title: Left-right asymmetry is formed in individual cells by intrinsic cell chirality.
abstract: Many animals show left-right (LR) asymmetric morphology. The mechanisms of LR asymmetric development are evolutionarily divergent, and they remain elusive in invertebrates. Various organs in Drosophila melanogaster show stereotypic LR asymmetry, including the embryonic gut. The Drosophila embryonic hindgut twists 90° left-handedly, thereby generating directional LR asymmetry. We recently revealed that the hindgut epithelial cell is chiral in shape and other properties; this is termed planar cell chirality (PCC). We previously showed by computer modeling that PCC is sufficient to induce the hindgut rotation. In addition, both the PCC and the direction of hindgut twisting are reversed in Myosin31DF (Myo31DF) mutants. Myo31DF encodes Drosophila MyosinID, an actin-based motor protein, whose molecular functions in LR asymmetric development are largely unknown. Here, to understand how PCC directs the asymmetric cell-shape, we analyzed PCC in genetic mosaics composed of cells homozygous for mutant Myo31DF, some of which also overexpressed wild-type Myo31DF. Wild-type cell-shape chirality only formed in the Myo31DF-overexpressing cells, suggesting that cell-shape chirality was established in each cell and reflects intrinsic PCC. A computer model recapitulating the development of this genetic mosaic suggested that mechanical interactions between cells are required for the cell-shape behavior seen in vivo. Our mosaic analysis also suggested that during hindgut rotation in vivo, wild-type Myo31DF suppresses the elongation of cell boundaries, supporting the idea that cell-shape chirality is an intrinsic property determined in each cell. However, the amount and distribution of F-actin and Myosin II, which are known to help generate the contraction force on cell boundaries, did not show differences between Myo31DF mutant cells and wild-type cells, suggesting that the static amount and distribution of these proteins are not involved in the suppression of cell-boundary elongation. Taken together, our results suggest that cell-shape chirality is intrinsically formed in each cell, and that mechanical force from intercellular interactions contributes to its formation and/or maintenance.
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Katsushika, Tokyo 122-8585, Japan; Department of Biological Sciences, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Hatori
authors.affiliation: Laboratory for Biomolecular Function Simulation, Computational Biology Research Core, RIKEN Quantitative Biology Center (QBiC), Kobe, Hyogo 650-0047, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ando
authors.affiliation: Department of Biological Sciences, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sasamura
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Katsushika, Tokyo 122-8585, Japan; Department of Biological Sciences, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Naotaka
authors.initials: N
authors.lastname: Nakazawa
authors.affiliation: Department of Biological Sciences, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Katsushika, Tokyo 122-8585, Japan.
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Taniguchi
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Katsushika, Tokyo 122-8585, Japan.
authors.forename: Shunya
authors.initials: S
authors.lastname: Hozumi
authors.affiliation: Department of Immunology and Cell Biology, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Kikuta
authors.affiliation: Department of Immunology and Cell Biology, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Ishii
authors.affiliation: Department of Biological Sciences, Osaka University, Toyonaka, Osaka 560-0043, Japan. Electronic address: kmatsuno@bio.sci.osaka-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsuno
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D016764:Cell Polarity / Q000235:genetics / Q000502:physiology*; D048430:Cell Shape / Q000235:genetics / Q000502:physiology; D003198:Computer Simulation; D004064:Digestive System / Q000166:cytology / Q000196:embryology; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology* / Q000235:genetics; D017344:Genes, Insect; D040542:Mechanotransduction, Cellular / Q000235:genetics; D008954:Models, Biological; D009030:Mosaicism; D009154:Mutation; D024461:Myosin Type I / Q000235:genetics / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; C513226:Myo31DF protein, Drosophila; D024461:Myosin Type I
keywords: Drosophila; Left–right asymmetry; Planar cell chirality