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The cell signaling adaptor protein EPS-8 is essential for C. elegans epidermal elongation and interacts with the ankyrin repeat protein VAB-19.

Ding M, King RS, Berry EC, Wang Y, Hardin J, Chisholm AD - PLoS ONE (2008)

Bottom Line: The epidermal cells of the C. elegans embryo undergo coordinated cell shape changes that result in the morphogenetic process of elongation.The function of EPS-8 in epidermal development involves its N-terminal PTB and central domains, and is independent of its C-terminal SH3 and actin-binding domains.The existence of EPS-8B-like isoforms in Drosophila suggests this function of EPS-8 proteins could be conserved among other organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, USA.

ABSTRACT

Background: The epidermal cells of the C. elegans embryo undergo coordinated cell shape changes that result in the morphogenetic process of elongation. The cytoskeletal ankyrin repeat protein VAB-19 is required for cell shape changes and localizes to cell-matrix attachment structures. The molecular functions of VAB-19 in this process are obscure, as no previous interactors for VAB-19 have been described.

Methodology/principal findings: In screens for VAB-19 binding proteins we identified the signaling adaptor EPS-8. Within C. elegans epidermal cells, EPS-8 and VAB-19 colocalize at cell-matrix attachment structures. The central domain of EPS-8 is necessary and sufficient for its interaction with VAB-19. eps-8 mutants, like vab-19 mutants, are defective in epidermal elongation and in epidermal-muscle attachment. The eps-8 locus encodes two isoforms, EPS-8A and EPS-8B, that appear to act redundantly in epidermal elongation. The function of EPS-8 in epidermal development involves its N-terminal PTB and central domains, and is independent of its C-terminal SH3 and actin-binding domains. VAB-19 appears to act earlier in the biogenesis of attachment structures and may recruit EPS-8 to these structures.

Conclusions/significance: EPS-8 and VAB-19 define a novel pathway acting at cell-matrix attachments to regulate epithelial cell shape. This is the first report of a role for EPS-8 proteins in cell-matrix attachments. The existence of EPS-8B-like isoforms in Drosophila suggests this function of EPS-8 proteins could be conserved among other organisms.

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Molecular epistasis, order of recruitment, and model for interaction of VAB-19 and EPS-8.(A) In early elongation EPS-8 (mCherry::EPS-8(central), juEx1784) is either diffuse or aggregated and unlike VAB-19 does not localize to longitudinal bands adjacent to muscle (cf. panel E). By the threefold stage of elongation mCherry::EPS-8(central) is localized to circumferential stripes corresponding to attachment structures (arrowhead, B). (C, D) In vab-19(e1036) mutant embryos grown at 15°C, mCherry::EPS-8 is diffuse and does not localize to attachment structures at 1.5-fold (C) or two-fold (D). (E,F) In wild-type embryos VAB-19::GFP (juIs169) is localized to longitudinal bands at the 1.5-fold stage (arrow, E) and by the threefold stage becomes localized to circumferential stripes (arrow, F). The initial phase of VAB-19::GFP localization to longitudinal bands occurs in eps-8(jc36) mutants (arrow, G). However VAB-19::GFP never became clearly localized to circumferential stripes in later jc36 embryos, remaining in longitudinal bands (arrow, H). (I) Model for the VAB-19/EPS-8 pathway. VAB-19 localization is directed by its N-terminal motifs, interacting with unknown components of attachment structures. The VAB-19 ANK repeats then recruit EPS-8 by interacting with its central domain. EPS-8 function may involve further interactions mediated by the EPS-8 PTB domain.
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pone-0003346-g004: Molecular epistasis, order of recruitment, and model for interaction of VAB-19 and EPS-8.(A) In early elongation EPS-8 (mCherry::EPS-8(central), juEx1784) is either diffuse or aggregated and unlike VAB-19 does not localize to longitudinal bands adjacent to muscle (cf. panel E). By the threefold stage of elongation mCherry::EPS-8(central) is localized to circumferential stripes corresponding to attachment structures (arrowhead, B). (C, D) In vab-19(e1036) mutant embryos grown at 15°C, mCherry::EPS-8 is diffuse and does not localize to attachment structures at 1.5-fold (C) or two-fold (D). (E,F) In wild-type embryos VAB-19::GFP (juIs169) is localized to longitudinal bands at the 1.5-fold stage (arrow, E) and by the threefold stage becomes localized to circumferential stripes (arrow, F). The initial phase of VAB-19::GFP localization to longitudinal bands occurs in eps-8(jc36) mutants (arrow, G). However VAB-19::GFP never became clearly localized to circumferential stripes in later jc36 embryos, remaining in longitudinal bands (arrow, H). (I) Model for the VAB-19/EPS-8 pathway. VAB-19 localization is directed by its N-terminal motifs, interacting with unknown components of attachment structures. The VAB-19 ANK repeats then recruit EPS-8 by interacting with its central domain. EPS-8 function may involve further interactions mediated by the EPS-8 PTB domain.

Mentions: Although VAB-19 and EPS-8 both promote attachment structure development, two lines of evidence suggest VAB-19 may act earlier than EPS-8. First, the elongation defects of vab-19 mutants become apparent slightly earlier than those of eps-8 mutants. Second, whereas VAB-19 is localized to attachment structures beginning in early elongation (1.5-fold), EPS-8 fusion proteins did not appear clearly localized to attachment structures until the three-fold stage (Figure 4A, B). These differences in phenotype and localization suggest VAB-19 might act earlier than EPS-8 in a pathway of attachment structure biogenesis.


