Wellcome Trust Sanger Institute

About: Wellcome Trust Sanger Institute is a nonprofit organization based out in Cambridge, United Kingdom. It is known for research contribution in the topics: Population & Genome. The organization has 4009 authors who have published 9671 publications receiving 1224479 citations.

The genome of the social amoeba Dictyostelium discoideum

Abstract: The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins, a high proportion of which have long, repetitive amino acid tracts. There are many genes for polyketide synthases and ABC transporters, suggesting an extensive secondary metabolism for producing and exporting small molecules. The genome is rich in complex repeats, one class of which is clustered and may serve as centromeres. Partial copies of the extrachromosomal ribosomal DNA (rDNA) element are found at the ends of each chromosome, suggesting a novel telomere structure and the use of a common mechanism to maintain both the rDNA and chromosomal termini. A proteome-based phylogeny shows that the amoebozoa diverged from the animal-fungal lineage after the plant-animal split, but Dictyostelium seems to have retained more of the diversity of the ancestral genome than have plants, animals or fungi.

The patterns and dynamics of genomic instability in metastatic pancreatic cancer

Abstract: Christine Iacobuzio-Donahue and colleagues use whole-genome exome sequencing to analyse primary pancreatic cancers and one or more metastases from the same patients, and find that tumours are composed of distinct subclones. The authors also determine the evolutionary maps by which metastatic cancer clones have evolved within the primary tumour, and estimate the timescales of tumour progression. On the basis of these data, they estimate a mean period of 11.8 years between the initiation of pancreatic tumorigenesis and the formation of the parental, non-metastatic tumour, and a further 6.8 years for the index metastasis clone to arise. These data point to a potentially large window of opportunity during which it might be possible to detect the cancer in a relatively early form. Peter Campbell and colleagues use next-generation sequencing to detect chromosomal rearrangements in 13 patients with pancreatic cancer. The results reveal considerable inter-patient heterogeneity and indicate ongoing genomic instability and evolution during the development of metastases. But for most of the patients studied, more than half of the genetic rearrangements found were present in all metastases and the primary tumour, making them potential targets for therapeutic intervention at early and late stages of the disease. Pancreatic cancer is highly aggressive, usually because of widespread metastasis. Here, next-generation DNA sequencing has been used to detect genomic rearrangements in 13 patients with pancreatic cancer and to explore clonal relationships among metastases. The results reveal not only considerable inter-patient heterogeneity, but also ongoing genomic instability and evolution during the development of metastases. Pancreatic cancer is an aggressive malignancy with a five-year mortality of 97–98%, usually due to widespread metastatic disease. Previous studies indicate that this disease has a complex genomic landscape, with frequent copy number changes and point mutations1,2,3,4,5, but genomic rearrangements have not been characterized in detail. Despite the clinical importance of metastasis, there remain fundamental questions about the clonal structures of metastatic tumours6,7, including phylogenetic relationships among metastases, the scale of ongoing parallel evolution in metastatic and primary sites7, and how the tumour disseminates. Here we harness advances in DNA sequencing8,9,10,11,12 to annotate genomic rearrangements in 13 patients with pancreatic cancer and explore clonal relationships among metastases. We find that pancreatic cancer acquires rearrangements indicative of telomere dysfunction and abnormal cell-cycle control, namely dysregulated G1-to-S-phase transition with intact G2–M checkpoint. These initiate amplification of cancer genes and occur predominantly in early cancer development rather than the later stages of the disease. Genomic instability frequently persists after cancer dissemination, resulting in ongoing, parallel and even convergent evolution among different metastases. We find evidence that there is genetic heterogeneity among metastasis-initiating cells, that seeding metastasis may require driver mutations beyond those required for primary tumours, and that phylogenetic trees across metastases show organ-specific branches. These data attest to the richness of genetic variation in cancer, brought about by the tandem forces of genomic instability and evolutionary selection.

Exome sequencing of hepatocellular carcinomas identifies new mutational signatures and potential therapeutic targets

Abstract: Genomic analyses promise to improve tumor characterization to optimize personalized treatment for patients with hepatocellular carcinoma (HCC). Exome sequencing analysis of 243 liver tumors identified mutational signatures associated with specific risk factors, mainly combined alcohol and tobacco consumption and exposure to aflatoxin B1. We identified 161 putative driver genes associated with 11 recurrently altered pathways. Associations of mutations defined 3 groups of genes related to risk factors and centered on CTNNB1 (alcohol), TP53 (hepatitis B virus, HBV) and AXIN1. Analyses according to tumor stage progression identified TERT promoter mutation as an early event, whereas FGF3, FGF4, FGF19 or CCND1 amplification and TP53 and CDKN2A alterations appeared at more advanced stages in aggressive tumors. In 28% of the tumors, we identified genetic alterations potentially targetable by US Food and Drug Administration (FDA)-approved drugs. In conclusion, we identified risk factor-specific mutational signatures and defined the extensive landscape of altered genes and pathways in HCC, which will be useful to design clinical trials for targeted therapy.

A rapid and robust method for single cell chromatin accessibility profiling

Abstract: The assay for transposase-accessible chromatin using sequencing (ATAC-seq) is widely used to identify regulatory regions throughout the genome. However, very few studies have been performed at the single cell level (scATAC-seq) due to technical challenges. Here we developed a simple and robust plate-based scATAC-seq method, combining upfront bulk Tn5 tagging with single-nuclei sorting. We demonstrate that our method works robustly across various systems, including fresh and cryopreserved cells from primary tissues. By profiling over 3000 splenocytes, we identify distinct immune cell types and reveal cell type-specific regulatory regions and related transcription factors. ATAC-seq is widely used to identify regulatory regions in the genome. Here the authors develop a simple and robust plate-based single-cell ATAC-seq method that works in fresh and cryopreserved cells.

Diet and the evolution of human amylase gene copy number variation.

Abstract: Starch consumption is a prominent characteristic of agricultural societies and hunter-gatherers in arid environments. In contrast, rainforest and circum-arctic hunter-gatherers and some pastoralists consume much less starch. This behavioral variation raises the possibility that different selective pressures have acted on amylase, the enzyme responsible for starch hydrolysis. We found that copy number of the salivary amylase gene (AMY1) is correlated positively with salivary amylase protein level and that individuals from populations with high-starch diets have, on average, more AMY1 copies than those with traditionally low-starch diets. Comparisons with other loci in a subset of these populations suggest that the extent of AMY1 copy number differentiation is highly unusual. This example of positive selection on a copy number-variable gene is, to our knowledge, one of the first discovered in the human genome. Higher AMY1 copy numbers and protein levels probably improve the digestion of starchy foods and may buffer against the fitness-reducing effects of intestinal disease.