De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment.

The endosomal sorting complexes required for transport (ESCRTs) are essential for multiple membrane modeling and membrane-independent cellular processes. Here we describe six unrelated individuals with de novo missense variants affecting the ATPase domain of VPS4A, a critical enzyme regulating ESCRT function. Probands had structural brain abnormalities, severe neurodevelopmental delay, cataracts, growth impairment, and anemia. In cultured cells, overexpression of VPS4A mutants caused enlarged endosomal vacuoles resembling those induced by expression of known dominant-negative ATPase-defective forms of VPS4A. Proband-derived fibroblasts had enlarged endosomal structures with abnormal accumulation of the ESCRT protein IST1 on the limiting membrane. VPS4A function was also required for normal endosomal morphology and IST1 localization in iPSC-derived human neurons. Mutations affected other ESCRT-dependent cellular processes, including regulation of centrosome number, primary cilium morphology, nuclear membrane morphology, chromosome segregation, mitotic spindle formation, and cell cycle progression. We thus characterize a distinct multisystem disorder caused by mutations affecting VPS4A and demonstrate that its normal function is required for multiple human developmental and cellular processes.

BMP- and neuropilin 1-mediated motor axon navigation relies on spastin alternative translation.

Functional analyses of genes responsible for neurodegenerative disorders have unveiled crucial links between neurodegenerative processes and key developmental signalling pathways. Mutations in SPG4-encoding spastin cause hereditary spastic paraplegia (HSP). Spastin is involved in diverse cellular processes that couple microtubule severing to membrane remodelling. Two main spastin isoforms are synthesised from alternative translational start sites (M1 and M87). However, their specific roles in neuronal development and homeostasis remain largely unknown. To selectively unravel their neuronal function, we blocked spastin synthesis from each initiation codon during zebrafish development and performed rescue analyses. The knockdown of each isoform led to different motor neuron and locomotion defects, which were not rescued by the selective expression of the other isoform. Notably, both morphant neuronal phenotypes were observed in a CRISPR/Cas9 spastin mutant. We next showed that M1 spastin, together with HSP proteins atlastin 1 and NIPA1, drives motor axon targeting by repressing BMP signalling, whereas M87 spastin acts downstream of neuropilin 1 to control motor neuron migration. Our data therefore suggest that defective BMP and neuropilin 1 signalling may contribute to the motor phenotype in a vertebrate model of spastin depletion.

ESCRT-III-associated proteins and spastin inhibit protrudin-dependent polarised membrane traffic.

Mutations in the gene encoding the microtubule severing ATPase spastin are the most frequent cause of hereditary spastic paraplegia, a genetic condition characterised by length-dependent axonal degeneration. Here, we show that HeLa cells lacking spastin and embryonic fibroblasts from a spastin knock-in mouse model become highly polarised and develop cellular protrusions. In HeLa cells, this phenotype was rescued by wild-type spastin, but not by forms unable to sever microtubules or interact with endosomal ESCRT-III proteins. Cells lacking the spastin-interacting ESCRT-III-associated proteins IST1 or CHMP1B also developed protrusions. The protrusion phenotype required protrudin, a RAB-interacting protein that interacts with spastin and localises to ER-endosome contact sites, where it promotes KIF5-dependent endosomal motility to protrusions. Consistent with this, the protrusion phenotype in cells lacking spastin also required KIF5. Lack or mutation of spastin resulted in functional consequences for receptor traffic of a pathway implicated in HSP, as Bone Morphogenetic Protein receptor distribution became polarised. Our results, therefore, identify a novel role for ESCRT-III proteins and spastin in regulating polarised membrane traffic.

Mechanistic basis of an epistatic interaction reducing age at onset in hereditary spastic paraplegia.

Many genetic neurological disorders exhibit variable expression within affected families, often exemplified by variations in disease age at onset. Epistatic effects (i.e. effects of modifier genes on the disease gene) may underlie this variation, but the mechanistic basis for such epistatic interactions is rarely understood. Here we report a novel epistatic interaction between SPAST and the contiguous gene DPY30, which modifies age at onset in hereditary spastic paraplegia, a genetic axonopathy. We found that patients with hereditary spastic paraplegia caused by genomic deletions of SPAST that extended into DPY30 had a significantly younger age at onset. We show that, like spastin, the protein encoded by SPAST, the DPY30 protein controls endosomal tubule fission, traffic of mannose 6-phosphate receptors from endosomes to the Golgi, and lysosomal ultrastructural morphology. We propose that additive effects on this pathway explain the reduced age at onset of hereditary spastic paraplegia in patients who are haploinsufficient for both genes.

