Project description:Long non-coding RNAs (lncRNAs) play fundamental roles in cellular processes and pathologies, regulating gene expression at multiple levels. Despite being highly cell-type specific, their study at single-cell level has been challenging due to their less accurate annotation and low expression. Here, we show that single-cell RNA-seq (scRNA-seq) preprocessing workflows using the pseudoaligner Kallisto enhance the detection and quantification of lncRNAs. Further, using single-cell multiome data, we demonstrate that the ATAC-seq profiles exhibit higher concordance when the scRNA-seq is processed by Kallisto. We then experimentally confirmed the expression patterns of cell-type specific lncRNAs exclusively detected by Kallisto and unveiled biologically relevant lncRNAs, such as AL121895.1, a previously undocumented cis-repressor lncRNA, whose role in proliferation of breast cancer cells was detected by Kallisto and overlooked by other pipelines. Our results emphasize the necessity for an alternative scRNA-seq preprocessing workflow tailored to lncRNAs that sheds light on the multifaceted roles of lncRNAs.
Project description:Small, compact genomes confer a selective advantage to viruses, yet human cytomegalovirus (HCMV) expresses the long non-coding RNAs (lncRNAs) RNA1.2, RNA2.7, RNA4.9, and RNA5.0. These lncRNAs account for majority of the viral transcriptome, but their functions remain largely unknown. Here, we showed that HCMV lncRNAs, except for RNA5.0, are required throughout the entire viral life cycle. Deletion of each lncRNA resulted in a decrease in viral progeny during lytic replication and failing to efficiently establish latent reservoirs and reactivate. Nanopore direct RNA sequencing of native lncRNA molecules revealed that each lncRNA exhibited a dynamic modification landscape, depending on the state of infection. Global analysis of the lncRNA interactome identified 32, 11, and 89 host factors that specifically bind to RNA1.2, RNA2.7, and RNA4.9, respectively. Moreover, 52 proteins commonly bound to the three lncRNAs were identified, including 11 antiviral immunity-related proteins. Our molecular analyses found that three lncRNAs are modified with N⁶-methyladenosine (m6A) and interact with m6A readers in all infection states. In-depth functional analysis revealed that m6A–mediated lncRNA stabilization as the key mechanism by which lncRNAs are maintained at high levels. Our study lays the groundwork for understanding viral lncRNA–mediated regulation of host-virus interaction throughout the HCMV life cycle.
Project description:A vast portion of the mammalian genome is transcribed as long non-coding RNAs (lncRNAs) acting in the cytoplasm with largely unknown functions. Surprisingly, lncRNAs have been shown to interact with ribosomes, encode uncharacterized proteins, or act as ribosome sponges. These functions still remain mostly undetected and understudied owing to the lack of efficient tools for genome-wide simultaneous identification of ribosome-associated lncRNAs and peptide-producing lncRNAs. Here we present AHARIBO, a method for the detection of lncRNAs either untranslated, but associated with ribosomes, or encoding small peptides. Using AHARIBO in mouse embryonic stem cells during neuronal differentiation, we isolated ribosome-protected RNA fragments, translated RNAs and corresponding de novo synthesized polypeptides. Besides identifying mRNAs under active translation and associated ribosomes, we found and distinguished lncRNAs acting as ribosome sponges or encoding micropeptides, laying the ground for a better functional understanding of hundreds lncRNAs.
Project description:Functional studies of long noncoding RNAs (lncRNAs) have long been hindered by a lack of methods to assess their evolution. Here, we present lncHOME (lncRNA Homology Explorer), a computational pipeline that identifies a unique coPARSE-lncRNA class with conserved genomic locations and patterns of RNA binding protein (RBP) binding sites. Remarkably, several hundred human coPARSE-lncRNAs can be evolutionarily traced to zebrafish. Using CRISPR-Cas12a knockout and rescue assays, we found that knocking out many human coPARSE-lncRNAs led to cell proliferation defects that were rescued by predicted zebrafish homologs. Knocking down the coPARSE-lncRNAs in zebrafish embryos caused severe developmental delays that were rescued by human homologs. Moreover, we verified that human, mouse, and zebrafish coPARSE-lncRNA homologs tend to bind similar RBPs with their conserved fuctions relying on specific RBP binding sites. Overall, our study demonstrates a comprehensive approach for studying functional conservation of lncRNAs and implicates numerous lncRNAs in regulating cellular physiology.
