Limits...
The Caenorhabditis elegans vab-10 spectraplakin isoforms protect the epidermis against internal and external forces.

Bosher JM, Hahn BS, Legouis R, Sookhareea S, Weimer RM, Gansmuller A, Chisholm AD, Rose AM, Bessereau JL, Labouesse M - J. Cell Biol. (2003)

Bottom Line: We suggest that this isoform protects against forces external to the epidermis.In contrast, lack of VAB-10B leads to increased epidermal thickness during embryonic morphogenesis when epidermal cells change shape.We suggest that this isoform protects cells against tension that builds up within the epidermis.

View Article: PubMed Central - PubMed

Affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP10142, CU de Strasbourg, Illkirch Cedex F-67404, France.

ABSTRACT
Morphogenesis of the Caenorhabditis elegans embryo is driven by actin microfilaments in the epidermis and by sarcomeres in body wall muscles. Both tissues are mechanically coupled, most likely through specialized attachment structures called fibrous organelles (FOs) that connect muscles to the cuticle across the epidermis. Here, we report the identification of new mutations in a gene known as vab-10, which lead to severe morphogenesis defects, and show that vab-10 corresponds to the C. elegans spectraplakin locus. Our analysis of vab-10 reveals novel insights into the role of this plakin subfamily. vab-10 generates isoforms related either to plectin (termed VAB-10A) or to microtubule actin cross-linking factor plakins (termed VAB-10B). Using specific antibodies and mutations, we show that VAB-10A and VAB-10B have distinct distributions and functions in the epidermis. Loss of VAB-10A impairs the integrity of FOs, leading to epidermal detachment from the cuticle and muscles, hence demonstrating that FOs are functionally and molecularly related to hemidesmosomes. We suggest that this isoform protects against forces external to the epidermis. In contrast, lack of VAB-10B leads to increased epidermal thickness during embryonic morphogenesis when epidermal cells change shape. We suggest that this isoform protects cells against tension that builds up within the epidermis.

Show MeSH

Related in: MedlinePlus

VAB-10 antibodies recognize regions of epidermis–muscle contact. Confocal projections of embryos stained with antibodies against VAB-10A (4F2: A, C, and E; MH5: B and D) or VAB-10B (K22: F, G, I, and J; K32: H, K, and L), and with the mAbs MH46 (recognizes myotactin at the basal epidermal membrane in regions of muscle contact; A, F, and I), NE8/4C6 (K, muscle-specific), or MH27 (D, adherens junction-specific; staining with mAbs is in red). (A and F) Early wild-type comma embryos; VAB-10A and VAB-10B staining is detected at the basal (b) and apical (a) membranes as further shown in optical cross sections along the apico–basal axis at the level of arrows (3× insets surrounded by a dotted line). (B and C) Wild-type embryo revealing three muscle–epidermis contact areas. (D and E) vab-10(h1356) embryo (arrow) and a neighboring heterozygous sibling (right); the VAB-10A signal is absent in the h1356 mutant embryo even at a stage when muscles are not yet functional (MH27 staining reveals that fusion between dorsal epidermal cells (dots), which normally precedes the first muscle contraction, did not occur yet; arrowheads show two areas of muscle contact in the control). (G and H) Wild-type embryos revealing two muscle–epidermis contact areas, the pharynx and the intestine (arrowhead). (I and J) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is a very faint residual staining with K22 antibodies. (K) Z-optical projection through the entire stack of images for the embryo in H at the level of the white bar; VAB-10B is found above muscles (in red) and in the intestine (arrowhead). (L) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is essentially no staining with K32 antibodies. Bars, 10 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2199363&req=5

