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Modulation of mouse neural crest cell motility by N-cadherin and connexin 43 gap junctions.

Xu X, Li WE, Huang GY, Meyer R, Chen T, Luo Y, Thomas MP, Radice GL, Lo CW - J. Cell Biol. (2001)

Bottom Line: Alternatively, Cx43alpha1 may serve a novel function in motility.We observed that p120 catenin (p120ctn), an Armadillo protein known to modulate cell motility, is colocalized not only with N-cadherin but also with Cx43alpha1.Moreover, the subcellular distribution of p120ctn was altered with N-cadherin or Cx43alpha1 deficiency.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Goddard Laboratory, University of Pennsylvania, Philadelphia, PA 19104, USA.

ABSTRACT
Connexin 43 (Cx43alpha1) gap junction has been shown to have an essential role in mediating functional coupling of neural crest cells and in modulating neural crest cell migration. Here, we showed that N-cadherin and wnt1 are required for efficient dye coupling but not for the expression of Cx43alpha1 gap junctions in neural crest cells. Cell motility was found to be altered in the N-cadherin-deficient neural crest cells, but the alterations were different from that elicited by Cx43alpha1 deficiency. In contrast, wnt1-deficient neural crest cells showed no discernible change in cell motility. These observations suggest that dye coupling may not be a good measure of gap junction communication relevant to motility. Alternatively, Cx43alpha1 may serve a novel function in motility. We observed that p120 catenin (p120ctn), an Armadillo protein known to modulate cell motility, is colocalized not only with N-cadherin but also with Cx43alpha1. Moreover, the subcellular distribution of p120ctn was altered with N-cadherin or Cx43alpha1 deficiency. Based on these findings, we propose a model in which Cx43alpha1 and N-cadherin may modulate neural crest cell motility by engaging in a dynamic cross-talk with the cell's locomotory apparatus through p120ctn signaling.

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Cx43α1 and β-catenin expression in N-cadherin– and Cx43α1-deficient neural crest cells. Neural crest cells in explant cultures derived from Cx43α1 and N-cadherin knockout mouse embryos were examined for the expression of Cx43α1 (A and C) or β-catenin (B and D) by immunofluorescence microscopy. N-cadherin–deficient neural crest cells show abundant expression of Cx43α1 gap junctions at regions of cell–cell contact (A), whereas no expression was detected in neural crest cells derived from the Cx43α1 knockout mouse embryos (B). In the N-cadherin–deficient neural crest cells, β-catenin expression at the cell surface was reduced compared with wild-type neural crest cells (not shown; Fig. 1 B) and neural crest cells from the Cx43α1 knockout mouse embryos (D). These images were obtained by merging darkfield fluorescence and phase–contrast images. All images are at the same magnification. Bar, 25 μm.
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fig2: Cx43α1 and β-catenin expression in N-cadherin– and Cx43α1-deficient neural crest cells. Neural crest cells in explant cultures derived from Cx43α1 and N-cadherin knockout mouse embryos were examined for the expression of Cx43α1 (A and C) or β-catenin (B and D) by immunofluorescence microscopy. N-cadherin–deficient neural crest cells show abundant expression of Cx43α1 gap junctions at regions of cell–cell contact (A), whereas no expression was detected in neural crest cells derived from the Cx43α1 knockout mouse embryos (B). In the N-cadherin–deficient neural crest cells, β-catenin expression at the cell surface was reduced compared with wild-type neural crest cells (not shown; Fig. 1 B) and neural crest cells from the Cx43α1 knockout mouse embryos (D). These images were obtained by merging darkfield fluorescence and phase–contrast images. All images are at the same magnification. Bar, 25 μm.

Mentions: Our studies focused on the cardiac neural crest cells, a subpopulation of neural crest cells that emerge from the postotic hindbrain neuroepithelium at E8.5 (Fukiishi and Morriss-Kay, 1992). This is before the time when N-cadherin–deficient embryos die from cell adhesion defects in the developing myocardium (Radice et al., 1997). To determine if N-cadherin is expressed in the cardiac neural crest cells, postotic hindbrain neural tube explant cultures were generated, and immunofluorescence microscopy was used to examine the newly emerged neural crest cells. Such studies showed the distribution of N-cadherin diffusely over the cell surface and also clustered in punctate spots along extended cell processes, many of which were thin projections barely visible by phase–contrast microscopy (Fig. 1 A). This pattern is similar to that reported for N-cadherin expression in neural crest cells in chick neural tube explant cultures (Monier-Gavelle and Duband, 1995). Double immunostaining with Cx43α1 and N-cadherin antibodies revealed in some regions the close juxtapositioning or colocalization of N-cadherin with Cx43α1, particularly along cell processes (Fig. 1 A, arrows). Examination of neural crest cells from the N-cadherin–deficient embryos surprisingly showed no detectable change in the abundance of Cx43α1 gap junction plaques at the cell surface (Fig. 2 A). The specificity of the Cx43α1 antibody was demonstrated by a parallel analysis of Cx43α1-deficient neural crest cells, which showed no significant immunostaining (Fig. 2 C). We also examined the expression of N-cadherin in the Cx43α1-deficient neural crest cells and showed no obvious change in the distribution of N-cadherin, which remained abundant at regions of cell–cell contact (data not shown).


