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LAD-1, the Caenorhabditis elegans L1CAM homologue, participates in embryonic and gonadal morphogenesis and is a substrate for fibroblast growth factor receptor pathway-dependent phosphotyrosine-based signaling.

Chen L, Ong B, Bennett V - J. Cell Biol. (2001)

Bottom Line: In addition, the ubiquitously expressed LAD-1, which binds to ankyrin-G, colocalizes with the C. elegans ankyrin, UNC-44, in multiple tissues at sites of cell-cell contact.These findings suggest a novel ankyrin-independent role for LAD-1 related to FGFR signaling.Taken together, these results indicate that L1CAMs constitute a family of ubiquitous adhesion molecules, which participate in tissue morphogenesis and maintaining tissue integrity in metazoans.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Department of Cell Biology, and Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA. l.chen@cellbio.duke.edu

ABSTRACT
This study shows that L1-like adhesion (LAD-1), the sole Caenorhabditis elegans homologue of the L1 family of neuronal adhesion molecules, is required for proper development of the germline and the early embryo and embryonic and gonadal morphogenesis. In addition, the ubiquitously expressed LAD-1, which binds to ankyrin-G, colocalizes with the C. elegans ankyrin, UNC-44, in multiple tissues at sites of cell-cell contact. Finally, we show that LAD-1 is phosphorylated in a fibroblast growth factor receptor (FGFR) pathway-dependent manner on a tyrosine residue in the highly conserved ankyrin-binding motif, FIGQY, which was shown previously to abolish the L1 family of cell adhesion molecule (L1CAM) binding to ankyrin in cultured cells. Immunofluorescence studies revealed that FIGQY-tyrosine-phosphorylated LAD-1 does not colocalize with nonphosphorylated LAD-1 or UNC-44 ankyrin but instead is localized to sites that undergo mechanical stress in polarized epithelia and axon-body wall muscle junctions. These findings suggest a novel ankyrin-independent role for LAD-1 related to FGFR signaling. Taken together, these results indicate that L1CAMs constitute a family of ubiquitous adhesion molecules, which participate in tissue morphogenesis and maintaining tissue integrity in metazoans.

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LAD-1P is detected along the sublateral axons and commissural axons crossing the sublateral axons in a regularly spaced punctate pattern. (A) A schematic of the C. elegans nervous system with two major nerve cords (ventral and dorsal) and smaller sublateral axon tracts on either side of the body. Sublateral axons grow along the body wall muscle basement membrane unlike the dorsal and ventral nerve cords. LAD-1P is localized specifically to sublateral axons (B, arrow) and the part of the commissural axons in contact with body wall muscles (B, arrowhead). A magnified portion of the axon tract shown in B highlights the regular punctate localization pattern of LAD-1P. (C and E) LAD-1P (green) is detected only in sublateral axons that overlay the body wall muscles (D, red, and E). The body wall muscle (red) is detected by MH24, a monoclonal antibody that recognizes vinculin. The arrow in C points to a sublateral axon tract, whereas the arrowhead points to the transversing commissural axon. Bars: (A) 50 μm; (B) 5 μm; (C) 20 μm.
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fig8: LAD-1P is detected along the sublateral axons and commissural axons crossing the sublateral axons in a regularly spaced punctate pattern. (A) A schematic of the C. elegans nervous system with two major nerve cords (ventral and dorsal) and smaller sublateral axon tracts on either side of the body. Sublateral axons grow along the body wall muscle basement membrane unlike the dorsal and ventral nerve cords. LAD-1P is localized specifically to sublateral axons (B, arrow) and the part of the commissural axons in contact with body wall muscles (B, arrowhead). A magnified portion of the axon tract shown in B highlights the regular punctate localization pattern of LAD-1P. (C and E) LAD-1P (green) is detected only in sublateral axons that overlay the body wall muscles (D, red, and E). The body wall muscle (red) is detected by MH24, a monoclonal antibody that recognizes vinculin. The arrow in C points to a sublateral axon tract, whereas the arrowhead points to the transversing commissural axon. Bars: (A) 50 μm; (B) 5 μm; (C) 20 μm.

Mentions: The major longitudinal axon tracts in C. elegans include the ventral and dorsal nerve cords, which are flanked by the sublateral axon tracts (Fig. 8 A, schematic) (White et al., 1986). Sublateral axons grow along the body wall muscle basement membrane unlike the ventral and dorsal nerve cord. Commissural axons, originating from either the dorsal or ventral nerve cord, also grow along the body wall muscle basement membrane when they cross the sublateral axons (White et al., 1986).