Ultrasound-guided hip injections: a comparative study with fluoroscopy-guided injections.

PURPOSE: The purpose was to assess ultrasound-guided injections through patient satisfaction in a comparative internally controlled study of fluoroscopic versus ultrasound technique and to quantitate the reliability of the ultrasound method. In addition, the reliability of the ultrasound method was quantitated. METHODS: This study consisted of the first 50 consecutive patients to undergo ultrasound-guided intra-articular injection of the hip (by a nurse practitioner) and who had previously undergone fluoroscopy-guided intra-articular injections by our center's fellowship-trained musculoskeletal radiologists. The patients rated the ultrasound and fluoroscopic experiences on a scale from 1 to 10 for convenience and pain; in addition, they indicated their preference between the 2 techniques. Success of the injection was documented among a total of 206 consecutive patients who underwent ultrasound-guided injections during the period of the controlled study. RESULTS: For convenience, ultrasound injection had a mean rating of 9.8 whereas fluoroscopic injection had a mean rating of 3.1. For pain, ultrasound had a mean rating of 3 and fluoroscopy had a mean rating of 5.6. These differences were statistically significant (P < .01) in favor of ultrasound. For preference, 49 of 50 patients in the control study (98%) stated that they would prefer the ultrasound injection, whereas 1 was uncertain. The injection was successful in 202 of the first 206 patients (98%) to undergo ultrasound injection, whereas 4 patients required a second pass for successful injection. CONCLUSIONS: In this study in-office ultrasound-guided injections of the hip were more convenient and less painful than fluoroscopy-guided hospital-based injections and were preferred by patients who have undergone both. Furthermore, the ultrasound-guided injections were performed by a recently trained physician extender in contrast to the fluoroscopic method, which was performed by experienced fellowship-trained musculoskeletal radiologists. The procedure is highly successful in the hands of a properly trained clinician. LEVEL OF EVIDENCE: Level II, prospective comparative study.

The AAA ATPase spastin links microtubule severing to membrane modelling.

In 1999, mutations in the gene encoding the microtubule severing AAA ATPase spastin were identified as a major cause of a genetic neurodegenerative condition termed hereditary spastic paraplegia (HSP). This finding stimulated intense study of the spastin protein and over the last decade, a combination of cell biological, in vivo, in vitro and structural studies have provided important mechanistic insights into the cellular functions of the protein, as well as elucidating cell biological pathways that might be involved in axonal maintenance and degeneration. Roles for spastin have emerged in shaping the endoplasmic reticulum and the abscission stage of cytokinesis, in which spastin appears to couple membrane modelling to microtubule regulation by severing.

Activation of a microRNA response in trans reveals a new role for poly(A) in translational repression.

Here, we report that the untreated rabbit reticulocyte lysate contains over 300 different endogenous microRNAs together with the major components of the RNA-induced silencing complex and thus can be used as a model in vitro system to study the effects of microRNAs on gene expression. By using this system, we were able to show that microRNA hybridization to its target resulted in a very rapid and strong inhibition of expression that was exerted exclusively at the level of translation initiation with no involvement of transcript degradation or deadenylation. Moreover, we demonstrate that the magnitude of microRNA-induced repression can only be recapitulated in the context of a competitive translating environment. By using a wide spectrum of competitor cellular and viral RNAs, we could further show that competition was not exerted at the level of general components of the translational machinery, but relied exclusively on the presence of the poly(A) tail with virtually no involvement of the cap structure.

Evaluating the impact of using mobile vaccination units to increase COVID-19 vaccination uptake in Cheshire and Merseyside, UK: a synthetic control analysis.

OBJECTIVE: To evaluate the impact of mobile vaccination units on COVID-19 vaccine uptake of the first dose, the percentage of vaccinated people among the total eligible population. We further investigate whether such an effect differed by deprivation, ethnicity and age. DESIGN: Synthetic control analysis. SETTING: The population registered with general practices (GPs) in nine local authority areas in Cheshire and Merseyside in Northwest England, UK. INTERVENTION: Mobile vaccination units that visited 37 sites on 54 occasions between 12 April 2021 and 28 June 2021. We defined intervention neighbourhoods as having their population weighted centroid located within 1 km of mobile vaccination sites (338 006 individuals). A weighted combination of neighbourhoods that had not received the intervention (1 495 582 individuals) was used to construct a synthetic control group. OUTCOME: The weekly number of first-dose vaccines received among people aged 18 years and over as a proportion of the population. RESULTS: The introduction of a mobile vaccination unit into a neighbourhood increased the number of first vaccinations conducted in the neighbourhood by 25% (95% CI 21% to 28%) within 3 weeks after the first visit to a neighbourhood, compared with the synthetic control group. Interaction analyses showed smaller or no effect among older age groups, Asian and black ethnic groups, and the most socioeconomically deprived populations. CONCLUSIONS: Mobile vaccination units are effective interventions for increasing vaccination uptake, at least in the short term. While mobile units can be geographically targeted to reduce inequalities, we found evidence that they may increase inequalities in vaccine uptake within targeted areas, as the intervention was less effective among groups that tended to have lower vaccination uptake. Mobile vaccination units should be used in combination with activities to maximise outreach with black and Asian communities and socioeconomically disadvantaged groups.

