Ectomesoderm and epithelial–mesenchymal transition‐related genes in spiralian development. Issue 10 (4th October 2018)

• Record Type: Journal Article
• Authors: Osborne, C. Cornelia; Perry, Kimberly J.; Shankland, Marty; Henry, Jonathan Q.
• Is Part Of: Developmental dynamics. Volume 247:Issue 10(2018)
• Page Start: 1097
• Page End: 1120
• Publication Date: 2018-10-04
• Subjects: Spiralia -- gastrulation -- mesoderm -- epithelial–mesenchymal transition -- evolution; Morphogenesis -- Periodicals; Anatomy -- Periodicals; Anatomie -- Périodiques; Biologie du développement -- Périodiques; 571.833
• DOI: 10.1002/dvdy.24667
• Languages: English
• ISSNs: 1058-8388

Abstract

Abstract : Background : Spiralians (e.g., annelids, molluscs, and flatworms) possess two sources of mesoderm. One is from endodermal precursors (endomesoderm), which is considered to be the ancestral source in metazoans. The second is from ectoderm (ectomesoderm) and may represent a novel cell type in the Spiralia. In the mollusc Crepidula fornicata, ectomesoderm is derived from micromere daughters within the A and B cell quadrants. Their progeny lie along the anterolateral edges of the blastopore. There they undergo epithelial–mesenchymal transition (EMT), become rounded and undergo delamination/ingression. Subsequently, they assume the mesenchymal phenotype, and migrate beneath the surface ectoderm to differentiate various cell types, including muscles and pigment cells.Results : We examined expression of several genes whose homologs are known to regulate Type 1 EMT in other metazoans. Most of these genes were expressed within spiralian ectomesoderm during EMT.Conclusions : We propose that spiralian ectomesoderm, which exhibits analogous cellular behaviors to other populations of mesenchymal cells, may be controlled by the same genes that drive EMT in other metazoans. Perhaps these genes comprise a conserved metazoan EMT gene regulatory network (GRN). This study represents the first step in elucidating the GRN controlling the development of a novel spiralian cell type (ectomesoderm). Developmental Dynamics 247:1097‐1120, 2018 . © 2018 Wiley Periodicals, Inc. Key Findings: Spiralian ectomesoderm represents a potentially novel population of cells that undergo epithelial‐mesenchymal transition (EMT) during gastrulation. The EMT behavior of spiralian ectomesoderm appears to be similar to that displayed by other mesenchymal cells, such as the sea urchin primary mesenchyme and vertebrate neural crest. Spiralian ectomesoderm cells also express many of the key regulatory genes expressed by other metazoan ectomesencyhme cells. We propose that this suite of regulatory genes may include members that belong to a more broadly conserved metazoan EMT gene regulatory network (GRN).