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mua-3, a gene required for mechanical tissue integrity in Caenorhabditis elegans, encodes a novel transmembrane protein of epithelial attachment complexes.

Bercher M, Wahl J, Vogel BE, Lu C, Hedgecock EM, Hall DH, Plenefisch JD - J. Cell Biol. (2001)

Bottom Line: The extracellular domain contains four distinct protein modules: 5 low density lipoprotein type A, 52 epidermal growth factor, 1 von Willebrand factor A, and 2 sea urchin-enterokinase-agrin modules.In addition, it is shown that MUA-3 colocalizes with cytoplasmic intermediate filaments (IFs) at these sites.Thus, MUA-3 appears to be a protein that links the IF cytoskeleton of nematode epithelia to the cuticle at sites of mechanical stress.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Toledo, Toledo, OH 43606, USA.

ABSTRACT
Normal locomotion of the nematode Caenorhabditis elegans requires transmission of contractile force through a series of mechanical linkages from the myofibrillar lattice of the body wall muscles, across an intervening extracellular matrix and epithelium (the hypodermis) to the cuticle. Mutations in mua-3 cause a separation of the hypodermis from the cuticle, suggesting this gene is required for maintaining hypodermal-cuticle attachment as the animal grows in size postembryonically. mua-3 encodes a predicted 3,767 amino acid protein with a large extracellular domain, a single transmembrane helix, and a smaller cytoplasmic domain. The extracellular domain contains four distinct protein modules: 5 low density lipoprotein type A, 52 epidermal growth factor, 1 von Willebrand factor A, and 2 sea urchin-enterokinase-agrin modules. MUA-3 localizes to the hypodermal hemidesmosomes and to other sites of mechanically robust transepithelial attachments, including the rectum, vulva, mechanosensory neurons, and excretory duct/pore. In addition, it is shown that MUA-3 colocalizes with cytoplasmic intermediate filaments (IFs) at these sites. Thus, MUA-3 appears to be a protein that links the IF cytoskeleton of nematode epithelia to the cuticle at sites of mechanical stress.

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In mua-3 mutants hemidesmosomes show normal assembly and patterning. (A and B) L4 stage mua-3(rh169) doubly labeled for IFs (p70) (A) and MUA-3 (B). Note presence of organized IFs (between arrows), despite disorganized MUA-3 localization. (C) L2 stage mua-3(rh169) stained with hemidesmosomal marker MH5. Arrows indicate region of separation of MH5 staining from the cuticle. Dotted rectangle indicates area of enlargement in D. (D) Different mua-3(rh169) animal also stained with MH5. MH5 staining separates from cuticle at arrowhead and runs through interior of animal (arrowheads). (E) Same animal as in E under DIC illumination shows muscle, visible as detached band (arrowheads), separating from body wall at arrow. Note that MH5 in E localizes with the muscle, suggesting that the basal hypodermis remains attached to the musculature. (F) Same animal as D, enlarged view of area indicated in C showing that MH5 localization is normal where muscles remain attached to the body wall. (G) Age-matched wild-type animal, showing normal MH5 pattern Bars: (A–E) 10 μm; (F and G) 1 μm.
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fig7: In mua-3 mutants hemidesmosomes show normal assembly and patterning. (A and B) L4 stage mua-3(rh169) doubly labeled for IFs (p70) (A) and MUA-3 (B). Note presence of organized IFs (between arrows), despite disorganized MUA-3 localization. (C) L2 stage mua-3(rh169) stained with hemidesmosomal marker MH5. Arrows indicate region of separation of MH5 staining from the cuticle. Dotted rectangle indicates area of enlargement in D. (D) Different mua-3(rh169) animal also stained with MH5. MH5 staining separates from cuticle at arrowhead and runs through interior of animal (arrowheads). (E) Same animal as in E under DIC illumination shows muscle, visible as detached band (arrowheads), separating from body wall at arrow. Note that MH5 in E localizes with the muscle, suggesting that the basal hypodermis remains attached to the musculature. (F) Same animal as D, enlarged view of area indicated in C showing that MH5 localization is normal where muscles remain attached to the body wall. (G) Age-matched wild-type animal, showing normal MH5 pattern Bars: (A–E) 10 μm; (F and G) 1 μm.

Mentions: Animals mutant for mua-3 were stained with anti-MUA-3, anti-p70, and MH5, an antibody that recognizes a non-IF hemidesmosome–associated antigen (Francis and Waterston, 1991). In the non rh169 and rh195 mutants, MUA-3 no longer localizes to the hypodermal hemidesmosomes, but rather appears to be diffusely staining throughout the hypodermis (Fig. 7 A). However, these same mutations did not result in disruption of IF organization in the hypodermis (Fig. 7 B). In mua-3 animals, MH5 is also normally organized in regions where muscle detachment has not occurred (Fig. 7 F). However, where muscles have detached, MH5 staining is lost from the body wall and can be seen associated with the detached muscle, consistent with separation between the apical hypodermal surface and cuticle (Fig. 7, C–E). These results suggest that IFs may help to localize MUA-3, but also that MUA-3 is not required for IF localization or hemidesmosome assembly.


mua-3, a gene required for mechanical tissue integrity in Caenorhabditis elegans, encodes a novel transmembrane protein of epithelial attachment complexes.

