Biology subjects

Chu, C.-W.

Publications and source records attributed to Chu, C.-W..

6 recordsLinked to original sources

bioRxiv2026

Planar polarization of endogenous ADIP during Xenopus neurulation

Coordinated cell polarity and force-responsive protein localization are essential for tissue morphogenesis, yet how embryonic cells sense forces and respond to mechanical cues remains a challenging question. Afadin- and alpha-actinin-binding protein (ADIP) has been implicated in microtubule minus-end anchoring, centrosome maturation and ciliogenesis. ADIP is also proposed to associate with the actomyosin cortex and regulate collective cell migration. ADIP behaves as a mechanosensitive planar cell polarity (PCP) protein when overexpressed in Xenopus embryos, but the distribution and regulation of endogenous ADIP has been unknown. Here we show that ADIP is present in early ectoderm as randomly distributed puncta that rapidly reorganize and polarize during epithelial wound repair. Endogenous ADIP also becomes enriched and planar polarized in the anterior neural plate towards the midline, consistent with its regulation by mechanical forces that operate during neural tube closure. ADIP polarization is attenuated by depletion of the core PCP component Diversin/Ankrd6, in agreement with the proposed interaction between the two proteins during PCP establishment. Finally, pharmacological disruption of microtubules, F-actin, and nonmuscle myosin II eliminates ADIP polarization in the neuroectoderm, indicating roles for microtubules and actomyosin networks in PCP. Together, these findings suggest that endogenous ADIP senses mechanical cues via the cytoskeletal machinery and functions in the context-dependent manner to control collective cell behaviors during vertebrate morphogenesis.

developmental biology↗

bioRxiv2025

Mechanosensitive localization of Diversin highlights its function in vertebrate morphogenesis and planar cell polarity

Diversin is a vertebrate homolog of the core planar cell polarity (PCP) protein Diego. Here we studied the function of Diversin in Xenopus embryo morphogenesis and its subcellular localization at different locations in superficial ectoderm cells. Depletion of Diversin in the neuroectoderm inhibited apical domain size and neural tube closure and disrupted the polarized localization of endogenous Vangl2, another PCP protein. Whereas Diversin puncta were randomly distributed in early ectoderm, they acquired planar polarity in the neuroectoderm in a stage- and position-specific manner. We find that Diversin is accumulated at the cell junctions adjacent to apically constricting cells at the Xenopus neural plate border and the gastrula blastopore lip. Moreover, Diversin cytoplasmic puncta redistributed in the direction of the pulling forces from the cells with constricting apical domains, suggesting a mechanosensitive process. PCP complexes of Dishevelled (Dvl2) and Diversin or the mechanosensitive adaptor ADIP exhibited planar polarity in the neural plate and the wound edge and promoted wound healing. We propose that Diversin- and Dvl2-containing PCP complexes control morphogenesis in a tension-dependent manner.

cell biology↗

bioRxiv2025

Mechanical cues organize planar cell polarity during vertebrate morphogenesis and embryonic wound repair

Planar cell polarity (PCP) is a phenomenon of coordinated cell orientation in many epithelia and is required for early morphogenetic events, such as vertebrate gastrulation or neural tube closure that place embryonic tissues in their proper locations. Known PCP complexes segregate to opposite edges of each cell due to regulatory feedback interactions, however, whether and how PCP is connected to the tension-sensing machinery has been elusive. Here we observed dynamic polarization of Afadin- and -Actinin-interacting protein (ADIP) in the epithelia adjacent to the involuting marginal zone and the folding neural plate of Xenopus embryos, suggesting that it is controlled by mechanical cues. Supporting this hypothesis, ADIP puncta relocated in response to the pulling forces of neighboring ectoderm cells undergoing apical constriction. Moreover, ADIP puncta rapidly polarized in embryos subjected to stretching and during embryonic wound healing. ADIP formed a mechanosensitive complex with the PCP protein Diversin that was distinct from known core PCP complexes and required for wound repair. We propose that mechanically controlled planar polarization of the ADIP-Diversin complex guides cell behaviors in normal morphogenesis and during wound healing. HighlightsO_LIADIP is a mechanosensing protein that is planar polarized together with Diversin in epithelia during morphogenesis and wound repair C_LIO_LIEpithelial wound healing redistributes ADIP-containing complexes towards the wound. C_LIO_LIADIP and Diversin are interdependent and form a complex regulating morphogenesis and wound healing C_LIO_LIPositive regulatory feedback between mechanical forces and PCP signaling drives morphogenesis C_LI

developmental biology↗

bioRxiv2023

Variable PD-1 glycosylation modulates the activity of immune checkpoint inhibitors

