The roles of maternal alpha-catenin and plakoglobin in the early Xenopus embryo.
Catenins (alpha-, beta- and gamma- or plakoglobin) are cytoplasmic cadherin-associated proteins. Studies on cultured cells have suggested that both alpha-catenin and plakoglobin are important for the adhesive function of cadherins. alpha-catenin binds to both beta-catenin and plakoglobin and may link the cadherin/catenin complex to actin filaments. Separate domains of plakoglobin bind to cadherin and alpha-catenin, suggesting it may act as a bridge between these molecules. However, plakoglobin may have other activities: it is expressed in both desmosomal junctions in association with desmogleins and the cytoplasm in conjunction with APC, and previous work suggests it may act in a dorsal signalling pathway when overexpressed in Xenopus embryos. Here, we have studied the roles of alpha-catenin and plakoglobin directly, by depleting the maternal mRNAs coding for each of them in developing Xenopus embryos. We find that depletion of maternal alpha-catenin causes the loss of intercellular adhesion at the blastula stage, similar to that reported previously for EP cadherin. Depletion of plakoglobin results in a partial loss of adhesion, and a loss of embryonic shape, but does not affect dorsal signalling.
Kofron
M
M
Department of Pediatrics, University of Minnesota Medical School, Minneapolis 55455, USA.
Spagnuolo
A
A
Klymkowsky
M
M
Wylie
C
C
Heasman
J
J
D000818:Animals; D001755:Blastocyst / Q000166:cytology; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000502:physiology*; D051182:Desmogleins; D051180:Desmoplakins; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008297:Male; D009024:Morphogenesis; D017570:MyoD Protein / Q000235:genetics; D016376:Oligonucleotides, Antisense; D010063:Ovum / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D014982:Xenopus laevis / Q000196:embryology*; D051178:alpha Catenin; D051185:gamma Catenin
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D051182:Desmogleins; D051180:Desmoplakins; D017570:MyoD Protein; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D051178:alpha Catenin; D051185:gamma Catenin