Limits...
The Rho GTPase Cdc42 regulates hair cell planar polarity and cellular patterning in the developing cochlea.

Kirjavainen A, Laos M, Anttonen T, Pirvola U - Biol Open (2015)

Bottom Line: Atypical protein kinase C (aPKC), a putative Cdc42 effector, colocalized with Cdc42 at the hair cell apex, and aPKC expression was altered upon Cdc42 depletion.Our data suggest that Cdc42 together with aPKC is part of the machinery establishing hair cell planar polarity and that Cdc42 acts on polarity through the cell-surface microtubule network.In addition, our data demonstrates that Cdc42 is required for stereociliogenesis in the immature cochlea.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences, Viikinkaari 1, 00014 University of Helsinki, Finland.

No MeSH data available.


Disorganized apical microtubule network in outer hair cells of Cdc42loxP/loxP;Fgfr3-iCre-ERT2 mice.Confocal views of cochlear whole mount specimens dissected from the medial coil of control and mutant mice at E18.5. (A–B′) Specimens double-labeled for acetylated tubulin, marking microtubules and basal body, and for phalloidin that labels the hair bundle. Z-stacks cover the level from the basal body to the apicalmost astral microtubules of OHCs. Boxed OHCs in (A′,B′) are shown in higher magnification in A1,B1,B2,B3. (A1) Control specimen shows the localization of the basal body (arrow) close to the vertex of hair bundle and ordered radiation of microtubules at the OHC surface. (B1–B3) In the mutant specimen, the microtubule network is rotated with respect to hair bundle misorientation and microtubules around the basal body are disorganized (B1). Some OHCs show complete loss of the ordered microtubular radiation (B3). Scale bar shown in B3: A–B′, 5 µm; A1–B3, 2 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4400594&req=5

f07: Disorganized apical microtubule network in outer hair cells of Cdc42loxP/loxP;Fgfr3-iCre-ERT2 mice.Confocal views of cochlear whole mount specimens dissected from the medial coil of control and mutant mice at E18.5. (A–B′) Specimens double-labeled for acetylated tubulin, marking microtubules and basal body, and for phalloidin that labels the hair bundle. Z-stacks cover the level from the basal body to the apicalmost astral microtubules of OHCs. Boxed OHCs in (A′,B′) are shown in higher magnification in A1,B1,B2,B3. (A1) Control specimen shows the localization of the basal body (arrow) close to the vertex of hair bundle and ordered radiation of microtubules at the OHC surface. (B1–B3) In the mutant specimen, the microtubule network is rotated with respect to hair bundle misorientation and microtubules around the basal body are disorganized (B1). Some OHCs show complete loss of the ordered microtubular radiation (B3). Scale bar shown in B3: A–B′, 5 µm; A1–B3, 2 µm.

Mentions: In the apices of epithelial cells, astral microtubules radiate from the basal body and are captured by plus-ends to the cell cortex. Pulling forces provided by microtubules are essential for the migration of the basal body and primary cilium and for docking of these structures to their final position (Tang and Marshall, 2012). Recent studies on cochlear hair cells have linked abnormal positioning of the kinocilium to disorganized cell-surface microtubule network (Ezan et al., 2013; Sipe et al., 2013). Compared to control specimens (Fig. 7A–A1), acetylated tubulin-staining at E18.5 showed disorganized microtubules at the OHC surface in the Cdc42 mutant mice (Fig. 7B–B3). Both microtubules around the basal body and those radiating at the cell surface were abnormal. Further, both dysmorphology of the hair bundle and abnormal position of the basal body/kinocilium correlated with microtubule disorganization, a finding clearly seen in high magnification views (Fig. 7B1–B3). These results suggest that altered planar polarity of OHCs is mediated by microtubular disturbances.


The Rho GTPase Cdc42 regulates hair cell planar polarity and cellular patterning in the developing cochlea.

Kirjavainen A, Laos M, Anttonen T, Pirvola U - Biol Open (2015)

Disorganized apical microtubule network in outer hair cells of Cdc42loxP/loxP;Fgfr3-iCre-ERT2 mice.Confocal views of cochlear whole mount specimens dissected from the medial coil of control and mutant mice at E18.5. (A–B′) Specimens double-labeled for acetylated tubulin, marking microtubules and basal body, and for phalloidin that labels the hair bundle. Z-stacks cover the level from the basal body to the apicalmost astral microtubules of OHCs. Boxed OHCs in (A′,B′) are shown in higher magnification in A1,B1,B2,B3. (A1) Control specimen shows the localization of the basal body (arrow) close to the vertex of hair bundle and ordered radiation of microtubules at the OHC surface. (B1–B3) In the mutant specimen, the microtubule network is rotated with respect to hair bundle misorientation and microtubules around the basal body are disorganized (B1). Some OHCs show complete loss of the ordered microtubular radiation (B3). Scale bar shown in B3: A–B′, 5 µm; A1–B3, 2 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4400594&req=5

f07: Disorganized apical microtubule network in outer hair cells of Cdc42loxP/loxP;Fgfr3-iCre-ERT2 mice.Confocal views of cochlear whole mount specimens dissected from the medial coil of control and mutant mice at E18.5. (A–B′) Specimens double-labeled for acetylated tubulin, marking microtubules and basal body, and for phalloidin that labels the hair bundle. Z-stacks cover the level from the basal body to the apicalmost astral microtubules of OHCs. Boxed OHCs in (A′,B′) are shown in higher magnification in A1,B1,B2,B3. (A1) Control specimen shows the localization of the basal body (arrow) close to the vertex of hair bundle and ordered radiation of microtubules at the OHC surface. (B1–B3) In the mutant specimen, the microtubule network is rotated with respect to hair bundle misorientation and microtubules around the basal body are disorganized (B1). Some OHCs show complete loss of the ordered microtubular radiation (B3). Scale bar shown in B3: A–B′, 5 µm; A1–B3, 2 µm.
Mentions: In the apices of epithelial cells, astral microtubules radiate from the basal body and are captured by plus-ends to the cell cortex. Pulling forces provided by microtubules are essential for the migration of the basal body and primary cilium and for docking of these structures to their final position (Tang and Marshall, 2012). Recent studies on cochlear hair cells have linked abnormal positioning of the kinocilium to disorganized cell-surface microtubule network (Ezan et al., 2013; Sipe et al., 2013). Compared to control specimens (Fig. 7A–A1), acetylated tubulin-staining at E18.5 showed disorganized microtubules at the OHC surface in the Cdc42 mutant mice (Fig. 7B–B3). Both microtubules around the basal body and those radiating at the cell surface were abnormal. Further, both dysmorphology of the hair bundle and abnormal position of the basal body/kinocilium correlated with microtubule disorganization, a finding clearly seen in high magnification views (Fig. 7B1–B3). These results suggest that altered planar polarity of OHCs is mediated by microtubular disturbances.

Bottom Line: Atypical protein kinase C (aPKC), a putative Cdc42 effector, colocalized with Cdc42 at the hair cell apex, and aPKC expression was altered upon Cdc42 depletion.Our data suggest that Cdc42 together with aPKC is part of the machinery establishing hair cell planar polarity and that Cdc42 acts on polarity through the cell-surface microtubule network.In addition, our data demonstrates that Cdc42 is required for stereociliogenesis in the immature cochlea.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences, Viikinkaari 1, 00014 University of Helsinki, Finland.

No MeSH data available.