| 1. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 2. |
- Holmqvist, Fredrik, et al.
(författare)
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A decade of catheter ablation of cardiac arrhythmias in Sweden : ablation practices and outcomes
- 2019
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 40:10, s. 820-830
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Catheter ablation is considered the treatment of choice for many tachyarrhythmias, but convincing 'real-world' data on efficacy and safety are lacking. Using Swedish national registry data, the ablation spectrum, procedural characteristics, as well as ablation efficacy and reported adverse events are reported.Methods and Results: Consecutive patients (≥18 years of age) undergoing catheter ablation in Sweden between 01 January 2006 and 31 December 2015 were included in the study. Follow-up (repeat ablation and vital status) was collected through 31 December 2016. A total of 26 642 patients (57 ± 15 years, 62% men), undergoing a total of 34 428 ablation procedures were included in the study. In total, 4034 accessory pathway/Wolff-Parkinson-White syndrome (12%), 7358 AV-nodal re-entrant tachycardia (21%), 1813 atrial tachycardia (5.2%), 5481 typical atrial flutter (16%), 11 916 atrial fibrillation (AF, 35%), 2415 AV-nodal (7.0%), 581 premature ventricular contraction (PVC, 1.7%), and 964 ventricular tachycardia (VT) ablations (2.8%) were performed. Median follow-up time was 4.7 years (interquartile range 2.7-7.0). The spectrum of treated arrhythmias changed over time, with a gradual increase in AF, VT, and PVC ablation (P < 0.001). Decreasing procedural times and utilization of fluoroscopy with time, were seen for all arrhythmia types. The rates of repeat ablation differed between ablation types, with the highest repeat ablation seen in AF (41% within 3 years). The rate of reported adverse events was low (n = 595, 1.7%). Death in the immediate period following ablation was rare (n = 116, 0.34%).Conclusion: Catheter ablations have shifted towards more complex procedures over the past decade. Fluoroscopy time has markedly decreased and the efficacy of catheter ablation seems to improve for AF.
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| 3. |
- Lagou, Vasiliki, et al.
(författare)
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Sex-dimorphic genetic effects and novel loci for fasting glucose and insulin variability
- 2021
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Differences between sexes contribute to variation in the levels of fasting glucose and insulin. Epidemiological studies established a higher prevalence of impaired fasting glucose in men and impaired glucose tolerance in women, however, the genetic component underlying this phenomenon is not established. We assess sex-dimorphic (73,089/50,404 women and 67,506/47,806 men) and sex-combined (151,188/105,056 individuals) fasting glucose/fasting insulin genetic effects via genome-wide association study meta-analyses in individuals of European descent without diabetes. Here we report sex dimorphism in allelic effects on fasting insulin at IRS1 and ZNF12 loci, the latter showing higher RNA expression in whole blood in women compared to men. We also observe sex-homogeneous effects on fasting glucose at seven novel loci. Fasting insulin in women shows stronger genetic correlations than in men with waist-to-hip ratio and anorexia nervosa. Furthermore, waist-to-hip ratio is causally related to insulin resistance in women, but not in men. These results position dissection of metabolic and glycemic health sex dimorphism as a steppingstone for understanding differences in genetic effects between women and men in related phenotypes.
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| 4. |
- Laurent, Timothée, et al.
(författare)
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Architecture of the chikungunya virus replication organelle
- 2022
-
Ingår i: eLIFE. - : eLife Sciences Publications. - 2050-084X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Alphaviruses are mosquito-borne viruses that cause serious disease in humans and other mammals. Along with its mosquito vector, the Alphavirus chikungunya virus (CHIKV) has spread explosively in the last 20 years, and there is no approved treatment for chikungunya fever. On the plasma membrane of the infected cell, CHIKV generates dedicated organelles for viral RNA replication, so-called spherules. Whereas structures exist for several viral proteins that make up the spherule, the architecture of the full organelle is unknown. Here, we use cryo-electron tomography to image CHIKV spherules in their cellular context. This reveals that the viral protein nsP1 serves as a base for the assembly of a larger protein complex at the neck of the membrane bud. Biochemical assays show that the viral helicase-protease nsP2, while having no membrane affinity on its own, is recruited to membranes by nsP1. The tomograms further reveal that full-sized spherules contain a single copy of the viral genome in double-stranded form. Finally, we present a mathematical model that explains the membrane remodeling of the spherule in terms of the pressure exerted on the membrane by the polymerizing RNA, which provides a good agreement with the experimental data. The energy released by RNA polymerization is found to be sufficient to remodel the membrane to the characteristic spherule shape.
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| 5. |
- Martínez-Carranza, Markel, et al.