fig4: VAB-10 antibodies recognize regions of epidermis–muscle contact. Confocal projections of embryos stained with antibodies against VAB-10A (4F2: A, C, and E; MH5: B and D) or VAB-10B (K22: F, G, I, and J; K32: H, K, and L), and with the mAbs MH46 (recognizes myotactin at the basal epidermal membrane in regions of muscle contact; A, F, and I), NE8/4C6 (K, muscle-specific), or MH27 (D, adherens junction-specific; staining with mAbs is in red). (A and F) Early wild-type comma embryos; VAB-10A and VAB-10B staining is detected at the basal (b) and apical (a) membranes as further shown in optical cross sections along the apico–basal axis at the level of arrows (3× insets surrounded by a dotted line). (B and C) Wild-type embryo revealing three muscle–epidermis contact areas. (D and E) vab-10(h1356) embryo (arrow) and a neighboring heterozygous sibling (right); the VAB-10A signal is absent in the h1356 mutant embryo even at a stage when muscles are not yet functional (MH27 staining reveals that fusion between dorsal epidermal cells (dots), which normally precedes the first muscle contraction, did not occur yet; arrowheads show two areas of muscle contact in the control). (G and H) Wild-type embryos revealing two muscle–epidermis contact areas, the pharynx and the intestine (arrowhead). (I and J) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is a very faint residual staining with K22 antibodies. (K) Z-optical projection through the entire stack of images for the embryo in H at the level of the white bar; VAB-10B is found above muscles (in red) and in the intestine (arrowhead). (L) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is essentially no staining with K32 antibodies. Bars, 10 μm.

Mentions: vab-10 mutants display elongation and body morphology defects. Differential interference contrast micrographs of terminal-stage vab-10 mutants. (A) Wild-type twofold embryo (mid-embryogenesis). (B) vab-10(h1356) embryo; the body (demarcated by arrowheads) failed to elongate. (C) vab-10A(ju281) embryo with a localized detachment of the epidermis from the cuticle (arrow); all vab-10A(ju281) embryos raised at 20°C and 79% of those raised at 25°C (n = 149) elongated 2.5-fold like this embryo, and occasionally hatched to generate kinked and paralyzed larvae, whereas 21% of those raised at 25°C looked like h1356 embryos. (D) vab-10A(RNAi) embryo; 95% of these embryos (n = 135) resembled h1356 embryos. (E) Arrested L1 vab-10B(mc44) larva (65%, n = 403, could hatch), and (F) hatching L1 vab-10B(RNAi) larva; the body morphology is very irregular. Embryos laid after eliciting an RNAi response against vab-10A– or vab-10B–specific exons are denoted vab-10A(RNAi) or vab-10B(RNAi). Here (as in Figs. 4, 6, and 8), dorsal is up, anterior is left, and bars represent 10 μm.


The Caenorhabditis elegans vab-10 spectraplakin isoforms protect the epidermis against internal and external forces.

Bosher JM, Hahn BS, Legouis R, Sookhareea S, Weimer RM, Gansmuller A, Chisholm AD, Rose AM, Bessereau JL, Labouesse M - J. Cell Biol. (2003)

VAB-10 antibodies recognize regions of epidermis–muscle contact. Confocal projections of embryos stained with antibodies against VAB-10A (4F2: A, C, and E; MH5: B and D) or VAB-10B (K22: F, G, I, and J; K32: H, K, and L), and with the mAbs MH46 (recognizes myotactin at the basal epidermal membrane in regions of muscle contact; A, F, and I), NE8/4C6 (K, muscle-specific), or MH27 (D, adherens junction-specific; staining with mAbs is in red). (A and F) Early wild-type comma embryos; VAB-10A and VAB-10B staining is detected at the basal (b) and apical (a) membranes as further shown in optical cross sections along the apico–basal axis at the level of arrows (3× insets surrounded by a dotted line). (B and C) Wild-type embryo revealing three muscle–epidermis contact areas. (D and E) vab-10(h1356) embryo (arrow) and a neighboring heterozygous sibling (right); the VAB-10A signal is absent in the h1356 mutant embryo even at a stage when muscles are not yet functional (MH27 staining reveals that fusion between dorsal epidermal cells (dots), which normally precedes the first muscle contraction, did not occur yet; arrowheads show two areas of muscle contact in the control). (G and H) Wild-type embryos revealing two muscle–epidermis contact areas, the pharynx and the intestine (arrowhead). (I and J) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is a very faint residual staining with K22 antibodies. (K) Z-optical projection through the entire stack of images for the embryo in H at the level of the white bar; VAB-10B is found above muscles (in red) and in the intestine (arrowhead). (L) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is essentially no staining with K32 antibodies. Bars, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199363&req=5

