Basal filopodia and vascular mechanical stress organize fibronectin into pillars bridging the mesoderm-endoderm gap

Abstract

Cells may exchange information with other cells and tissues by exerting forces on the extracellular matrix (ECM). Fibronectin (FN) is an important ECM component that forms fibrils through cell contacts and creates directionally biased geometry. Here, we demonstrate that FN is deposited as pillars between widely separated germ layers, namely the somitic mesoderm and the endoderm, in quail embryos. Alongside the FN pillars, long filopodia protrude from the basal surfaces of somite epithelial cells. Loss-of-function of Ena/VASP, α5β1-integrins or talin in the somitic cells abolished the FN pillars, indicating that FN pillar formation is dependent on the basal filopodia through these molecules. The basal filopodia and FN pillars are also necessary for proper somite morphogenesis. We identified a new mechanism contributing to FN pillar formation by focusing on cyclic expansion of adjacent dorsal aorta. Maintenance of the directional alignment of the FN pillars depends on pulsatile blood flow through the dorsal aortae. These results suggest that the FN pillars are specifically established through filopodia-mediated and pulsating force-related mechanisms.

Protein Deimination and Extracellular Vesicle Profiles in Antarctic Seabirds

“…Fibronectin is an important part of the extracellular matrix and is a hepatic glycoprotein protein which constitutes a major protein component of blood plasma. It has major roles in cell migration, differentiation, migration and growth and plays important roles in wound healing, as well as in embryogenesis [111,112]. Fibronectin is associated with a number of pathologies, including cancer and fibrosis [113].…”

FiloQuant reveals increased filopodia density during DCIS progression

“…We next sought to investigate whether DCIS.COM filopodia observed in vitro are present in vivo. As filopodia in vivo are often lost upon chemical fixation Sato et al, 2017), we used intravital microscopy to directly visualise filopodia in an in vivo setting. Specifically, Life-act DCIS.COM cells were injected into the pericardial cavity of zebrafish embryos and imaged live 24 h post-injection using a spinning disk confocal microscope (Figure 7).…”

“…For instance, in neurons, filopodia have been implicated in neurite outgrowth and in the formation of both neurite and dendritic spines (Mattila and Lappalainen, 2008;Björkblom et al, 2012). In vivo, filopodia have been reported to contribute to processes such as endothelial sprouting and angiogenesis (Wakayama et al, 2015;Phng et al, 2013), ECM deposition and remodeling (Sato et al, 2017), epithelial sheet migration during wound healing and dorsal closure Millard and Martin, 2008) and embryonic development (Fierro-González et al, 2013).…”

“…In spite of their wide biological importance, filopodia remain poorly studied primarily due to technical difficulties. In particular, filopodia are difficult to observe, especially in vivo, owing to their small size, the absence of specific markers and due to an often labile nature particularly affected by fixation protocols Sato et al, 2017). In addition, automatic quantification of filopodia properties remains a challenge, despite the availability of dedicated tools, and therefore filopodia features are often described using manual analyses.…”

In vivocharacterization of chick embryo mesoderm by optical coherence tomography assisted microindentation

“…2A widefield). This aids in anchoring the PSM cells by providing a substrate on which they can undergo collective migration and mesenchymal-epithelial transition (MET) to form epithelial spheres(Cheney and Lash, 1984; Oster et al, 1983; Sato et al, 2017). The PSM cells compact together, adhere to the ECM and each other, and become more contractile (Fig.…”