Biology subjects

Mii, Y.

Publications and source records attributed to Mii, Y..

8 recordsLinked to original sources

bioRxiv2026

Wnt signaling and tissue tension reconstitute planar cell polarity in vitro

Planar cell polarity (PCP) aligns cells within the plane of a tissue through asymmetric localization of core PCP proteins. In vivo, PCP arises from integration of biochemical signaling and mechanical inputs, making it challendging to reconstruct in vitro. Here we reconstitute PCP in cultured MDCK epithelial cells using Wnt signaling, collective migration, and Prickle3 overexpression. Loss of Vangl1 disrupts reconstituted PCP, directional collective migration, and propagation of ERK traveling waves. Orthogonal manipulation of signaling and mechanics show that tissue tension contributes to establishing a polarity axis, but not its direction, whereas local Wnt input specifies polarity direction. Together, these inputs generate tissue-wide vectorial polarity. This system provides a tractable framework for dissecting how signaling and mechanics are integrated to organize tissues. TeaserWnt signaling and tissue tension reconstitute planar cell polarity in cultured epithelial cells through core-component interdependence and ERK dynamics.

synthetic biology↗

bioRxiv2025

Self-organized fingering instabilities drive the emergence of tissue morphogenesis in digit organoids.

The emergence of complex anatomical structures -such as the hands- from unstructured tissues remains a fundamental question in developmental biology. Turing-type reaction-diffusion models have provided a molecular explanation for the periodic pre-patterning of digits; however, the physical principles driving 3D morphogenesis remain incompletely understood. To identify the biophysical design principles leading to digit formation, we develop a limb-mesenchymal organoid system that spontaneously forms elongated, digit-like protrusions. Iterations between experiments and agent-based models at the cellular level identify sufficient microscopic mechanisms leading to morphogenesis of digit-like structures: symmetry-breaking and the elongation of digits result from a combination of differential cell adhesion and morphogen-induced chemotaxis and convergent-extension. Lastly, to describe tissue-scale deformations, we perform a coarse-graining analysis of the agent-based model and derive a continuum model that reveals a structural analogy to Cahn-Hilliard-type equations. These equations are typically used to describe fluid phase separation and so-called ''fingering instabilities'' in fluid physics. Here, we show that they also accurately describe organoid morphogenesis. These findings suggest that ''finger'' formation is driven by a mechanical fingering instability acting in concert with chemical patterning, shedding a new light on vertebrate limb morphogenesis.

developmental biology↗

bioRxiv2025

Differential spreading behaviors of Nodal signalling molecules in the extracellular space cooperatively shape left-right asymmetry

Left-right (LR) patterning of vertebrate embryos is mediated by diffusive proteins secreted mainly from the left-right organizer (LRO), such as TGF-{beta} superfamily ligands Nodal and Gdf1, as well as their inhibitors Dand5 and Lefty. However, precise modes of action for these proteins remain unclear due to difficulties in visualizing and manipulating their extracellular behaviors. Here we visualize and manipulate the extracellular dynamics of these proteins employing novel transgenic zebrafish lines and extracellular trapping molecules including the morphotrap. We demonstrate that the heterodimer of Nodal and Gdf1, which is the major signal transducer in vertebrate Nodal signalling, spreads from the LRO through the extracellular space in the paraxial mesoderm (PM) to its target tissue, the lateral plate mesoderm (LPM), in a free-diffusion-like manner. By contrast, Dand5 is highly enriched in the right PM, where it is immobilized through interaction with heparan sulfate proteoglycans and asymmetrically suppresses Nodal signalling. Our study uncovers diverse modes of action for LR-related secreted proteins in the extracellular space, providing a new framework for understanding how spatially organized Nodal signalling molecules shape embryonic LR asymmetry.

developmental biology↗

bioRxiv2025

Emergence of cell polarity by reciprocal interactions between Wnt and core PCP components

Planar cell polarity (PCP) is established by asymmetric localization of core PCP components in each cell. Since some Wnt proteins can induce PCP in vertebrates, it has been proposed that Wnt concentration gradients provide spatial cues for polarization. Here, however, we present evidence that Wnt11 can regulate PCP in a gradient-independent manner. In the neural plate of Xenopus embryos, endogenous Wnt11 does not form an obvious gradient in the direction of PCP, but is polarized at cell boundaries together with core PCP components. Wnt11 polarization is dependent on core PCP components, while polarization of core PCP components can also be induced by Wnt11, indicating a mutual amplification loop between Wnt11 and core PCP components in PCP formation. Furthermore, Wnt11 and core PCP components compose an intercellular loop to coordinate the direction of polarity. Thus, we propose that local and reciprocal interactions between Wnt11 and core PCP components can generate PCP.

developmental biology↗

bioRxiv2025

Dynamic polarization of heparan sulfate proteoglycans is involved in planar cell polarity and localization of endogenous Wnt11 during vertebrate neural tube formation.

