RGS12 polarizes the GPSM2-GNAI complex to organize and elongate stereocilia in sensory hair cells

Akturk, Anil; Day, Matthew; Tarchini, Basile

doi:10.1126/sciadv.abq2826

Cited by 8 publications

(8 citation statements)

References 78 publications

(132 reference statements)

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“…Variable GNAI2 amounts thus likely explain why IHC stereocilia have variably reduced heights in absence of GNAI3 (Figure 2B-C; Figure 5D-E), unlike in Gpsm2 or LSL-myc:ptxA mutants where they are more uniformly stunted (Beer-Hammer et al, 2018; Mauriac et al, 2017; Tadenev et al, 2019; Tarchini et al, 2016). Loss of GNAI2 signals that coincides at the bare zone and at stereocilia tips on the same HC side adds to previous evidence suggesting that bare zone enrichment is essential for GPSM2-GNAI trafficking to adjacent row 1 stereocilia (Akturk et al, 2022; Jarysta & Tarchini, 2021; Tarchini et al, 2016).…”

Section: Resultssupporting

confidence: 75%

“…HC polarization along the epithelial plane starts with the off-center migration of the basal body and its associated primary cilium, the kinocilium (Denman-Johnson & Forge, 1999; Mbiene & Sans, 1986; Tilney et al, 1992). At that stage, Regulator of G protein Signaling 12 (RGS12) is required for GNAI and the G protein signaling modulator 2 (GPSM2) scaffold to form a polarized complex at the apical membrane on the side of the off-center basal body (Akturk et al, 2022; Ezan et al, 2013; Tarchini et al, 2013). GPSM2-GNAI is best known as a highly conserved protein complex orienting the mitotic spindle during progenitor divisions (Du et al, 2001; Schaefer et al, 2001; Schaefer et al, 2000; Woodard et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Inhibitory G proteins play multiple roles to polarize sensory hair cell morphogenesis

Jarysta,

Tadenev,

Day

et al. 2023

Preprint

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Inhibitory G alpha (GNAI or Gαi) proteins are critical for the polarized morphogenesis of sensory hair cells and for hearing. The extent and nature of their actual contributions remains unclear, however, as previous studies did not investigate all GNAI proteins and included non-physiological approaches. Pertussis toxin can downregulate functionally redundant GNAI1, GNAI2, GNAI3 and GNAO proteins, but may also induce unrelated defects. Here we directly and systematically determined the role(s) of each individual GNAI protein in mouse auditory hair cells. GNAI2 and GNAI3 are similarly polarized at the hair cell apex with their binding partner GPSM2, whereas GNAI1 and GNAO are neither detected nor polarized. In Gnai3 mutants, GNAI2 progressively fails to fully occupy the subcellular compartments where GNAI3 is missing. In contrast, GNAI3 can fully compensate for the loss of GNAI2 and is essential for hair bundle morphogenesis and auditory function. Simultaneous inactivation of Gnai2 and Gnai3 recapitulates for the first time two distinct types of defects only observed so far with pertussis toxin: 1) a delay or failure of the basal body to migrate off-center in prospective hair cells, and 2) a reversal in the orientation of some hair cell types. We conclude that GNAI proteins are critical for hair cells to break planar symmetry and to orient properly before GNAI2/3 regulate hair bundle morphogenesis with GPSM2.

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Section: Resultssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Inhibitory G proteins play multiple roles to polarize sensory hair cell morphogenesis

Jarysta,

Tadenev,

Day

et al. 2023

Preprint

Self Cite

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“…In stereocilia, as long as functional RGS12 is present [68], GPSM2 and its partner GNAI3 are exclusively found at row 1 tips [7,8]; there, they assemble with the EPS8-MYO15A complex [7][8][9] using WHRN as an adapter [9]. GPSM2 forms large protein condensates in vitro, both by itself and with the entire row 1 complex [11], and it is reasonable to suggest that GPSM2 drives the formation of similar condensates at the tips of row 1 stereocilia.…”

Section: The Row 1 Tip Complex Controls Lengthening In Stages II and Ivmentioning