(författare)
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A ribonucleotide reductase from Clostridium botulinum reveals distinct evolutionary pathways to regulation via the overall activity site
- 2020
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 295:46, s. 15576-15587
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Tidskriftsartikel (refereegranskat)abstract
- Ribonucleotide reductase (RNR) is a central enzyme for the synthesis of DNA building blocks. Most aerobic organisms, including nearly all eukaryotes, have class I RNRs consisting of R1 and R2 subunits. The catalytic R1 subunit contains an overall activity site that can allosterically turn the enzyme on or off by the binding of ATP or dATP, respectively. The mechanism behind the ability to turn the enzyme off via the R1 subunit involves the formation of different types of R1 oligomers in most studied species and R1–R2 octamers in Escherichia coli. To better understand the distribution of different oligomerization mechanisms, we characterized the enzyme from Clostridium botulinum, which belongs to a subclass of class I RNRs not studied before. The recombinantly expressed enzyme was analyzed by size-exclusion chromatography, gas-phase electrophoretic mobility macromolecular analysis, EM, X-ray crystallography, and enzyme assays. Interestingly, it shares the ability of the E. coli RNR to form inhibited R1–R2 octamers in the presence of dATP but, unlike the E. coli enzyme, cannot be turned off by combinations of ATP and dGTP/dTTP. A phylogenetic analysis of class I RNRs suggests that activity regulation is not ancestral but was gained after the first subclasses diverged and that RNR subclasses with inhibition mechanisms involving R1 oligomerization belong to a clade separated from the two subclasses forming R1–R2 octamers. These results give further insight into activity regulation in class I RNRs as an evolutionarily dynamic process.
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| 6. |
- Persson, B. David, et al.
(författare)
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Human species D adenovirus hexon capsid protein mediates cell entry through a direct interaction with CD46
- 2021
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 118:3
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Tidskriftsartikel (refereegranskat)abstract
- Human adenovirus species D (HAdV-D) types are currently being explored as vaccine vectors for coronavirus disease 2019 (COVID-19) and other severe infectious diseases. The efficacy of such vector-based vaccines depends on functional interactions with receptors on host cells. Adenoviruses of different species are assumed to enter host cells mainly by interactions between the knob domain of the protruding fiber capsid protein and cellular receptors. Using a cell-based receptor-screening assay, we identified CD46 as a receptor for HAdV-D56. The function of CD46 was validated in infection experiments using cells lacking and overexpressing CD46, and by competition infection experiments using soluble CD46. Remarkably, unlike HAdV-B types that engage CD46 through interactions with the knob domain of the fiber protein, HAdV-D types infect host cells through a direct interaction between CD46 and the hexon protein. Soluble hexon proteins (but not fiber knob) inhibited HAdV-D56 infection, and surface plasmon analyses demonstrated that CD46 binds to HAdV-D hexon (but not fiber knob) proteins. Cryoelectron microscopy analysis of the HAdV-D56 virion-CD46 complex confirmed the interaction and showed that CD46 binds to the central cavity of hexon trimers. Finally, soluble CD46 inhibited infection by 16 out of 17 investigated HAdV-D types, suggesting that CD46 is an important receptor for a large group of adenoviruses. In conclusion, this study identifies a noncanonical entry mechanism used by human adenoviruses, which adds to the knowledge of adenovirus biology and can also be useful for development of adenovirus-based vaccine vectors.
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| 7. |
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| 8. |
- Wehlin, Anna, 1994-
(författare)
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Structural and Functional Studies on Evolutionary Repurposing of H-box/NC-proteins : From Host Factor to Virus Protein
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Picornaviridae are a large family of biomedically important viruses causing diseases such as the common cold, hepatitis A and polio in humans and foot-and-mouth disease in cattle. These diseases have great impact on people’s everyday life and cause economical losses all around the world. To date, no antiviral treatments are available. In attempts to identify potential drug targets for novel antiviral therapies, a human protein was identified as a common host factor for several enteroviruses, a genus within the picornavirus family. This host factor, PLAAT3, facilitates genome transfer from the virus particle into the cytoplasm early in the viral lifecycle prior to virus clearance by autophagy. PLAAT3 is part of a human phospholipid-modifying enzyme family of five members, PLAAT1-5, which all have a conserved H-box/NC-motif forming the active site of these enzymes as well as a hydrophobic C-terminal region that is critical for enzymatic function. This H-box/ NC-motif is also found in the 2A locus of some picornaviruses, suggesting that these viruses might have acquired the protein through horizontal gene transfer to become independent of the human host factor.This thesis focuses on understanding the structural mechanism allowing picornavirus infection. Therefore, two members of the PLAAT-family were studied together with viral 2A proteins sharing the H-box/NC-motif.PLAAT3 was studied with the aim to elucidate its molecular mechanism underpinning its role as a host factor enabling genome transfer. PLAAT3 is composed of a globular N-terminal domain (NTD), whose structure has previously been determined, followed by a 30 amino acid long hydrophobic region (CTR). The catalytic site is located within the NTD, but the hydrophobic CTR is essential both for the catalytic activity as well as cellular localization of PLAAT3.PLAAT4 shares 50% sequence identity with PLAAT3 and exhibits a similar structure with a globular NTD followed by a hydrophobic tail. However, PLAAT4 shows a different activity pattern and displays enzymatic activity even in the absence of the CTR. By comparing the structural properties of PLAAT3 and PLAAT4 more can be understood of the structural characteristics enabling biological functions.The viral 2A proteins studied in this thesis originate from different picornavirus genera but all share the conserved H-box/NC-motif with the PLAAT-family. By investigating the structure and function of representative 2AH/NC proteins from different branches of the phylogenetic tree we aim to identify different steps of evolutionary repurposing to help us understand their role(s) in the viral lifecycle and determine the molecular mechanism allowing them to by-pass PLAAT3 as a host factor.
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| 9. |
- Andréasson, Maia, 1960, et al.