Modulation of mouse neural crest cell motility by N-cadherin and connexin 43 gap junctions.

Xu X, Li WE, Huang GY, Meyer R, Chen T, Luo Y, Thomas MP, Radice GL, Lo CW - J. Cell Biol. (2001)

Cx43α1 and β-catenin expression in N-cadherin– and Cx43α1-deficient neural crest cells. Neural crest cells in explant cultures derived from Cx43α1 and N-cadherin knockout mouse embryos were examined for the expression of Cx43α1 (A and C) or β-catenin (B and D) by immunofluorescence microscopy. N-cadherin–deficient neural crest cells show abundant expression of Cx43α1 gap junctions at regions of cell–cell contact (A), whereas no expression was detected in neural crest cells derived from the Cx43α1 knockout mouse embryos (B). In the N-cadherin–deficient neural crest cells, β-catenin expression at the cell surface was reduced compared with wild-type neural crest cells (not shown; Fig. 1 B) and neural crest cells from the Cx43α1 knockout mouse embryos (D). These images were obtained by merging darkfield fluorescence and phase–contrast images. All images are at the same magnification. Bar, 25 μm.
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fig2: Cx43α1 and β-catenin expression in N-cadherin– and Cx43α1-deficient neural crest cells. Neural crest cells in explant cultures derived from Cx43α1 and N-cadherin knockout mouse embryos were examined for the expression of Cx43α1 (A and C) or β-catenin (B and D) by immunofluorescence microscopy. N-cadherin–deficient neural crest cells show abundant expression of Cx43α1 gap junctions at regions of cell–cell contact (A), whereas no expression was detected in neural crest cells derived from the Cx43α1 knockout mouse embryos (B). In the N-cadherin–deficient neural crest cells, β-catenin expression at the cell surface was reduced compared with wild-type neural crest cells (not shown; Fig. 1 B) and neural crest cells from the Cx43α1 knockout mouse embryos (D). These images were obtained by merging darkfield fluorescence and phase–contrast images. All images are at the same magnification. Bar, 25 μm.
Mentions: Our studies focused on the cardiac neural crest cells, a subpopulation of neural crest cells that emerge from the postotic hindbrain neuroepithelium at E8.5 (Fukiishi and Morriss-Kay, 1992). This is before the time when N-cadherin–deficient embryos die from cell adhesion defects in the developing myocardium (Radice et al., 1997). To determine if N-cadherin is expressed in the cardiac neural crest cells, postotic hindbrain neural tube explant cultures were generated, and immunofluorescence microscopy was used to examine the newly emerged neural crest cells. Such studies showed the distribution of N-cadherin diffusely over the cell surface and also clustered in punctate spots along extended cell processes, many of which were thin projections barely visible by phase–contrast microscopy (Fig. 1 A). This pattern is similar to that reported for N-cadherin expression in neural crest cells in chick neural tube explant cultures (Monier-Gavelle and Duband, 1995). Double immunostaining with Cx43α1 and N-cadherin antibodies revealed in some regions the close juxtapositioning or colocalization of N-cadherin with Cx43α1, particularly along cell processes (Fig. 1 A, arrows). Examination of neural crest cells from the N-cadherin–deficient embryos surprisingly showed no detectable change in the abundance of Cx43α1 gap junction plaques at the cell surface (Fig. 2 A). The specificity of the Cx43α1 antibody was demonstrated by a parallel analysis of Cx43α1-deficient neural crest cells, which showed no significant immunostaining (Fig. 2 C). We also examined the expression of N-cadherin in the Cx43α1-deficient neural crest cells and showed no obvious change in the distribution of N-cadherin, which remained abundant at regions of cell–cell contact (data not shown).

Bottom Line: Alternatively, Cx43alpha1 may serve a novel function in motility.We observed that p120 catenin (p120ctn), an Armadillo protein known to modulate cell motility, is colocalized not only with N-cadherin but also with Cx43alpha1.Moreover, the subcellular distribution of p120ctn was altered with N-cadherin or Cx43alpha1 deficiency.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Goddard Laboratory, University of Pennsylvania, Philadelphia, PA 19104, USA.

ABSTRACT
Connexin 43 (Cx43alpha1) gap junction has been shown to have an essential role in mediating functional coupling of neural crest cells and in modulating neural crest cell migration. Here, we showed that N-cadherin and wnt1 are required for efficient dye coupling but not for the expression of Cx43alpha1 gap junctions in neural crest cells. Cell motility was found to be altered in the N-cadherin-deficient neural crest cells, but the alterations were different from that elicited by Cx43alpha1 deficiency. In contrast, wnt1-deficient neural crest cells showed no discernible change in cell motility. These observations suggest that dye coupling may not be a good measure of gap junction communication relevant to motility. Alternatively, Cx43alpha1 may serve a novel function in motility. We observed that p120 catenin (p120ctn), an Armadillo protein known to modulate cell motility, is colocalized not only with N-cadherin but also with Cx43alpha1. Moreover, the subcellular distribution of p120ctn was altered with N-cadherin or Cx43alpha1 deficiency. Based on these findings, we propose a model in which Cx43alpha1 and N-cadherin may modulate neural crest cell motility by engaging in a dynamic cross-talk with the cell's locomotory apparatus through p120ctn signaling.

Show MeSH
Related in: MedlinePlus