Feng Zhou1, Vijay Narasimhan1, Mohammad Shboul2, Yan Ling Chong1, Bruno Reversade2,3 and Sudipto Roy1,3,4,*
1 Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive Singapore 138673
2 Institute of Medical Biology, 8A Biomedical Grove, Singapore 138648
3 Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore 119288
4 Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
*Author for correspondence: firstname.lastname@example.org
Published in Current Biology on 19 November 2015.
Multiciliated cells (MCCs) differentiate hundreds of motile cilia that generate mechanical force required to drive fluid movement over epithelia. For example, metachronal beating of MCC cilia in the mammalian airways clears mucus that traps inhaled pathogens and pollutants. Consequently, abnormalities in MCC differentiation or ciliary motility have been linked to an expanding spectrum of human airway diseases. Current view posits that MCC precursors are singled out by the inhibition of Notch signaling. MCC precursors then support an explosive production of basal bodies, which migrate to the apical surface, dock with the plasma membrane and seed the growth of multiple motile cilia. At the center of this elaborate differentiation program resides the coiled-coil containing protein Multicilin, which transcriptionally activates genes for basal body production as well as the gene for FoxJ1, the master regulator for basal body docking, cilia formation and motility. Here, using genetic analysis in the zebrafish embryo, we discovered that Gmnc is a novel determinant of the MCC fate. Like Multicilin, Gmnc is a coiled-coil containing protein of the Geminin family. We show that Gmnc functions downstream of Notch signaling, but upstream of Multicilin in the developmental pathway controlling MCC specification. Moreover, we find that loss of Gmnc in Xenopus embryos also causes loss of MCC differentiation, and over-expression of the protein is sufficient to induce supernumerary MCCs. Together, our data identify Gmnc as an evolutionarily conserved master regulator functioning at the top of the hierarchy of transcription factors involved in MCC differentiation.
GMNC is sufficient to induce ectopic multiciliated cells in Xenopus. Human GMNC RNA was injected into 2 cells of a 4-celled stage Xenopus embryo producing a mosaic tadpole with one half (that inherited the GMNC RNA; bottom) replete with a lawn of ectopic multiciliated cells, and the other half (control; top) having the normal pattern of multiciliated cells intercalated with other epidermal cell types. Cilia were stained with anti-acetylated tubulin antibodies (green), centrioles/basal bodies with γ-tubulin antibodies (red) and DNA with DAPI (blue). Image acquired by F. Zhou, B. Reversade and S. Roy.
For more information on Sudipto ROY's lab, please click here.