Biology subjects

Taniguchi, A.

Publications and source records attributed to Taniguchi, A..

4 recordsLinked to original sources

bioRxiv2024

Rho-ROCK liberates sequestered claudin for rapid de novo tight junction formation

The epithelial cell sheet maintains its integrity as a barrier while undergoing turnover of constituent cells. To sustain the barrier continuously, its essential to preserve the old tight junctions (TJs) between cells being excluded from the sheet and their neighbors while simultaneously forming de novo TJs between newly adjacent cells. However, the molecular mechanisms involved in the formation of de novo TJs remain largely unknown. This study investigates two scenarios: the formation of de novo TJs during the removal of apoptotic cells from monolayer epithelial sheets and during the differentiation of the granular layer in stratified epidermis. We revealed that rapid claudin assembly is achieved by actively regulating the dissociation of the EpCAM/TROP2-claudin complex in both situations. Furthermore, we found that the Rho-ROCK pathway initiates the activation of matriptase, which cleaves EpCAM/TROP2, resulting in the supply of polymerizable claudin from the stockpiled EpCAM/TROP2-claudin complex at the plasma membrane to induce rapid de novo TJ formation.

cell biology↗

bioRxiv2023

Discovery of essential kinetoplastid-insect adhesion proteins and their function in Leishmania-sand fly interactions

Leishmania species, members of the kinetoplastid parasites, cause leishmaniasis, a neglected tropical disease, in millions of people worldwide1. Leishmania has a complex life cycle with multiple developmental forms, as it cycles between a sand fly vector and a mammalian host; understanding their life cycle is critical to understanding disease spread2. One of the key life cycle stages is the haptomonad form, which is attached to the insect through its flagellum. This adhesion, which is conserved across kinetoplastid parasites, is implicated to have an important function within their life cycles and hence on disease transmission3-5. Here, we discovered kinetoplastid-insect adhesion proteins (KIAPs), which are localised in the attached haptomonad flagellum. Deletion of these KIAPs impaired cell adhesion in vitro and prevented Leishmania from colonising the stomodeal valve in the sand fly, without affecting cell growth. This result will provide important insights for a comprehensive understanding of the Leishmania life cycle.

microbiology↗

bioRxiv2023

Left-right asymmetry is formed in the basal bodies of the mouse node cilia in a cilia motility-dependent manner

Laterality of the shapes and arrangements of the visceral organs in mice is determined in the node, a small cavity found at the ventral side of 7.5 dpc (days post coitum) embryos. On the node cells, motile cilia which are tilted toward the posterior side of the embryos show clockwise movement and thus produce fluid flow in the node toward the left side of the embryos. This left-ward flow regulates left/right (L/R) asymmetric gene expressions and L/R asymmetric morphogenesis in later stages. Structurally, node cilia have the characteristics of primary cilia and their basal body (mother centriole) is accompanied by a daughter centriole. Here, to obtain insights into the process of symmetry breaking by node cilia, we investigated whether the structure of the cilia themselves have L/R asymmetry, and found that positions of the daughter centrioles become biased to the right side of the mother centrioles in a stage-dependent manner. We found that this L/R asymmetry of the basal bodies is absent in iv mutant mice, in which node cilia are immotile, suggesting that formation of this L/R asymmetry in the basal bodies requires cilia motility. It has been reported that culturing embryos in a flow chamber with artificial counter-flow, which is toward the opposite direction to the endogenous leftward flow in the node, results in reversed laterality of the visceral organs in later stages. However, we found that applying such artificial counter-flow did not reverse the L/R asymmetry of the basal bodies, and the daughter centrioles were still biased to the right side of the mother centrioles, suggesting that the L/R asymmetry of the basal bodies is formed independently from the direction of the fluid flow in the node and that it is independent from the laterality of the visceral organs. Although the biological significance of this phenomenon is unknown so far, these results suggest that node cilia have a previously unknown mechanism to produce L/R asymmetry in the basal bodies inside the cells in early development, independently from the canonical fluid flow-dependent L/R determining pathway.

developmental biology↗

bioRxiv2022

Formation and three-dimensional architecture of Leishmania adhesion in the sand fly vector

Attachment to a substrate to maintain position in a specific ecological niche is a common strategy across biology, especially for eukaryotic parasites. During development in the sand fly vector, the eukaryotic parasite Leishmania adheres to the stomodeal valve, as the specialised haptomonad form. Dissection of haptomonad adhesion is a critical step for understanding parasite transmission. Nevertheless, haptomonad studies are limited, as this is a technically challenging life cycle form to investigate. Here, we have combined three-dimensional electron microscopy approaches, including serial block face scanning electron microscopy (SBFSEM) and serial tomography to dissect the organisation and architecture of haptomonads in the sand fly. We showed that the attachment plaque contains distinct structural elements. Using time-lapse light microscopy, we identified five stages of haptomonad differentiation, and showed that calcium is necessary for haptomonad adhesion to the surface. This study provides the structural and regulatory foundations of the haptomonad form, which are critical for a holistic understanding of Leishmania transmission.

microbiology↗