Project description:This is a continuation of the Chordoma Sequencing Project. All cancers arise due to somatically acquired abnormalities in DNA sequence. Systematic sequencing of cancer genomes allows acquisition of complete catalogues of all classes of somatic mutation present in cancer. These mutation catalogues will allow identification of the somatically mutated cancer genes that are operative and characterise patterns of somatic mutation that may reflect previous exogenous and endogenous mutagenic exposures. In this application, we aim to perform whole genome sequencing on 10 chordoma matched genome pairs. RNA Sequencing/Methylation and SNP6 and an additional sequencing of three cancer cell lines will be added to this work.
Project description:Background: Canonical Nonsense Mediated Decay (NMD) is an important splicing-dependent process for mRNA surveillance in mammals. However, processed pseudogenes are not able to trigger NMD due to their lack of introns. It is largely unknown whether they have evolved other surveillance mechanisms. Results: Here, we find that the RNAs of pseudogenes, especially processed pseudogenes, have dramatically higher m6A levels than their cognate protein-coding genes, associated with de novo m6A peaks and motifs in human cells. Furthermore, pseudogenes have rapidly accumulated m6A motifs during evolution. The m6A sites of pseudogenes are evolutionarily younger than neutral sites and their m6A levels are increasing, supporting the idea that m6A on the RNAs of pseudogenes is under positive selection. We then find that the m6A RNA modification of processed, rather than unprocessed, pseudogenes promotes cytosolic RNA degradation and attenuates interference with the RNAs of their cognate protein-coding genes. We experimentally validate the m6A RNA modification of two processed pseudogenes, DSTNP2 and NAP1L4P1, which promotes the RNA degradation of both pseudogenes and their cognate protein-coding genes DSTN and NAP1L4. In addition, the m6A of DSTNP2 regulation of DSTN is partially dependent on the miRNA miR-362-5p. Conclusions: Our discovery reveals a novel evolutionary role of m6A RNA modification in cleaning up the unnecessary processed pseudogene transcripts to attenuate their interfering with the regulatory network of proteincoding genes.
Project description:Pseudogenes are gene copies presumed to mainly be functionless relics of evolution due to acquired deleterious mutations or transcriptional silencing. When transcribed, pseudogenes may encode proteins or enact RNA-intrinsic regulatory mechanisms. However, the extent, characteristics and functional relevance of the human pseudogene transcriptome are unclear. Short-read sequencing platforms have limited power to resolve and accurately quantify pseudogene transcripts owing to the high sequence similarity of pseudogenes and their parent genes. Using deep full-length PacBio cDNA sequencing of normal human tissues and cancer cell lines, we identify here hundreds of novel transcribed pseudogenes. Pseudogene transcripts are expressed in tissue-specific patterns, exhibit complex splicing patterns and contribute to the coding sequences of known genes. We survey pseudogene transcripts encoding intact open reading frames (ORFs), representing potential unannotated protein-coding genes, and demonstrate their efficient translation in cultured cells. To assess the impact of noncoding pseudogenes on the cellular transcriptome, we delete the nucleus-enriched pseudogene PDCL3P4 transcript from HAP1 cells and observe hundreds of perturbed genes. This study highlights pseudogenes as a complex and dynamic component of the transcriptional landscape underpinning human biology and disease.
Project description:Somatic mutations acquired by hematopoietic stem cells (HSCs) are commonly found over the course of a lifespan. Some of these clones will outgrow through a process known as clonal hematopoiesis (CH) and produce mutated immune cell progeny, which will shape host immunity. Individuals with CH are asymptomatic but have increased risk of developing leukemia, cardiovascular and pulmonary inflammatory diseases, and severe infections. Despite the key role that neutrophils play in the development of such diseases, little is known about how these prevalent somatic mutations affect neutrophil functionality. In this work, we describe how mutations in TET2, one of the most common mutated genes in individuals with CH, affect human neutrophil biology.
Project description:Somatic mutations acquired by hematopoietic stem cells (HSCs) are commonly found over the course of a lifespan. Some of these clones will outgrow through a process known as clonal hematopoiesis (CH) and produce mutated immune cell progeny, which will shape host immunity. Individuals with CH are asymptomatic but have increased risk of developing leukemia, cardiovascular and pulmonary inflammatory diseases, and severe infections. Despite the key role that neutrophils play in the development of such diseases, little is known about how these prevalent somatic mutations affect neutrophil functionality. In this work, we describe how mutations in TET2, one of the most common mutated genes in individuals with CH, affect human neutrophil biology.
Project description:Pseudogenes are defined as regions of the genome that resemble functional genes but contain disabling mutations and lack regulatory elements needed for transcription or translation. They are excellent markers for genome evolution and are emerging as crucial regulators of the development and disease, especially cancer. However, systematic functional characterization and evolution of pseudogene remain largely unexplored. In particular, the contribution of pseudogene to organ development is still unknown. Meanwhile, studies of pseudogene transcription, which is the first step for generating functional RNA, is precluded by the limited capacity of short-read sequencing. To address these issues, we systematically inferred the origin time and characterized the evolution pattern of pseudogenes. We leveraged PacBio full-length sequencing in combination with deep Illumina data as well as public developmental time-course RNA-seq, we dramatically expanded the analyzed samples and profiled genome-wide pseudogene expression paradigm. Additionally, we prioritized functional pseudogenes at multiple regulatory layers and determined their implications in disease and cancer biology.
Project description:Pro-spermatogonia (SG) serve as the gateway to spermatogenesis. Using single-cell RNA sequencing (RNAseq), we studied the development of ProSG, their SG descendants, and testicular somatic cells, during the perinatal period in mice. We identified both gene and protein markers for 3 temporally distinct ProSG cell subsets, including a migratory cell population with a distinct transcriptome from the previously defined T1- and T2-ProSG stages. This intermediate (I)-ProSG subset translocates from the center of seminiferous tubules to the spermatogonial stem cell (SSC) “niche” in its periphery soon after birth. We identified 3 undifferentiated SG subsets at postnatal day 7, each of which express distinct genes, including transcription factor and signaling genes. Two of these subsets have the characteristics of newly emergent SSCs. We also molecularly defined the development of Sertoli, Leydig, and peritubular myoid cells during the perinatal period, allowing us to identify candidate signaling pathways acting between somatic and germ cells in a stage-specific manner during the perinatal period. Our study provides a rich resource for those investigating testicular germ and somatic cell developmental during the perinatal period.