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The ciliary transition zone functions in cell adhesion but is dispensable for axoneme assembly in C. elegans.

Schouteden C, Serwas D, Palfy M, Dammermann A - J. Cell Biol. (2015)

Bottom Line: Previous work in Caenorhabditis elegans identified two ciliopathy-associated protein complexes or modules that direct assembly of transition zone Y-links.Co-inhibition of all three modules completely disrupted transition zone structure.Surprisingly, axoneme assembly was only mildly perturbed.

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Affiliation: Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), A-1030 Vienna, Austria.

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A role for the transition zone in dendrite attachment. (A) Schematic of dendrite formation by retrograde extension in C. elegans amphids. (B) Stills from time-lapse movie of embryo expressing myristoylated GFP in amphid neurons undergoing retrograde migration. Overlay of GFP signal is shown on transmitted light images of the embryo. Insets show GFP only. Note that the position of dendritic tips (arrowhead) appears fixed as cell bodies (asterisk) move. See also Video 3. (C) Quantitation of phasmid dendrite lengths in wild-type and transition zone mutants at the L4 stage, using CHE-11:GFP. Each dot on the scatter plot represents a single dendrite, with bars indicating average and 95% confidence intervals. n > 20 dendrites per condition. Asterisks indicate statistically significant differences to wild-type (t test; ***, P < 0.001). (D) Tail of a ccep-290;nphp-1 mutant animal expressing CHE-11:GFP. While dendrite extension has failed in both phasmids on the left hand side, right-hand-side phasmids have formed normally. Note that cell bodies are positioned similarly on both sides (broken line). (E) Immunofluorescence micrographs of amphids and phasmids of late embryos expressing myristoylated GFP and LAP:CCEP-290 stained for CCEP-290 with antibody to S-tag. CCEP-290 is located at the tip of the elongating dendrite (arrowheads). (F) Phasmid dendrite lengths in combinations of dex-1/dyf-7 and nphp-4 mutants, quantified as in C. Wild-type data are shown for comparison. ns42 and ns117 are hypomorphic alleles of dex-1 and dyf-7, dyf-7(m537) closer to a loss of function (Heiman and Shaham, 2009). Asterisks indicate statistically significant differences to dex-1/dyf-7 single mutants (t test; ***, P < 0.001; **, P < 0.01). (G) Still images of wild-type and ccep-290;nphp-4 mutant embryos expressing DYF-7:GFP. Overlay of GFP signal on transmitted light images of the embryo. Note the enrichment of DYF-7:GFP at the tips of elongating dendrites (arrowheads). Bars: (D) 5 µm; (B, E, and G) 10 µm. Insets in E are magnified 2×.
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fig3: A role for the transition zone in dendrite attachment. (A) Schematic of dendrite formation by retrograde extension in C. elegans amphids. (B) Stills from time-lapse movie of embryo expressing myristoylated GFP in amphid neurons undergoing retrograde migration. Overlay of GFP signal is shown on transmitted light images of the embryo. Insets show GFP only. Note that the position of dendritic tips (arrowhead) appears fixed as cell bodies (asterisk) move. See also Video 3. (C) Quantitation of phasmid dendrite lengths in wild-type and transition zone mutants at the L4 stage, using CHE-11:GFP. Each dot on the scatter plot represents a single dendrite, with bars indicating average and 95% confidence intervals. n > 20 dendrites per condition. Asterisks indicate statistically significant differences to wild-type (t test; ***, P < 0.001). (D) Tail of a ccep-290;nphp-1 mutant animal expressing CHE-11:GFP. While dendrite extension has failed in both phasmids on the left hand side, right-hand-side phasmids have formed normally. Note that cell bodies are positioned similarly on both sides (broken line). (E) Immunofluorescence micrographs of amphids and phasmids of late embryos expressing myristoylated GFP and LAP:CCEP-290 stained for CCEP-290 with antibody to S-tag. CCEP-290 is located at the tip of the elongating dendrite (arrowheads). (F) Phasmid dendrite lengths in combinations of dex-1/dyf-7 and nphp-4 mutants, quantified as in C. Wild-type data are shown for comparison. ns42 and ns117 are hypomorphic alleles of dex-1 and dyf-7, dyf-7(m537) closer to a loss of function (Heiman and Shaham, 2009). Asterisks indicate statistically significant differences to dex-1/dyf-7 single mutants (t test; ***, P < 0.001; **, P < 0.01). (G) Still images of wild-type and ccep-290;nphp-4 mutant embryos expressing DYF-7:GFP. Overlay of GFP signal on transmitted light images of the embryo. Note the enrichment of DYF-7:GFP at the tips of elongating dendrites (arrowheads). Bars: (D) 5 µm; (B, E, and G) 10 µm. Insets in E are magnified 2×.

Mentions: While cilia assembly was largely unaffected in transition zone mutants, neuronal morphology was strongly perturbed. This was most clearly seen in phasmids, where dendrites collapsed almost entirely, with cilia found immediately adjacent to the cell body (Fig. 2 A). This phenomenon was previously reported in certain combinations of transition zone mutants (Williams et al., 2008, 2011). Loss of contact with the external environment rather than ciliogenesis defects could explain the observed lack of dye-filling, and dendrite lengths do correlate with dye-fill phenotypes (compare Figs. 3 C and S2 E). Complete dendrite collapse was not observed in amphids (Fig. S3, C and D). However, cilia frequently failed to extend into the channel formed by socket and sheath glia (Fig. S3, A and B).