confidence: 99%

Control of stereocilia length during development of hair bundles

Krey

Chatterjee

Halford

et al. 2022

Preprint

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Assembly of the hair bundle, the sensory organelle of the inner ear, depends on differential growth of actin-based stereocilia. Separate rows of stereocilia, labeled 1 through 3 from tallest to shortest, lengthen or shorten during discrete time intervals during development. We used lattice structured illumination microscopy and surface rendering of mouse apical inner hair cells to measure stereocilia dimensions during early postnatal development; these measurements revealed a sharp transition at postnatal day 8 between stage III (row 1 and 2 widening; row 2 shortening) and stage IV (final row 1 lengthening and widening). Tip proteins that determine row 1 lengthening did not accumulate simultaneously during stages III and IV; while the actin-bundling protein EPS8 peaked at the end of stage III, GNAI3 peaked several days later—in early stage IV—and GPSM2 peaked near the end of stage IV. To establish the contributions of key macromolecular assemblies to bundle structure, we examined mouse mutants that eliminated tip links (Cdh23v2J or Pcdh15av3J), transduction channels (TmieKO), or the row 1 tip complex (Myo15ash2). Cdh23v2J/v2J and Pcdh15av3J/av3J bundles had adjacent stereocilia in the same row that were not matched in length, revealing that a major role of these cadherins is to synchronize lengths of side-by-side stereocilia. Use of the tip-link mutants also allowed us to distinguish the role of transduction from effects of transduction proteins themselves. While levels of GNAI3 and GPSM2, which stimulate stereocilia elongation, were greatly attenuated at the tips of TmieKO/KO row 1 stereocilia, they accumulated normally in Cdh23v2J/v2J and Pcdh15av3J/av3J stereocilia. These results reinforced the suggestion that the transduction proteins themselves facilitate localization of proteins in the row 1 complex. By contrast, EPS8 concentrates at tips of all TmieKO/KO, Cdh23v2J/v2J and Pcdh15av3J/av3J stereocilia, correlating with the less polarized distribution of stereocilia lengths in these bundles. These latter results indicated that in wild-type hair cells, the transduction complex prevents accumulation of EPS8 at the tips of shorter stereocilia, causing them to shrink (row 2 and 3) or disappear (row 4 and microvilli). Reduced rhodamine-actin labeling at row 2 stereocilia tips of tip-link and transduction mutants suggests that transduction's role is to destabilize actin filaments there. These results suggest that regulation of stereocilia length occurs through EPS8, and that CDH23 and PCDH15 regulate stereocilia lengthening beyond their role in gating mechanotransduction channels.

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“…As long as functional RGS12 is present [73], GPSM2 and GNAI3 are exclusively found at row 1 tips [8,9]; they assemble with the EPS8-MYO15A complex [7][8][9] using WHRN as an adapter [7]. GPSM2 forms large protein condensates in vitro, both by itself and with the entire row 1 complex [11], and it is reasonable to suggest that GPSM2 drives the formation of similar condensates at the tips of row 1 stereocilia.…”

Section: The Row 1 Tip Complex Controls Lengthening In Stages II and Ivmentioning

confidence: 99%

Control of stereocilia length during development of hair bundles

et al. 2023

View full text Add to dashboard Cite

Assembly of the hair bundle, the sensory organelle of the inner ear, depends on differential growth of actin-based stereocilia. Separate rows of stereocilia, labeled 1 through 3 from tallest to shortest, lengthen or shorten during discrete time intervals during development. We used lattice structured illumination microscopy and surface rendering to measure dimensions of stereocilia from mouse apical inner hair cells during early postnatal development; these measurements revealed a sharp transition at postnatal day 8 between stage III (row 1 and 2 widening; row 2 shortening) and stage IV (final row 1 lengthening and widening). Tip proteins that determine row 1 lengthening did not accumulate simultaneously during stages III and IV; while the actin-bundling protein EPS8 peaked at the end of stage III, GNAI3 peaked several days later—in early stage IV—and GPSM2 peaked near the end of stage IV. To establish the contributions of key macromolecular assemblies to bundle structure, we examined mouse mutants that eliminated tip links (Cdh23v2J or Pcdh15av3J), transduction channels (TmieKO), or the row 1 tip complex (Myo15ash2). Cdh23v2J/v2J and Pcdh15av3J/av3J bundles had adjacent stereocilia in the same row that were not matched in length, revealing that a major role of these cadherins is to synchronize lengths of side-by-side stereocilia. Use of the tip-link mutants also allowed us to distinguish the role of transduction from effects of transduction proteins themselves. While levels of GNAI3 and GPSM2, which stimulate stereocilia elongation, were greatly attenuated at the tips of TmieKO/KO row 1 stereocilia, they accumulated normally in Cdh23v2J/v2J and Pcdh15av3J/av3J stereocilia. These results reinforced the suggestion that the transduction proteins themselves facilitate localization of proteins in the row 1 complex. By contrast, EPS8 concentrates at tips of all TmieKO/KO, Cdh23v2J/v2J, and Pcdh15av3J/av3J stereocilia, correlating with the less polarized distribution of stereocilia lengths in these bundles. These latter results indicated that in wild-type hair cells, the transduction complex prevents accumulation of EPS8 at the tips of shorter stereocilia, causing them to shrink (rows 2 and 3) or disappear (row 4 and microvilli). Reduced rhodamine-actin labeling at row 2 stereocilia tips of tip-link and transduction mutants suggests that transduction’s role is to destabilize actin filaments there. These results suggest that regulation of stereocilia length occurs through EPS8 and that CDH23 and PCDH15 regulate stereocilia lengthening beyond their role in gating mechanotransduction channels.

show abstract

RGS12 polarizes the GPSM2-GNAI complex to organize and elongate stereocilia in sensory hair cells

Cited by 8 publications

References 78 publications

Inhibitory G proteins play multiple roles to polarize sensory hair cell morphogenesis

Inhibitory G proteins play multiple roles to polarize sensory hair cell morphogenesis

Control of stereocilia length during development of hair bundles

Control of stereocilia length during development of hair bundles

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