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 a...

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Bibliographic Details
Published in:The FASEB journal 2007-03, Vol.21 (3), p.647-655
Main Authors: Goossens, Steven, Janssens, Barbara, Vanpoucke, Griet, De Rycke, Riet, van Hengel, Jolanda, van Roy, Frans
Format: Article
Language:English
Subjects:
alpha Catenin - genetics
alpha Catenin - metabolism
alpha Catenin - physiology
Animals
Gene Deletion
Male
Mice
Molecular Sequence Data
Protein Isoforms - genetics
Protein Isoforms - metabolism
Protein Isoforms - physiology
Rats
Rats, Wistar
Testis - metabolism
Yeasts
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Summary: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.
ISSN:1530-6860