Fascin structural plasticity mediates flexible actin bundle construction

Nature Structural & Molecular Biology, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 20, 2025

Abstract Fascin cross-links actin filaments (F-actin) into bundles that support tubular membrane protrusions including filopodia and stereocilia. dysregulation drives aberrant cell migration during metastasis, fascin inhibitors are under development as cancer therapeutics. Here, we use cryo-EM, cryo-electron tomography coupled with custom denoising computational modeling to probe human fascin-1’s F-actin cross-linking mechanisms across spatial scales. Our cross-bridge structure reveals an asymmetric binding conformation is allosterically blocked by the inhibitor G2. Reconstructions of seven-filament hexagonal bundle elements, variability analysis simulations show how structural plasticity enables bridge varied interfilament orientations, accommodating mismatches between F-actin’s helical symmetry packing. Tomography many-filament uncover geometric rules underlying emergent patterns, well accumulation unfavorable limit size. Collectively, this work shows harnesses fine-tuned nanoscale dynamics build regulate micron-scale bundles.

Language: Английский

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Tunneling nanotube–like structures regulate distant cellular interactions during heart formation

Science, Journal Year: 2025, Volume and Issue: 387(6739)

Published: March 13, 2025

In the developing mammalian heart, endocardium and myocardium are separated by so-called cardiac jelly. Communication between is essential for morphogenesis. How membrane-localized receptors ligands achieve interaction across jelly not understood. Working in mouse morphogenesis models, we used a variety of cellular, imaging, genetic approaches to elucidate this question. We found that interacted directly through microstructures termed tunneling nanotube–like structures (TNTLs). TNTLs extended from cardiomyocytes (CMs) contact endocardial cells (ECs) directly. transported cytoplasmic proteins, transduced signals CMs ECs, initiated myocardial growth toward heart lumen form ventricular trabeculae-like structures. Loss disturbed signaling interactions and, subsequently, patterning.

Language: Английский

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The cellular protrusions for inter-cellular material transfer: similarities between filopodia, cytonemes, tunneling nanotubes, viruses, and extracellular vesicles

Frontiers in Cell and Developmental Biology, Journal Year: 2024, Volume and Issue: 12

Published: July 5, 2024

Extracellular vesicles (EVs) are crucial for transferring bioactive materials between cells and play vital roles in both health diseases. Cellular protrusions, including filopodia microvilli, generated by the bending of plasma membrane considered to be rigid structures facilitating various cellular functions, such as cell migration, adhesion, environment sensing. Compelling evidence suggests that these protrusions dynamic flexible can serve sources a new class EVs, highlighting unique role they intercellular material transfer. Cytonemes specialized make direct contact with neighboring cells, mediating transfer through their tips. In some cases, tips fuse creating tunneling nanotubes directly connect cytosols adjacent cells. Additionally, virus particles released from infected small bud-like protrusions. These different types which materials, share common protein components, I-BAR domain-containing proteins, actin cytoskeleton, regulatory proteins. The nature highlights importance communication within body, development, cancer progression, other

Language: Английский

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Sonic Hedgehog activates prostaglandin signaling to stabilize primary cilium length

The Journal of Cell Biology, Journal Year: 2024, Volume and Issue: 223(9)

Published: June 10, 2024

Sonic Hedgehog (SHH) is a driver of embryonic patterning that, when corrupted, triggers developmental disorders and cancers. SHH effector responses are organized through primary cilia (PC) that grow retract with the cell cycle in response to extracellular cues. Disruption PC homeostasis corrupts regulation, placing significant pressure on pathway maintain ciliary fitness. Mechanisms by which robustness ensured SHH-stimulated cells not yet known. Herein, we reveal crosstalk circuit induced activation Phospholipase A2α drives E-type prostanoid receptor 4 (EP4) signaling ensure function stabilize length. We demonstrate blockade SHH-EP4 destabilizes cyclic AMP (cAMP) equilibrium, slows transport, reduces length, attenuates induction. Accordingly, Ep4-/- mice display shortened neuroepithelial altered SHH-dependent neuronal fate specification. Thus, initiates coordination between distinct receptors length for robust downstream signaling.

Language: Английский

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Fascin structural plasticity mediates flexible actin bundle construction

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Jan. 4, 2024

Summary Fascin crosslinks actin filaments (F-actin) into bundles that support tubular membrane protrusions including filopodia and stereocilia. dysregulation drives aberrant cell migration during metastasis, fascin inhibitors are under development as cancer therapeutics. Here, we use cryo-electron microscopy, tomography coupled with custom denoising, computational modeling to probe fascin’s F-actin crosslinking mechanisms across spatial scales. Our crossbridge structure reveals an asymmetric binding conformation is allosterically blocked by the inhibitor G2. Reconstructions of seven-filament hexagonal bundle elements, variability analysis, simulations show how structural plasticity enables bridge varied inter-filament orientations, accommodating mismatches between F-actin’s helical symmetry packing. Tomography many-filament uncovers geometric rules underlying emergent patterns, well accumulation unfavorable limit size. Collectively, this work shows harnesses fine-tuned nanoscale dynamics build regulate micron-scale bundles.

