Publications
210 results found
Xu A, Basant A, Schleich S, et al., 2023, Kinesin-1 transports morphologically distinct intracellular virions during vaccinia infection., J Cell Sci, Vol: 136
Intracellular mature viruses (IMVs) are the first and most abundant infectious form of vaccinia virus to assemble during its replication cycle. IMVs can undergo microtubule-based motility, but their directionality and the motor involved in their transport remain unknown. Here, we demonstrate that IMVs, like intracellular enveloped viruses (IEVs), the second form of vaccinia that are wrapped in Golgi-derived membranes, recruit kinesin-1 and undergo anterograde transport. In vitro reconstitution of virion transport in infected cell extracts revealed that IMVs and IEVs move toward microtubule plus ends with respective velocities of 0.66 and 0.56 µm/s. Quantitative imaging established that IMVs and IEVs recruit an average of 139 and 320 kinesin-1 motor complexes, respectively. In the absence of kinesin-1, there was a near-complete loss of in vitro motility and reduction in the intracellular spread of both types of virions. Our observations demonstrate that kinesin-1 transports two morphologically distinct forms of vaccinia. Reconstitution of vaccinia-based microtubule motility in vitro provides a new model to elucidate how motor number and regulation impacts transport of a bona fide kinesin-1 cargo.
Hernandez-Gonzalez M, Calcraft T, Nans A, et al., 2023, A succession of two viral lattices drives vaccinia virus assembly., PLoS Biol, Vol: 21
During its cytoplasmic replication, vaccinia virus assembles non-infectious spherical immature virions (IV) coated by a viral D13 lattice. Subsequently, IV mature into infectious brick-shaped intracellular mature virions (IMV) that lack D13. Here, we performed cryo-electron tomography (cryo-ET) of frozen-hydrated vaccinia-infected cells to structurally characterise the maturation process in situ. During IMV formation, a new viral core forms inside IV with a wall consisting of trimeric pillars arranged in a new pseudohexagonal lattice. This lattice appears as a palisade in cross-section. As maturation occurs, which involves a 50% reduction in particle volume, the viral membrane becomes corrugated as it adapts to the newly formed viral core in a process that does not appear to require membrane removal. Our study suggests that the length of this core is determined by the D13 lattice and that the consecutive D13 and palisade lattices control virion shape and dimensions during vaccinia assembly and maturation.
Sindram E, Caballero-Oteyza A, Kogata N, et al., 2023, ARPC5 deficiency leads to severe early onset systemic inflammation and early mortality
<jats:title>Abstract</jats:title><jats:p>The seven subunit Arp2/3 complex drives the formation of branched actin networks that are essential for many cellular processes including cell migration. In humans, the ARPC5 subunit of the Arp2/3 complex is encoded by two paralogous genes (<jats:italic>ARPC5</jats:italic>and<jats:italic>ARPC5L</jats:italic>), resulting in proteins with 67% identity. Through whole-exome sequencing, we identified a biallelic ARPC5 frameshift variant in a female child who presented with recurrent infections, multiple congenital anomalies, diarrhea, and thrombocytopenia, and suffered early demise from sepsis. Her consanguineous parents also had a previous child who died with similar clinical features. Using CRISPR/Cas9-mediated approaches, we demonstrate that loss of ARPC5 affects actin cytoskeleton organization and function, as well as chemokine-dependent cell migration<jats:italic>in vitro</jats:italic>. Homozygous<jats:italic>Arpc5</jats:italic>-/- mice do not survive past embryonic day 9 due to severe developmental defects, including loss of the second pharyngeal arch which contributes to craniofacial and heart development. Our results indicate that ARPC5 is important for both prenatal development and postnatal immune signaling, in a non-redundant manner with ARPC5L. Moreover, our observations add the<jats:italic>ARPC5</jats:italic>locus to the list of genes that should be considered when patients present with syndromic early-onset immunodeficiency, particularly if recessive inheritance is suspected.</jats:p>
