Volume 48 Issue 3, March 2016

Current efforts in cellular disease modeling and regenerative medicine are limited by the paucity of cell types that can be generated in the laboratory. A new study introduces a computational framework, Mogrify, that uses network biology to predict combinations of transcription factors necessary for direct conversion between human cell types to ameliorate this issue.

The recently discovered chromatin compartments called topologically associating domains (TADs) are essential for the three-dimensional organization of regulatory interactions driving gene expression. A new study documents the emergence of a TAD flanking the amphioxus Hox cluster, prefiguring the vertebrate anterior Hox TAD and preceding the appearance of the concurring posterior Hox TAD.

The integration of large, well-sampled collections of bacterial isolates with genomics and experimental methods provides opportunities for 'top-down' discovery of the genetic basis of phenotypes of interest. In a new report, the authors apply this approach to investigate the heterogeneity in manifestations of disease caused by Listeria monocytogenes and demonstrate that a previously uncharacterized cellobiose PTS system is involved in central nervous system infection.

Shamil Sunyaev, Alexander Gimelbrant and colleagues report an analysis of the genetic variability in human monoallelically expressed genes. They find that genes with monoallelic expression show greater genetic diversity than biallelically expressed genes and that this diversity is associated with greater allelic age.

Andrea Sottoriva, Trevor Graham and colleagues analyze tumor sequencing data and show that a substantial proportion of cancers of many different types are characterized by neutral evolution resulting in a characteristic power-law distribution of the mutant allele frequencies. This neutral framework provides a new way to interpret cancer genomic data and to discriminate between functional and non-functional intratumoral heterogeneity.

Alexander Gusev, Bogdan Pasaniuc and colleagues present a strategy that integrates gene expression measurements with summary statistics from large-scale genome-wide association studies to identify genes whose cis-regulated expression is associated with complex traits. They identify 69 new genes significantly associated with obesity-related traits and illustrate how this approach can provide insights into the genetic basis of complex traits.

Christoph Plass, Christopher Oakes and colleagues study genome-wide DNA methylation dynamics during B cell maturation and the pathogenic role of transcription factor dysregulation in chronic lymphocytic leukemia (CLL). By comparing normal and malignant B cells, they find that tumors derive from a continuum of maturation states, which correlate with different clinical outcomes.

Bradley Bernstein, Birgit Knoechel and colleagues identify super-enhancer translocations that drive overexpression of MYB in adenoid cystic carcinoma (ACC). They find that MYB binds to the translocated enhancers and to other active enhancers that drive different regulatory programs in alternate cell lineages in ACC.

Keith Ligon, Adam Resnick, Rameen Beroukhim and colleagues identify MYB-QKI fusions in angiocentric gliomas and show that these rearrangements promote tumorigenesis through activation of MYB by truncation, enhancer translocation driving aberrant MYB-QKI expression and hemizygous loss of QKI.

Haifan Lin, Jamy Peng and colleagues report that the Drosophila Piwi protein is a negative regulator of PRC2 in the fly ovary, a function required for the maintenance of germline stem cells. Their results indicate that Piwi sequesters PRC2 in the nucleoplasm, thereby reducing genome-wide levels of H3K27me3.

Justin Crocker, Garth Ilsley and David Stern use engineered transcription factors to regulate enhancers in a quantitatively predictable manner in Drosophila embryos. Their models of enhancer function provide a framework for the quantitative control of enhancers in vivo.

Taisei Kikuchi, Mark Viney, Matthew Berriman and colleagues report the genome sequences of six species of nematodes from the Strongyloides clade of nematodes, including human and animal pathogens, facultative parasites and a free-living species. They find that expansions of the astacin and SCP/TAPS gene families are associated with parasitism in these species.

Marc Lecuit, Sylvain Brisse and colleagues combine Listeria monocytogenes population genomic data with human epidemiological and clinical data to study human listeriosis. They report new putative virulence factors and demonstrate that some clones are hypervirulent in a humanized mouse model of listeriosis and have enhanced neural and placental tropism.

Daniel Gudbjartsson, Kari Stefansson and colleagues propose a new weighted Bonferroni approach for determining significance thresholds for human genome-wide association studies (GWAS). They demonstrate that the weighted approach, which is based on sequence annotation enrichments, improves power over standard GWAS methods.

Ingileif Jonsdottir, Kari Stefansson and colleagues show that variants in the HLA class II region contribute to tuberculosis risk in populations of European ancestry. They propose that the associated variants influence disease risk by altering expression of HLA class II molecules presenting protective M. tuberculosis antigens to T cells.

Swapan Nath, Sang-Cheol Bae and colleagues report the results of a large-scale association study of systemic lupus erythematosus in individuals of Asian ancestry. They identify several new susceptibility loci and find enrichment for signals near genes implicated in B cell and T cell function.

Owen Rackham, Jose Polo, Julian Gough and colleagues present a method, Mogrify, for predicting sets of transcription factors that can induce transdifferentiation between cell types. They show that Mogrify is able to predict known factors for published cell conversions and experimentally validate factors for two new conversions.

José Luis Gómez-Skarmeta, Hector Escrivá, Ignacio Maeso, Damien Devos and colleagues perform 4C-seq profiling of the Hox cluster in amphioxus embryos and find that, unlike in vertebrate embryos, the cluster is organized into a single chromatin interaction domain. They suggest that the vertebrate Hox bipartite regulatory system is an evolutionary novelty.