A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies—a whole-genome assembly and a regional chromosome assembly—were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional ∼12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.
A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.
The high degree of similarity between the mouse and human genomes is demonstrated through analysis of the sequence of mouse chromosome 16 (Mmu 16), which was obtained as part of a whole-genome shotgun assembly of the mouse genome. The mouse genome is about 10% smaller than the human genome, owing to a lower repetitive DNA content. Comparison of the structure and protein-coding potential of Mmu 16 with that of the homologous segments of the human genome identifies regions of conserved synteny with human chromosomes (Hsa) 3, 8, 12, 16, 21, and 22. Gene content and order are highly conserved between Mmu 16 and the syntenic blocks of the human genome. Of the 731 predicted genes on Mmu 16, 509 align with orthologs on the corresponding portions of the human genome, 44 are likely paralogous to these genes, and 164 genes have homologs elsewhere in the human genome; there are 14 genes for which we could find no human counterpart.
Background: Myocardial ischemia-reperfusion (MI/R) injury is a significant clinical problem without effective therapy. Unbiased omics approaches may reveal key MI/R mediators to initiate MI/R injury. Methods: We used a dynamic transcriptome analysis of mouse heart exposed to various MI/R periods to identify S100a8/a9 as an early mediator. Using loss/gain-of-function approaches to understand the role of S100a8/a9 in MI/R injury, we explored the mechanisms through transcriptome and functional experiment. Dynamic serum S100a8/a9 levels were measured in patients with acute myocardial infarction before and after percutaneous coronary intervention. Patients were prospectively followed for the occurrence of major adverse cardiovascular events. Results: S100a8/a9 was identified as the most significantly upregulated gene during the early reperfusion stage. Knockout of S100a9 markedly decreased cardiomyocyte death and improved heart function, whereas hematopoietic overexpression of S100a9 exacerbated MI/R injury. Transcriptome/functional studies revealed that S100a8/a9 caused mitochondrial respiratory dysfunction in cardiomyocytes. Mechanistically, S100a8/a9 downregulated NDUF gene expression with subsequent mitochondrial complex I inhibition via Toll-like receptor 4/Erk–mediated Pparg coactivator 1 alpha/nuclear respiratory factor 1 signaling suppression. Administration of S100a9 neutralizing antibody significantly reduced MI/R injury and improved cardiac function. Finally, we demonstrated that serum S100a8/a9 levels were significantly increased 1 day after percutaneous coronary intervention in patients with acute myocardial infarction, and elevated S100a8/a9 levels were associated with the incidence of major adverse cardiovascular events. Conclusions: Our study identified S100a8/a9 as a master regulator causing cardiomyocyte death in the early stage of MI/R injury via the suppression of mitochondrial function. Targeting S100a8/a9-intiated signaling may represent a novel therapeutic intervention against MI/R injury. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT03752515
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