Baldauf L, Frey F, Perez MA, et al., 2023, Biomimetic actin cortices shape cell-sized lipid vesicles
<jats:title>Abstract</jats:title><jats:p>Animal cells are shaped by a thin layer of actin filaments underneath the plasma membrane known as the actin cortex. This cortex stiffens the cell surface and thus opposes cellular deformation, yet also actively generates membrane protrusions by exerting polymerization forces. It is unclear how the interplay between these two opposing mechanical functions plays out to shape the cell surface. To answer this question, we reconstitute biomimetic actin cortices nucleated by the Arp2/3 complex inside cell-sized lipid vesicles. We show that thin Arp2/3-nucleated actin cortices strongly deform and rigidify the shapes of giant unilamellar vesicles and impart a shape memory on time scales that exceeds the time of actin turnover. In addition, actin cortices can produce finger-like membrane protrusions, showing that Arp2/3-mediated actin polymerization forces alone are sufficient to initiate protrusions in the absence of actin bundling or membrane curving proteins. Combining mathematical modeling and our experimental results reveals that the concentration of actin nucleating proteins, rather than actin polymerization speed, is crucial for protrusion formation. This is because locally concentrated actin polymerization forces can drive a positive feedback loop between recruitment of actin and its nucleators to drive membrane deformation. Our work paints a picture where the actin cortex can either drive or inhibit deformations depending on the local distribution of nucleators.</jats:p><jats:sec><jats:title>Significance Statement</jats:title><jats:p>The cells in our body must actively change shape in order to migrate, grow and divide, but they also need to maintain their shape to withstand external forces during tissue development. Cellular shape control results from an interplay between the plasma membrane and its underlying cortex, a shell composed of crosslinked actin filaments. Using cell-
Way M, 2023, Publishing where it matters., J Cell Sci, Vol: 136
Way M, 2022, I wish I were more organised, like the rest of me!, JOURNAL OF CELL SCIENCE, Vol: 135, ISSN: 0021-9533
Hernandez-Gonzalez M, Calcraft T, Nans A, et al., 2022, Cryo-ET of infected cells reveals that a succession of two lattices drives vaccinia virus assembly
<jats:title>Abstract</jats:title><jats:p>During its cytoplasmic replication, vaccinia virus assembles non-infectious spherical immature virions (IV) coated by a viral D13 lattice. Subsequently, IV mature into infectious brick-shaped intracellular mature virus (IMV) that lack D13. Here, we performed cryo-electron tomography of frozen-hydrated vaccinia-infected cells to structurally characterise the maturation process in situ. During IMV formation a new viral core forms inside IV with a wall consisting of trimeric pillars arranged in a new pseudohexagonal lattice. This lattice appears as a palisade in cross-section. During maturation, which involves a 50% reduction in virion volume, the viral membrane becomes corrugated as it adapts to the newly formed viral core in a process that does not appear to require membrane removal. Our study suggests that the length of this core is determined by the D13 lattice and that the consecutive D13 and palisade lattices control virion shape and dimensions during vaccinia assembly and maturation.</jats:p>
Basant A, Way M, 2022, The relative binding position of Nck and Grb2 adaptors impacts actin-based motility of Vaccinia virus, ELIFE, Vol: 11, ISSN: 2050-084X
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- Citations: 1
Cao L, Ghasemi F, Way M, et al., 2022, Nucleation and stability of branched versus linear Arp2/3-generated actin filaments