The cell signaling adaptor protein EPS-8 is essential for C. elegans epidermal elongation and interacts with the ankyrin repeat protein VAB-19.

Ding M, King RS, Berry EC, Wang Y, Hardin J, Chisholm AD - PLoS ONE (2008)

Molecular epistasis, order of recruitment, and model for interaction of VAB-19 and EPS-8.(A) In early elongation EPS-8 (mCherry::EPS-8(central), juEx1784) is either diffuse or aggregated and unlike VAB-19 does not localize to longitudinal bands adjacent to muscle (cf. panel E). By the threefold stage of elongation mCherry::EPS-8(central) is localized to circumferential stripes corresponding to attachment structures (arrowhead, B). (C, D) In vab-19(e1036) mutant embryos grown at 15°C, mCherry::EPS-8 is diffuse and does not localize to attachment structures at 1.5-fold (C) or two-fold (D). (E,F) In wild-type embryos VAB-19::GFP (juIs169) is localized to longitudinal bands at the 1.5-fold stage (arrow, E) and by the threefold stage becomes localized to circumferential stripes (arrow, F). The initial phase of VAB-19::GFP localization to longitudinal bands occurs in eps-8(jc36) mutants (arrow, G). However VAB-19::GFP never became clearly localized to circumferential stripes in later jc36 embryos, remaining in longitudinal bands (arrow, H). (I) Model for the VAB-19/EPS-8 pathway. VAB-19 localization is directed by its N-terminal motifs, interacting with unknown components of attachment structures. The VAB-19 ANK repeats then recruit EPS-8 by interacting with its central domain. EPS-8 function may involve further interactions mediated by the EPS-8 PTB domain.
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Related In: Results  -  Collection

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pone-0003346-g004: Molecular epistasis, order of recruitment, and model for interaction of VAB-19 and EPS-8.(A) In early elongation EPS-8 (mCherry::EPS-8(central), juEx1784) is either diffuse or aggregated and unlike VAB-19 does not localize to longitudinal bands adjacent to muscle (cf. panel E). By the threefold stage of elongation mCherry::EPS-8(central) is localized to circumferential stripes corresponding to attachment structures (arrowhead, B). (C, D) In vab-19(e1036) mutant embryos grown at 15°C, mCherry::EPS-8 is diffuse and does not localize to attachment structures at 1.5-fold (C) or two-fold (D). (E,F) In wild-type embryos VAB-19::GFP (juIs169) is localized to longitudinal bands at the 1.5-fold stage (arrow, E) and by the threefold stage becomes localized to circumferential stripes (arrow, F). The initial phase of VAB-19::GFP localization to longitudinal bands occurs in eps-8(jc36) mutants (arrow, G). However VAB-19::GFP never became clearly localized to circumferential stripes in later jc36 embryos, remaining in longitudinal bands (arrow, H). (I) Model for the VAB-19/EPS-8 pathway. VAB-19 localization is directed by its N-terminal motifs, interacting with unknown components of attachment structures. The VAB-19 ANK repeats then recruit EPS-8 by interacting with its central domain. EPS-8 function may involve further interactions mediated by the EPS-8 PTB domain.
Mentions: Although VAB-19 and EPS-8 both promote attachment structure development, two lines of evidence suggest VAB-19 may act earlier than EPS-8. First, the elongation defects of vab-19 mutants become apparent slightly earlier than those of eps-8 mutants. Second, whereas VAB-19 is localized to attachment structures beginning in early elongation (1.5-fold), EPS-8 fusion proteins did not appear clearly localized to attachment structures until the three-fold stage (Figure 4A, B). These differences in phenotype and localization suggest VAB-19 might act earlier than EPS-8 in a pathway of attachment structure biogenesis.

Bottom Line: The epidermal cells of the C. elegans embryo undergo coordinated cell shape changes that result in the morphogenetic process of elongation.The function of EPS-8 in epidermal development involves its N-terminal PTB and central domains, and is independent of its C-terminal SH3 and actin-binding domains.The existence of EPS-8B-like isoforms in Drosophila suggests this function of EPS-8 proteins could be conserved among other organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, USA.

ABSTRACT

Background: The epidermal cells of the C. elegans embryo undergo coordinated cell shape changes that result in the morphogenetic process of elongation. The cytoskeletal ankyrin repeat protein VAB-19 is required for cell shape changes and localizes to cell-matrix attachment structures. The molecular functions of VAB-19 in this process are obscure, as no previous interactors for VAB-19 have been described.

Methodology/principal findings: In screens for VAB-19 binding proteins we identified the signaling adaptor EPS-8. Within C. elegans epidermal cells, EPS-8 and VAB-19 colocalize at cell-matrix attachment structures. The central domain of EPS-8 is necessary and sufficient for its interaction with VAB-19. eps-8 mutants, like vab-19 mutants, are defective in epidermal elongation and in epidermal-muscle attachment. The eps-8 locus encodes two isoforms, EPS-8A and EPS-8B, that appear to act redundantly in epidermal elongation. The function of EPS-8 in epidermal development involves its N-terminal PTB and central domains, and is independent of its C-terminal SH3 and actin-binding domains. VAB-19 appears to act earlier in the biogenesis of attachment structures and may recruit EPS-8 to these structures.

Conclusions/significance: EPS-8 and VAB-19 define a novel pathway acting at cell-matrix attachments to regulate epithelial cell shape. This is the first report of a role for EPS-8 proteins in cell-matrix attachments. The existence of EPS-8B-like isoforms in Drosophila suggests this function of EPS-8 proteins could be conserved among other organisms.

Show MeSH