Planar cell polarity (PCP) on a tissue plane is established by asymmetric polarization of core PCP components in individual cells. Recently, we found that Wnt11 organizes PCP in Xenopus embryos by accumulating locally with core PCP components to be polarized, but not by acting as a directional cue forming a global gradient. Since heparan sulfate proteoglycans (HSPGs) associate with Wnt on cell membranes, how HSPGs are involved in Wnt polarization and PCP formation is a central issue. Here, we show that HSPGs are dynamically organized in a polarized manner, as with core PCP components and Wnt11, by associating with them. While HSPGs with HS chains enriched by N-sulfation and N-deacetylation are polarized, depending on Wnt and core PCP components, NDST1, which catalyzes these modifications, is required for Wnt11 polarization and PCP formation. Thus, mutual regulation among HS chains, Wnt11, and PCP components appears to be essential for PCP formation. HighlightsO_LIndst1 is required for Wnt11 localization and proper PCP formation. C_LIO_LINDST1-modified HS chains are polarized in the neural plate during development. C_LIO_LIPolarization of NDST1-modified HS chains depends on PCP formation. C_LIO_LIPositive feedback loop results in polarized distribution of HSPGs, Wnt11, and PCP. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=173 SRC="FIGDIR/small/669988v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1db75adorg.highwire.dtl.DTLVardef@10aec47org.highwire.dtl.DTLVardef@1e50d5org.highwire.dtl.DTLVardef@4cd41c_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2025

Identification of N-acetyl-rich heparan sulfate binding motifs and their role in expanding BMP distribution and signaling by Cerberus

Secreted signaling molecules called morphogens including BMP and Wnt provide positional information by their concentration gradient. Although binding to an extracellular matrix, heparan sulfate (HS), is essential for morphogen gradient formation, it is still unclear how different ranges of gradients can be achieved. We previously found that two types of HS, N-acetyl-rich HS (NAc-HS) and N-sulfo-rich HS (NS-HS), are differentially clustered on the cell membrane, and bind to Frzb and Wnt8, respectively. Furthermore, we demonstrated that Frzb expands Wnt8 distribution by transferring Wnt8 from NS-HS to NAc-HS. This indicates that NAc-HS or its unsulfated form, heparan, which has been considered as a precursor of HS including N-sulfo HS, has an essential role in morphogen distribution. Here, we identified a so-called BMP antagonist, Cerberus (Cer), as another NAc-HS-binding protein. Binding of Cer to NAc-HS was enhanced by knockdown and repressed by overexpression of ndst1, which catalyzes the conversion of NAc-HS to NS-HS, suggesting that Cer binds to NAc-HS and/or heparan as does Frzb. We then explored NAc-HS binding motifs using deletion or alanine-substitution mutants of Frzb and Cer, and revealed that clusters of basic amino acids, Lys and Arg, are critical for their binding to NAc-HS. Functionally, Cer was able to expand distribution and signaling ranges of BMP4 through relocation of BMP4 from NS-HS to NAc-HS as has been shown with Wnt8 and Frzb. For this Cer activity, its NAc-HS binding motifs were essential. These results suggest that NAc-HS clusters and NAc-HS binding motifs constitute an interacting unit to modulate extracellular distribution of BMP4 as well as Wnt8.

developmental biology↗

bioRxiv2020

Asymmetric requirement of Dpp/BMP morphogen dispersal in the Drosophila wing disc

How morphogen gradients control patterning and growth in developing tissues remains largely unknown due to lack of tools manipulating morphogen gradients. Here, we generate two membrane-tethered protein binders that manipulate different aspects of Decapentaplegic (Dpp), a morphogen required for overall patterning and growth of the Drosophila wing. "HA trap" is based on a single-chain variable fragment (scFv) against the HA tag that traps HA-Dpp to mainly block its dispersal, while "Dpp trap" is based on a Designed Ankyrin Repeat Protein (DARPin) against Dpp that traps Dpp to block both its dispersal and signaling. Using these tools, we found that, while posterior patterning and growth require Dpp dispersal, anterior patterning and growth largely proceed without Dpp dispersal. We show that dpp transcriptional refinement from an initially uniform to a localized expression and persistent signaling in transient dpp source cells render the anterior compartment robust against the absence of Dpp dispersal. Furthermore, despite a critical requirement of dpp for the overall wing growth, neither Dpp dispersal nor direct signaling is critical for lateral wing growth after wing pouch specification. These results challenge the long-standing dogma that Dpp dispersal is strictly required to control and coordinate overall wing patterning and growth.

developmental biology↗

bioRxiv2020

Quantitative analyses reveal extracellular dynamics of Wnt ligands in Xenopus embryos

The mechanism of intercellular transport of Wnt ligands is still a matter of debate. Here, to better understand this issue, we examined distribution and dynamics of Wnt8 in Xenopus embryos. While Venus-tagged Wnt8 was found on the surfaces of cells close to Wnt-producing cells, we also detected its dispersal over distances of 15 cell diameters. A combination of fluorescence correlation spectroscopy and quantitative imaging revealed that only a small proportion of Wnt8 ligands diffuses freely, whereas most Wnt8 molecules are bound to cell surfaces. Fluorescence decay after photoconversion showed that Wnt8 ligands bound on cell surfaces decreased exponentially, suggesting a dynamic exchange of bound forms of Wnt ligands. Mathematical modelling based on this exchange recapitulates a graded distribution of bound, but not free, Wnt ligands. Based on these results, we propose that Wnt distribution in tissues is controlled by a dynamic exchange of its abundant bound and rare free populations.

developmental biology↗