<jats:title>ABSTRACT</jats:title><jats:p>Activation of the Arp2/3 complex by VCA-domain-bearing NPFs results in the formation of ‘daughter’ actin filaments branching off the sides of pre-existing ‘mother filaments.’ Alternatively, when stimulated by SPIN90, Arp2/3 directly nucleates ‘linear’ actin filaments. Uncovering the similarities and differences of these two activation mechanisms is fundamental to understanding the regulation and function of Arp2/3. Analysis of individual filaments reveals that the catalytic VCA domain of WASP, N-WASP and WASH, accelerate the Arp2/3-mediated nucleation of linear filaments by SPIN90, in addition to their known branch-promoting activity. Unexpectedly, these VCA domains also destabilize existing branches, as well as SPIN90-Arp2/3 at filament pointed ends. Furthermore, cortactin and GMF, which respectively stabilize and destabilize Arp2/3 at branch junctions, have a similar impact on SPIN90-activated Arp2/3. However, unlike branch junctions, SPIN90-Arp2/3 at the pointed end of linear filaments is not destabilized by piconewton forces, and does not become less stable with time. It thus appears that linear and branched Arp2/3-generated filaments respond similarly to regulatory proteins, albeit with quantitative differences, and that they differ greatly in their responses to aging and to mechanical stress. These results indicate that SPIN90- and VCA-activated Arp2/3 complexes adopt similar yet non-identical conformations, and that their turnover in cells may be regulated differently.</jats:p>
Xu A, Basant A, Schleich S, et al., 2022, Kinesin-1 transports morphologically distinct intracellular virions during vaccinia infection
<jats:title>Abstract</jats:title><jats:p>Intracellular mature virions (IMV) are the first and most abundant infectious form of vaccinia virus to assemble during its replication cycle. IMV can undergo microtubule-based motility, but their directionality and the motor involved in their transport remain unknown. Here, we demonstrate that IMV, like intracellular enveloped virions (IEV), the second form of vaccinia, undergo anterograde transport and recruit kinesin-1. In vitro reconstitution of virion transport reveals that IMV and IEV move toward microtubule plus-ends with respective velocities of 0.66 and 0.56 μm/s. Quantitative imaging establishes IMV and IEV recruit an average of 65 and 115 kinesin-1 motor complexes respectively. In the absence of kinesin-1 there is a near-complete loss of in vitro motility and defects in the cellular spread of both virions. Our observations demonstrate kinesin-1 transports two morphologically distinct forms of vaccinia. Reconstitution of vaccinia-based microtubule motility in vitro provides a new model to investigate how motor number and regulation impacts transport of a bona fide kinesin-1 cargo.</jats:p>
Ahmad S, Way M, 2022, Essay series on equity, diversity and inclusion in cell biology, JOURNAL OF CELL SCIENCE, Vol: 135, ISSN: 0021-9533
Way M, Ahmad S, 2022, Thank you to our peer reviewers in 2021, and a look back over the year, JOURNAL OF CELL SCIENCE, Vol: 135, ISSN: 0021-9533
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- Citations: 1
Sadhu L, Tsopoulidis N, Laketa V, et al., 2022, ARPC5 Isoforms and Their Regulation by Calcium-Calmodulin-N-WASP Drive Distinct Arp2/3-dependent Actin Remodeling Events in CD4 T Cells
<jats:title>Abstract</jats:title><jats:p>Arp2/3-dependent formation of nuclear F-actin networks of different morphology and stability is observed in an increasing number of biological processes. In CD4 T cells, T cell receptor (TCR) signaling induces cytoplasmic and nuclear F-actin assembly via Arp2/3 to strengthen contacts to antigen presenting cells and to regulate gene expression, respectively. How Arp2/3 complex is regulated to mediate these distinct actin polymerization events in response to a common stimulus is unknown. Arp2/3-complex consists of 7 subunits where ARP3, ARPC1 and ARPC5 exist as two different isoforms in humans that can assemble in complexes with different properties. Examining whether specific Arp2/3 subunit isoforms govern distinct actin remodeling events in CD4 T cells, we find that the ARPC5L isoform drives nuclear actin polymerization, while cytoplasmic actin dynamics and TCR proximal signalling selectively relies on ARPC5. In contrast, formation of stable nuclear F-actin networks triggered by DNA replication stress in CD4 T cells requires ARPC5 and is independent of ARPC5L. Moreover, nuclear actin polymerization induced by TCR signaling but not by DNA replication stress is controlled by nuclear calcium-calmodulin signalling and N-WASP. Specific ARPC5 isoforms thus govern Arp2/3 complex activity in distinct actin polymerization events. ARPC5 isoform diversity thus emerges as a mechanism to tailor Arp2/3 activity to different physiological stimuli.</jats:p>
