Functional landscape of SARS-CoV-2 cellular restriction.

A deficient interferon (IFN) response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been implicated as a determinant of severe coronavirus disease 2019 (COVID-19). To identify the molecular effectors that govern IFN control of SARS-CoV-2 infection, we conducted a large-scale gain-of-function analysis that evaluated the impact of human IFN-stimulated genes (ISGs) on viral replication. A limited subset of ISGs were found to control viral infection, including endosomal factors inhibiting viral entry, RNA binding proteins suppressing viral RNA synthesis, and a highly enriched cluster of endoplasmic reticulum (ER)/Golgi-resident ISGs inhibiting viral assembly/egress. These included broad-acting antiviral ISGs and eight ISGs that specifically inhibited SARS-CoV-2 and SARS-CoV-1 replication. Among the broad-acting ISGs was BST2/tetherin, which impeded viral release and is antagonized by SARS-CoV-2 Orf7a protein. Overall, these data illuminate a set of ISGs that underlie innate immune control of SARS-CoV-2/SARS-CoV-1 infection, which will facilitate the understanding of host determinants that impact disease severity and offer potential therapeutic strategies for COVID-19.

The capsid lattice engages a bipartite NUP153 motif to mediate nuclear entry of HIV-1 cores.

Increasing evidence has suggested that the HIV-1 capsid enters the nucleus in a largely assembled, intact form. However, not much is known about how the cone-shaped capsid interacts with the nucleoporins (NUPs) in the nuclear pore for crossing the nuclear pore complex. Here, we elucidate how NUP153 binds HIV-1 capsid by engaging the assembled capsid protein (CA) lattice. A bipartite motif containing both canonical and noncanonical interaction modules was identified at the C-terminal tail region of NUP153. The canonical cargo-targeting phenylalanine-glycine (FG) motif engaged the CA hexamer. By contrast, a previously unidentified triple-arginine (RRR) motif in NUP153 targeted HIV-1 capsid at the CA tri-hexamer interface in the capsid. HIV-1 infection studies indicated that both FG- and RRR-motifs were important for the nuclear import of HIV-1 cores. Moreover, the presence of NUP153 stabilized tubular CA assemblies in vitro. Our results provide molecular-level mechanistic evidence that NUP153 contributes to the entry of the intact capsid into the nucleus.

Functionalized DNA-Origami-Protein Nanopores Generate Large Transmembrane Channels with Programmable Size-Selectivity.

The DNA-origami technique has enabled the engineering of transmembrane nanopores with programmable size and functionality, showing promise in building biosensors and synthetic cells. However, it remains challenging to build large (>10 nm), functionalizable nanopores that spontaneously perforate lipid membranes. Here, we take advantage of pneumolysin (PLY), a bacterial toxin that potently forms wide ring-like channels on cell membranes, to construct hybrid DNA-protein nanopores. This PLY-DNA-origami complex, in which a DNA-origami ring corrals up to 48 copies of PLY, targets the cholesterol-rich membranes of liposomes and red blood cells, readily forming uniformly sized pores with an average inner diameter of ∼22 nm. Such hybrid nanopores facilitate the exchange of macromolecules between perforated liposomes and their environment, with the exchange rate negatively correlating with the macromolecule size (diameters of gyration: 8-22 nm). Additionally, the DNA ring can be decorated with intrinsically disordered nucleoporins to further restrict the diffusion of traversing molecules, highlighting the programmability of the hybrid nanopores. PLY-DNA pores provide an enabling biophysical tool for studying the cross-membrane translocation of ultralarge molecules and open new opportunities for analytical chemistry, synthetic biology, and nanomedicine.

Allosteric differences dictate GroEL complementation of E. coli.