(författare)
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Swedish CLARIN activities
- 2009
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Ingår i: Proceedings of the Nodalida 2009 workshop on CLARIN activities in the Nordic countries. NEALT Proceedings Series. - 1736-6305. ; 5, s. 1-5
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Konferensbidrag (refereegranskat)
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| 10. |
- Carlson, Rolf, et al.
(författare)
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Speech and music performance : parallels and contrasts
- 1989
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Ingår i: Contemporary Music Review. - 0749-4467 .- 1477-2256. ; 4, s. 389-402
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Tidskriftsartikel (refereegranskat)abstract
- Speech and music performance are two important systems for interhuman communication by means of acoustic signals. These signals must be adapted to the human perceptual and cognitive systems. Hence a comparitive analysis of speech and music performances is likely to shed light on these systems, particularly regarding basic requirements for acoustic communication. Two computer programs are compared, one for text-to-speech conversion and one for note-to-tone conversion. Similarities are found in the need for placing emphasis on unexpected elements, for increasing the dissimilarities between different categories, and for flagging structural constituents. Similarities are also found in the code chosen for conveying this information, e.g. emphasis by lengthening and constituent marking by final lengthening.
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| 11. |
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| 12. |
- Chotiwan, Nunya, et al.
(författare)
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Type I interferon shapes brain distribution and tropism of tick-borne flavivirus
- 2023
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Viral tropism within the brain and the role(s) of vertebrate immune response to neurotropic flaviviruses infection is largely understudied. We combine multimodal imaging (cm-nm scale) with single nuclei RNA-sequencing to study Langat virus in wildtype and interferon alpha/beta receptor knockout (Ifnar-/-) mice to visualize viral pathogenesis and define molecular mechanisms. Whole brain viral infection is imaged by Optical Projection Tomography coregistered to ex vivo MRI. Infection is limited to grey matter of sensory systems in wildtype mice, but extends into white matter, meninges and choroid plexus in Ifnar-/- mice. Cells in wildtype display strong type I and II IFN responses, likely due to Ifnb expressing astrocytes, infiltration of macrophages and Ifng-expressing CD8+ NK cells, whereas in Ifnar-/-, the absence of this response contributes to a shift in cellular tropism towards non-activated resident microglia. Multimodal imaging-transcriptomics exemplifies a powerful way to characterize mechanisms of viral pathogenesis and tropism.
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| 13. |
- Dahmane, Selma, et al.
(författare)
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A 3D view of how enteroviruses hijack autophagy
- 2023
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Ingår i: Autophagy. - : Taylor & Francis Group. - 1554-8627 .- 1554-8635. ; 19:7, s. 2156-2158
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Tidskriftsartikel (refereegranskat)abstract
- Viruses are masters at using cellular pathways to aid their replication. Cryo-electron tomography of poliovirus-infected cells revealed how it utilizes macroautophagy to its advantage. Assembly of these non-enveloped virions takes place directly on membranes and requires PIK3C3/VPS34 activity to be completed, whereas the canonical autophagy inducer ULK1 restricts virus assembly. The tomograms further revealed that enterovirus-induced autophagy is selective for RNA-loaded virions, which may help ensure maximum infectivity of the virus-laden vesicles released through secretory autophagy.
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| 14. |
- Dahmane, Selma, et al.
(författare)
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Membrane-assisted assembly and selective secretory autophagy of enteroviruses
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Enteroviruses are non-enveloped positive-sense RNA viruses that cause diverse diseases in humans. Their rapid multiplication depends on remodeling of cytoplasmic membranes for viral genome replication. It is unknown how virions assemble around these newly synthesized genomes and how they are then loaded into autophagic membranes for release through secretory autophagy. Here, we use cryo-electron tomography of infected cells to show that poliovirus assembles directly on replication membranes. Pharmacological untethering of capsids from membranes abrogates RNA encapsidation. Our data directly visualize a membrane-bound half-capsid as a prominent virion assembly intermediate. Assembly progression past this intermediate depends on the class III phosphatidylinositol 3-kinase VPS34, a key host-cell autophagy factor. On the other hand, the canonical autophagy initiator ULK1 is shown to restrict virion production since its inhibition leads to increased accumulation of virions in vast intracellular arrays, followed by an increased vesicular release at later time points. Finally, we identify multiple layers of selectivity in virus-induced autophagy, with a strong selection for RNA-loaded virions over empty capsids and the segregation of virions from other types of autophagosome contents. These findings provide an integrated structural framework for multiple stages of the poliovirus life cycle. Enteroviruses are non-enveloped positive-sense RNA viruses that modulate cytoplasmic membranes for replication. To enlighten how enteroviruses assemble around nascent RNA genomes and get package into autophagosomes for release, Dahmane et al. perform cryo-electron tomography of poliovirus-infected cells. They find assembly intermediates that are only present on the cytosolic side of the replication compartment and provide evidence that host factor VPS34 is involved in progression of assembly intermediates.
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| 15. |
- Duffy, Stephen W., et al.
