RNA sequencing of blastocyst-stage mouse embryos in the presence or absence of RNA decay activator UPF2
Ontology highlight
ABSTRACT: Purpose: The goal of this study is to compare transcriptome profiles of whole blastocysts in the presence or absence of UPF2, via an approach optimized for low-input samples. Methods: Blastocyst mRNA profiles of wild-type (WT) and Upf2 knockout (Upf2−/−) mice were generated by deep sequencing, using Illumina 2500. The sequence reads that passed quality filters were analyzed at the transcript isoform level with DESeq2 and with IsoformSwitchAnalyzeR. Results: We identified transcripts targeted for decay by UPF2 and the NMD pathway in the blastocyst via multiple methods. We found that NMD regulates a cohort of RNAs involved in cell survival.
Project description:Nonsense-mediated decay (NMD) is an evolutionarily conserved surveillance mechanism that targets mRNAs undergoing premature translation termination for rapid degradation as well as normal physiological transcripts. From yeast to humans, NMD requires the function of three conserved Up-frameshift (Upf) factors (Upf1, Upf2, Upf3). Interestingly, in humans, mutations in UPF2 and UPF3B are associated with intellectual disability and autism spectrum disorder (ASD). However, the neurobiological mechanism by which deficient NMD leads to neurodevelopmental disorders remains unknown. Consequently, no treatment is currently available. Here we report that mice lacking Upf2 in the murine forebrain (Upf2 fb-KO mice) show endophenotypes associated with ASD and deficits in learning and memory. In addition, Upf2-mediated deficient NMD leads to abnormal long-term potentiation (LTP) in the hippocampus. Like patients with mutations in UPF2, Upf2 fb-KO mice showed neuroanatomical abnormalities including a smaller corpus callosum. Surprisingly, transcriptomic analysis revealed elevated mRNA expression of immune-related genes in the hippocampus of Upf2-fb-KO mice, which was accompanied by increased inflammation and progressive infiltration of peripheral immune cells. More importantly, treatment with an FDA-approved immunosuppressant, cyclophosphamide (CyP), significantly reduces brain inflammation, improves the neuroanatomical defects and the deficits in LTP and memory deficits, and reverses some of the ASD-like behaviors, notably the social deficits. Collectively, our results reveal the biological basis underlying neurodevelopmental disorders associated with dysfunctional NMD. Moreover, these findings suggest that immunosuppressant drugs, like CyP, may provide a new therapeutic approach for the treatment of patients with mutations in core NMD components.
Project description:Deletion of the NMD component UPF2 in fetal liver. Upf2flox/+ females were mated to Upf2flox/+; Alfp-Cre males. Fetal livers were isolated from Upf2+/+; Alfp-Cre (WT) and Upf2flox/flox; AlfpCre (UPF2 null) E16.5 and E18.5 embryos.
Project description:Over one million cases of gastric cancer are diagnosed each year and metastatic disease continues to have a poor prognosis. A significant proportion of gastric tumors have defects in the DNA damage response pathway creating therapeutic opportunities through synthetic lethal approaches. In particular, several small molecule inhibitors of Ataxia-Telangiectasia Mutated and Rad3-related protein kinase (ATR), a key regulator of the DNA Damage response, are now in clinical development as targeted agents for gastric cancer. Here, we sought to discover genetic determinants of response and resistance to ATRi in gastric cancer cells. We performed a large-scale CRISPR interference screen to discover determinants of resistance to ATRi in gastric cancer. Top hits were validated and further evaluated to define mechanisms of resistance. We identified components of the nonsense-mediated decay pathway and the UPF2 gene, in particular, as mediators of sensitivity to ATRi. We show loss of UPF2 causes resistance to ATRi through the abrogation of ATRi mediated cell cycle arrest and find evidence that UPF2 regulates R-loops. Our results uncover a novel role for NMD factors in R-loop formation and resistance to ATRi in gastric cancer cells, potentially through R-loop formation.
Project description:Purpose: Probe the transcriptome-wide changes in the expression pattern between WT and Sertoli-specific Upf2 KO testes Methods: Total RNA were extracted from WT and Sertoli-specific Upf2 KO testes in triplicates and subject to deep-sequencing in Ion Torrent seq platform. Results: Using an optimized data analysis workflow, we mapped about 30 million sequence reads per sample to the mouse genome (build mm9) and identified 16,014 transcripts in the retinas of WT and Nrl−/− mice with BWA workflow and 34,115 transcripts with TopHat workflow. RNA-seq data confirmed stable expression of 25 known housekeeping genes, and 12 of these were validated with qRT–PCR. RNA-seq data had a linear relationship with qRT–PCR for more than four orders of magnitude and a goodness of fit (R2) of 0.8798. Approximately 10% of the transcripts showed differential expression between the WT and Nrl−/− retina, with a fold change ≥1.5 and p value <0.05. Altered expression of 25 genes was confirmed with qRT–PCR, demonstrating the high degree of sensitivity of the RNA-seq method. Hierarchical clustering of differentially expressed genes uncovered several as yet uncharacterized genes that may contribute to retinal function. Data analysis with BWA and TopHat workflows revealed a significant overlap yet provided complementary insights in transcriptome profiling. Conclusions: Our study represents the first detailed analysis of Upf2-mediated NMD pathway in Sertoli cell development
Project description:Eukaryotic cells have evolved a mechanism called nonsense mediated mRNA decay (NMD) that detects and degrades aberrant mRNAs that contain premature termination codons (PTCs). NMD has recently acquired broader importance as it has been found to regulate not only aberrant mRNAs but also a great diversity of transcripts, including wild type genes in mammals, Drosophila and yeast. Seven proteins are the core of the NMD complex: SMG1, SMG2 (UPF1), SMG3 (UPF2), SMG4 (UPF3), SMG5, SMG6 and SMG7. Plants have orthologues of most of these proteins. We have identified and characterized a number of alleles of UPF1, UPF3 and SMG5 and made 35S:UPF2 RNAi (upf2i) transgenic plants, all of which share some phenotypic characteristics. Transcriptome analysis of upf1 and upf3 mutants has identified a subset of genes coregulated by UPF1 and UPF3 and, therefore, by NMD (unpublished data). By doing further transcriptome analysis on smg5 mutants and upf2i plants we aim to build a more robust subset of NMD targets in Arabidopsis. RNA will be extracted from 17 day-old mutant, transgenic and wild type seedlings grown at 22-24 C under constant light.