GroES/GroEL is the only bacterial chaperone essential under all conditions, making it a potential antibiotic target. Rationally targeting ESKAPE GroES/GroEL as an antibiotic strategy necessitates studying their structure and function. Herein, we outline the structural similarities between Escherichia coli and ESKAPE GroES/GroEL and identify significant differences in intra- and inter-ring cooperativity, required in the refolding cycle of client polypeptides. Previously, we observed that one-half of ESKAPE GroES/GroEL family members could not support cell viability when each was individually expressed in GroES/GroEL-deficient E. coli cells. Cell viability was found to be dependent on the allosteric compatibility between ESKAPE and E. coli subunits within mixed (E. coli and ESKAPE) tetradecameric GroEL complexes. Interestingly, differences in allostery did not necessarily result in differences in refolding rate for a given homotetradecameric chaperonin. Characterization of ESKAPE GroEL allostery, ATPase, and refolding rates in this study will serve to inform future studies focused on inhibitor design and mechanism of action studies.

A first-principles study on the multiferroicity of semi-modified X2M (X = C, Si; M = F, Cl) monolayers.

The research of two-dimensional multiferroic materials has attracted extensive attention in recent years. In this work, we systematically investigated the multiferroic properties of semi-fluorinated and semi-chlorinated graphene and silylene X2M (X = C, Si; M = F, Cl) monolayers under strain using first principles calculations based on density functional theory. We find that the X2M monolayer has a frustrated antiferromagnetic order, and a large polarization with a high reversal potential barrier. When increasing the applied biaxial tensile strain, the magnetic order remains unchanged, but the polarization flipping potential barrier of X2M gradually decreases. When the strain increases to 35%, although the energy required to flip the fluorine and chlorine atoms is still very high in the C2F and C2Cl monolayers, it goes down to 312.5 meV and 260 meV in unit cells of the Si2F and Si2Cl monolayers, respectively. At the same time, both semi-modified silylenes exhibit metallic ferroelectricity with a band gap of at least 0.275 eV in the direction perpendicular to the plane. The results of these studies show that Si2F and Si2Cl monolayers may become a new generation of information storage materials with magnetoelectric multifunctional properties.

Iodine nutrition status and thyroid autoimmunity during pregnancy: a cross-sectional study of 4635 pregnant women.

BACKGROUND: Pregnant women in Shanghai have long been at risk for mild iodine deficiency. Because thyroid autoimmunity in pregnant women can lead to premature birth and miscarriage as well as neurodevelopmental deficits in the fetus, the aim of this study was to explore the association of iodine nutrition status with thyroid antibodies during pregnancy. METHODS: A pregnancy-birth cohort was conducted including 4635 pregnant women in Shanghai, China. The eligible participants underwent a face-to-face interview and completed questionnaire surveys to collect baseline information and diet intake. Spot urine samples were collected to test urine iodine. Thyroid antibodies including thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and thyrotrophic antibodies (TRAb) were tested. Single-factor analysis and logistic regression were used to evaluate the association between iodine status and thyroid autoimmunity during pregnancy. RESULTS: The median urinary iodine excretion level in the sample was 138.14 µg/L (interquartile range [IQR] 80.90-219.00 µg/L). Among all the subjects, 25.9% consumed non-iodized salt, 54.5% had iodine deficiency, and 31.0% had thyroid autoimmunity. The proportion of patients with iodine deficiency was significantly higher among those who consumed non-iodized salt (36.9% vs. 33.1%; p = 0.04). After adjusting for age, educational status, former smoker status, former drinker status, first pregnancy, and previous thyroid disease, non-iodized salt (odds ratio [OR] = 1.394 [confidence interval, CI, 1.165-1.562]; p = 0.003), iodine-rich food (OR = 0.681 [CI 0.585-0.793]; p = 0.003), iodized nutritional supplements (OR = 0.427 [CI 0.347-0.526]; p = 0.003), were found to be individually associated with thyroid autoimmunity in all participants. The results of the multivariable restricted cubic spline regression analysis showed a non-linear relationship between the continuous change in iodine intake and thyroid autoimmunity (p = 0.019). Participants with iodine deficiency (urinary iodine concentration, UIC,< 100 µg/L) had an increased risk of testing positive for thyroid antibodies (TPOAb/TgAb/TRAb[+]; OR = 1.324 [CI 1.125-1.559]; p < 0.001). Moreover, this associated existed even after removing participants with previous thyroid disease. CONCLUSION: Inadequate iodine nutrition in pregnant women is an independent risk factor for thyroid autoimmunity in Shanghai. It's important to maintain the adequate iodine status in pregnant women.