(författare)
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Mammography screening reduces rates of advanced and fatal breast cancers : Results in 549,091 women
- 2020
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Ingår i: Cancer. - : John Wiley & Sons. - 0008-543X .- 1097-0142. ; 126:13, s. 2971-2979
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Tidskriftsartikel (refereegranskat)abstract
- Background: It is of paramount importance to evaluate the impact of participation in organized mammography service screening independently from changes in breast cancer treatment. This can be done by measuring the incidence of fatal breast cancer, which is based on the date of diagnosis and not on the date of death.Methods: Among 549,091 women, covering approximately 30% of the Swedish screening‐eligible population, the authors calculated the incidence rates of 2473 breast cancers that were fatal within 10 years after diagnosis and the incidence rates of 9737 advanced breast cancers. Data regarding each breast cancer diagnosis and the cause and date of death of each breast cancer case were gathered from national Swedish registries. Tumor characteristics were collected from regional cancer centers. Aggregated data concerning invitation and participation were provided by Sectra Medical Systems AB. Incidence rates were analyzed using Poisson regression.Results: Women who participated in mammography screening had a statistically significant 41% reduction in their risk of dying of breast cancer within 10 years (relative risk, 0.59; 95% CI, 0.51‐0.68 [P < .001]) and a 25% reduction in the rate of advanced breast cancers (relative risk, 0.75; 95% CI, 0.66‐0.84 [P < .001]).Conclusions: Substantial reductions in the incidence rate of breast cancers that were fatal within 10 years after diagnosis and in the advanced breast cancer rate were found in this contemporaneous comparison of women participating versus those not participating in screening. These benefits appeared to be independent of recent changes in treatment regimens.
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| 16. |
- Jia, Xiaotong, et al.
(författare)
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V. cholerae MakA is a cholesterol-binding pore-forming toxin that induces non-canonical autophagy
- 2022
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Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 221:12
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Tidskriftsartikel (refereegranskat)abstract
- Pore-forming toxins (PFTs) are important virulence factors produced by many pathogenic bacteria. Here, we show that the Vibrio cholerae toxin MakA is a novel cholesterol-binding PFT that induces non-canonical autophagy in a pH-dependent manner. MakA specifically binds to cholesterol on the membrane at pH < 7. Cholesterol-binding leads to oligomerization of MakA on the membrane and pore formation at pH 5.5. Unlike other cholesterol-dependent cytolysins (CDCs) which bind cholesterol through a conserved cholesterol-binding motif (Thr-Leu pair), MakA contains an Ile-Ile pair that is essential for MakA-cholesterol interaction. Following internalization, endosomal acidification triggers MakA pore-assembly followed by ESCRT-mediated membrane repair and V-ATPase-dependent unconventional LC3 lipidation on the damaged endolysosomal membranes. These findings characterize a new cholesterol-binding toxin that forms pores in a pH-dependent manner and reveals the molecular mechanism of host autophagy manipulation.
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| 17. |
- Jin, Jing, et al.
(författare)
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An attenuated replication-competent chikungunya virus with a fluorescently tagged envelope
- 2018
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Ingår i: PLoS Neglected Tropical Diseases. - : PUBLIC LIBRARY SCIENCE. - 1935-2727 .- 1935-2735. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Chikungunya virus (CHIKV) is the most common alphavirus infecting humans worldwide, causing acute and chronically debilitating arthralgia at a great economic expense.Methodology/Principal findings: To facilitate our study of CHIKV, we generated a mCherry tagged replication-competent chimeric virus, CHIKV 37997-mCherry. Single particle cryoEM demonstrated icosahedral organization of the chimeric virus and the display of mCherry proteins on virus surface. CHIKV 37997-mCherry is attenuated in both IFN alpha R knockout and wild-type mice. Strong antiCHIKV and anti-mCherry antibody responses were induced in CHIKV 37997-mCherry infected mice.Conclusions/Significance: Our work suggests that chimeric alphaviruses displaying foreign antigen can serve as vaccines against both aphaviruses and other pathogens and diseases.
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| 18. |
- Jin, Jing, et al.
(författare)
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Neutralizing Antibodies Inhibit Chikungunya Virus Budding at the Plasma Membrane
- 2018
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Ingår i: Cell Host and Microbe. - : Cell Press. - 1931-3128 .- 1934-6069. ; 24:3, s. 417-
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Tidskriftsartikel (refereegranskat)abstract
- Neutralizing antibodies (NAbs) are traditionally thought to inhibit virus infection by preventing virion entry into target cells. In addition, antibodies can engage Fc receptors (FcRs) on immune cells to activate antiviral responses. We describe a mechanism by which NAbs inhibit chikungunya virus (CHIKV), the most common alphavirus infecting humans, by preventing virus budding from infected human cells and activating IgG-specific Fc gamma receptors. NAbs bind to CHIKV glycoproteins on the infected cell surface and induce glycoprotein coalescence, preventing budding of nascent virions and leaving structurally heterogeneous nucleocapsids arrested in the cytosol. Furthermore, NAbs induce clustering of CHIKV replication spherules at sites of budding blockage. Functionally, these densely packed glycoprotein-NAb complexes on infected cells activate Fc gamma receptors, inducing a strong, antibody-dependent, cell-mediated cytotoxicity response from immune effector cells. Our findings describe a triply functional antiviral pathway for NAbs that might be broadly applicable across virus-host systems, suggesting avenues for therapeutic innovation through antibody design.
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| 19. |
- Knyazeva, Anastasia, 1995-, et al.
