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Curr Biol. 2018 Mar 5;28(5):810-816.e3. doi: 10.1016/j.cub.2018.01.075. Epub 2018 Feb 22.

A Conserved Role of the Unconventional Myosin 1d in Laterality Determination.

Author information

1
University of Hohenheim, Institute of Zoology, Garbenstrasse 30, 70593 Stuttgart, Germany.
2
Department of Biology, Merrimack College, 315 Turnpike Street, North Andover, MA 01845, USA.
3
Université Côte d'Azur, CNRS, INSERM, Institut de Biologie Valrose, Parc Valrose, 06108 Nice, France.
4
University of Hohenheim, Institute of Zoology, Garbenstrasse 30, 70593 Stuttgart, Germany. Electronic address: martin.blum@uni-hohenheim.de.

Abstract

Anatomical and functional asymmetries are widespread in the animal kingdom [1, 2]. In vertebrates, many visceral organs are asymmetrically placed [3]. In snails, shells and inner organs coil asymmetrically, and in Drosophila, genitalia and hindgut undergo a chiral rotation during development. The evolutionary origin of these asymmetries remains an open question [1]. Nodal signaling is widely used [4], and many, but not all, vertebrates use cilia for symmetry breaking [5]. In Drosophila, which lacks both cilia and Nodal, the unconventional myosin ID (myo1d) gene controls dextral rotation of chiral organs [6, 7]. Here, we studied the role of myo1d in left-right (LR) axis formation in Xenopus. Morpholino oligomer-mediated myo1d downregulation affected organ placement in >50% of morphant tadpoles. Induction of the left-asymmetric Nodal cascade was aberrant in >70% of cases. Expression of the flow-target gene dand5 was compromised, as was flow itself, due to shorter, fewer, and non-polarized cilia at the LR organizer. Additional phenotypes pinpointed Wnt/planar cell polarity signaling and suggested that myo1d, like in Drosophila [8], acted in the context of the planar cell polarity pathway. Indeed, convergent extension of gastrula explant cultures was inhibited in myo1d morphants, and the ATF2 reporter gene for non-canonical Wnt signaling was downregulated. Finally, genetic interference experiments demonstrated a functional interaction between the core planar cell polarity signaling gene vangl2 and myo1d in LR axis formation. Thus, our data identified myo1d as a common denominator of arthropod and chordate asymmetry, in agreement with a monophyletic origin of animal asymmetry.

KEYWORDS:

PCP; Xenopus; cilia; gastroeol roof plate; left-right asymmetry; left-right organizer; myold; myosin; planar cell polarity

PMID:
29478852
DOI:
10.1016/j.cub.2018.01.075
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