Limits...
Atypical protein kinase C controls sea urchin ciliogenesis.

Prulière G, Cosson J, Chevalier S, Sardet C, Chenevert J - Mol. Biol. Cell (2011)

Bottom Line: We found that in the early embryo aPKC is uniformly cortical and becomes excluded from the vegetal pole during unequal cleavages at the 8- to 64-cell stages.A dose-dependent and reversible inhibition of aPKC results in mislocalization of the kinase, defective ciliogenesis, and lack of swimming.Thus, as in the primary cilium of differentiated mammalian cells, aPKC controls the growth of motile cilia in invertebrate embryos.

View Article: PubMed Central - PubMed

Affiliation: Observatoire Océanologique, Biologie du Développement, Université Pierre et Marie Curie and CNRS, Villefranche-sur-Mer, France. pruliere@obs-vlfr.fr

ABSTRACT
The atypical protein kinase C (aPKC) is part of the conserved aPKC/PAR6/PAR3 protein complex, which regulates many cell polarity events, including the formation of a primary cilium at the apical surface of epithelial cells. Cilia are highly organized, conserved, microtubule-based structures involved in motility, sensory processes, signaling, and cell polarity. We examined the distribution and function of aPKC in the sea urchin embryo, which forms a swimming blastula covered with motile cilia. We found that in the early embryo aPKC is uniformly cortical and becomes excluded from the vegetal pole during unequal cleavages at the 8- to 64-cell stages. During the blastula and gastrula stages the kinase localizes at the base of cilia, forming a ring at the transition zone between the basal body and the elongating axoneme. A dose-dependent and reversible inhibition of aPKC results in mislocalization of the kinase, defective ciliogenesis, and lack of swimming. Thus, as in the primary cilium of differentiated mammalian cells, aPKC controls the growth of motile cilia in invertebrate embryos. We suggest that aPKC might function to phosphorylate kinesin and so activate the transport of intraflagellar vesicles.

Show MeSH

Related in: MedlinePlus

aPKC is associated with microtubule structures during mitotic divisions in the early sea urchin embryo. Sixty-four–cell stage embryos were fixed and labeled with DM1A antitubulin antibody (red) and anti-aPKC antibody (green). aPKC associates with the MTOC (arrows in B and C) during prophase (A–C); decorates spindle microtubules during metaphase (D–F); starts to concentrate in the spindle midzone (arrow) during anaphase (G–I), and ends up in the midbody (arrow) during telophase (J–L). The nucleus (in C) and chromosomes (in F, I, and L) are stained in blue with Hoescht stain. Bar, 5 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3113769&req=5

Figure 3: aPKC is associated with microtubule structures during mitotic divisions in the early sea urchin embryo. Sixty-four–cell stage embryos were fixed and labeled with DM1A antitubulin antibody (red) and anti-aPKC antibody (green). aPKC associates with the MTOC (arrows in B and C) during prophase (A–C); decorates spindle microtubules during metaphase (D–F); starts to concentrate in the spindle midzone (arrow) during anaphase (G–I), and ends up in the midbody (arrow) during telophase (J–L). The nucleus (in C) and chromosomes (in F, I, and L) are stained in blue with Hoescht stain. Bar, 5 μm.

Mentions: A careful examination of the staining of 16-cell embryos reveals that in addition to enrichment at the cortical layer, a significant amount of aPKC protein resides in the region of mitotic structures in the cytoplasm (Figure 2-IIE), suggesting that aPKC could also bind to microtubules. To further investigate this possibility, we double-stained embryos fixed at different stages of mitosis for microtubules and aPKC. Figure 3 shows the results obtained for a population of 64-cell stage embryos in which mitotic divisions are still fairly synchronous, except for the descendants of micromeres. During prophase (Figure 3, A–C), aPKC is found not only at the cell periphery but also in the two MTOCs (arrows in Figure 3, B and C) on both sides of the nucleus. During metaphase (Figure 3, D–F), aPKC is mostly present all along spindle microtubules, whereas at anaphase, aPKC becomes enriched in the region of the spindle midzone (Figures 3, G–I, arrow in H), suggesting that aPKC might travel toward the plus end of microtubules. The specific accumulation of aPKC in the midbody at the end of mitosis seems to confirm this possibility (Figure 3, J–L, arrow in K).