A study on the multiferroic properties of semi-hydrogenated X2H (X = C, Si, and Ge) monolayer films.

In recent years, the research on the physical properties of two-dimensional (2D) materials has attracted much attention. In this paper, the magnetic and ferroelectric (FE) properties of semi-hydrogenated graphene, silylene and germanene X2H (X = C, Si, and Ge) under strain are systematically investigated. The results have shown that X2H is a magnetic FE semiconductor with ferromagnetic (FM) and FE structures, both perpendicular to the plane, a large energy gap, and a high polarization reversal barrier. It is found that both the polarization reversal barrier and the magnitude of FE polarization gradually decrease, but the FM state remains the same, upon gradually increasing the tensile strain. As the tensile strain is increased to 19%, the barriers of the Si2H and Ge2H monolayer films to flip a single valence bond are decreased to 1.123 eV and 0.768 eV, respectively, and the systems still maintain semiconductor characteristics. When the strain is increased to 20%, the films begin to show metallicity in the plane of films, but still have the polarity perpendicular to the plane because of the anisotropy of the band structure. These research results suggest that the magnetoelectric properties of Si2H and Ge2H monolayer films provide the possibility for achieving a new generation of information storage materials.

Parkinson's disease-associated mutations in the GTPase domain of LRRK2 impair its nucleotide-dependent conformational dynamics.

Mutation in leucine-rich repeat kinase 2 (LRRK2) is a common cause of familial Parkinson's disease (PD). Recently, we showed that a disease-associated mutation R1441H rendered the GTPase domain of LRRK2 catalytically less active and thereby trapping it in a more persistently "on" conformation. However, the mechanism involved and characteristics of this on conformation remained unknown. Here, we report that the Ras of complex protein (ROC) domain of LRRK2 exists in a dynamic dimer-monomer equilibrium that is oppositely driven by GDP and GTP binding. We also observed that the PD-associated mutations at residue 1441 impair this dynamic and shift the conformation of ROC to a GTP-bound-like monomeric conformation. Moreover, we show that residue Arg-1441 is critical for regulating the conformational dynamics of ROC. In summary, our results reveal that the PD-associated substitutions at Arg-1441 of LRRK2 alter monomer-dimer dynamics and thereby trap its GTPase domain in an activated state.

The Parkinson's disease-associated mutation N1437H impairs conformational dynamics in the G domain of LRRK2.

Parkinson disease-associated mutations within the GTPase domain Ras of complex proteins (ROC) of leucine rich repeat kinase 2 (LRRK2) result in an abnormal over-activation of its kinase domain. However, the mechanisms involved remain unclear. Recent study has shown that LRRK2 G-domain cycles between monomeric and dimeric conformations upon binding to GTP or guanosine diphosphate, and that the Parkinson's disease (PD)-associated R1441C/G/H mutations impair the G-domain monomer-dimer dynamics and trap the G-domain in a constitutive monomeric conformation. That led us to question whether other disease-associated mutations in G-domain would also affect its conformation. Here, we report that another PD-associated N1437H mutation also impairs its monomer-dimer conformational dynamics and GTPase activity. In contrast with mutations at R1441, ROCN1437H was found to be locked in a stable dimeric conformation in solution and its GTPase activity was ∼4-fold lower than that of the wild-type. Furthermore, the N1437H mutation reduced the GTP binding affinity by ∼2.5-fold when compared with other pathogenic G-domain mutations. Moreover, ROCN1437H was found to have a slower GTP dissociation rate, indicating that N1437H might interrupt the nucleotide exchange cycle. Taken together, our data support that conformational dynamics is important for LRRK2 GTPase activity and that the N1437H mutation impairs GTPase activity by locking the ROC domain in a persistently dimeric state.-Huang, X., Wu, C., Park, Y., Long, X., Hoang, Q. Q., Liao, J. The Parkinson's disease-associated mutation N1437H impairs conformational dynamics in the G domain of LRRK2.