(författare)
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A chemical inhibitor of IST1-CHMP1B interaction impairs endosomal recycling and induces noncanonical LC3 lipidation
- 2024
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 121:17
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Tidskriftsartikel (refereegranskat)abstract
- The endosomal sorting complex required for transport (ESCRT) machinery constitutes multisubunit protein complexes that play an essential role in membrane remodeling and trafficking. ESCRTs regulate a wide array of cellular processes, including cytokinetic abscission, cargo sorting into multivesicular bodies (MVBs), membrane repair, and autophagy. Given the versatile functionality of ESCRTs, and the intricate organizational structure of the ESCRT machinery, the targeted modulation of distinct ESCRT complexes is considerably challenging. This study presents a pseudonatural product targeting IST1-CHMP1B within the ESCRT-III complexes. The compound specifically disrupts the interaction between IST1 and CHMP1B, thereby inhibiting the formation of IST1-CHMP1B copolymers essential for normal-topology membrane scission events. While the compound has no impact on cytokinesis, MVB sorting, or biogenesis of extracellular vesicles, it rapidly inhibits transferrin receptor recycling in cells, resulting in the accumulation of transferrin in stalled sorting endosomes. Stalled endosomes become decorated by lipidated LC3, suggesting a link between noncanonical LC3 lipidation and inhibition of the IST1-CHMP1B complex.
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| 20. |
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| 21. |
- Kumar, Pravin, et al.
(författare)
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Clinically observed deletions in SARS-CoV-2 Nsp1 affect its stability and ability to inhibit translation
- 2022
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Ingår i: FEBS Letters. - : John Wiley & Sons. - 0014-5793 .- 1873-3468. ; 596:9, s. 1203-1213
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Tidskriftsartikel (refereegranskat)abstract
- Nonstructural protein 1 (Nsp1) of SARS-CoV-2 inhibits host cell translation through an interaction between its C-terminal domain and the 40S ribosome. The N-terminal domain (NTD) of Nsp1 is a target of recurring deletions, some of which are associated with altered COVID-19 disease progression. Here, we characterize the efficiency of translational inhibition by clinically observed Nsp1 deletion variants. We show that a frequent deletion of residues 79–89 severely reduces the ability of Nsp1 to inhibit translation while not abrogating Nsp1 binding to the 40S. Notably, while the SARS-CoV-2 5′ untranslated region enhances translation of mRNA, it does not protect from Nsp1-mediated inhibition. Finally, thermal stability measurements and structure predictions reveal a correlation between stability of the NTD and the efficiency of translation inhibition.
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| 22. |
- Lasswitz, Lisa, et al.
(författare)
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The tetraspanin CD81 is a host factor for Chikungunya virus replication
- 2022
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Ingår i: mBio. - : ASM International. - 2161-2129 .- 2150-7511. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Chikungunya virus (CHIKV) is an arthritogenic reemerging virus replicating in plasma membrane-derived compartments termed "spherules." Here, we identify the human transmembrane protein CD81 as host factor required for CHIKV replication. Ablation of CD81 results in decreased CHIKV permissiveness, while overexpression enhances infection. CD81 is dispensable for virus uptake but critically required for viral genome replication. Likewise, murine CD81 is crucial for CHIKV permissiveness and is expressed in target cells such as dermal fibroblasts, muscle and liver cells. Whereas related alphaviruses, including Ross River virus (RRV), Semliki Forest virus (SFV), Sindbis virus (SINV) and Venezuelan equine encephalitis virus (VEEV), also depend on CD81 for infection, RNA viruses from other families, such as coronaviruses, replicate independently of CD81. Strikingly, the replication-enhancing function of CD81 is linked to cholesterol binding. These results define a mechanism exploited by alphaviruses to hijack the membrane microdomain-modeling protein CD81 for virus replication through interaction with cholesterol.IMPORTANCE: In this study, we discover the tetraspanin CD81 as a host factor for the globally emerging chikungunya virus and related alphaviruses. We show that CD81 promotes replication of viral genomes in human and mouse cells, while virus entry into cells is independent of CD81. This provides novel insights into how alphaviruses hijack host proteins to complete their life cycle. Alphaviruses replicate at distinct sites of the plasma membrane, which are enriched in cholesterol. We found that the cholesterol-binding ability of CD81 is important for its function as an alphavirus host factor. This discovery thus broadens our understanding of the alphavirus replication process and the use of host factors to reprogram cells into virus replication factories.
