title: Convergence and extrusion are required for normal fusion of the mammalian secondary palate.
abstract: The fusion of two distinct prominences into one continuous structure is common during development and typically requires integration of two epithelia and subsequent removal of that intervening epithelium. Using confocal live imaging, we directly observed the cellular processes underlying tissue fusion, using the secondary palatal shelves as a model. We find that convergence of a multi-layered epithelium into a single-layer epithelium is an essential early step, driven by cell intercalation, and is concurrent to orthogonal cell displacement and epithelial cell extrusion. Functional studies in mice indicate that this process requires an actomyosin contractility pathway involving Rho kinase (ROCK) and myosin light chain kinase (MLCK), culminating in the activation of non-muscle myosin IIA (NMIIA). Together, these data indicate that actomyosin contractility drives cell intercalation and cell extrusion during palate fusion and suggest a general mechanism for tissue fusion in development.
authors.affiliation: Department of Cell and Tissue Biology, Program in Craniofacial Biology and Institute for Human Genetics, University of California, San Francisco, California, United States of America.
authors.forename: Seungil
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Cell and Tissue Biology, Program in Craniofacial Biology and Institute for Human Genetics, University of California, San Francisco, California, United States of America.
authors.forename: Ace E
authors.initials: AE
authors.lastname: Lewis
authors.affiliation: Department of Cell and Tissue Biology, Program in Craniofacial Biology and Institute for Human Genetics, University of California, San Francisco, California, United States of America.
authors.forename: Vivek
authors.initials: V
authors.lastname: Singh
authors.affiliation: Laboratory of Molecular Cardiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Xuefei
authors.initials: X
authors.lastname: Ma
authors.affiliation: Laboratory of Molecular Cardiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Robert
authors.initials: R
authors.lastname: Adelstein
authors.affiliation: Department of Cell and Tissue Biology, Program in Craniofacial Biology and Institute for Human Genetics, University of California, San Francisco, California, United States of America.
authors.forename: Jeffrey O
authors.initials: JO
authors.lastname: Bush
mesh_terms: D000818:Animals; D051379:Mice; D009024:Morphogenesis; D009218:Myosins / Q000502:physiology; D010159:Palate / Q000196:embryology*
chemical_list: D009218:Myosins
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