The 1000 Genomes Project set out to provide a comprehensive description of common human genetic variation by applying whole-genome sequencing to a diverse set of individuals from multiple populations. Here we report completion of the project, having reconstructed the genomes of 2,504 individuals from 26 populations using a combination of low-coverage whole-genome sequencing, deep exome sequencing, and dense microarray genotyping. We characterized a broad spectrum of genetic variation, in total over 88 million variants (84.7 million single nucleotide polymorphisms (SNPs), 3.6 million short insertions/deletions (indels), and 60,000 structural variants), all phased onto high-quality haplotypes. This resource includes >99% of SNP variants with a frequency of >1% for a variety of ancestries. We describe the distribution of genetic variation across the global sample, and discuss the implications for common disease studies.
Summary Structural variants (SVs) are implicated in numerous diseases and make up the majority of varying nucleotides among human genomes. Here we describe an integrated set of eight SV classes comprising both balanced and unbalanced variants, which we constructed using short-read DNA sequencing data and statistically phased onto haplotype-blocks in 26 human populations. Analyzing this set, we identify numerous gene-intersecting SVs exhibiting population stratification and describe naturally occurring homozygous gene knockouts suggesting the dispensability of a variety of human genes. We demonstrate that SVs are enriched on haplotypes identified by genome-wide association studies and exhibit enrichment for expression quantitative trait loci. Additionally, we uncover appreciable levels of SV complexity at different scales, including genic loci subject to clusters of repeated rearrangement and complex SVs with multiple breakpoints likely formed through individual mutational events. Our catalog will enhance future studies into SV demography, functional impact and disease association.
Profound global loss of DNA methylation is a hallmark of many cancers. One potential consequence of this is the reactivation of transposable elements (TEs) which could stimulate the immune system via cell-intrinsic antiviral responses. Here, we develop REdiscoverTE, a computational method for quantifying genome-wide TE expression in RNA sequencing data. Using The Cancer Genome Atlas database, we observe increased expression of over 400 TE subfamilies, of which 262 appear to result from a proximal loss of DNA methylation. The most recurrent TEs are among the evolutionarily youngest in the genome, predominantly expressed from intergenic loci, and associated with antiviral or DNA damage responses. Treatment of glioblastoma cells with a demethylation agent results in both increased TE expression and de novo presentation of TE-derived peptides on MHC class I molecules. Therapeutic reactivation of tumor-specific TEs may synergize with immunotherapy by inducing inflammation and the display of potentially immunogenic neoantigens.
Scope: Recent evidences demonstrate that abnormal gut microbiota (GM) might be involved in the pathogenesis of Alzheimer's disease (AD). However, the role of probiotics in preventing AD by regulating GM-gut-brain axis remains unclear. Here, the anti-neuroinflammatory effect and its mechanism of probiotic Clostridium butyricum (CB) against AD is investigated by regulating GM-gut-brain axis. Methods and results: APPswe/PS1dE9 (APP/PS1) transgenic are treated intragastrically with CB for 4 weeks then cognitively tested. Amyloid-(A ) burden, microglial activation, proinflammatory cytokines production, GM, and metabolites butyrate are analyzed. Moreover, A -induced BV2 microglia are pretreated with butyrate, and the levels of cluster of differentiation 11b (CD11b), cyclooxygenase-2 (COX-2), and NF-B p65 phosphorylation are determined. The results show that CB treatment prevents cognitive impairment, A deposits, microglia activation, and production of tumor necrosis factor (TNF)-and interleukin (IL)-1 in the brain of APP/PS1 mice. Meanwhile, abnormal GM and butyrate are reversed after CB treatment. Notably, butyrate treatment reduces the levels of CD11b and COX-2, and suppresses phosphorylation of NF-B p65 in the A -induced BV2 microglia. Conclusions: These findings indicate that CB treatment could attenuate microglia-mediated neuroinflammation via regulating the GM-gut-brain axis, which is mediated by the metabolite butyrate.
Enhancer II (ENII) of hepatitis B virus (HBV) is one of the essential cis-elements for the transcriptional regulation of HBV gene expression. Its function is highly liver-specific, suggesting that liver-enriched transcriptional factors play critical roles in regulating the activity of ENII. In this report, a novel hepatocyte transcription factor, which binds specifically to the B1 region (AACGACCGACCTTGAG) within the major functional unit (B unit) of ENII, has been cloned from a human liver cDNA library by yeast one-hybrid screening, and demonstrated to trans-activate ENII via the B1 region. We named this factor hB1F, for human B1-binding factor. Amino acid analysis revealed this factor structurally belongs to nuclear receptor superfamily. Based on the sequence similarities, hB1F is characterized to be a novel human homolog of the orphan receptor fushi tarazu factor I (FTZ-F1). Using reverse transcriptionpolymerase chain reaction, a splicing isoform of hB1F (hB1F-2) was identified, which has an extra 46 amino acid residues in the A/B region. Examination of the tissue distribution has revealed an abundant 5.2-kilobase transcript of hB1F is present specifically in human pancreas and liver. Interestingly, an additional transcript of 3.8 kilobases was found to be present in hepatoma cells HepG2. Fluorescent in situ hybridization has mapped the gene locus of hB1F to the region q31-32.1 of human chromosome 1. Altogether, this study provides the first report that a novel human homolog of FTZ-F1 binds and regulates ENII of HBV. The potential roles of this FTZ-F1 homolog in tissue-specific gene regulation, in embryonic development, as well as in liver carcinogenesis are discussed. Hepatitis B virus (HBV)1 is the major cause of acute and chronic hepatitis, also closely associated with the development of hepatocellular carcinoma (1). HBV predominantly infects hepatocytes, which is a prominent characteristic of hepadnaviruses. The genome of HBV is a small, circular, partially doublestranded DNA of about 3.2 kb, which contains four partially overlapping open reading frames (ORF) encoding the surface antigens (preS/S), the core antigen/e antigen (preC/C), the polymerase (P) and the X protein (X), respectively (2, 3). These HBV genes express specifically in liver, controlled by the combinatorial action of the promoters and enhancers. To date, four promoters (Sp1, Sp2, Cp, and Xp) (4) have been identified to be responsible for the transcription of the viral mRNAs, and they are regulated by two HBV enhancers. Enhancer I (ENI) functions in a relatively tissue independent manner (5, 6), while enhancer II (ENII) shows strong hepatocyte specificity. Enhancer II of HBV is located within the X ORF, about 600 bp downstream of ENI (7-9). In our previous study, ENII was mapped in a 148-bp region from nt 1627 to 1774 (HBV adr1 subtype), partially overlapped with the core promoter (Cp) (7). According to the functional analyses, it can be divided into two parts, A and B, with part B as the basal functional unit, which could be further subdi...
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