title: Basolateral protrusion and apical contraction cooperatively drive Drosophila germ-band extension.
abstract: Throughout development, tissues undergo complex morphological changes, resulting from cellular mechanics that evolve over time and in three-dimensional space. During Drosophila germ-band extension (GBE), cell intercalation is the key mechanism for tissue extension, and the associated apical junction remodelling is driven by polarized myosin-II-dependent contraction. However, the contribution of the basolateral cellular mechanics to GBE remains poorly understood. Here, we characterize how cells coordinate their shape from the apical to the basal side during rosette formation, a hallmark of cell intercalation. Basolateral rosette formation is driven by cells mostly located at the dorsal/ventral part of the rosette (D/V cells). These cells exhibit actin-rich wedge-shaped basolateral protrusions and migrate towards each other. Surprisingly, the formation of basolateral rosettes precedes that of the apical rosettes. Basolateral rosette formation is independent of apical contractility, but requires Rac1-dependent protrusive motility. Furthermore, we identified Src42A as a regulator of basolateral rosette formation. Our data show that in addition to apical contraction, active cell migration driven by basolateral protrusions plays a pivotal role in rosette formation and contributes to GBE.
authors.affiliation: Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, Singapore 117411, Singapore.
authors.forename: Zijun
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, Singapore 117411, Singapore.
authors.forename: Christopher
authors.identifier: 0000-0001-5173-0159
authors.initials: C
authors.lastname: Amourda
authors.affiliation: Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, Singapore 117411, Singapore.
authors.forename: Murat
authors.initials: M
authors.lastname: Shagirov
authors.affiliation: Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, Singapore 117411, Singapore.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hara
authors.affiliation: Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, Singapore 117411, Singapore.|Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.|Institute for Molecular and Cell Biology, Agency for Science Technology and Research, 61 Biopolis Drive, Singapore 138673, Singapore.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Saunders
authors.affiliation: Mechanobiology Institute, National University of Singapore, T-Lab, 5A Engineering Drive 1, Singapore 117411, Singapore.|Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.|Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Singapore.
authors.forename: Yusuke
authors.identifier: 0000-0002-2005-7704
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D019521:Body Patterning; D016764:Cell Polarity; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000166:cytology; D036641:Microscopy, Fluorescence, Multiphoton; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D059008:Time-Lapse Imaging; D020744:rac GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000199:Actins; D029721:Drosophila Proteins; D018129:Phosphatidylinositol Phosphates; C060974:phosphatidylinositol 3,4,5-triphosphate; D020744:rac GTP-Binding Proteins