The ciliary transition zone functions in cell adhesion but is dispensable for axoneme assembly in C. elegans.

Schouteden C, Serwas D, Palfy M, Dammermann A - J. Cell Biol. (2015)

A role for the transition zone in dendrite attachment. (A) Schematic of dendrite formation by retrograde extension in C. elegans amphids. (B) Stills from time-lapse movie of embryo expressing myristoylated GFP in amphid neurons undergoing retrograde migration. Overlay of GFP signal is shown on transmitted light images of the embryo. Insets show GFP only. Note that the position of dendritic tips (arrowhead) appears fixed as cell bodies (asterisk) move. See also Video 3. (C) Quantitation of phasmid dendrite lengths in wild-type and transition zone mutants at the L4 stage, using CHE-11:GFP. Each dot on the scatter plot represents a single dendrite, with bars indicating average and 95% confidence intervals. n > 20 dendrites per condition. Asterisks indicate statistically significant differences to wild-type (t test; ***, P < 0.001). (D) Tail of a ccep-290;nphp-1 mutant animal expressing CHE-11:GFP. While dendrite extension has failed in both phasmids on the left hand side, right-hand-side phasmids have formed normally. Note that cell bodies are positioned similarly on both sides (broken line). (E) Immunofluorescence micrographs of amphids and phasmids of late embryos expressing myristoylated GFP and LAP:CCEP-290 stained for CCEP-290 with antibody to S-tag. CCEP-290 is located at the tip of the elongating dendrite (arrowheads). (F) Phasmid dendrite lengths in combinations of dex-1/dyf-7 and nphp-4 mutants, quantified as in C. Wild-type data are shown for comparison. ns42 and ns117 are hypomorphic alleles of dex-1 and dyf-7, dyf-7(m537) closer to a loss of function (Heiman and Shaham, 2009). Asterisks indicate statistically significant differences to dex-1/dyf-7 single mutants (t test; ***, P < 0.001; **, P < 0.01). (G) Still images of wild-type and ccep-290;nphp-4 mutant embryos expressing DYF-7:GFP. Overlay of GFP signal on transmitted light images of the embryo. Note the enrichment of DYF-7:GFP at the tips of elongating dendrites (arrowheads). Bars: (D) 5 µm; (B, E, and G) 10 µm. Insets in E are magnified 2×.
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fig3: A role for the transition zone in dendrite attachment. (A) Schematic of dendrite formation by retrograde extension in C. elegans amphids. (B) Stills from time-lapse movie of embryo expressing myristoylated GFP in amphid neurons undergoing retrograde migration. Overlay of GFP signal is shown on transmitted light images of the embryo. Insets show GFP only. Note that the position of dendritic tips (arrowhead) appears fixed as cell bodies (asterisk) move. See also Video 3. (C) Quantitation of phasmid dendrite lengths in wild-type and transition zone mutants at the L4 stage, using CHE-11:GFP. Each dot on the scatter plot represents a single dendrite, with bars indicating average and 95% confidence intervals. n > 20 dendrites per condition. Asterisks indicate statistically significant differences to wild-type (t test; ***, P < 0.001). (D) Tail of a ccep-290;nphp-1 mutant animal expressing CHE-11:GFP. While dendrite extension has failed in both phasmids on the left hand side, right-hand-side phasmids have formed normally. Note that cell bodies are positioned similarly on both sides (broken line). (E) Immunofluorescence micrographs of amphids and phasmids of late embryos expressing myristoylated GFP and LAP:CCEP-290 stained for CCEP-290 with antibody to S-tag. CCEP-290 is located at the tip of the elongating dendrite (arrowheads). (F) Phasmid dendrite lengths in combinations of dex-1/dyf-7 and nphp-4 mutants, quantified as in C. Wild-type data are shown for comparison. ns42 and ns117 are hypomorphic alleles of dex-1 and dyf-7, dyf-7(m537) closer to a loss of function (Heiman and Shaham, 2009). Asterisks indicate statistically significant differences to dex-1/dyf-7 single mutants (t test; ***, P < 0.001; **, P < 0.01). (G) Still images of wild-type and ccep-290;nphp-4 mutant embryos expressing DYF-7:GFP. Overlay of GFP signal on transmitted light images of the embryo. Note the enrichment of DYF-7:GFP at the tips of elongating dendrites (arrowheads). Bars: (D) 5 µm; (B, E, and G) 10 µm. Insets in E are magnified 2×.
Mentions: While cilia assembly was largely unaffected in transition zone mutants, neuronal morphology was strongly perturbed. This was most clearly seen in phasmids, where dendrites collapsed almost entirely, with cilia found immediately adjacent to the cell body (Fig. 2 A). This phenomenon was previously reported in certain combinations of transition zone mutants (Williams et al., 2008, 2011). Loss of contact with the external environment rather than ciliogenesis defects could explain the observed lack of dye-filling, and dendrite lengths do correlate with dye-fill phenotypes (compare Figs. 3 C and S2 E). Complete dendrite collapse was not observed in amphids (Fig. S3, C and D). However, cilia frequently failed to extend into the channel formed by socket and sheath glia (Fig. S3, A and B).

Bottom Line: Previous work in Caenorhabditis elegans identified two ciliopathy-associated protein complexes or modules that direct assembly of transition zone Y-links.Co-inhibition of all three modules completely disrupted transition zone structure.Surprisingly, axoneme assembly was only mildly perturbed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), A-1030 Vienna, Austria.

Show MeSH
Related in: MedlinePlus