LAD-1, the Caenorhabditis elegans L1CAM homologue, participates in embryonic and gonadal morphogenesis and is a substrate for fibroblast growth factor receptor pathway-dependent phosphotyrosine-based signaling.

Chen L, Ong B, Bennett V - J. Cell Biol. (2001)

LAD-1P is detected along the sublateral axons and commissural axons crossing the sublateral axons in a regularly spaced punctate pattern. (A) A schematic of the C. elegans nervous system with two major nerve cords (ventral and dorsal) and smaller sublateral axon tracts on either side of the body. Sublateral axons grow along the body wall muscle basement membrane unlike the dorsal and ventral nerve cords. LAD-1P is localized specifically to sublateral axons (B, arrow) and the part of the commissural axons in contact with body wall muscles (B, arrowhead). A magnified portion of the axon tract shown in B highlights the regular punctate localization pattern of LAD-1P. (C and E) LAD-1P (green) is detected only in sublateral axons that overlay the body wall muscles (D, red, and E). The body wall muscle (red) is detected by MH24, a monoclonal antibody that recognizes vinculin. The arrow in C points to a sublateral axon tract, whereas the arrowhead points to the transversing commissural axon. Bars: (A) 50 μm; (B) 5 μm; (C) 20 μm.
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Related In: Results  -  Collection

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fig8: LAD-1P is detected along the sublateral axons and commissural axons crossing the sublateral axons in a regularly spaced punctate pattern. (A) A schematic of the C. elegans nervous system with two major nerve cords (ventral and dorsal) and smaller sublateral axon tracts on either side of the body. Sublateral axons grow along the body wall muscle basement membrane unlike the dorsal and ventral nerve cords. LAD-1P is localized specifically to sublateral axons (B, arrow) and the part of the commissural axons in contact with body wall muscles (B, arrowhead). A magnified portion of the axon tract shown in B highlights the regular punctate localization pattern of LAD-1P. (C and E) LAD-1P (green) is detected only in sublateral axons that overlay the body wall muscles (D, red, and E). The body wall muscle (red) is detected by MH24, a monoclonal antibody that recognizes vinculin. The arrow in C points to a sublateral axon tract, whereas the arrowhead points to the transversing commissural axon. Bars: (A) 50 μm; (B) 5 μm; (C) 20 μm.
Mentions: The major longitudinal axon tracts in C. elegans include the ventral and dorsal nerve cords, which are flanked by the sublateral axon tracts (Fig. 8 A, schematic) (White et al., 1986). Sublateral axons grow along the body wall muscle basement membrane unlike the ventral and dorsal nerve cord. Commissural axons, originating from either the dorsal or ventral nerve cord, also grow along the body wall muscle basement membrane when they cross the sublateral axons (White et al., 1986).

Bottom Line: In addition, the ubiquitously expressed LAD-1, which binds to ankyrin-G, colocalizes with the C. elegans ankyrin, UNC-44, in multiple tissues at sites of cell-cell contact.These findings suggest a novel ankyrin-independent role for LAD-1 related to FGFR signaling.Taken together, these results indicate that L1CAMs constitute a family of ubiquitous adhesion molecules, which participate in tissue morphogenesis and maintaining tissue integrity in metazoans.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Department of Cell Biology, and Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA. l.chen@cellbio.duke.edu

ABSTRACT
This study shows that L1-like adhesion (LAD-1), the sole Caenorhabditis elegans homologue of the L1 family of neuronal adhesion molecules, is required for proper development of the germline and the early embryo and embryonic and gonadal morphogenesis. In addition, the ubiquitously expressed LAD-1, which binds to ankyrin-G, colocalizes with the C. elegans ankyrin, UNC-44, in multiple tissues at sites of cell-cell contact. Finally, we show that LAD-1 is phosphorylated in a fibroblast growth factor receptor (FGFR) pathway-dependent manner on a tyrosine residue in the highly conserved ankyrin-binding motif, FIGQY, which was shown previously to abolish the L1 family of cell adhesion molecule (L1CAM) binding to ankyrin in cultured cells. Immunofluorescence studies revealed that FIGQY-tyrosine-phosphorylated LAD-1 does not colocalize with nonphosphorylated LAD-1 or UNC-44 ankyrin but instead is localized to sites that undergo mechanical stress in polarized epithelia and axon-body wall muscle junctions. These findings suggest a novel ankyrin-independent role for LAD-1 related to FGFR signaling. Taken together, these results indicate that L1CAMs constitute a family of ubiquitous adhesion molecules, which participate in tissue morphogenesis and maintaining tissue integrity in metazoans.

Show MeSH
Related in: MedlinePlus