Project description:Fragile X syndrome (FXS) is caused by inactivation of FMR1 gene and loss of its encoded product the RNA binding protein FMRP, which generally represses translation of its target transcripts in the brain. In mouse models of FXS (i.e., Fmr1 knockout animals; Fmr1 KO), deletion of Cpeb1, which encodes a translational activator, mitigates nearly all pathophysiologies associated with the disorder. Here we reveal unexpected wide-spread dys-regulation of RNA abundance in Fmr1 KO brain cortex and its rescue to normal levels in Fmr1/Cpeb1 double KO mice. Alteration and restoration of RNA levels are the dominant molecular events that drive the observed dys-regulation and rescue of translation as measured by whole transcriptome ribosome occupany in the brain. The RNAs down-regulated and rescued in these animal models are highly enriched for FMRP binding targets and have an optimal codon bias that would predict their stability in wild type and possible instability in FMRP knock-out brain. These results leads to a further study to profile RNA metabolism rates in Fragile X neurons.
Project description:Dysregulated protein synthesis is a major underlying cause of many neurodevelopmental diseases such as Fragile X Syndrome. A very robust technique is required to capture subtle but biologically significant differences in neurological disorders. Ribosome profiling, which is based on deep sequencing of mRNA fragments protected from ribonuclease digestion by ribosomes, is a powerful tool to study translational control. However, it has been mainly applied to rapidly dividing cells where translation is robust and where large amounts of starting material are readily available. The application of ribosome profiling to low-input brain tissue where translation is modest and where gene expression changes between genotypes are expected to be small has not been carefully evaluated. Using hippocampal tissue from wide type and fragile X mental retardation 1 (Fmr1) knockout mice, we show that variable RNase digestion can lead to significant sample batch effects. We also establish GC content and ribosome footprint length as quality control metrics for ribonuclease digestion. We performed ribonuclease titration experiments for low-input samples to identify optimal conditions for this critical step that is often improperly conducted. Our data reveal that optimal RNase digestion is essential to ensure high quality and reproducibility of ribosome profiling especially for low-input brain tissue.
Project description:Fragile X syndrome (FXS) is caused by inactivation of FMR1 gene and loss of its encoded product the RNA binding protein FMRP, which generally represses translation of its target transcripts in the brain. In mouse models of FXS (i.e., Fmr1 knockout animals; Fmr1 KO), deletion of Cpeb1, which encodes a translational activator, mitigates nearly all pathophysiologies associated with the disorder. We have observed that the wide-spread dys-regulation of RNA abundance in Fmr1 KO brain cortex and its rescue to normal levels in Fmr1/Cpeb1 double KO mice were the driver of the observed dys-regulation and rescue of translation as measured by whole transcriptome ribosome occupany in the brain. We hypothesize that in Fragile X brain there is wide spread dys-regulation at RNA stability level. Here we test this hypothesis by profiling RNA synthesis, processing and degradation rates in Fragile X and wild type neurons, by taking advantage of short 5-EU labeling and computational modeling. We show that, while RNA synthesis and processing rates were barely changed, there is wide-spread evelated RNA degradation rates in the Fragile X neurons, particularly for genes using optimal codons.
Project description:N6-Methyladenosine (m6A) and N6,2′-O-dimethyladenosine (m6Am) are abundant mRNA modifications that regulate transcript processing and translation. The role of both, here termed m6A/m, in the stress response in the adult brain in vivo are currently unknown. Here, we provide ribosome profiling data of 10-12 w male C57BL/6 mouse cortex of unstressed or acutely stressed mice (4 h after 15 min restraint stress) of 6 samples per condition to relate to m6A/m-Seq data of similiar samples.
Project description:Fragile X syndrome (FXS), the leading cause of inherited form of mental retardation and autism, is caused by the transcriptional silencing of fmr1 encoding the protein of FMRP. FMRP, acting as an RNA binding protein, FMRP is a wide expressed protein, but primarily in the brain and testis and can regulate approximately 4% of transcripts. Macroorchidism is one of the common symptoms observed both in the FXS people and mice. Thus, we analyzed the protein profiles of cerebral cortex, hippocampus and testis from both the fmr1-KO and WT mouse using a quantitative proteomics. Proteins (FMRP, RS8, RL23A and MPZ) identified by MS/MS were also verified by Western blot. Among the identified proteins, most of the significant changed proteins were downregulated in the FMRP absence. The Gene Ontology and pathway analysis revealed that the changed proteins were clustered in polyribosome and RNA binding proteins in both cerebral cortex and hippocampus, but not the same in testis. Our results provide detailed insights to the ribosome protein profiles of cerebral cortex, hippocampus and testis in the absence of FMRP. Our studies also give a better understanding of protein profile changes and underling dysregulated pathways arising from the fmr1 silencing in the FXS.
Project description:We perform Ribosome Profiling (Ribo-seq) analysis of mouse brain neocortex during development embyonic days 12.5, 14, 15.5, 17, and postnatal day 0 in biological duplicate
Project description:This SuperSeries is composed of the following subset Series:; GSE9788: Gene expression analysis of brain cortex of reserpine-treated rats; GSE9789: Gene expression analysis of brain cortex of olfactory-bulbectomized rats; GSE9797: Gene expression analysis of brain cortex of corticosterone-treated rats Experiment Overall Design: Refer to individual Series