Truncated isoform of mouse alphaT-catenin is testis-restricted in expression and function.
AlphaT-catenin is a recently identified member of the alpha-catenin family of cell-cell adhesion molecules. For decades it was thought that alpha-catenins mediate solid cell-cell adhesion by linking the cadherin-mediated cell-cell adhesion complex with the actin cytoskeleton. However, the roles of alpha-catenins in this classical adhesion model have been questioned recently. AlphaT-catenin has a restricted expression pattern, in contrast to the ubiquitously expressed alphaE-catenin. High levels of alphaT-catenin were detected in heart and testis. Northern and Western blot experiments indicated that besides the standard full-length alphaT-catenin transcript, smaller alternative transcripts are expressed in testis. We report the cloning of two alternative transcripts of the mouse alphaT-catenin gene (transcript-B and -X), both of which are expressed in a testis-restricted manner from two putative alternative promoters. Alternative transcript-X encodes a smaller protein, isoform-X, which lacks the amino-terminal beta-catenin binding domain of the standard mouse alphaT-catenin protein, and is therefore unable to restore cell-cell adhesion in an alpha-catenin-negative colon carcinoma cell line. Immunohistochemical analysis showed specific localization of the alphaT-catenin isoform-X in the differentiating germ cells. In contrast to the standard full-length alphaT-catenin protein, this shortened isoform-X can bind to l-afadin, an important component of the nectin/afadin/ponsin adhesion complex that reportedly is essential for spermatogenesis.
Goossens
Steven
S
Department for Molecular Biomedical Research, VIB-Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.
Janssens
Barbara
B
Vanpoucke
Griet
G
De Rycke
Riet
R
van Hengel
Jolanda
J
van Roy
Frans
F
D000818:Animals; D017353:Gene Deletion; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013737:Testis / Q000378:metabolism*; D015003:Yeasts; D051178:alpha Catenin / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
D020033:Protein Isoforms; D051178:alpha Catenin