fig4: VAB-10 antibodies recognize regions of epidermis–muscle contact. Confocal projections of embryos stained with antibodies against VAB-10A (4F2: A, C, and E; MH5: B and D) or VAB-10B (K22: F, G, I, and J; K32: H, K, and L), and with the mAbs MH46 (recognizes myotactin at the basal epidermal membrane in regions of muscle contact; A, F, and I), NE8/4C6 (K, muscle-specific), or MH27 (D, adherens junction-specific; staining with mAbs is in red). (A and F) Early wild-type comma embryos; VAB-10A and VAB-10B staining is detected at the basal (b) and apical (a) membranes as further shown in optical cross sections along the apico–basal axis at the level of arrows (3× insets surrounded by a dotted line). (B and C) Wild-type embryo revealing three muscle–epidermis contact areas. (D and E) vab-10(h1356) embryo (arrow) and a neighboring heterozygous sibling (right); the VAB-10A signal is absent in the h1356 mutant embryo even at a stage when muscles are not yet functional (MH27 staining reveals that fusion between dorsal epidermal cells (dots), which normally precedes the first muscle contraction, did not occur yet; arrowheads show two areas of muscle contact in the control). (G and H) Wild-type embryos revealing two muscle–epidermis contact areas, the pharynx and the intestine (arrowhead). (I and J) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is a very faint residual staining with K22 antibodies. (K) Z-optical projection through the entire stack of images for the embryo in H at the level of the white bar; VAB-10B is found above muscles (in red) and in the intestine (arrowhead). (L) vab-10B(mc44) embryo (arrow) and a neighboring heterozygous sibling (bottom); there is essentially no staining with K32 antibodies. Bars, 10 μm.
Mentions: vab-10 mutants display elongation and body morphology defects. Differential interference contrast micrographs of terminal-stage vab-10 mutants. (A) Wild-type twofold embryo (mid-embryogenesis). (B) vab-10(h1356) embryo; the body (demarcated by arrowheads) failed to elongate. (C) vab-10A(ju281) embryo with a localized detachment of the epidermis from the cuticle (arrow); all vab-10A(ju281) embryos raised at 20°C and 79% of those raised at 25°C (n = 149) elongated 2.5-fold like this embryo, and occasionally hatched to generate kinked and paralyzed larvae, whereas 21% of those raised at 25°C looked like h1356 embryos. (D) vab-10A(RNAi) embryo; 95% of these embryos (n = 135) resembled h1356 embryos. (E) Arrested L1 vab-10B(mc44) larva (65%, n = 403, could hatch), and (F) hatching L1 vab-10B(RNAi) larva; the body morphology is very irregular. Embryos laid after eliciting an RNAi response against vab-10A– or vab-10B–specific exons are denoted vab-10A(RNAi) or vab-10B(RNAi). Here (as in Figs. 4, 6, and 8), dorsal is up, anterior is left, and bars represent 10 μm.

Bottom Line: We suggest that this isoform protects against forces external to the epidermis.In contrast, lack of VAB-10B leads to increased epidermal thickness during embryonic morphogenesis when epidermal cells change shape.We suggest that this isoform protects cells against tension that builds up within the epidermis.

View Article: PubMed Central - PubMed

Affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP10142, CU de Strasbourg, Illkirch Cedex F-67404, France.

ABSTRACT
Morphogenesis of the Caenorhabditis elegans embryo is driven by actin microfilaments in the epidermis and by sarcomeres in body wall muscles. Both tissues are mechanically coupled, most likely through specialized attachment structures called fibrous organelles (FOs) that connect muscles to the cuticle across the epidermis. Here, we report the identification of new mutations in a gene known as vab-10, which lead to severe morphogenesis defects, and show that vab-10 corresponds to the C. elegans spectraplakin locus. Our analysis of vab-10 reveals novel insights into the role of this plakin subfamily. vab-10 generates isoforms related either to plectin (termed VAB-10A) or to microtubule actin cross-linking factor plakins (termed VAB-10B). Using specific antibodies and mutations, we show that VAB-10A and VAB-10B have distinct distributions and functions in the epidermis. Loss of VAB-10A impairs the integrity of FOs, leading to epidermal detachment from the cuticle and muscles, hence demonstrating that FOs are functionally and molecularly related to hemidesmosomes. We suggest that this isoform protects against forces external to the epidermis. In contrast, lack of VAB-10B leads to increased epidermal thickness during embryonic morphogenesis when epidermal cells change shape. We suggest that this isoform protects cells against tension that builds up within the epidermis.

Show MeSH
Related in: MedlinePlus