Atypical protein kinase C controls sea urchin ciliogenesis.

Prulière G, Cosson J, Chevalier S, Sardet C, Chenevert J - Mol. Biol. Cell (2011)

aPKC is associated with microtubule structures during mitotic divisions in the early sea urchin embryo. Sixty-four–cell stage embryos were fixed and labeled with DM1A antitubulin antibody (red) and anti-aPKC antibody (green). aPKC associates with the MTOC (arrows in B and C) during prophase (A–C); decorates spindle microtubules during metaphase (D–F); starts to concentrate in the spindle midzone (arrow) during anaphase (G–I), and ends up in the midbody (arrow) during telophase (J–L). The nucleus (in C) and chromosomes (in F, I, and L) are stained in blue with Hoescht stain. Bar, 5 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3113769&req=5

Figure 3: aPKC is associated with microtubule structures during mitotic divisions in the early sea urchin embryo. Sixty-four–cell stage embryos were fixed and labeled with DM1A antitubulin antibody (red) and anti-aPKC antibody (green). aPKC associates with the MTOC (arrows in B and C) during prophase (A–C); decorates spindle microtubules during metaphase (D–F); starts to concentrate in the spindle midzone (arrow) during anaphase (G–I), and ends up in the midbody (arrow) during telophase (J–L). The nucleus (in C) and chromosomes (in F, I, and L) are stained in blue with Hoescht stain. Bar, 5 μm.
Mentions: A careful examination of the staining of 16-cell embryos reveals that in addition to enrichment at the cortical layer, a significant amount of aPKC protein resides in the region of mitotic structures in the cytoplasm (Figure 2-IIE), suggesting that aPKC could also bind to microtubules. To further investigate this possibility, we double-stained embryos fixed at different stages of mitosis for microtubules and aPKC. Figure 3 shows the results obtained for a population of 64-cell stage embryos in which mitotic divisions are still fairly synchronous, except for the descendants of micromeres. During prophase (Figure 3, A–C), aPKC is found not only at the cell periphery but also in the two MTOCs (arrows in Figure 3, B and C) on both sides of the nucleus. During metaphase (Figure 3, D–F), aPKC is mostly present all along spindle microtubules, whereas at anaphase, aPKC becomes enriched in the region of the spindle midzone (Figures 3, G–I, arrow in H), suggesting that aPKC might travel toward the plus end of microtubules. The specific accumulation of aPKC in the midbody at the end of mitosis seems to confirm this possibility (Figure 3, J–L, arrow in K).

Bottom Line: We found that in the early embryo aPKC is uniformly cortical and becomes excluded from the vegetal pole during unequal cleavages at the 8- to 64-cell stages.A dose-dependent and reversible inhibition of aPKC results in mislocalization of the kinase, defective ciliogenesis, and lack of swimming.Thus, as in the primary cilium of differentiated mammalian cells, aPKC controls the growth of motile cilia in invertebrate embryos.

View Article: PubMed Central - PubMed

Affiliation: Observatoire Océanologique, Biologie du Développement, Université Pierre et Marie Curie and CNRS, Villefranche-sur-Mer, France. pruliere@obs-vlfr.fr

ABSTRACT
The atypical protein kinase C (aPKC) is part of the conserved aPKC/PAR6/PAR3 protein complex, which regulates many cell polarity events, including the formation of a primary cilium at the apical surface of epithelial cells. Cilia are highly organized, conserved, microtubule-based structures involved in motility, sensory processes, signaling, and cell polarity. We examined the distribution and function of aPKC in the sea urchin embryo, which forms a swimming blastula covered with motile cilia. We found that in the early embryo aPKC is uniformly cortical and becomes excluded from the vegetal pole during unequal cleavages at the 8- to 64-cell stages. During the blastula and gastrula stages the kinase localizes at the base of cilia, forming a ring at the transition zone between the basal body and the elongating axoneme. A dose-dependent and reversible inhibition of aPKC results in mislocalization of the kinase, defective ciliogenesis, and lack of swimming. Thus, as in the primary cilium of differentiated mammalian cells, aPKC controls the growth of motile cilia in invertebrate embryos. We suggest that aPKC might function to phosphorylate kinesin and so activate the transport of intraflagellar vesicles.

Show MeSH
Related in: MedlinePlus