Caspase-1 causes truncation and aggregation of the Parkinson's disease-associated protein α-synuclein.

The aggregation of α-synuclein (aSyn) leading to the formation of Lewy bodies is the defining pathological hallmark of Parkinson's disease (PD). Rare familial PD-associated mutations in aSyn render it aggregation-prone; however, PD patients carrying wild type (WT) aSyn also have aggregated aSyn in Lewy bodies. The mechanisms by which WT aSyn aggregates are unclear. Here, we report that inflammation can play a role in causing the aggregation of WT aSyn. We show that activation of the inflammasome with known stimuli results in the aggregation of aSyn in a neuronal cell model of PD. The insoluble aggregates are enriched with truncated aSyn as found in Lewy bodies of the PD brain. Inhibition of the inflammasome enzyme caspase-1 by chemical inhibition or genetic knockdown with shRNA abated aSyn truncation. In vitro characterization confirmed that caspase-1 directly cleaves aSyn, generating a highly aggregation-prone species. The truncation-induced aggregation of aSyn is toxic to neuronal culture, and inhibition of caspase-1 by shRNA or a specific chemical inhibitor improved the survival of a neuronal PD cell model. This study provides a molecular link for the role of inflammation in aSyn aggregation, and perhaps in the pathogenesis of sporadic PD as well.

Effect of pretreatment with oral contraceptives and progestins on IVF outcomes in women with polycystic ovary syndrome.

STUDY QUESTION: Do oral contraceptives (OCs) and progestins impact live birth rate of IVF when used for cycle scheduling in women with polycystic ovary syndrome (PCOS)? SUMMARY ANSWER: OCs used for scheduling IVF cycle were associated with lowered rates of pregnancy and live birth after fresh embryo transfer, whereas progestins used for this purpose yield higher rates of pregnancy and live birth than OCs. WHAT IS KNOWN ALREADY: Due to oligo-menorrhea in PCOS, OCs and progestin are extensively used to schedule the start of an IVF cycle in women with PCOS. Little is known about the effect of such pretreatments on outcomes, especially, the rate of live birth. STUDY DESIGN, SIZE, DURATION: This was a nested cohort study and secondary analysis of a multicenter randomized trial, which was designed to compare live birth rate after fresh embryo transfer vs frozen embryo transfer (FET) in women with PCOS (Frefro-PCOS). A total of 1508 women were enrolled from 14 centers between June 2013 and May 2014. PARTICIPANTS/MATERIALS, SETTING, METHODS: At the discretion of local investigators, subjects were instructed to wait for spontaneous menses (Control group, n = 323), or were prescribed progestins (P group, n = 283) or OCs (OCs group, n = 902) to induce menstruation prior to the start of ovarian stimulation. GnRH antagonist protocol was initiated at Day 2 or 3 of induced or spontaneous menses cycle. The rates of pregnancy, pregnancy loss and live birth after either fresh embryo transfer or FET were compared among these three groups. MAIN RESULTS AND THE ROLE OF CHANCE: With fresh embryo transfer, women with OC-induced menses had lower rates of clinical pregnancy (48.8% vs 63.6%, relative rate (RR): 0.77, 95% CI: 0.66-0.89) and live birth (36.1% vs 48.1%, RR: 0.75, 95% CI: 0.61-0.92) than women with spontaneous menses. With freeze-all and deferred FET, women with OC-induced menses had a similar pregnancy rate but a higher pregnancy loss rate (27.7% vs 13.0%, RR: 2.13, 95% CI: 1.28-3.52) after FET than women with spontaneous menses. The live birth rate after FET in women with OC-induced menses, progestin-induced menses and spontaneous menses was 49.4%, 50.7% and 60.2%, respectively (P = 0.06). Progestin-induced menses was associated with similar rates of pregnancy, pregnancy loss and live birth after transfer of either fresh or frozen embryos compared with spontaneous menses. Multivariate logistic regression analysis showed that OCs used for menses induction was associated with lower rate of live birth. LIMITATIONS, REASONS FOR CAUTION: The methods for menses induction were not assigned randomly, thus selection bias was highly likely because of the study design and significant differences that were observed in the baseline characteristics of the women in the different groups. The mean BMI in this study population was relatively normal; the applicability of this result to obese PCOS women needs to be evaluated in further study. WIDER IMPLICATIONS OF THE FINDINGS: Our results suggest that either waiting for a spontaneous menses or using progestin is a better option than using OCs to induce menses in women with PCOS prior to ovarian stimulation using GnRH antagonist protocol for IVF. Further randomized controlled studies are needed to confirm our findings. STUDY FUNDING/COMPETING INTERESTS: This study was funded by National Basic Research Program of China (973 Program) (2012CB944700), the State Key Program of National Natural Science Foundation of China (81430029), National Natural Science Foundation of China (81471428) and Thousand Talents Program (Drs Legro and Zhang H). Dr Legro reports receiving consulting fees from Euroscreen, Kindex, Bayer and Millendo Pharmaceuticals and research funding from Ferring. Others report no disclosures. TRIAL REGISTRATION NUMBER: Frefro-PCOS was registered at Clinicaltrials.gov: NCT01841528.