Vg1RBP phosphorylation by Erk2 MAP kinase correlates with the cortical release of Vg1 mRNA during meiotic maturation of Xenopus oocytes.

Xenopus Vg1RBP is a member of the highly conserved IMP family of four KH-domain RNA binding proteins, with roles in RNA localization, translational control, RNA stability, and cell motility. Vg1RBP has been implicated in localizing Vg1 mRNAs to the vegetal cortex during oogenesis, in a process mediated by microtubules and microfilaments, and in migration of neural crest cells in embryos. Using c-mos morpholino, kinase inhibitors, and constitutely active recombinant kinases we show that Vg1RBP undergoes regulated phosphorylation by Erk2 MAPK during meiotic maturation, on a single residue, S402, located between the KH2 and KH3 domains. Phosphorylation temporally correlates with the release of Vg1 mRNA from its tight cortical association, assayed in lysates in physiological salt buffers, but does not affect RNA binding, nor self-association of Vg1RBP. U0126, a MAP kinase inhibitor, prevents Vg1RBP cortical release and Vg1 mRNA solubilization in meiotically maturing eggs, while injection of MKK6-DD, a constitutively activated MAP kinase kinase, promotes the release of both Vg1RBP and Vg1 mRNA from insoluble cortical structures. We propose that Erk2 MAP kinase phosphorylation of Vg1RBP regulates the protein:protein-mediated association of Vg1 mRNP with the cytoskeleton and/or ER. Since the MAP kinase site in Vg1RBP is conserved in several IMP homologs, this modification also has important implications for the regulation of IMP proteins in somatic cells.

Translational control assessed using the tethered function assay in Xenopus oocytes.

The tethered function assay is a method designed to address the role of an RNA-binding protein upon the metabolism of a reporter RNA. The basis of this assay is to artificially tether a test protein to a reporter mRNA by employing an unrelated bacteriophage MS2 or lambda N RNA-protein interaction, and to assess the effects of the test protein on the reporter RNA. In this chapter, we first discuss the principles and validity of the tethered function approach, drawing on appropriate examples from several cell types and of many proteins that regulate RNA in a variety of processes, including RNA processing (splicing, polyadenylation/deadenylation, decay), localisation and protein synthesis. Secondly, we will focus on the use of this approach to monitor translational activation and repression in Xenopus oocytes, giving a detailed protocol, and discussing possible optimizations we have explored.

Brine-Releasable Hydrogen Sulfide in Wine: Mechanism of Release from Copper Complexes and Effects of Glutathione.

Copper-sulfhydryl complexes in wine can be disrupted by addition of brine to release free hydrogen sulfide (H2S), and the resulting "brine-releasable H2S" is reported to correlate with formation of H2S during bottle storage. However, both the mechanism of the brine-release assay and factors affecting the stability of copper sulfhydryls under brine-release conditions are not well understood. By varying brine composition and concentration, it is shown that release of copper-complexed H2S requires the presence of a halide (Cl- and Br-) and is not due to a general "salting-out" effect. Release of copper-complexed H2S by the brine dilution assay is highly temperature-dependent. When H2S and Cu(II) are added to a model wine, brine-releasable H2S decreases markedly (∼10-fold) after a 20 min incubation period prior to performing the brine-release assay. In commercial wines, the fraction of added H2S recovered through the brine-release assay was correlated with the initial glutathione (GSH) concentration (r2 = 0.58) but not with initial Cu. Negligible additional release of H2S from organopolysulfanes was observed following addition of a disulfide-reducing agent (tris(2-carboxyethyl)phosphine). As previous studies have reported a correlation between H2S formed under brine-release conditions and normal storage, these results suggest that the susceptibility of a wine to form latent copper-sulfhydryl precursors of H2S following copper addition is dependent on the concentration of sulfhydryls like GSH.

