Project description:Small non-coding RNAs have emerged as key players in modulation of viral infection. A unique example is the critical dependence of hepatitis C virus (HCV) on the liver-specific microRNA (miRNA), miR-122, which has surfaced as therapeutic target. Here, we used crosslinking immunoprecipitation (CLIP) of the Argonaute (AGO) protein to characterize strengths and specificities of miRNA interactions across 15 viral genomes. Intriguingly, replication of pestiviruses, which are major threats to milk and meat industry, critically depends on cellular miR-17 and let-7 interactions with the viral 3âUTR. Like HCV, miRNA binding enhanced translation and prevented viral RNA degradation. On the cellular transcriptome, pestiviral miR-17 sequestration in vitro and ex vivo conferred reduced AGO binding and functional mRNA de-repression for miR-17 targets. These findings generalize the concept of RNA virus dependence on cellular miRNAs, highlight such interactions as therapeutic targets, and connect functional regulation of the transcriptome in primary cells to miRNA sequestration. Several subseries of analyses were performed. For each sample, subseries to which it belongs are indicated. In the âVirus AGO-CLIPâ subseries, AGO-CLIP was performed on cells infected with virus as indicated. Processed reads were aligned to the host genome (hg18 or BosTau7) and to the respective viral genome. The primary data of interest from this subseries concerns AGO binding to viral RNA, and is given as processed data file âTable S1â. In the âVirus AGO-CLIP: BVDV vs. Mockâ subseries, AGO-CLIP was performed on four replicates each of BVDV and mock infected MDBK cells. CLIP reads aligned to BosTau7 were clustered, and differential analysis was performed on binding to each cluster. In addition, differential analysis of AGO bound miRNAs was performed. The associated data is given as processed data file âTable S3 and S4â. In the âAGO-CLIP: tinyLNA-17 vs. Mockâ AGO-CLIP was performed on four replicates each of tinyLNA-17 and mock treated MDBK cells. CLIP reads aligned to BosTau7 were clustered, and differential analysis was performed on binding to each cluster. The associated data is given as processed data file âTable S5â. In the âRNA-seq: BVDV vs. Mockâ subseries, mRNA-seq was performed on two replicates each of MDBK cells infected with different biotypes of BVDV or with miR-17 seed site mutant BVDV. The latter (incl. mock controls) were trans-complemented with the corresponding mutated miR-17. Differential gene expression analysis was performed between selected conditions. The associated data is given as processed data file âTable S6â.
Project description:Background: DNA epigenetic modifications, such as methylation, are important regulators of tissue differentiation, contributing to processes of both development and cancer. Profiling the tissue-specific DNA methylome patterns will provide novel insights into normal and pathogenic mechanisms, as well as help in future epigenetic therapies. In this study, 17 somatic tissues from four autopsied humans were subjected to functional genome analysis using the Illumina Infinium HumanMethylation450 BeadChip, covering 486 428 CpG sites. Results: Only 2% of the CpGs analyzed are hypermethylated in all 17 tissue specimens; these permanently methylated CpG sites are located predominantly in gene-body regions. In contrast, 15% of the CpGs are hypomethylated in all specimens and are primarily located in regions proximal to transcription start sites. A vast number of tissue-specific differentially methylated regions are identified and considered likely mediators of tissue-specific gene regulatory mechanisms since the hypomethylated regions are closely related to known functions of the corresponding tissue. Finally, a clear inverse correlation is observed between promoter methylation within CpG islands and gene expression data obtained from publicly available databases. Conclusions: This genome-wide methylation profiling study identified tissue-specific differentially methylated regions in 17 human somatic tissues. Many of the genes corresponding to these differentially methylated regions contribute to tissue-specific functions. Future studies may use these data as a reference to identify markers of perturbed differentiation and disease-related pathogenic mechanisms.
Project description:Background: DNA epigenetic modifications, such as methylation, are important regulators of tissue differentiation, contributing to processes of both development and cancer. Profiling the tissue-specific DNA methylome patterns will provide novel insights into normal and pathogenic mechanisms, as well as help in future epigenetic therapies. In this study, 17 somatic tissues from four autopsied humans were subjected to functional genome analysis using the Illumina Infinium HumanMethylation450 BeadChip, covering 486 428 CpG sites. Results: Only 2% of the CpGs analyzed are hypermethylated in all 17 tissue specimens; these permanently methylated CpG sites are located predominantly in gene-body regions. In contrast, 15% of the CpGs are hypomethylated in all specimens and are primarily located in regions proximal to transcription start sites. A vast number of tissue-specific differentially methylated regions are identified and considered likely mediators of tissue-specific gene regulatory mechanisms since the hypomethylated regions are closely related to known functions of the corresponding tissue. Finally, a clear inverse correlation is observed between promoter methylation within CpG islands and gene expression data obtained from publicly available databases. Conclusions: This genome-wide methylation profiling study identified tissue-specific differentially methylated regions in 17 human somatic tissues. Many of the genes corresponding to these differentially methylated regions contribute to tissue-specific functions. Future studies may use these data as a reference to identify markers of perturbed differentiation and disease-related pathogenic mechanisms. DNA methylation analysis of the total 72 tissue samples and controls was performed with the Illumina Infinium HumanMethylation450 BeadChip. The 17 post-mortem human somatic tissues used in this study were collected at the time of autopsy. Controls for unmethylated and methylated DNA were represented, respectively, by whole-genome amplified DNA from subcutaneous adipose tissue (using the GenomiPhi DNA amplification kit; GE Healthcare, Piscataway, NJ, USA) and the universal methylated human DNA standard (Zymo Research). We had two technical and two biological replicates processed by chip technique.