Combining long-read and strand-specific sequencing technologies, a team led by scientists from Heinrich Heine University and the University of Washington School of Medicine has assembled haplotype-resolved human genomes from 32 individuals to reveal a range of previously unrecognized structural variants. In their study, which appears in Science, the researchers use a recently developed method for phased genome assembly, which combines long-read PacBio whole-genome sequencing and Strand-seq data, to generate the highly contiguous haplotype assemblies. With these, they identify roughly 107,000 structural variants, 68 percent of which are not found by short-read sequencing, as well as 278 structural variant hotspots. The work, the researchers write, provides "fundamental new insights into the structure, variation, and mutation of the human genome providing a framework for more systematic analyses of thousands of human genomes going forward." GenomeWeb has more on this, here.
A complex involved in microRNA processing has been found to play a key role in ribosomal protein production and may represent a therapeutic target for certain anemias, according to a study in this week's Science Signaling. In eukaryotes, ribosome biogenesis requires the production of 80 ribosomal proteins and four ribosomal RNAs at a rate synchronized with cellular growth. In an effort to better understand this process, investigators from the University of California, San Francisco, discover that the microprocessor complex, which is required for miRNA processing, drives the transcription of ribosomal protein genes by eliminating DNA/RNA hybrids called R-loops that inhibit RNA polymerase and interfere with gene expression. Notably, nutrient deprivation triggered the nuclear export of Drosha, a component of the microprocessor complex, reducing ribosomal protein production and protein synthesis. Knocking out Drosha in mouse red blood cell progenitors led to reduced production of ribosomal proteins, inhibiting of an erythroid transcription factor, and impaired erythropoiesis, mirroring the clinical presentation of anemias in humans caused by ribosome insufficiency or dysfunction. The findings reveal a previously unknown function for the microprocessor complex and point to a potential therapeutic target for ribosomopathies, the researchers say.