Bercher M, Wahl J, Vogel BE, Lu C, Hedgecock EM, Hall DH, Plenefisch JD - J. Cell Biol. (2001)

In mua-3 mutants hemidesmosomes show normal assembly and patterning. (A and B) L4 stage mua-3(rh169) doubly labeled for IFs (p70) (A) and MUA-3 (B). Note presence of organized IFs (between arrows), despite disorganized MUA-3 localization. (C) L2 stage mua-3(rh169) stained with hemidesmosomal marker MH5. Arrows indicate region of separation of MH5 staining from the cuticle. Dotted rectangle indicates area of enlargement in D. (D) Different mua-3(rh169) animal also stained with MH5. MH5 staining separates from cuticle at arrowhead and runs through interior of animal (arrowheads). (E) Same animal as in E under DIC illumination shows muscle, visible as detached band (arrowheads), separating from body wall at arrow. Note that MH5 in E localizes with the muscle, suggesting that the basal hypodermis remains attached to the musculature. (F) Same animal as D, enlarged view of area indicated in C showing that MH5 localization is normal where muscles remain attached to the body wall. (G) Age-matched wild-type animal, showing normal MH5 pattern Bars: (A–E) 10 μm; (F and G) 1 μm.
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Related In: Results  -  Collection

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fig7: In mua-3 mutants hemidesmosomes show normal assembly and patterning. (A and B) L4 stage mua-3(rh169) doubly labeled for IFs (p70) (A) and MUA-3 (B). Note presence of organized IFs (between arrows), despite disorganized MUA-3 localization. (C) L2 stage mua-3(rh169) stained with hemidesmosomal marker MH5. Arrows indicate region of separation of MH5 staining from the cuticle. Dotted rectangle indicates area of enlargement in D. (D) Different mua-3(rh169) animal also stained with MH5. MH5 staining separates from cuticle at arrowhead and runs through interior of animal (arrowheads). (E) Same animal as in E under DIC illumination shows muscle, visible as detached band (arrowheads), separating from body wall at arrow. Note that MH5 in E localizes with the muscle, suggesting that the basal hypodermis remains attached to the musculature. (F) Same animal as D, enlarged view of area indicated in C showing that MH5 localization is normal where muscles remain attached to the body wall. (G) Age-matched wild-type animal, showing normal MH5 pattern Bars: (A–E) 10 μm; (F and G) 1 μm.
Mentions: Animals mutant for mua-3 were stained with anti-MUA-3, anti-p70, and MH5, an antibody that recognizes a non-IF hemidesmosome–associated antigen (Francis and Waterston, 1991). In the non rh169 and rh195 mutants, MUA-3 no longer localizes to the hypodermal hemidesmosomes, but rather appears to be diffusely staining throughout the hypodermis (Fig. 7 A). However, these same mutations did not result in disruption of IF organization in the hypodermis (Fig. 7 B). In mua-3 animals, MH5 is also normally organized in regions where muscle detachment has not occurred (Fig. 7 F). However, where muscles have detached, MH5 staining is lost from the body wall and can be seen associated with the detached muscle, consistent with separation between the apical hypodermal surface and cuticle (Fig. 7, C–E). These results suggest that IFs may help to localize MUA-3, but also that MUA-3 is not required for IF localization or hemidesmosome assembly.

Bottom Line: The extracellular domain contains four distinct protein modules: 5 low density lipoprotein type A, 52 epidermal growth factor, 1 von Willebrand factor A, and 2 sea urchin-enterokinase-agrin modules.In addition, it is shown that MUA-3 colocalizes with cytoplasmic intermediate filaments (IFs) at these sites.Thus, MUA-3 appears to be a protein that links the IF cytoskeleton of nematode epithelia to the cuticle at sites of mechanical stress.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Toledo, Toledo, OH 43606, USA.

ABSTRACT
Normal locomotion of the nematode Caenorhabditis elegans requires transmission of contractile force through a series of mechanical linkages from the myofibrillar lattice of the body wall muscles, across an intervening extracellular matrix and epithelium (the hypodermis) to the cuticle. Mutations in mua-3 cause a separation of the hypodermis from the cuticle, suggesting this gene is required for maintaining hypodermal-cuticle attachment as the animal grows in size postembryonically. mua-3 encodes a predicted 3,767 amino acid protein with a large extracellular domain, a single transmembrane helix, and a smaller cytoplasmic domain. The extracellular domain contains four distinct protein modules: 5 low density lipoprotein type A, 52 epidermal growth factor, 1 von Willebrand factor A, and 2 sea urchin-enterokinase-agrin modules. MUA-3 localizes to the hypodermal hemidesmosomes and to other sites of mechanically robust transepithelial attachments, including the rectum, vulva, mechanosensory neurons, and excretory duct/pore. In addition, it is shown that MUA-3 colocalizes with cytoplasmic intermediate filaments (IFs) at these sites. Thus, MUA-3 appears to be a protein that links the IF cytoskeleton of nematode epithelia to the cuticle at sites of mechanical stress.

Show MeSH
Related in: MedlinePlus