title: A link between planar polarity and staircase-like bundle architecture in hair cells.
abstract: Sensory perception in the inner ear relies on the hair bundle, the highly polarized brush of movement detectors that crowns hair cells. We previously showed that, in the mouse cochlea, the edge of the forming bundle is defined by the 'bare zone', a microvilli-free sub-region of apical membrane specified by the Insc-LGN-Gαi protein complex. We now report that LGN and Gαi also occupy the very tip of stereocilia that directly abut the bare zone. We demonstrate that LGN and Gαi are both essential for promoting the elongation and differential identity of stereocilia across rows. Interestingly, we also reveal that total LGN-Gαi protein amounts are actively balanced between the bare zone and stereocilia tips, suggesting that early planar asymmetry of protein enrichment at the bare zone confers adjacent stereocilia their tallest identity. We propose that LGN and Gαi participate in a long-inferred signal that originates outside the bundle to model its staircase-like architecture, a property that is essential for direction sensitivity to mechanical deflection and hearing.
authors.affiliation: The Jackson Laboratory, Bar Harbor, ME 04609, USA basile.tarchini@jax.org michel.cayouette@ircm.qc.ca.|Department of Medicine, Tufts University, Boston, MA 02111, USA.|Graduate School of Biomedical Science and Engineering (GSBSE), University of Maine, Orono, ME 04469, USA.|Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7.
authors.forename: Basile
authors.identifier: 0000-0003-2708-6273
authors.initials: B
authors.lastname: Tarchini
authors.affiliation: The Jackson Laboratory, Bar Harbor, ME 04609, USA.
authors.forename: Abigail L D
authors.initials: AL
authors.lastname: Tadenev
authors.affiliation: The Jackson Laboratory, Bar Harbor, ME 04609, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Devanney
authors.affiliation: Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7 basile.tarchini@jax.org michel.cayouette@ircm.qc.ca.|Department of Medicine, Université de Montréal, Montreal, Quebec, Canada H3T 1J4.|Department of Anatomy and Cell Biology, and Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada H3A 0G4.
authors.forename: Michel
authors.identifier: 0000-0003-4655-9048
authors.initials: M
authors.lastname: Cayouette
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins; D016764:Cell Polarity / Q000235:genetics; D003051:Cochlea / Q000166:cytology / Q000196:embryology*; D003638:Deafness / Q000196:embryology / Q000235:genetics; D004622:Embryo, Mammalian; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D006198:Hair Cells, Auditory / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C579276:Gnai1 protein, mouse; C502655:LGN protein, mouse; D019206:GTP-Binding Protein alpha Subunits, Gi-Go
keywords: Gαi; Hair bundle; Hair cell; LGN/Gpsm2; Mouse; Staircase-like organization; Stereocilia