Actin Dynamics Drive Microvillar Motility and Clustering during Brush Border Assembly

Meenderink, Leslie M.; Gaeta, Isabella; Postema, Meagan M.; Cencer, Caroline; Chinowsky, Colbie R.; Krystofiak, Evan; Millis, Bryan A.; Tyska, Matthew J.

doi:10.1016/j.devcel.2019.07.008

Cited by 62 publications

(113 citation statements)

References 58 publications

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“…EPS8 is also required for proper apical morphogenesis in the C. elegans intestine, where genetic ablation leads to gross defects in tissue morphology and lethality if both isoforms are lost (Croce et al, 2004). Consistent with these findings, our lab recently determined that EPS8 and IRTKS work together to promote microvilli elongation (Postema et al, 2018a) and promote directional persistence of motile microvilli early in differentiation, in a manner dependent on their actin binding activities (Meenderink et al, 2019). Mechanistically, EPS8 has been assigned both actin capping and bundling functions (Disanza et al, 2004;Hertzog et al, 2010).…”

Section: Introductionsupporting

confidence: 56%

“…Microvilli also typically extend from the surface in large numbers, making it difficult to visually isolate individual growth events. Moreover, our recent studies demonstrate that early in differentiation, microvilli are highly dynamic and are capable of translocating across the apical surface (Meenderink et al, 2019). Although small, dim, and crowded moving targets present a significant live cell microscopy challenge, addressing these hurdles would allow us to generate insight on factors involved in microvilli growth as well as the timing of their recruitment to the apical surface.…”

Section: Introductionmentioning

confidence: 99%

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Direct visualization of epithelial microvilli biogenesis

Gaeta

Meenderink

Postema

et al. 2020

Preprint

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Microvilli are actin bundle supported surface protrusions that play essential roles in diverse epithelial cell functions. To develop our understanding of microvilli biogenesis, we used live imaging to directly visualize protrusion growth at early stages of epithelial differentiation. Time-lapse data revealed that an 'initiation complex' enriched in EPS8 and IRTKS appears at future sites of microvillus growth minutes before core actin bundle assembly. Elongation of a new core bundle occurs in parallel with the arrival of EZRIN and plasma membrane encapsulation. In addition to de novo growth, we also observed that new microvilli emerge from pre-existing protrusions. Additionally, we found that new microvilli can also collapse, characterized first by loss of membrane wrapping and Ezrin enrichment, followed by a sharp decrease in distal tip EPS8 and IRTKS. These studies are the first to offer a temporally resolved microvillus growth mechanism and highlight critical factors that drive this process.

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Section: Introductionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Direct visualization of epithelial microvilli biogenesis

Gaeta

Meenderink

Postema

et al. 2020

Preprint

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“…A previous study from our group established that the parallel actin bundles that support microvilli exhibit robust treadmilling (i.e. retrograde flow), where actin monomer incorporation at tip oriented barbed-ends is balanced by subunit removal from the pointed-ends that emerge from the base of these structures (56). Early in differentiation this treadmilling activity is coupled to directed motion of microvilli across the apical surface, which in turn promotes the adherent packing and organization of these protrusions (56).…”

Section: Nm2 Promotes Actin Turnover In Brush Border Microvillimentioning

confidence: 96%

“…retrograde flow), where actin monomer incorporation at tip oriented barbed-ends is balanced by subunit removal from the pointed-ends that emerge from the base of these structures (56). Early in differentiation this treadmilling activity is coupled to directed motion of microvilli across the apical surface, which in turn promotes the adherent packing and organization of these protrusions (56). In treadmilling actin structures, steady-state length can be increased by raising the incorporation rate at the barbed-ends, lowering the disassembly rate at the pointed-ends, or some combination of the two (57)(58)(59).…”

Section: Nm2 Promotes Actin Turnover In Brush Border Microvillimentioning

confidence: 99%

“…How does NM2C activity promote the shortening of microvillar actin bundles? Previous work established that growing and nascent microvilli are supported by highly dynamic core bundles of parallel actin filaments, which collectively exhibit robust treadmilling (56,80). In treadmilling actin networks, new subunits incorporate at filament barbed-ends, whereas disassembly dominates at the pointed-ends.…”