Project description:This report not only adds a novel mechanism to the current dogma on achieving global shortening of 3'UTRs, but also unveils a novel function of the NMD pathway in establishing tissue-specific transcriptome identity We first generated prospermatogonia-specific Upf2 conditional knockout mice (Ddx4-Cre; Upf2 fl/Δ, hereafter called Ddx4-KO) by crossing Ddx4-Cre13 with Upf2 floxed.
Project description:Purpose: Probe the transcriptome-wide changes in the expression pattern between WT and Sertoli-specific Upf2 KO testes Methods: Total RNA were extracted from WT and Sertoli-specific Upf2 KO testes in triplicates and subject to deep-sequencing in Ion Torrent seq platform. Results: Using an optimized data analysis workflow, we mapped about 30 million sequence reads per sample to the mouse genome (build mm9) and identified 16,014 transcripts in the retinas of WT and Nrl−/− mice with BWA workflow and 34,115 transcripts with TopHat workflow. RNA-seq data confirmed stable expression of 25 known housekeeping genes, and 12 of these were validated with qRT–PCR. RNA-seq data had a linear relationship with qRT–PCR for more than four orders of magnitude and a goodness of fit (R2) of 0.8798. Approximately 10% of the transcripts showed differential expression between the WT and Nrl−/− retina, with a fold change ≥1.5 and p value <0.05. Altered expression of 25 genes was confirmed with qRT–PCR, demonstrating the high degree of sensitivity of the RNA-seq method. Hierarchical clustering of differentially expressed genes uncovered several as yet uncharacterized genes that may contribute to retinal function. Data analysis with BWA and TopHat workflows revealed a significant overlap yet provided complementary insights in transcriptome profiling. Conclusions: Our study represents the first detailed analysis of Upf2-mediated NMD pathway in Sertoli cell development Testis mRNA profiling was generated from postnatal day 4 WT and Amh-cKO (Sertoli specific Upf2 KO) testes, in triplicates.
Project description:Eukaryotic cells have evolved a mechanism called nonsense mediated mRNA decay (NMD) that detects and degrades aberrant mRNAs that contain premature termination codons (PTCs). NMD has recently acquired broader importance as it has been found to regulate not only aberrant mRNAs but also a great diversity of transcripts, including wild type genes in mammals, Drosophila and yeast. Seven proteins are the core of the NMD complex: SMG1, SMG2 (UPF1), SMG3 (UPF2), SMG4 (UPF3), SMG5, SMG6 and SMG7. Plants have orthologues of most of these proteins. We have identified and characterized a number of alleles of UPF1, UPF3 and SMG5 and made 35S:UPF2 RNAi (upf2i) transgenic plants, all of which share some phenotypic characteristics. Transcriptome analysis of upf1 and upf3 mutants has identified a subset of genes coregulated by UPF1 and UPF3 and, therefore, by NMD (unpublished data). By doing further transcriptome analysis on smg5 mutants and upf2i plants we aim to build a more robust subset of NMD targets in Arabidopsis. RNA will be extracted from 17 day-old mutant, transgenic and wild type seedlings grown at 22-24 C under constant light. 6 samples were used in this experiment
Project description:Nonsense-mediated mRNA decay (NMD) is a conserved co-translational mRNA surveillance and turnover pathway across eukaryotes. NMD has a central role in degrading defective mRNAs and also regulates the stability of a significant portion of the transcriptome. The pathway is organized around UPF1, an RNA helicase that can interact with several NMD-specific factors. In human cells, degradation of the targeted mRNAs begins with a cleavage event that requires the recruitment of the SMG6 endonuclease to UPF1. Previous studies have identified functional links between SMG6 and UPF1, but the underlying molecular mechanisms have remained elusive. In this work, we used mass spectrometry, structural biology and biochemical approaches to identify and characterize a conserved short linear motif in SMG6 that interacts with the cysteine/histidine-rich (CH) domain of UPF1. Unexpectedly, we found that the UPF1-SMG6 interaction is precluded when the UPF1 CH domain is engaged with another NMD factor, UPF2. Based on cryo-EM data, we propose that the formation of distinct SMG6-containing and UPF2-containing NMD complexes may be dictated by the RNA-binding status of UPF1. Our findings rationalize a key event in the metazoan NMD quality control pathway and progress our understanding of mechanisms regulating activity and guiding substrate recognition by the SMG6 endonuclease.