Basant A, Way M, 2021, The Relative Binding Position of Nck and Grb2 Adaptors Dramatically Impacts Actin-Based Motility of Vaccinia Virus
<jats:title>ABSTRACT</jats:title><jats:p>Phosphotyrosine (pTyr) motifs in unstructured polypeptides orchestrate important cellular processes by engaging SH2-containing adaptors to nucleate complex signalling networks. The concept of phase separation has recently changed our appreciation of such multivalent networks, however, the role of pTyr motif positioning in their function remains to be explored. We have now explored this parameter in the assembly and operation of the signalling cascade driving actin-based motility and spread of Vaccinia virus. This network involves two pTyr motifs in the viral protein A36 that recruit the adaptors Nck and Grb2 upstream of N-WASP and Arp2/3-mediated actin polymerization. We generated synthetic networks on Vaccinia by manipulating pTyr motifs in A36 and the unrelated p14 from Orthoreovirus. In contrast to predictions, we find that only specific spatial arrangements of Grb2 and Nck binding sites result in robust N-WASP recruitment, Arp2/3 driven actin polymerization and viral spread. Our results suggest that the relative position of pTyr adaptor binding sites is optimised for signal output. This finding may explain why the relative positions of pTyr motifs are usually conserved in proteins from widely different species. It also has important implications for regulation of physiological networks, including those that undergo phase transitions.</jats:p>
Way M, 2021, A motor is not just for quarantine, it's for life!, JOURNAL OF CELL SCIENCE, Vol: 134, ISSN: 0021-9533
Way M, Ahmad S, 2021, Our Editorial Advisory Board is evolving, JOURNAL OF CELL SCIENCE, Vol: 134, ISSN: 0021-9533
Galloni C, Carra D, Abella JVG, et al., 2021, MICAL2 enhances branched actin network disassembly by oxidizing Arp3B-containing Arp2/3 complexes, JOURNAL OF CELL BIOLOGY, Vol: 220, ISSN: 0021-9525
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- Citations: 9
Way M, Ahmad S, 2021, Thank you to our peer reviewers in 2020, JOURNAL OF CELL SCIENCE, Vol: 134, ISSN: 0021-9533
Way M, 2021, 2020 winner: Tadayoshi Murakawa, JOURNAL OF CELL SCIENCE, Vol: 134, ISSN: 0021-9533
Buch S, Sharma A, Ryan E, et al., 2021, Variants in PCSK7, PNPLA3 and TM6SF2 are risk factors for the development of cirrhosis in hereditary haemochromatosis., Aliment Pharmacol Ther, Vol: 53, Pages: 830-843
BACKGROUND: Cirrhosis develops in <10% of individuals homozygous for the C282Y variant in the homeostatic iron regulator (HFE) gene. Carriage of PCSK7:rs236918 is associated with an increased risk of cirrhosis in this population. AIM: To determine if genetic variants significantly associated with the risk of alcohol- and NAFLD-related cirrhosis also modulate the cirrhosis risk in C282Y homozygotes. METHODS: Variants in PCSK7, PNPLA3, TM6SF2, MBOAT7 and HSD17B13 were genotyped in 1319 C282Y homozygotes, from six European countries, of whom 171 (13.0%) had cirrhosis. Genotypic and allelic associations with the risk for developing cirrhosis were assessed, adjusting for age and sex. Fixed effects meta-analyses of the adjusted summary data for each country were performed. Post hoc association testing was undertaken in the 131 (76.6%) cases and 299 (26.0%) controls with available liver histology. RESULTS: Significant associations were observed between PCSK7:rs236918 (OR = 1.52 [95% CI 1.06-2.19]; P = 0.022; I2 = 0%); PNPLA3:rs738409 (OR = 1.60 [95% CI 1.22-2.11]; P = 7.37 × 10-4 ; I2 = 45.5%) and TM6SF2:rs58542926 (OR = 1.94 [95% CI 1.28-2.95]; P = 1.86 × 10-3 ; I2 = 0%) and the cirrhosis risk in C282Y homozygotes. These findings remained significant in the subpopulation with available liver histology. The population-attributable fractions were 5.6% for PCSK7:rs236918, 13.8% for PNPLA3:rs738409, 6.5% for TM6SF2:rs58542926 and 24.0% for carriage of all three variants combined. CONCLUSIONS: The risk of cirrhosis associated with carriage of PCSK7:rs236918 was confirmed in this much larger population of C282Y homozygotes. In addition, PNPLA3:rs738409 and TM6SF2:rs58542926 were established as significant additional risk factors. More detailed genetic testing of C282Y homozygotes would allow risk stratification and help guide future management.