Asymmetrical beta-actin mRNA translation in growth cones mediates attractive turning to netrin-1.

Local protein synthesis regulates the turning of growth cones to guidance cues, yet little is known about which proteins are synthesized or how they contribute to directional steering. Here we show that beta-actin mRNA resides in Xenopus laevis retinal growth cones where it binds to the RNA-binding protein Vg1RBP. Netrin-1 induces the movement of Vg1RBP granules into filopodia, suggesting that it may direct the localization and translation of mRNAs in growth cones. Indeed, a gradient of netrin-1 activates a translation initiation regulator, eIF-4E-binding protein 1 (4EBP), asymmetrically and triggers a polarized increase in beta-actin translation on the near side of the growth cone before growth cone turning. Inhibition of beta-actin translation abolishes both the asymmetric rise in beta-actin and attractive, but not repulsive, turning. Our data suggest that newly synthesized beta-actin, concentrated near sites of signal reception, provides the directional bias for polymerizing actin in the direction of an attractive stimulus.

Spastin MIT Domain Disease-Associated Mutations Disrupt Lysosomal Function.

The hereditary spastic paraplegias (HSPs) are genetic motor neuron diseases characterized by progressive degeneration of corticospinal tract axons. Mutations in SPAST, encoding the microtubule-severing ATPase spastin, are the most common causes of HSP. The broad SPAST mutational spectrum indicates a haploinsufficiency pathogenic mechanism in most cases. Most missense mutations cluster in the ATPase domain, where they disrupt the protein's ability to sever microtubules. However, several putative missense mutations in the protein's microtubule interacting and trafficking (MIT) domain have also been described, but the pathogenicity of these mutations has not been verified with functional studies. Spastin promotes endosomal tubule fission, and defects in this lead to lysosomal enzyme mistrafficking and downstream lysosomal abnormalities. We investigated the function of three disease-associated spastin MIT mutants and found that none was able to promote normal endosomal tubule fission, lysosomal enzyme receptor trafficking, or lysosomal morphology. One of the mutations affected recruitment of spastin to endosomes, a property that requires the canonical function of the MIT domain in binding endosomal sorting complex required for transport (ESCRT)-III proteins. However, the other mutants did not affect spastin's endosomal recruitment, raising the possibility of pathologically important non-canonical roles for the MIT domain. In conclusion, we demonstrate that spastin MIT mutants cause functional abnormalities related to the pathogenesis of HSP. These mutations do not directly affect spastin's microtubule-severing capacity, and so we identify a new molecular pathological mechanism by which spastin mutations may cause disease.

Role of Elemental Sulfur in Forming Latent Precursors of H2S in Wine.

The level of hydrogen sulfide (H2S) can increase during abiotic storage of wines, and potential latent sources of H2S are still under investigation. We demonstrate that elemental sulfur (S0) residues on grapes not only can produce H2S during fermentation but also can form precursors capable of generating additional H2S after bottle storage for 3 months. H2S could be released from S0-derived precursors by addition of a reducing agent (TCEP), but not by addition of strong brine to induce release of H2S from metal sulfide complexes. The size of the TCEP-releasable pool varied among yeast strains. Using the TCEP assay, multiple polar S0-derived precursors were detected following normal-phase preparative chromatography. Using reversed-phase liquid chromatography and high-resolution mass spectrometry, we detected an increase in the levels of diglutathione trisulfane (GSSSG) and glutathione disulfide (GSSG) in S0-fermented red wine and an increase in the levels of glutathione S-sulfonate (GSSO3-) and tetrathionate (S4O62-) in S0-fermented white wine as compared to controls. GSSSG, but not S4O62-, was shown to evolve H2S in the presence of TCEP. Pathways for the formation of GSSSG, GSSG, GSSO3-, and S4O62- from S0 are proposed.

Defects in ER-endosome contacts impact lysosome function in hereditary spastic paraplegia.

Contacts between endosomes and the endoplasmic reticulum (ER) promote endosomal tubule fission, but the mechanisms involved and consequences of tubule fission failure are incompletely understood. We found that interaction between the microtubule-severing enzyme spastin and the ESCRT protein IST1 at ER-endosome contacts drives endosomal tubule fission. Failure of fission caused defective sorting of mannose 6-phosphate receptor, with consequently disrupted lysosomal enzyme trafficking and abnormal lysosomal morphology, including in mouse primary neurons and human stem cell-derived neurons. Consistent with a role for ER-mediated endosomal tubule fission in lysosome function, similar lysosomal abnormalities were seen in cellular models lacking the WASH complex component strumpellin or the ER morphogen REEP1. Mutations in spastin, strumpellin, or REEP1 cause hereditary spastic paraplegia (HSP), a disease characterized by axonal degeneration. Our results implicate failure of the ER-endosome contact process in axonopathy and suggest that coupling of ER-mediated endosomal tubule fission to lysosome function links different classes of HSP proteins, previously considered functionally distinct, into a unifying pathway for axonal degeneration.

