Reviews & Analysis

Cryo-electron microscopy (cryo-EM) imaging of DNA replication origin activation explains the role of Mcm10, a minichromosome maintenance (MCM) protein homolog, during initiation. Mcm10 acts as a wedge to split the two MCM hexamers of the activated replicative helicase. Diverging replication forks are then established, with changes in the MCM hexamers that promote the topological separation of two DNA strands.

In this Perspective, the authors propose a framework to explain membrane protein biogenesis, wherein different parts of a nascent substrate are triaged between Oxa1 and SecY family members for insertion.

The molecular mechanisms that regulate the transition from totipotency into divergent cellular states are unclear. Two new studies show that the transcription factors TFAP2C, NR5A2 and TEAD4 (TNT) support the formation of a transient bipotent state by activating early pluripotency and trophectoderm genes and modulating HIPPO signaling.

The commander complex was recently shown through interactomic screens to be a ubiquitous and conserved protein complex with fundamental biological roles. Two recent reports together revealed the structure of the complete commander assembly and explored its functional implications.

NAD(H) redox homeostasis has a fundamental role in cellular metabolism. We screened for potential modulators of NAD(H) using a genome-scale RNA interference (RNAi) approach combined with SoNar, a high-performance sensor that is sensitive to the redox state of NAD(H). Our analysis identified HES4 as a negative regulator of the NADH/NAD⁺ ratio that influences pyrimidine biosynthesis and exerts a potent oncogenic effect.

Hexasomes are non-canonical nucleosomes that package DNA with six instead of eight histones. Here, the author contextualizes two recent studies on the interplay of the chromatin remodeler INO80 with hexasomes with historical literature on the subject.

Branch point selection is required for pre-mRNA splicing, and its mis-regulation is associated with many diseases. Two structural studies provide insights into the dynamics of active site formation and the spliceosomal proteins that may contribute to activation of the correct branch point in eukaryotic introns.

Targeted biologics delivery requires programming multicomponent protein nanomaterials to enable selective targeting and response to environment changes in a single unified framework. A novel protein nanoparticle platform has been designed to modulate cell-surface target specificity, cargo packaging, and pH-dependent release of encapsulated cargo, providing exciting possibilities in biologics delivery.

Stabilization of a branch structure would intuitively suggest a direct connection between trunk and bough, but in actin filament networks, cortactin clamps the branching Arp2/3 complex to the daughter filament. This has fundamental consequences for mechanistic understanding of actin branch turnover and cortactin biology.

ADP-ribosylation regulates the activity of numerous proteins involved in the DNA damage response and repair. A new study shows that telomeric DNA can be ADP-ribosylated by PARP1, and prompt removal of the ADP-ribose by TARG1 is essential to preserve telomere integrity, unveiling DNA–ADP-ribosylation as a novel player in telomere stability.

Systemic RNA interference (RNAi) in Caenorhabditis elegans is initiated by SID-1-mediated double-stranded RNA (dsRNA) internalization. By combining cryo-electron microscopy (cryo-EM), in vitro and in vivo assays, we show how SID-1 specifically recognizes dsRNA and provide important insights into dsRNA internalization by SID-1.

The human cytoskeleton consists of three major classes of filaments: microfilaments, microtubules and intermediate filaments. Here, we summarize recent progress in deciphering the structure and function of intermediate filaments and their implications for human disease.

Spliceosome biogenesis and recycling remains a largely unexplored area. Two papers now reveal how protein chaperones remodel the 20S U5 snRNP, leading to formation of the U4/U6.U5 tri-snRNP.

In this Perspective, the author describes the recent progress in understanding solute carrier (SLC) biology and discusses the roles of new families of atypical SLCs.

Pregnancy loss is common in humans, but maternal genetic factors modulating its incidence are largely unknown. In a meta-analysis of genome-wide association studies, researchers identified a genetic variant that seems to increase risk of pregnancy loss by dysregulating meiotic recombination between homologous chromosomes during egg formation.

Cryo-electron microscopy of brain tissue from two individuals with Down syndrome showed amyloid-β (Aβ) and tau filaments identical to those found in individuals with sporadic or dominantly inherited Alzheimer disease (AD), but also two types of Aβ₄₀ filaments with distinct structures different from those previously reported in AD and cerebral amyloid angiopathy.

In this Review, the authors present an overview of our current understanding of the relationship between DNA methylation and three-dimensional chromatin architecture, discussing the extent to which DNA methylation may regulate the folding of the genome.