Project description:High-throughput small RNA sequencing (sRNA-seq) has facilitated many discoveries, but extracellular sRNA (ExRNA) present unique analytical challenges that are not met by current software. Therefore, we developed a novel data analysis pipeline entitled, “TIGER”, which caters to exRNA. To demonstrate the power of this tool, sRNA-seq was performed on high-density lipoproteins (HDL), apolipoprotein B particles (APOB), bile, urine, and liver samples. TIGER was able to characterize approximately 60% of lipoprotein, and >85% of liver, bile, and urine sRNA-seq depth, a significant advance compared to existing software. A key advance for the TIGER pipeline is the ability to analyze host and non-host sRNAs at genomic, parent RNA, and individual fragment levels. Results suggest that the majority of sRNAs on lipoproteins are derived from bacterial sources in the microbiome and environment. Collectively, TIGER facilitated novel discoveries of lipoprotein and biofluid sRNAs and has tremendous applicability for the field of exRNA.
Project description:Background: Cytoplasmic degradation of endogenous RNAs is an integral part of RNA quality control (RQC) and often relies on the removal of the 5' cap structure and their subsequent 5M-bM-^@M-^Y to 3M-bM-^@M-^Y degradation. In parallel, many eukaryotes degrade exogenous and selected endogenous RNAs through post-transcriptional gene silencing (PTGS). In plants, PTGS depends on small interfering (si)RNAs produced after the conversion of single-stranded RNAs to double-stranded RNAs by the cellular RNA DEPENDENT RNA POLYMERASE 6 (RDR6). PTGS and RQC compete for transgene-derived RNAs, but it is unknown whether this competition also occurs for endogenous transcripts. Results: We show that that upon decapping impairment hundreds of endogenous mRNAs give rise to a new class of siRNAs, a subset of which depends on RDR6 for their production. Conclusions: Our results suggest that the decapping of aberrant endogenous RNA in P-bodies limits their entry into the PTGS pathway and prevents the subsequent deleterious consequences arising from this entry. We anticipate that the siRNAs identified in decapping mutants represent a subset of a larger ensemble of endogenous siRNAs that we coin rqc-siRNAs because they accumulate when RQC processes are impaired. Small RNA-seq experiments performed in duplicates for each condition.
Project description:Study of high-density lipoproteins using 6 human plasma samples. The study sought to find small RNA signatures in systemic erythematosus lupus.
Project description:Background: Cytoplasmic degradation of endogenous RNAs is an integral part of RNA quality control (RQC) and often relies on the removal of the 5' cap structure and their subsequent 5’ to 3’ degradation. In parallel, many eukaryotes degrade exogenous and selected endogenous RNAs through post-transcriptional gene silencing (PTGS). In plants, PTGS depends on small interfering (si)RNAs produced after the conversion of single-stranded RNAs to double-stranded RNAs by the cellular RNA DEPENDENT RNA POLYMERASE 6 (RDR6). PTGS and RQC compete for transgene-derived RNAs, but it is unknown whether this competition also occurs for endogenous transcripts. Results: We show that that upon decapping impairment hundreds of endogenous mRNAs give rise to a new class of siRNAs, a subset of which depends on RDR6 for their production. Conclusions: Our results suggest that the decapping of aberrant endogenous RNA in P-bodies limits their entry into the PTGS pathway and prevents the subsequent deleterious consequences arising from this entry. We anticipate that the siRNAs identified in decapping mutants represent a subset of a larger ensemble of endogenous siRNAs that we coin rqc-siRNAs because they accumulate when RQC processes are impaired.
Project description:To explore the potential functions of exogenous RNAs in circulation, we transfected several synthetic, double-stranded mature microRNA-like molecules selected from observed exogenous miRNA sequences and some highly abundant exogenous sequences (bacterial rRNAs) that have potential to form pre-miRNA-like secondary structures into a mouse, Dicer-deficient, fibroblast cell line. This provides a good tool for studying the function of miRNAs. By introducing individual miRNA into these cells and avoiding multiple interactions of microRNA and mRNA (Wang et al in preparation) it is possible to interrogate the cells for mRNA levels, which are informative as to specific miRNA function.
Project description:Genome stability relies on epigenetic mechanisms that enforce repression of endogenous retroviruses (ERVs). Current evidence suggests that distinct chromatin-based mechanisms repress ERVs in cells of embryonic origin (histone methylation-dominant) versus more differentiated cells (DNA methylation-dominant). However, the latter aspect of this model has not been tested. Remarkably, and in contrast to the prevailing model, we find that repressive histone methylation catalyzed by the enzyme SETDB1 is critical for suppression of specific ERV families and exogenous retroviruses in committed B-lineage cells from adult mice. The profile of ERV activation in SETDB1-deficient B cells is distinct from that observed in corresponding embryonic tissues, despite the loss of repressive chromatin modifications at all ERVs. We provide evidence that, upon loss of SETDB1, ERVs are activated in a lineage-specific manner depending on the set of transcription factors available to target proviral regulatory elements. These findings have important implications for genome stability in somatic cells, as well as the interface between epigenetic repression and viral latency. Expression profiling and bisulfite PCR sequencing in Setdb1 C/C and Setdb1 D/D pro-B cells
Project description:Genome stability relies on epigenetic mechanisms that enforce repression of endogenous retroviruses (ERVs). Current evidence suggests that distinct chromatin-based mechanisms repress ERVs in cells of embryonic origin (histone methylation-dominant) versus more differentiated cells (DNA methylation-dominant). However, the latter aspect of this model has not been tested. Remarkably, and in contrast to the prevailing model, we find that repressive histone methylation catalyzed by the enzyme SETDB1 is critical for suppression of specific ERV families and exogenous retroviruses in committed B-lineage cells from adult mice. The profile of ERV activation in SETDB1-deficient B cells is distinct from that observed in corresponding embryonic tissues, despite the loss of repressive chromatin modifications at all ERVs. We provide evidence that, upon loss of SETDB1, ERVs are activated in a lineage-specific manner depending on the set of transcription factors available to target proviral regulatory elements. These findings have important implications for genome stability in somatic cells, as well as the interface between epigenetic repression and viral latency.