Monoclonal antibodies targeting the immune checkpoint PD-1 have provided significant clinical benefit across a number of solid tumors, with differences in efficacy and toxicity profiles possibly related to their intrinsic molecular properties. Here, we report that camrelizumab and cemiplimab engage PD-1 through interactions with its fucosylated glycan. Using a combination of protein and cell glycoengineering, we demonstrate that the two antibodies bind preferentially to PD-1 with a core fucose at the asparagine N58 residue. We then provide evidence that the concentration of fucosylated PD-1 in the blood of non-small cell lung cancer patients varies across different stages of disease. This study illustrates how glycoprofiling of surface receptors and related circulating forms can inform the development of differentiated antibodies that discriminate glycosylation variants and achieve enhanced selectivity and paves the way towards the implementation of personalized therapeutic approaches.

immunology↗

bioRxiv2022

Myosin-dependent partitioning of junctional Prickle2 toward the anterior vertex during planar polarization of Xenopus neuroectoderm

Planar cell polarity (PCP) of tissues is established by mutually exclusive partitioning of transmembrane proteins Frizzled and Vangl with their respective binding partners, Dishevelled and Prickle. While the amplification and maintenance of this pattern have been well studied, it remains unclear how the anterior-biased protein localization is initiated. Moreover, PCP protein complexes are located at adherens junctions and their polarization requires the activity of non-muscle myosin II (NMII), but how NMII contributes to PCP is not fully understood. Here we analyze time-lapse images of mNeonGreen-tagged Prickle2 (Pk2) in mid-gastrula stage Xenopus presumptive neuroectoderm and demonstrate that Pk2 puncta move along bicellular apical junctions in a biased manner toward the anterior vertex, where the Vangl-Pk complexes are normally enriched. In addition, length changes of bicellular junction segments flanking each Pk2 punctum are often different from each other, and appear more dynamic near the vertices, suggesting that Pk2 movement is driven by intrinsic junction heterogeneity. Reducing NMII activity eliminates the anterior movement, and surprisingly, increases the displacement of Pk2 puncta. By assessing the correlation between Pk2 movement and the relative positioning of each Pk2 punctum along apical junctions, we uncovered that NMII activity is required for the anterior Pk2 movement by maintaining the elongation of posterior junction segment while inhibiting Pk2 movement toward both vertices flanking the junctions. Importantly, we found that the tight junction protein ZO-1 partitions alongside Pk2. Our findings provide the first evidence of biased partitioning of junctional PCP proteins toward the anterior vertex and support the hypothesis that NMII activity facilitates Pk2 polarization not via a direct transport but by regulating intrinsic dynamics of the bicellular junction.

cell biology↗

bioRxiv2021

LMO7-dependent apical constriction requires the binding of the Myosin heavy chain

Apical constriction, or reduction of the apical domain, underlies many morphogenetic events during development, such as furrow or tube formation. Actomyosin complexes play an essential role in apical constriction, however the detailed analysis of molecular mechanisms is still pending. Here we show that Lim domain only protein 7 (Lmo7), a multidomain adaptor at apical junctions, promotes apical constriction in the Xenopus superficial ectoderm, whereas apical domain size increases in Lmo7-depleted cells. Lmo7 is localized to and promotes the formation of the circumferential actomyosin belt adjacent to apical junctions. We find that Lmo7-dependent apical constriction requires the RhoA-ROCK-Non-muscle myosin II (NMII) pathway. Strikingly, Lmo7 binds and recruits NMII heavy chains to apical junctions. Lmo7 overexpression altered the subcellular distribution of Wtip, a sensor of mechanical tension. Our findings suggest that Lmo7 serves as a scaffold organizing the actomyosin network to regulate contractility at apical junctions.

cell biology↗