Section: Potential Mechanisms For Nm2-driven Contractility-dependent mentioning

confidence: 99%

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Non-muscle myosin-2 contractility-dependent actin turnover limits the length of epithelial microvilli

Chinowsky

Pinette

Meenderink

et al. 2020

Preprint

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Epithelial brush borders are large arrays of microvilli that enable efficient solute uptake from luminal spaces. In the context of the intestinal tract, brush border microvilli drive functions that are critical for physiological homeostasis, including nutrient uptake and host defense. However, cytoskeletal mechanisms that regulate the assembly and morphology of these protrusions are poorly understood. The parallel actin bundles that support microvilli have their pointed-end rootlets anchored in a highly crosslinked filamentous meshwork referred to as the "terminal web".Although classic EM studies revealed complex ultrastructure, the composition, organization, and function of the terminal web remains unclear. Here, we identify non-muscle myosin-2C (NM2C) as a major component of the brush border terminal web. NM2C is found in a dense, isotropic layer of puncta across the sub-apical domain, which transects the rootlets of microvillar actin bundles.Puncta in this network are separated by ~210 nm, dimensions that are comparable to the expected size of filaments formed by NM2C. In primary intestinal organoid cultures, the terminal web NM2C network is highly dynamic and exhibits continuous remodeling. Using pharmacological and genetic perturbations to disrupt NM2C activity in cultured intestinal epithelial cells, we found that this motor controls the length of growing microvilli by regulating actin turnover in a manner that requires a fully active motor domain. Our findings answer a decades old question on the function of terminal web myosin and hold broad implications for understanding apical morphogenesis in diverse epithelial systems.

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In Situ Visualization of Dynamic Cellular Effects of Phospholipid Nanoparticles via High‐Speed Scanning Ion Conductance Microscopy

Kenry

Sun

Yeo

et al. 2022

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Phospholipid nanoparticles have been actively employed for numerous biomedical applications. A key factor in ensuring effective and safe applications of these nanomaterials is the regulation of their interactions with target cells, which is significantly dependent on an in‐depth understanding of the nanoparticle‐cell interactions. To date, most studies investigating these nano‐bio interactions have been performed under static conditions and may lack crucial real‐time information. It is, however, noteworthy that the nanoparticle‐cell interactions are highly dynamic. Consequently, to gain a deeper insight into the cellular effects of phospholipid nanoparticles, real‐time observation of cellular dynamics after nanoparticle introduction is necessary. Herein, a proof‐of‐concept in situ visualization of the dynamic cellular effects of sub‐100 nm phospholipid nanoparticles using high‐speed scanning ion conductance microscopy (HS‐SICM) is reported. It is revealed that upon introduction into the cellular environment, within a short timescale of hundreds of seconds, phospholipid nanoparticles can selectively modulate the edge motility and surface roughness of healthy fibroblast and cancerous epithelial cells. Furthermore, the dynamic deformation profiles of these cells can be selectively altered in the presence of phospholipid nanoparticles. This work is anticipated to further shed light on the real‐time nanoparticle‐cell interactions for improved formulation of phospholipid nanoparticles for numerous bioapplications.

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Actin Dynamics Drive Microvillar Motility and Clustering during Brush Border Assembly

Abstract: Highlights d Microvilli exhibit persistent, active motility driven by actin assembly d Microvillar F-actin cores treadmill during motility d Barbed-end binding factors regulate microvillar motility d Motility promotes intermicrovillar collisions, adhesion, and cluster formation

Cited by 62 publications

References 58 publications

Direct visualization of epithelial microvilli biogenesis

Direct visualization of epithelial microvilli biogenesis

Non-muscle myosin-2 contractility-dependent actin turnover limits the length of epithelial microvilli

In Situ Visualization of Dynamic Cellular Effects of Phospholipid Nanoparticles via High‐Speed Scanning Ion Conductance Microscopy

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