Torsins are essential, disease-relevant ATPases, but their function is unknown. Monitoring of nuclear envelope morphology after deletion of multiple Torsins or their cofactors reveals a robust inner nuclear membrane–blebbing phenotype in HeLa cells. Nucleoporins and ubiquitin are defining molecular components of these omega-shaped blebs.

Lamin B receptor (LBR) is a polytopic membrane protein residing in the inner nuclear membrane in association with the nuclear lamina. We demonstrate that human LBR is essential for cholesterol synthesis. LBR mutant derivatives implicated in Greenberg skeletal dysplasia or Pelger-Huët anomaly fail to rescue the cholesterol auxotrophy of a LBR-deficient human cell line, consistent with a loss-of-function mechanism for these congenital disorders. These disease-causing variants fall into two classes: point mutations in the sterol reductase domain perturb enzymatic activity by reducing the affinity for the essential cofactor NADPH, while LBR truncations render the mutant protein metabolically unstable, leading to its rapid degradation at the inner nuclear membrane. Thus, metabolically unstable LBR variants may serve as long-sought-after model substrates enabling previously impossible investigations of poorly understood protein turnover mechanisms at the inner nuclear membrane of higher eukaryotes.DOI: http://dx.doi.org/10.7554/eLife.16011.001

Background:TorsinB is an AAAϩ ATPase of unknown function. Results: ATPase-arrested TorsinB induces the formation of LULL1-enriched, luminally constricted ER membranes requiring a highly conserved C-terminal motif in TorsinB. Conclusion: Membrane structures formed by the TorsinB dominant-negative mutant are dependent on association with ATPase-activating factor LULL1. Significance: This study supports a role for TorsinB in membrane dynamics.

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A boronic acid moiety was found to be a critical pharmacophore for enhanced in vitro potency against wild-type hepatitis C replicons and known clinical polymorphic and resistant HCV mutant replicons. The synthesis, optimization, and structure-activity relationships associated with inhibition of HCV replication in a subgenomic replication system for a series of non-nucleoside boron-containing HCV RNA-dependent RNA polymerase (NS5B) inhibitors are described. A summary of the discovery of 3 (GSK5852), a molecule which entered clinical trials in subjects infected with HCV in 2011, is included.

TorsinA is a membrane-tethered AAA؉ ATPase implicated in nuclear envelope dynamics as well as the nuclear egress of herpes simplex virus 1 (HSV-1). The activity of TorsinA and the related ATPase TorsinB strictly depends on LAP1 and LULL1, type II transmembrane proteins that are integral parts of the Torsin/cofactor AAA ring, forming a composite, membrane-spanning assembly. Here, we use CRISPR/Cas9-mediated genome engineering to create single-and double knockout (KO) cell lines of TorA and TorB as well as their activators, LAP1 and LULL1, to investigate the effect on HSV-1 production. Consistent with LULL1 being the more potent Torsin activator, a LULL1 KO reduces HSV-1 growth by one order of magnitude, while the deletion of other components of the Torsin system in combination causes subtle defects. Notably, LULL1 deficiency leads to a 10-fold decrease in the number of viral genomes per host cell without affecting viral protein production, allowing us to tentatively assign LULL1 to an unexpected role that precedes HSV-1 nuclear egress. IMPORTANCEIn this study, we conduct the first comprehensive genetic and phenotypic analysis of the Torsin/cofactor system in the context of HSV-1 infection, establishing LULL1 as the most important component of the Torsin system with respect to viral production. Herpesviruses are enveloped, double-stranded DNA viruses that enter the host cell by fusing with the plasma membrane. Following the microtubule-dependent transport of the nucleocapsid to the nuclear pore complex, the linear herpesvirus genome is ejected into the nucleus of the host cell, where it is transcribed and replicated. Viral genome replication (1), transcription of viral genes, and assembly and packaging of new viral particles take place in designated replication compartments located at the periphery of the nucleus (2).After the viral capsids are assembled and packaged, they must exit the nucleus to undergo further maturation in the cytoplasm. Herpesviruses undergo nuclear egress via a nuclear membrane budding mechanism in which the viral capsid first buds through the inner nuclear membrane (INM) to form an enveloped intermediate within the perinuclear space, which then fuses with the outer nuclear membrane (ONM) to release the deenveloped capsid into the cytosol (3, 4).Several viral proteins are required for efficient nuclear egress. Viral kinase U S 3 and the virally manipulated host cell protein kinase C phosphorylate and locally disassemble the nuclear lamina, which represents a physical barrier between the viral capsid and the INM (5-7). Additionally, the soluble phosphoprotein U L 31 and the type II inner nuclear membrane phosphoprotein U L 34, which together constitute the viral nuclear egress complex, accumulate at the INM to facilitate capsid envelopment (8-10). Both U L 31 and U L 34 are essential for herpesvirus growth (11), and their coexpression without viral infection is sufficient to cause vesicle formation (12,13). While the viral factors involved in nuclear egress are well characterized, muc...

CuSO4 Hb screening gives large numbers of false passes, particularly in women. Using venous samples, the majority correctly pass at the lower HemoCue cut-offs. The current dual-testing policy appears convenient for donor sessions, but because small percentages of false passes and fails represent large numbers of donors, every effort should be made to improve the accuracy of Hb screening.