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| 23. |
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| 24. |
- Laurent, Timothée, 1991-
(författare)
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Macromolecular organization of the chikungunya virus replication organelle
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The chikungunya virus is a positive-sense RNA virus responsible for the crippling chikungunya fever. It is transmitted through the bites of two species of mosquitoes: Aedes aegypti and Aedes albopictus. A key feature of this virus is that it is able to remodel the plasma membrane to form replication organelles called “spherules” in which the viral genomic RNA is replicated. There are four non-structural proteins in charge of the replication of the genome: nsP1, the capping enzyme, nsP2 the helicase, NTPase and protease, nsP3, a protein modulating the host-cell response to the infection and the RNA-dependent RNA polymerase nsP4. When I started my PhD, spherules had only been imaged using resin-embedding electron microscopy, which does not preserve macromolecular structure. It was unknown how the different non-structural proteins interacted with each other. The process leading to formation and maintenance of spherules at the plasma membrane was also not known. Using cryo-electron tomography, we could image spherules and unveil their macromolecular organization. We could identify a previously unreported two megadalton protein complex sitting at the neck of spherules, serving as an interface between the lumen of spherules and the cytoplasm. We found that nsP1 binds to negatively charged lipids at the plasma membrane. We also report that the host factor CD81, known to bind cholesterol at the plasma membrane, is a key element for the virus replication.We could establish a mathematical model highlighting the way those spherules form and are maintained at the plasma membrane. We quantified the amount of genomic RNA present in each spherule and found that a single copy was present as a double-stranded replication intermediate. We further studied the spatial organization of the viral genome in spherules and found that it occupies homogenously the lumen of these replication organelles and has a moderate preferential folding inside spherules.We aimed to characterize further the ATPase and helicase activities of nsP2 and nsP2 associated to nsP1 or nsP3 as polyproteins. These polyproteins are present in the early stages of the viral RNA replication. We estimated the kinetic parameters of the ATPase function of these proteins and showed that nsp2 had a helicase activity however; the helicase functions of P12 and P23 were severely reduced. We could show that P12 and P23 exhibited instead an ATP-independent chaperoning activity, able to partially unwind double-stranded RNA.
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| 25. |
- Laurent, Timothée, et al.
(författare)
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The organization of double-stranded RNA in the chikungunya virus replication organelle
- 2023
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Ingår i: PLoS Neglected Tropical Diseases. - : Public Library of Science (PLoS). - 1935-2727 .- 1935-2735. ; 17:7
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Tidskriftsartikel (refereegranskat)abstract
- Alphaviruses are mosquito-borne, positive-sense single-stranded RNA viruses. Amongst the alphaviruses, chikungunya virus is notable as a large source of human illness, especially in tropical and subtropical regions. When they invade a cell, alphaviruses generate dedicated organelles for viral genome replication, so-called spherules. Spherules form as outward-facing buds at the plasma membrane, and it has recently been shown that the thin membrane neck that connects this membrane bud with the cytoplasm is guarded by a two-megadalton protein complex that contains all the enzymatic functions necessary for RNA replication. The lumen of the spherules contains a single copy of the negative-strand template RNA, present in a duplex with newly synthesized positive-sense RNA. Less is known about the organization of this double-stranded RNA as compared to the protein components of the spherule. Here, we analyzed cryo-electron tomograms of chikungunya virus spherules in terms of the organization of the double-stranded RNA replication intermediate. We find that the double-stranded RNA has a shortened apparent persistence length as compared to unconstrained double-stranded RNA. Around half of the genome is present in either of five conformations identified by subtomogram classification, each representing a relatively straight segment of ~25–32 nm. Finally, the RNA occupies the spherule lumen at a homogeneous density, but has a preferred orientation to be perpendicular to a vector pointing from the membrane neck towards the spherule center. Taken together, this analysis lays another piece of the puzzle of the highly coordinated alphavirus genome replication.
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| 26. |
- Olsson-Strömberg, Ulla, et al.
(författare)
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Successful mobilization of Ph-negative blood stem cells with intensive chemotherapy + G-CSF in patients with chronic myelogenous leukemia in first chronic phase
- 2006
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Ingår i: Leukemia and Lymphoma. - : Informa UK Limited. - 1042-8194 .- 1029-2403. ; 47:9, s. 1768-73
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to investigate the feasibility of mobilizing Philadelphia chromosome negative (Ph-) blood stem cells (BSC) with intensive chemotherapy and lenograstim (G-CSF) in patients with CML in first chronic phase (CP1). During 1994-1999 12 centers included 37 patients <56 years. All patients received 6 months' IFN, stopping at median 36 (1-290) days prior to the mobilization chemotherapy. All received one cycle of daunorubicin 50 mg/m2 and 1 hour infusion on days 1-3, and cytarabine (ara-C) 200 mg/m2 24 hours' i.v. infusion on days 1-7 (DA) followed by G-CSF 526 microg s.c. once daily from day 8 after the start of chemotherapy. Leukaphereses were initiated when the number of CD 34+ cells was >5/microl blood. Patients mobilizing poorly could receive a 4-day cycle of chemotherapy with mitoxantrone 12 mg/m2/day and 1 hour i.v infusion, etoposide 100 mg/m2/day and 1 hour i.v. infusion and ara-C 1 g/m2/twice a day with 2 hours' i.v infusion (MEA) or a second DA, followed by G-CSF 526 microg s.c once daily from day 8 after the start of chemotherapy. Twenty-seven patients received one cycle of chemotherapy and G-CSF, whereas 10 were mobilized twice. Twenty-three patients (62%) were successfully (MNC >3.5 x 10(8)/kg, CFU-GM >1.0 x 10(4)/kg, CD34+ cells >2.0 x 10(6)/kg and no Ph+ cells in the apheresis product) [n = 16] or partially successfully (as defined above but 1-34% Ph+ cells in the apheresis product) [n = 7] mobilized. There was no mortality during the mobilization procedure. Twenty-one/23 patients subsequently underwent auto-SCT. The time with PMN <0.5 x 10(9)/l was 10 (range 7-49) and with platelets <20 x 10(9)/l was also 10 (2-173) days. There was no transplant related mortality. The estimated 5-year overall survival after auto-SCT was 68% (95% CI 47 - 90%), with a median follow-up time of 5.2 years.We conclude that in a significant proportion of patients with CML in CP 1, intensive chemotherapy combined with G-CSF mobilizes Ph- BSC sufficient for use in auto-SCT.