Quantitative Gait Analysis Using a Motorized Treadmill System Sensitively Detects Motor Abnormalities in Mice Expressing ATPase Defective Spastin.

The hereditary spastic paraplegias (HSPs) are genetic conditions in which there is progressive axonal degeneration in the corticospinal tract. Autosomal dominant mutations, including nonsense, frameshift and missense changes, in the gene encoding the microtubule severing ATPase spastin are the most common cause of HSP in North America and northern Europe. In this study we report quantitative gait analysis using a motorized treadmill system, carried out on mice knocked-in for a disease-associated mutation affecting a critical residue in the Walker A motif of the spastin ATPase domain. At 4 months and at one year of age homozygous mutant mice had a number of abnormal gait parameters, including in stride length and stride duration, compared to heterozygous and wild-type littermates. Gait parameters in heterozygous animals did not differ from wild-type littermates. We conclude that quantitative gait analysis using the DigiGait system sensitively detects motor abnormalities in a hereditary spastic paraplegia model, and would be a useful method for analyzing the effects of pharmacological treatments for HSP.

Preclinical evaluation of a miniaturized Deep Brain Stimulation electrode lead.

The effect of miniaturizing the electrode lead for Deep Brain Stimulation (DBS) therapy was investigated in this work. A direct comparison was made between a miniature lead (0.65 mm diameter) and a lead of standard size (1.3 mm). Acute in vivo implantation in two cat brains was performed to evaluate surgical trauma and confirm capacity to target thalamic nuclei. Insertion into a homogeneous gel model of neural tissue was used to compare insertion forces while visualizing the process. The standard size cannula, used first to guide lead insertion, required substantially higher insertion force compared with the miniature version and produced a significantly larger region of tissue disruption. The characteristic hemorrhage and edema extended 119-352 µm from the implanted track surface of the miniature lead and cannula, while these extended 311-571 µm for the standard size lead and cannula. A miniature DBS implant can reduce the extent of trauma and could potentially help improve neural function preservation after functional neurosurgery.

A double standard for "Hooking Up": How far have we come toward gender equality?

While sexual attitudes have liberalized in the past half century, research is mixed as to whether attitudes have become less gendered over time. Recent studies on college students' sexual and romantic relationships suggest that a sexual double standard continues to organize sexuality on many campuses. Data from the Online College Social Life Survey shed light on students' evaluation of casual sex, or "hooking up." In addition to exploring gendered attitudinal patterns, we use gender structure theory to explore how individual characteristics and normative expectations of campus group affiliations shape attitudes. While three quarters of students do not hold different standards for men and women's hooking up, attitudes are more conservative than liberal, with almost half of students losing respect for men and women who hook up "a lot." However, men are more likely to hold a traditional double standard, while women are more likely to espouse egalitarian conservative attitudes. Individual characteristics, including age, religion, race, social class and sexual orientation are frequently related to sexual attitudes, as are number of hook ups, fraternity/sorority affiliation and varsity athletic participation.

An ESCRT-spastin interaction promotes fission of recycling tubules from the endosome.

Mechanisms coordinating endosomal degradation and recycling are poorly understood, as are the cellular roles of microtubule (MT) severing. We show that cells lacking the MT-severing protein spastin had increased tubulation of and defective receptor sorting through endosomal tubular recycling compartments. Spastin required the ability to sever MTs and to interact with ESCRT-III (a complex controlling cargo degradation) proteins to regulate endosomal tubulation. Cells lacking IST1 (increased sodium tolerance 1), an endosomal sorting complex required for transport (ESCRT) component to which spastin binds, also had increased endosomal tubulation. Our results suggest that inclusion of IST1 into the ESCRT complex allows recruitment of spastin to promote fission of recycling tubules from the endosome. Thus, we reveal a novel cellular role for MT severing and identify a mechanism by which endosomal recycling can be coordinated with the degradative machinery. Spastin is mutated in the axonopathy hereditary spastic paraplegia. Zebrafish spinal motor axons depleted of spastin or IST1 also had abnormal endosomal tubulation, so we propose this phenotype is important for axonal degeneration.