Extracellular matrix couples the convergence movements of mesoderm and neural plate during the early stages of neurulation

Abstract

Background: During the initial stages zebrafish neurulation, neural plate cells undergo highly coordinated movements before they assemble into a multicellular solid neural rod. We have previously identified that the underlying mesoderm is critical to ensure such coordination and generate correct neural tube organization. However, how intertissue coordination is achieved in vivo during zebrafish neural tube morphogenesis is unknown. Results: In this work, we use quantitative live imaging to study the coordinated movements of neural ectoderm and mesoderm during dorsal tissue convergence. We show the extracellular matrix components laminin and fibronectin that lie between mesoderm and neural plate act to couple the movements of neural plate and mesoderm during early stages of neurulation and to maintain the close apposition of these two tissues. Conclusions: Our study highlights the importance of the extracellular matrix proteins laminin and libronectin in coupling the movements and spatial proximity of mesoderm and neuroectoderm during the morphogenetic movements of neurulation. Developmental Dynamics 245:580-589,

Cdh2 coordinates Myosin-II dependent internalisation of the zebrafish neural plate

“…Zebrafish embryos generate a neural tube by a complex array of cell behaviors 10,11,12,15 . Initially this involves the movement of a large body of cells towards the dorsal midline 14,15,16 . Then tissue internalisation at the midline transforms the neural plate into a neural keel and then solid cylindrical neural rod structure.…”

“…Then tissue internalisation at the midline transforms the neural plate into a neural keel and then solid cylindrical neural rod structure. These highly organised collective movements of dorsal midline cells are dependent on extrinsic cues from mesoderm and extracellular matrix 15,16,17 , as well as cell-cell interactions between the neural cells themselves 13,14,17,21,22 . While tissue internalisation is a fundamental step in this morphogenetic process, its cellular and molecular nature has remained rather elusive.…”

“…Whole-mount and tissue section immunohistochemistry was performed as previously described 12,16 . In this study we used mouse anti-ZO-1 (339111; Zymed) at 1:300, anti-rabbit…”

“…During this period of internalisation the cells of the neural plate and keel are not organised as a columnar neuroepithelium as found in other vertebrates. The pseudostratified epithelial organisation does not arise in teleosts until late neural rod stage, coincident with lumen formation 12,13,14,15,16,17,18,22 . This is in contrast to amniote and amphibian neural plates that have a clear epithelial organisation and use apical constriction to fold the epithelium and internalise the neuroectoderm during neurulation 19,20 .…”

“…The details of this process are incompletely understood but initially involve two components, one is convergence of neural plate cells towards the midline and the second is an internalisation of cells at or close to the midline 10,11 . The efficiency of convergence depends on Planar Cell Polarity signaling 12,13,14 and requires extracellular matrix and adjacent mesoderm for coordination 15,16 . Internalisation is less well understood but is a key step that deepens the most medial zone of the neural plate to generate the solid neural keel.…”