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| 27. |
- Rafie, Karim, et al.
(författare)
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The structure of enteric human adenovirus 41-A leading cause of diarrhea in children
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Human adenovirus (HAdV) types F40 and F41 are a prominent cause of diarrhea and diarrhea-associated mortality in young children worldwide. These enteric HAdVs differ notably in tissue tropism and pathogenicity from respiratory and ocular adenoviruses, but the structural basis for this divergence has been unknown. Here, we present the first structure of an enteric HAdV-HAdV-F41-determined by cryo-electron microscopy to a resolution of 3.8 angstrom. The structure reveals extensive alterations to the virion exterior as compared to nonenteric HAdVs, including a unique arrangement of capsid protein IX. The structure also provides new insights into conserved aspects of HAdV architecture such as a proposed location of core protein V, which links the viral DNA to the capsid, and assembly-induced conformational changes in the penton base protein. Our findings provide the structural basis for adaptation of enteric HAdVs to a fundamentally different tissue tropism.
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| 28. |
- Schoneberg, Johannes, et al.
(författare)
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ATP-dependent force generation and membrane scission by ESCRT-III and Vps4
- 2018
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 362:6421, s. 1423-
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Tidskriftsartikel (refereegranskat)abstract
- The endosomal sorting complexes required for transport (ESCRTs) catalyze reverse topology scission from the inner face of membrane necks in HIV budding, multivesicular endosome biogenesis, cytokinesis, and other pathways. We encapsulated ESCRT-III subunits Snf7, Vps24. and Vps2 and the AAA+ ATPase (adenosine triphosphatase) Vps4 in giant vesicles from which membrane nanotubes reflecting the correct topology of scission could be pulled. Upon ATP release by photo-uncaging, this system generated forces within the nanotubes that led to membrane scission in a manner dependent upon Vps4 catalytic activity and Vps4 coupling to the ESCRT-III proteins. Imaging of scission revealed Snf7 and Vps4 puncta within nanotubes whose presence followed ATP release, correlated with force generation and nanotube constriction, and preceded scission. These observations directly verify long-standing predictions that ATP-hydrolyzing assemblies of ESCRT-Ill and Vps4 sever membranes.
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| 29. |
- Shankar, Kasturika, 1993-
(författare)
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Biochemical and structural studies of proteins supporting the genome replication of enteroviruses and Giardia intestinalis
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Enterovirus genus of the Picornaviridae family includes non-enveloped, positive-sense single-stranded RNA (ssRNA) viruses. This genus of viruses causes many diseases such as poliomyelitis by poliovirus (PV), cardiomyopathy by coxsackievirus B3 (CVB3), common cold by rhinoviruses (RVs) and meningitis by Enterovirus 71 (EV 71). The 7.5 kb enterovirus genome encodes a polyprotein, which is subsequently cleaved to yield viral proteins. These viral proteins hijack and modify the membranes of the Golgi and ER to give rise to replication organelles (ROs).In the first paper of my thesis, we showed that membranes of the ROs act as an assembly line for the assembly of enteroviruses. Using cryo-electron tomography we studied poliovirusinfected cells. The one feature that we found most interesting was that a protein was tethering viral capsid to membranes as well as two membranes together. We hypothesized that viral protein 2C was a strong candidate. Therefore, I tried to mimic the interaction between 2C and viral capsid using purified Poliovirus and 2C protein. However, after trying several biochemical conditions I could not mimic this interaction. This strongly indicated that I might need to have a membrane in the system and this led me to study the membrane binding activity of 2C in the second paper.In the second paper, I studied an Enteroviral multi-functional protein: 2C, a highly conserved AAA+ ATPase that plays an important role in the biogenesis of ROs and virus assembly. One of the most interesting features of 2C is its N-terminal membrane-binding domain consisting of 40 amino acids. Using in vitro reconstitution methods and biochemistry, I investigated the association of full-length 2C with lipid vesicles and how this affects the function of the protein. I showed that amino acids 12 to 40 are important not only for membrane binding but also for hexamerization. Moreover, truncation of the first 11 amino acids leads to loss of membrane tethering activity of the protein, which is essential for the formation of ROs. I was also able to demonstrate that the protein is sufficient to recruit RNA to the membrane as it was not previously known how RNA replication is localized to the membrane and here, we found the possible mechanism. In this realistic reconstituted system, I have shown that 2C is not a helicase but an ATP-independent RNA chaperone. Collectively, these discoveries offer a biochemical foundation for various functions of 2C in enterovirus replication. This sets up a more practical biochemical framework for future research, which could potentially contribute to the development of drugs aimed at thwarting enterovirus infections.In the third project, I studied deoxyadenosine kinase (dAK) from Giardia intestinalis, a protozoan responsible for severe diarrhea spread by the fecal-oral route. Giardia is completely dependent on the host for deoxyribonucleosides as it lacks a de novo pathway for their synthesis. dAK uses ATP as a phosphate donor to phosphorylate deoxyadenosine, this activity is essential for genome replication of the protozoan. In this project, we have biochemically and structurally characterized dAK. Here, I used cryo-electron microscopy (cryo-EM) single particle analysis to show that dAK exists as a homo-tetramer in solution. This is an important finding because this is the first example of a non-thymidine kinase1-like deoxyribonucleoside kinase with a tetrameric structure and subsequent mutagenesis analysis showed that tetramerization allows the enzyme to achieve a higher affinity for its deoxyadenosine substrate.In summary, in my thesis, I have biochemically and structurally characterized proteins supporting the genome replication of enteroviruses and Giardia intestinalis.
