NF-protocadherin, a novel member of the cadherin superfamily, is required for Xenopus ectodermal differentiation.
BACKGROUND
The assembly of complex tissues during embryonic development is thought to depend on differential cell adhesion, mediated in part by the cadherin family of cell-adhesion molecules. The protocadherins are a new subfamily of cadherins; their extracellular domains comprise cadherin-like repeats but their intracellular domains differ significantly from those of classical cadherins. Little is known about the ability of protocadherins to mediate the adhesion of embryonic cells, or whether they play a role in the formation of embryonic tissues.


RESULTS
We report the isolation and characterization of a novel protocadherin, termed NF-protocadherin (NFPC), that is expressed in Xenopus embryos. NFPC showed a striking pattern of expression in early embryos, displaying predominant expression within the deep, sensorial layer of the embryonic ectoderm and in a restricted group of cells in the neural folds, but was largely absent from the neural plate and surrounding placodal regions. Ectopic expression in embryos demonstrated that NFPC could mediate cell adhesion within the embryonic ectoderm. In addition, expression of a dominant-negative form of NFPC disrupted the integrity of embryonic ectoderm, causing cells in the deep layer to dissociate, though leaving the outer layer relatively intact.


CONCLUSIONS
Our results indicate that NFPC is required as a cell-adhesion molecule during embryonic development, and its function is distinct from that of classical cadherins in governing the formation of a two-layer ectoderm. These results suggest that NFPC, and protocadherins in general, are involved in novel cell-cell adhesion mechanisms that play important roles in tissue histogenesis.
Bradley
R S
RS
Salk Institute for Biological Studies, San Diego, California 92186, USA.
Espeseth
A
A
Kintner
C
C
D000818:Animals; D001768:Blister / Q000139:chemically induced; D015820:Cadherins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000502:physiology*; D018076:DNA, Complementary; D004475:Ectoderm / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007120:Immunochemistry; D017403:In Situ Hybridization; D000091363:Protocadherins; D012313:RNA; D016415:Sequence Alignment; D014981:Xenopus / Q000196:embryology; D029867:Xenopus Proteins
D015820:Cadherins; D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; C112030:PCDH7 protein, Xenopus; D000091363:Protocadherins; D029867:Xenopus Proteins; D012313:RNA