Language: Английский

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Cellular signalling protrusions enable dynamic distant contacts in spinal cord neurogenesis

Biology Open, Journal Year: 2025, Volume and Issue: 14(1)

Published: Jan. 15, 2025

ABSTRACT In the developing mouse ventral spinal cord, HES5, a transcription factor downstream of Notch signalling, is expressed as evenly spaced clusters high HES5-expressing neural progenitor cells along dorsoventral axis. While signalling requires direct membrane contact for its activation, we have previously shown mathematically that needs to extend beyond neighbouring HES5 pattern emerge. However, presence cellular structures could enable such long-distance was unclear. Here, report protrusions are present all apicobasal axis individual cells. Through live imaging, show these dynamically and retract reaching lengths up ∼20 µm, enough adjacent The ligand DLL1 found colocalise with protrusions, further supporting idea can be transduced at distance. effect on tested by reducing density using CDC42 inhibitor ML141, leading tendency decrease distance between cell clusters. this not significant leaves an open question about their role in fine-grained organisation neurogenesis.

Language: Английский

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Receptor Allostery Promotes Context-Specific Sonic Hedgehog Signaling During Embryonic Development

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 29, 2025

Abstract Sonic Hedgehog (SHH) signaling functions in temporal- and context-dependent manners to pattern diverse tissues during embryogenesis. The signal transducer Smoothened (SMO) is activated by sterols, oxysterols, arachidonic acid (AA) through binding pockets its extracellular cysteine-rich domain (CRD) 7-transmembrane (7TM) bundle. In vitro analyses suggest SMO allosterically enhanced combinatorial ligand these but vivo evidence of allostery lacking. Herein, we map an AA pocket at the top 7TM bundle show that disruption attenuates SHH sterol-stimulated induction. A knockin mouse model compromised reveals homozygous mutant mice are cyanotic, exhibit high perinatal lethality, congenital heart disease. Surviving mutants demonstrate pulmonary maldevelopment fail thrive. Neurodevelopment unaltered mice, suggesting allosteric regulation allows for precise tuning pathway activity cardiopulmonary development.

Language: Английский

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The Drosophila epidermal growth factor receptor pathway regulates Hedgehog signalling and cytoneme behaviour

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: Feb. 26, 2025

During Drosophila epithelial development, dynamic signalling filopodia (cytonemes) establish direct contacts between distant cells to facilitate the formation of Hedgehog gradient. However, not much is known about how cytonemes are regulated. In this study, we show that cytoneme dynamics and in epithelia depend on Epidermal Growth Factor pathway its downstream effector Ras1. We describe EGFR/Ras1 required maintain wing disc epithelium basal plasma membrane levels Interference (Ihog), a critical Hh co-receptor adhesion protein. addition, our data demonstrate filamin A or Cheerio Drosophila, responds both Ihog EGFR recruited site membrane. This recruitment contributes Ihog's role stabilizing cytonemes. The gradient established by (cytonemes). Here, authors EGF may regulate maintaining epithelium.

Language: Английский

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Slik sculpts the plasma membrane into cytonemes to control cell-cell communication

The EMBO Journal, Journal Year: 2025, Volume and Issue: unknown

Published: March 6, 2025

Cytonemes are signaling filopodia that facilitate long-range cell-cell communication by forming synapses between cells. Initially discovered in Drosophila for transporting morphogens during embryogenesis, they have since been identified mammalian cells and implicated carcinogenesis. Despite their importance, mechanisms controlling cytoneme biogenesis remain elusive. Here, we demonstrate the Ser/Thr kinase Slik drives remote cell proliferation promoting formation. This function depends on coiled-coil domain of (SlikCCD), which directly sculpts membranes into tubules. Importantly, plays opposing roles biogenesis: its membrane-sculpting activity promotes formation, but this is counteracted activity, enhances actin association with plasma membrane via Moesin phosphorylation. In vivo, SlikCCD formation one epithelial layer wing disc to promote an adjacent layer. Finally, relies STRIPAK complex, controls governs at a distance regulating membrane. Our study unveils unexpected structural role sculpting membranes, crucial cytoneme-mediated control proliferation.

Language: Английский

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Diffusion barriers imposed by tissue topology shape Hedgehog morphogen gradients

Proceedings of the National Academy of Sciences, Journal Year: 2024, Volume and Issue: 121(36)

Published: Aug. 27, 2024

Animals use a small number of morphogens to pattern tissues, but it is unclear how evolution modulates morphogen signaling range match tissues varying sizes. Here, we used single-molecule imaging in reconstituted gradients and tissue explants determine that Hedgehog diffused extracellularly as monomer, rapidly transitioned between membrane-confined -unconfined states. Unexpectedly, the vertebrate-specific protein SCUBE1 expanded by accelerating transition rates states without affecting relative abundance molecules each state. This observation could not be explained under existing models diffusion. Instead, developed topology-limited diffusion model which cell–cell gaps create barriers, can only overcome passing through membrane-unconfined Under this model, promoted secretion allowing transiently barriers. multiscale understanding gradient formation unified prior identified knobs nature tune sizes across organisms.

Language: Английский

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