Project description:The adaptive limb of the immune system consists of antibody producing B cells and CD4 T helper and CD8 cytotoxic T cells. Besides these classical lymphocyte subsets, unconventional T cells exist that are characterized by a more limited repertoire of their TCR chains. Gamma delta (gd), mucosal-associated invariant (MAIT) and natural killer T cells (NKT) are the major cell types comprising this invariant T cell compartment. These cells are found throughout the body in the non- and lymphoid tissues and they recognize antigens that are linked to non-polymorphic antigen-presenting molecules like CD1 and MR1. Functionally, these cells typically recognize lipids, small-molecule metabolites and phosphoantigens that may be pathogen-derived or expressed by tissues in the context of activation or stress responses. Investigating these cell types on functional level as a group, we found that tissue-derived unconventional T cells constantly migrate like dendritic cells to draining lymph nodes. scRNAseq revealed transcriptional homogeneity of these subsets and shared functional outputs that as group, rather than separate entities, are critical to control bacterial infections. Importantly, since every tissue harbors a unique set of invariant T cells with specific differentiation states (Th1-like, Th2-like and Th17-like) every draining lymph node is as well populated by a unique composition of such cells. By comparing different lymph nodes using scRNA in an unbiased manner, we could resolve internodal differences and further demonstrate the functional consequences on humoral and cellular immune responses. The discovery that every lymph node mounts a unique immune response has a direct impact on vaccination strategies and immunotherapy approaches that aims at harnessing invariant T cells.
Project description:BLaER1 cells are human leukemia pre-B cells able to transdifferentiate into functional and non-tumorigenic macrophages. With the goal of uncovering the genes involved in the transdifferentiation process, we have designed a DECKO (Double Excision CRISPR Knockout) library to knockout lncRNAs and protein coding genes (pc-genes) overexpressed along the seven days the process lasts. We have seen that targeting pc-genes with two gRNAs synergistically enhances the efficiency of knock out, by inducing deletions and/or frameshifts that promote the expression of non-functional proteins. Thus, using the CRISPETa tool, we designed paired guide RNAs targeting either the region surrounding the Transcription Start Site of the 166 lncRNAs or the coding exons of the 874 pc candidate genes. Cas9-expressing BLaER1 cells were infected at low-multiplicity of infection with the combined library and induced transdifferentiation. Delayed and differentiated subpopulations of cells were isolated by Fluorescence-Activated Cell Sorting at 3 days and 6 days after induction, and pgRNAs were sequenced in an Illumina HiSeq2500 instrument. The sequencing reads were mapped and quantified to uncover the enriched pgRNAs found in each subpopulation. Among all genes targeted in the library, we identified twenty pc-genes and six lncRNAs as strong candidates to be involved in the process, as the pgRNAs targeting their loci were enriched in the delayed population compared to the differentiated one, either at 3 days or at 6 days after transdifferentiation induction. From these, we selected two pc-genes and two lncRNAs for deeper characterization.
Project description:The experiments were designed to gain insight into the gene expression of conventional and unconventional murine T cell subsets in the steady state and upon activation TCRαβ and TCRγδ intraepithelial lymphocytes (IEL) isolated from murine gut, naïve and virus-induced memory splenocytes, activated dendritic epidermal T cells (DETC)
Project description:Long noncoding RNA sequences evolve relatively rapidly, but it is unclear whether this is due to relaxed constraint or accelerated evolution. Here, we trace the recent evolutionary history of human lncRNAs, using genomes of multiple individuals from all great ape species to map fixed lineage-specific nucleotide variants. We find that the lower conservation of lncRNAs compared to protein coding genes partially arises from lncRNA’s more recent evolutionary origin. We identify more than one hundred lncRNAs that show some evidence of accelerated evolution in at least one primate species, including 17 in human. Several of these display transcriptional regulatory activity in an RNA-specific reporter assay. By experimentally reconstructing the ancestral lncRNA sequence, we find that this activity has been altered by human-specific nucleotide substitutions. Functional analysis of accelerated lncRNAs with specific expression in blood suggests lncRNAs have participated in adaptive regulatory changes in the immune system during recent human evolution. Together our results provide evidence that accelerated evolution of lncRNAs may have contributed, through regulatory changes, to human-specific phenotypes.
Project description:Background and Purpose: Long noncoding RNAs (lncRNAs) are an emerging class of genomic regulatory molecules reported in neurodevelopment and many diseases. Despite extensive studies have identified lncRNAs and discovered their functions in CNS diseases, the function of lncRNAs in ischemia stroke remains poorly understood. Method: Ischemia was induced by transient middle cerebral artery occlusion. Expression profiles of lncRNAs, miRNAs and mRNAs after ischemia stroke were obtained using high throughput sequencing technology. A correlation network was constructed to predict lncRNA functions. LncRNA-miRNA-mRNA network was constructed to discover ceRNAs. Results: 1924 novel lncRNAs were identified, indicating that the ischemia stroke has a complex effect on lncRNAs. The top 10 regulated lncRNAs was validated by qRT-PCR. We have also predicted function of lncRNAs, and subjected them to gene co-expression network analysis, revealing the involvement of lncRNAs in many important biological process including injury and repair that are implicated in the regulation of ischemia stroke. Furthermore, lncRNAs mediated SMD (Staufen1-mediated mRNA decay) was analyzed and ceRNA (competitive endogenous RNAs) network was constructed in ischemia stroke. Conclusions: This study reports the genome-wide lncRNA profiles in ischemia stroke using high throughput sequencing and constructs a systematic lncRNA-miRNA-mRNA network which reveals a complex functional noncoding RNA regulatory network in ischemia stroke.