Volume 50 Issue 2, February 2018

Creating large genome/phenome collections can require consortium-scale resources. DNA.Land is a digital biobank that collects genetic data from individuals tested by consumer genomic companies using a fraction of the resources of traditional studies.

Two new studies identify rare homozygous variants in ADCY3 that are causal for monogenic obesity in consanguineous families of Pakistani origin and are associated with increased risk of obesity in Greenlandic individuals. Greenlandic carriers of homozygous loss-of-function variants in ADCY3, and individuals from trans-ancestry studies with a burden of rare ADCY3 loss-of-function variants, also have increased risk of type 2 diabetes.

New genomic analyses indicate that pioneer transcription factors can sample a diverse repertoire of common binding sites among different cell types and become enriched where they cooperate with other factors specific to each cell. Pioneer-factor binding is mechanistically separate from, and is necessary for, subsequent phenomena of chromatin opening and epigenetic memory in vivo.

Dysregulated lipid metabolism is a prominent feature of prostate cancers. Two papers in this issue identify novel genomic drivers of lipid metabolism in prostate cancer and provide implications for the subtyping and treatment of the disease.

Individuals from a Greenlandic Inuit population with homozygous loss-of-function variants in ADCY3 (adenylate cyclase 3) have increased risk for obesity and type 2 diabetes. Carriers of rare ADCY3 variants in trans-ancestry populations also show increased association with type 2 diabetes.

Genetic analysis of children with severe obesity identifies mutations in the ADCY3 gene (encoding adenylate cyclase 3). These variants are rare in public databases and affect the functional activity of the protein, indicating that ADCY3 is a potential pharmacological target for obesity treatment.

MC4R colocalizes with ADCY3 at primary cilia in hypothalamic neurons, and MC4R mutations associated with human obesity impair this localization. Inhibition of adenylyl cyclase signaling at primary cilia of neurons leads to increased body weight in mice.

A conserved microRNA targets LTR retrotransposons in Arabidopsis pollen, stimulating epigenetically activated siRNAs in a dose-dependent manner through RNA Pol IV. These miR845b-dependent easiRNAs mediate the interploidy hybridization barrier that leads to seed abortion.

Depletion of easiRNAs (epigenetically activated small interfering RNAs) relieves the triploid block reproduction barrier mediated by increased paternal ploidy in Arabidposis. Loss of RNA Pol IV blocks easiRNA formation and rescues triploid seeds.

Reconstructing the genome of an ancestor: 788 Icelanders are descended from a man who arrived there in 1802. 38% of his African mother’s genome has now been reconstructed from their pedigree and the genomes and genotypes of current Icelanders up to 8 generations later.

This study shows that inactivation of Pml in the mouse prostate turns indolent Pten-null tumors into lethal metastatic disease. The authors identify an aberrant SREBP prometastatic lipogenic program and show that a high-fat diet induces lipid accumulation in prostate tumors and is sufficient to drive metastasis.

Inactivation of pyruvate dehydrogenase A1 (PDHA1), a subunit of the pyruvate dehydrogenase complex (PDC) regulating mitochondrial metabolism, inhibits lipid biosynthesis and prostate cancer development in mouse and human xenograft tumor models.

MTAG is a new method for joint analysis of summary statistics from genome-wide association studies of different traits. Applying MTAG to summary statistics for depressive symptoms, neuroticism and subjective well-being increased discovery of associated loci as compared to single-trait analyses.

The authors analyze time-resolved changes in genome topology, gene expression, transcription-factor binding, and chromatin state during iPSC generation. They conclude that 3D genome reorganization generally precedes gene expression changes and that removal of locus-specific topological barriers explains why pluripotency genes are activated sequentially during reprogramming.

Investigation of FOXA2, GATA4 and OCT4 binding across several cell types provides insights into the genetic determinants and epigenetic effects of pioneer-factor occupancy. The data suggest that FOXA2 samples most of its potential binding sites but is stabilized at only a subset of targets.

Analysis of Pax7 dynamics during pituitary lineage specification shows that Pax7 binds rapidly at uniquely marked heterochromatin pioneer sites and initiates chromatin opening that remains stable after Pax7 withdrawal, with loss of DNA hypermethylation at pioneered enhancers.

A new assembly of the sea lamprey germline genome identifies genomic regions that are systematically eliminated from somatic tissue during early development. Comparative analysis gives new insight into vertebrate evolution.

A pan-genome dataset of the Oryza sativa–Oryza rufipogon species complex generated through deep sequencing and de novo genome assembly of 66 divergent accessions will be helpful in pinpointing new causal variants underlying complex traits and in promoting evolutionary and functional studies in rice.

Genome assemblies of 13 domesticated and wild rice relatives reveal salient features of genome evolution across the genus Oryza, especially rapid species diversification and turnover of transposons. This study also releases a complete long-read assembly of IR 8 ‘Miracle Rice’.

The study reports map-based cloning and functional analysis of Bph6, which is associated with resistance to planthoppers in rice. BPH6 localizes to the exocyst and interacts with OsEXO70E1, and suppression of OsExo70E1 expression decreases resistance in Bph6-NIL plants.

A GWAS of multi- and extensively drug-resistant tuberculosis using 6,465 Mycobacterium tuberculosis clinical isolates from more than 30 countries identifies novel mutations associated with resistance. The capacity to detect resistance in particular to ethionamide, pyrazinamide, capreomycin, cycloserine and paraaminosalicylic acid was enhanced by inclusion of insertions and deletions.