Hernandez-Gonzalez M, Larocque G, Way M, 2021, Viral use and subversion of membrane organization and trafficking, JOURNAL OF CELL SCIENCE, Vol: 134, ISSN: 0021-9533
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- Citations: 8
Way M, 2020, Love your lipids!, JOURNAL OF CELL SCIENCE, Vol: 133, ISSN: 0021-9533
Galloni C, Carra D, Abella JVG, et al., 2020, MICAL2 acts through Arp3B isoform-specific Arp2/3 complexes to destabilize branched actin networks
<jats:title>Abstract</jats:title><jats:p>The Arp2/3 complex (Arp2, Arp3 and ARPC1-5) is essential to generate branched actin filament networks for many cellular processes. Human Arp3, ARPC1 and ARPC5 exist as two isoforms but the functional properties of Arp2/3 iso-complexes is largely unexplored. Here we show that Arp3B, but not Arp3 is subject to regulation by the methionine monooxygenase MICAL2, which is recruited to branched actin networks by coronin-1C. Although Arp3 and Arp3B iso-complexes promote actin assembly equally efficiently in vitro, they have different cellular properties. Arp3B turns over significantly faster than Arp3 within the network and upon its depletion actin turnover decreases. Substitution of Arp3B Met293 by Thr, the corresponding residue in Arp3 increases actin network stability, and conversely, replacing Arp3 Thr293 with Gln to mimic Met oxidation promotes network disassembly. Thus, MICAL2 regulates a subset of Arp2/3 complexes to control branched actin network disassembly.</jats:p>
Way M, Ahmad S, 2020, Thank you to our peer reviewers in 2019, JOURNAL OF CELL SCIENCE, Vol: 133, ISSN: 0021-9533
Ahmad S, Kyprianou C, Way M, 2020, FocalPlane - a meeting place for the microscopy minded., J Cell Sci, Vol: 133
Way M, 2020, 2019 Winner: Dominika Rudzka., J Cell Sci, Vol: 133
von Loeffelholz O, Purkiss A, Cao L, et al., 2020, Cryo-EM of human Arp2/3 complexes provides structural insights into actin nucleation modulation by ARPC5 isoforms, BIOLOGY OPEN, Vol: 9, ISSN: 2046-6390
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- Citations: 6
von Loeffelholz O, Purkiss A, Cao L, et al., 2020, Cryo-EM of human Arp2/3 complexes provides structural insights into actin nucleation modulation by ARPC5 isoforms
<jats:title>Abstract</jats:title><jats:p>The Arp2/3 complex regulates many cellular processes by stimulating formation of branched actin filament networks. Because three of its seven subunits exist as two different isoforms, mammals produce a family of Arp2/3 complexes with different properties that may be suited to different physiological contexts. To shed light on how isoform diversification affects Arp2/3 function, we determined a 4.2 Å resolution cryo-EM structure of the most active human Arp2/3 complex containing ARPC1B and ARPC5L, and compared it with the structure of the least active ARPC1A-ARPC5-containing complex. The architecture of each isoform-specified Arp2/3 is the same. Strikingly, however, the N-terminal half of ARPC5L is partially disordered compared to ARPC5, suggesting that this region of ARPC5/ARPC5L is an important determinant of complex activity. Confirming this idea, the nucleation activity of Arp2/3 complexes containing hybrid ARPC5/ARPC5L subunits is higher when the ARPC5L N-terminus is present, thereby explaining activity differences between the different Arp2/3 complexes.</jats:p>
Dimchev G, Amiri B, Humphries AC, et al., 2020, Lamellipodin tunes cell migration by stabilizing protrusions and promoting adhesion formation., Journal of Cell Science, Vol: 133, Pages: 1-17, ISSN: 0021-9533
Efficient migration on adhesive surfaces involves the protrusion of lamellipodial actin networks and their subsequent stabilization by nascent adhesions. The actin binding protein lamellipodin (Lpd) is thought to play a critical role in lamellipodium protrusion, by delivering Ena/VASP proteins onto the growing plus ends of actin filaments and by interacting with the WAVE regulatory complex (WRC), an activator of the Arp2/3 complex, at the leading edge. Using B16-F1 melanoma cell lines, we demonstrate that genetic ablation of Lpd compromises protrusion efficiency and coincident cell migration without altering essential parameters of lamellipodia, including their maximal rate of forward advancement and actin polymerization. We also confirmed lamellipodia and migration phenotypes with CRISPR/Cas9-mediated Lpd knockout Rat2 fibroblasts, excluding cell type-specific effects. Moreover, computer-aided analysis of cell edge morphodynamics on B16-F1 cell lamellipodia revealed that loss of Lpd correlates with reduced temporal protrusion maintenance as a prerequisite of nascent adhesion formation. We conclude that Lpd optimizes protrusion and nascent adhesion formation by counteracting frequent, chaotic retraction and membrane ruffling.
Dimchev G, Amiri B, Humphries AC, et al., 2020, Lamellipodin tunes cell migration by stabilizing protrusions and promoting adhesion formation, JOURNAL OF CELL SCIENCE, Vol: 133, ISSN: 0021-9533
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- Citations: 14
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