Parkinson disease-associated mutation R1441H in LRRK2 prolongs the "active state" of its GTPase domain.

Mutation in leucine-rich-repeat kinase 2 (LRRK2) is a common cause of Parkinson disease (PD). A disease-causing point mutation R1441H/G/C in the GTPase domain of LRRK2 leads to overactivation of its kinase domain. However, the mechanism by which this mutation alters the normal function of its GTPase domain [Ras of complex proteins (Roc)] remains unclear. Here, we report the effects of R1441H mutation (RocR1441H) on the structure and activity of Roc. We show that Roc forms a stable monomeric conformation in solution that is catalytically active, thus demonstrating that LRRK2 is a bona fide self-contained GTPase. We further show that the R1441H mutation causes a twofold reduction in GTPase activity without affecting the structure, thermal stability, and GDP-binding affinity of Roc. However, the mutation causes a twofold increase in GTP-binding affinity of Roc, thus suggesting that the PD-causing mutation R1441H traps Roc in a more persistently activated state by increasing its affinity for GTP and, at the same time, compromising its GTP hydrolysis.

Structural and Biochemical Characterization of AidC, a Quorum-Quenching Lactonase with Atypical Selectivity.

Quorum-quenching catalysts are of interest for potential application as biochemical tools for interrogating interbacterial communication pathways, as antibiofouling agents, and as anti-infective agents in plants and animals. Herein, the structure and function of AidC, an N-acyl-l-homoserine lactone (AHL) lactonase from Chryseobacterium, is characterized. Steady-state kinetics show that zinc-supplemented AidC is the most efficient wild-type quorum-quenching enzymes characterized to date, with a kcat/KM value of approximately 2 × 10(6) M(-1) s(-1) for N-heptanoyl-l-homoserine lactone. The enzyme has stricter substrate selectivity and significantly lower KM values (ca. 50 µM for preferred substrates) compared to those of typical AHL lactonases (ca. >1 mM). X-ray crystal structures of AidC alone and with the product N-hexanoyl-l-homoserine were determined at resolutions of 1.09 and 1.67 Å, respectively. Each structure displays as a dimer, and dimeric oligiomerization was also observed in solution by size-exclusion chromatography coupled with multiangle light scattering. The structures reveal two atypical features as compared to previously characterized AHL lactonases: a "kinked" α-helix that forms part of a closed binding pocket that provides affinity and enforces selectivity for AHL substrates and an active-site His substitution that is usually found in a homologous family of phosphodiesterases. Implications for the catalytic mechanism of AHL lactonases are discussed.

Thermodynamic and structural characterization of the specific binding of Zn(II) to human protein DJ-1.