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| 30. |
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| 31. |
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| 32. |
- Sharma, Himanshu, et al.
(författare)
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Ultrastructural insights into the microsporidian infection apparatus reveal the kinetics and morphological transitions of polar tube and cargo during host cell invasion
- 2024
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 22:2
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Tidskriftsartikel (refereegranskat)abstract
- During host cell invasion, microsporidian spores translocate: their entire cytoplasmic content through a thin, hollow superstructure known as the polar tube. To achieve this, the polar tube transitions from a compact spring-like state inside the environmental spore to a long needle-like tube capable of long-range sporoplasm delivery. The unique mechanical properties of the building blocks of the polar tube allow for an explosive transition from compact to extended state and support the rapid cargo translocation process. The molecular and structural factors enabling this ultrafast process and the structural changes during cargo delivery are unknown. Here, we employ light microscopy and in situ cryo-electron tomography to visualize multiple ultrastructural states of the Vairimorpha necatrix polar tube, allowing us to evaluate the kinetics of its germination and characterize the underlying morphological transitions. We describe a cargo-filled state with a unique ordered arrangement of microsporidian ribosomes, which cluster along the thin tube wall, and an empty post-translocation state with a reduced diameter but a thicker wall. Together with a proteomic analysis of endogenously affinity-purified polar tubes, our work provides comprehensive data on the infection apparatus of microsporidia and uncovers new aspects of ribosome regulation and transport.
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| 33. |
- Tabar, Laszlo, et al.
(författare)
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Early detection of breast cancer rectifies inequality of breast cancer outcomes
- 2020
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Ingår i: Journal of Medical Screening. - : Sage Publications. - 0969-1413 .- 1475-5793. ; 28:1, s. 34-38
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To explain apparent differences among mammography screening services in Sweden using individual data on participation in screening and with breast cancer-specific survival as an outcome.Methods: We analysed breast cancer survival data from the Swedish Cancer Register on breast cancer cases from nine Swedish counties diagnosed in women eligible for screening. Data were available on 38,278 breast cancers diagnosed and 4312 breast cancer deaths. Survival to death from breast cancer was estimated using the Kaplan-Meier estimate, for all cases in each county, and separately for cases of women participating and not participating in their last invitation to screening. Formal statistical comparisons of survival were made using proportional hazards regression.Results: All counties showed a reduction in the hazard of breast cancer death with participation in screening, but the reductions for individual counties varied substantially, ranging from 51% (95% confidence interval 46-55%) to 81% (95% confidence interval 74-85%). Survival rates in nonparticipating women ranged from 53% (95% confidence interval 40-65%) to 74% (95% confidence interval 72-77%), while the corresponding survival in women participating in screening varied from 80% (95% confidence interval 77-84%) to 86% (95% confidence interval 83-88%), a considerably narrower range.Conclusions: Differences among counties in the effect of screening on breast cancer outcomes were mainly due to variation in survival in women not participating in screening. Screening conferred similarly high survival rates in all counties. This indicates that the performance of screening services was similar across counties and that detection and treatment of breast cancer in early-stage reduces inequalities in breast cancer outcome.
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| 34. |
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| 35. |
- Taha, Yesuf, et al.
(författare)
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Steroids reduce local inflammatory mediator secretion and mucosal permeability in collagenous colitis patients
- 2006
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Ingår i: World Journal of Gastroenterology. - : Baishideng Publishing Group Inc.. - 1007-9327 .- 2219-2840. ; 12:43, s. 7012-7018
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To study the effect of oral steroids upon clinical response and rectal mucosa secretion of eosinophil cationic protein (ECP), myeloperoxiclase (MPO), basic fibroblast growth factor (bFGF), vascular enclothelial growth factor (VEGF) and albumin in patients with collagenous colitis (CC). METHODS: A segmental perfusion technique was used to collect perfusates from rectum of CC patients once before and twice (one and four weeks) after the start of steroid treatment. Clinical data was monitored and ECP, MPO, bFGF, VEGF and albumin concentrations were analyzed by immunochernical methods in perfusates and in serum. RESULTS: Steroids reduced the number of bowel movements by more than five times within one week and all patients reported improved subjective wellbeing at wk 1 and 4. At the same time, the median concentrations of ECP, bFGF, VEGF and albumin in rectal perfusates decreased significantly. MPO values were above the detection limit in only 3 patients before treatment and in none during treatment. VEGF, bFGF, ECP and albumin concentrations correlated with each other with the exception of ECP and albumin. A decrease of serum ECP and VEGF concentrations was also seen even if the overtime reduction was not significant. CONCLUSION: Oral steroid treatment in CC patients induced a simultaneous reduction of bowel movements and rectal release of ECP, bFGF, VEGF and albumin, suggesting that these polypeptides and increased mucosal permeability are important components of the pathophysiology in collagenous colitis.
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| 36. |
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| 37. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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