molecular mechanisms underlying pulmonary toxicity following sub-chronic exposure to silica in rats. 36 samples were analyzed in this experiment. 6 rats were exposed to crystalline silica by inhalation 15 mg/m3, 6 hours/day, 5 days, 3 weeks. 6 rats were exposed to crystalline silica by inhalation 15 mg/m3, 6 hours/day, 5 days, 6 weeks. 6 rats were exposed to crystalline silica by inhalation 15 mg/m3, 6 hours/day, 5 days, 12 weeks. 18 rats served as controls (6 for each 3 week, 6 week, and 12 week exposure) and were exposed to air during treatment times. Lung gene expression profiling was performed using RNA isolated from rat lung samples.

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