Mutations of DJ-1 cause familial Parkinson's disease (PD), although the role of DJ-1 in PD remains unresolved. Very recent reports have shown that DJ-1 interacts with copper ions. This evidence opens new avenues to understanding the function of DJ-1 and its role in PD. Herein, we report that Zn(II) binds to DJ-1 with great selectivity among the other metals examined: Mn(II), Fe(II), Co(II), Ni(II), and Cu(II). High-resolution X-ray crystallography (1.18 Å resolution) shows Zn(II) is coordinated to the protein by the key residues Cys106 and Glu18. These results suggest that DJ-1 may be regulated and/or stabilized by Zn(II).

Structural insights into PPP2R5A degradation by HIV-1 Vif.

HIV-1 Vif recruits host cullin-RING-E3 ubiquitin ligase and CBFß to degrade the cellular APOBEC3 antiviral proteins through diverse interactions. Recent evidence has shown that Vif also degrades the regulatory subunits PPP2R5(A-E) of cellular protein phosphatase 2A to induce G2/M cell cycle arrest. As PPP2R5 proteins bear no functional or structural resemblance to A3s, it is unclear how Vif can recognize different sets of proteins. Here we report the cryogenic-electron microscopy structure of PPP2R5A in complex with HIV-1 Vif-CBFß-elongin B-elongin C at 3.58 Å resolution. The structure shows PPP2R5A binds across the Vif molecule, with biochemical and cellular studies confirming a distinct Vif-PPP2R5A interface that partially overlaps with those for A3s. Vif also blocks a canonical PPP2R5A substrate-binding site, indicating that it suppresses the phosphatase activities through both degradation-dependent and degradation-independent mechanisms. Our work identifies critical Vif motifs regulating the recognition of diverse A3 and PPP2R5A substrates, whereby disruption of these host-virus protein interactions could serve as potential targets for HIV-1 therapeutics.

Bone morphogenetic protein 9 is a candidate prognostic biomarker and host-directed therapy target for sepsis.

Defining next-generation immune therapeutics for the treatment of sepsis will involve biomarker-based therapeutic decision-making. Bone morphogenetic protein 9 (BMP9) is a cytokine in the transforming growth factor-ß superfamily. Here, circulating BMP9 concentrations were quantified in two independent cohorts of patients with sepsis. Decreased concentrations of serum BMP9 were observed in the patients with sepsis at the time of admission as compared with healthy controls. Concentrations of BMP9 at the time of admission were also associated with 28-day mortality, because patients with sepsis at a higher risk of death had lower BMP9 concentrations. The mechanism driving the contribution of BMP9 to host immunity was further investigated using in vivo murine sepsis models and in vitro cell models. We found that BMP9 treatment improved outcome in mice with experimental sepsis. BMP9-treated mice exhibited increased macrophage influx into the peritoneal cavity and more efficient bacterial clearance than untreated mice. In vitro, BMP9 promoted macrophage recruitment, phagocytosis, and subsequent bacterial killing. We further found that deletion of the type 1 BMP receptor ALK1 in macrophages abolished BMP9-mediated protection against polymicrobial sepsis in vivo. Further experiments indicated that the regulation of macrophage activation by the BMP9-ALK1 axis was mainly mediated through the suppressor of mother against decapentaplegic 1/5 signaling pathway. Together, these results suggest that BMP9 can both serve as a biomarker for patient stratification with an independent prognostic value and be developed as a host-directed therapy for sepsis.

Channel width modulates the permeability of DNA origami based nuclear pore mimics.

Nucleoporins (nups) in the central channel of nuclear pore complexes (NPCs) form a selective barrier that suppresses the diffusion of most macromolecules while enabling rapid transport of nuclear transport receptors (NTRs) with bound cargos. The complex molecular interactions between nups and NTRs have been thought to underlie the gatekeeping function of the NPC. Recent studies have shown considerable variation in NPC diameter but how altering NPC diameter might impact the selective barrier properties remains unclear. Here, we build DNA nanopores with programmable diameters and nup arrangement to mimic NPCs of different diameters. We use hepatitis B virus (HBV) capsids as a model for large-size cargos. We find that Nup62 proteins form a dynamic cross-channel meshwork impermeable to HBV capsids when grafted on the interior of 60-nm wide nanopores but not in 79-nm pores, where Nup62 cluster locally. Furthermore, importing substantially changes the dynamics of Nup62 assemblies and facilitates the passage of HBV capsids through NPC mimics containing Nup62 and Nup153. Our study shows the transport channel width is critical to the permeability of nup barriers and underscores the role of NTRs in dynamically remodeling nup assemblies and mediating the nuclear entry of viruses.

Bifidobacterium as a Potential Biomarker of Sarcopenia in Elderly Women.

Gut microbial dysbiosis influences the development of sarcopenia. This case-control study explored the gut microbiota composition in elderly Chinese women with sarcopenia. The information from 50 cases and 50 controls was collected. Grip strength, body weight, body mass index, skeletal muscle mass, energy intake, and total and high-quality protein intake were lower in cases than in controls (p < 0.05). Gut microbiota metagenomic sequencing showed that phylum Bacteroides was significantly reduced in the case group, whereas genus Prevotella was more abundant (p < 0.05). Linear discriminant analysis (LDA) effect size showed that 9 and 13 distinct microbial taxa were enriched in the case and control groups, respectively (LDA > 2, p < 0.05), among which Prevotella copri and Bifidobacterium longum were significantly different (LDA > 4, p < 0.05). The AUC of Bifidobacterium longum was 0.674 (95% CI: 0.539-0.756). Elderly women with sarcopenia exhibited significantly different gut microbiota compositions than healthy controls.

Abl2 repairs microtubules and phase separates with tubulin to promote microtubule nucleation.

Abl family kinases are evolutionarily conserved regulators of cell migration and morphogenesis. Genetic experiments in Drosophila suggest that Abl family kinases interact functionally with microtubules to regulate axon guidance and neuronal morphogenesis. Vertebrate Abl2 binds to microtubules and promotes their plus-end elongation, both in vitro and in cells, but the molecular mechanisms by which Abl2 regulates microtubule (MT) dynamics are unclear. We report here that Abl2 regulates MT assembly via condensation and direct interactions with both the MT lattice and tubulin dimers. We find that Abl2 promotes MT nucleation, which is further facilitated by the ability of the Abl2 C-terminal half to undergo liquid-liquid phase separation (LLPS) and form co-condensates with tubulin. Abl2 binds to regions adjacent to MT damage, facilitates MT repair via fresh tubulin recruitment, and increases MT rescue frequency and lifetime. Cryo-EM analyses strongly support a model in which Abl2 engages tubulin C-terminal tails along an extended MT lattice conformation at damage sites to facilitate repair via fresh tubulin recruitment. Abl2Δ688-790, which closely mimics a naturally occurring splice isoform, retains binding to the MT lattice but does not bind tubulin, promote MT nucleation, or increase rescue frequency. In COS-7 cells, MT reassembly after nocodazole treatment is greatly slowed in Abl2 knockout COS-7 cells compared with wild-type cells, and these defects are rescued by re-expression of Abl2, but not Abl2Δ688-790. We propose that Abl2 locally concentrates tubulin to promote MT nucleation and recruits it to defects in the MT lattice to enable repair and rescue.

Modeling HIV-1 nuclear entry with nucleoporin-gated DNA-origami channels.

Delivering the virus genome into the host nucleus through the nuclear pore complex (NPC) is pivotal in human immunodeficiency virus 1 (HIV-1) infection. The mechanism of this process remains mysterious owing to the NPC complexity and the labyrinth of molecular interactions involved. Here we built a suite of NPC mimics-DNA-origami-corralled nucleoporins with programmable arrangements-to model HIV-1 nuclear entry. Using this system, we determined that multiple cytoplasm-facing Nup358 molecules provide avid binding for capsid docking to the NPC. The nucleoplasm-facing Nup153 preferentially attaches to high-curvature regions of the capsid, positioning it for tip-leading NPC insertion. Differential capsid binding strengths of Nup358 and Nup153 constitute an affinity gradient that drives capsid penetration. Nup62 in the NPC central channel forms a barrier that viruses must overcome during nuclear import. Our study thus provides a wealth of mechanistic insight and a transformative toolset for elucidating how viruses like HIV-1 enter the nucleus.