Junctional adhesion molecule-a participates in the formation of apico-basal polarity through different domains.
Junctional adhesion molecule (JAM)-A is an integral membrane protein at tight junctions of epithelial cells which associates with the cell polarity protein PAR-3. Here, we demonstrate that downregulation of JAM-A impairs the ability of MDCK II cells to form cysts in a three-dimensional matrix indicating the requirement of JAM-A for the development of apico-basal polarity. To define the regions of JAM-A important for this function, we have generated MDCK II cell lines stably expressing inducible JAM-A mutants. Mutants of JAM-A which were designed to mislocalize strongly impaired the development of cysts and the formation of functional tight junctions. Surprisingly, similar mutants that lacked the PDZ domain-binding motif at the C-terminus were still impaired in apico-basal polarity formation suggesting that additional regions within the cytoplasmic tail of JAM-A are important for the function of JAM-A. A JAM-A mutant lacking the first Ig-like domain necessary for homophilic binding localized to cell-cell contacts similar to wild-type JAM-A. However, despite this same localization, this mutant interfered with cell polarity and tight junction formation. Together our findings suggest an important role for JAM-A in the development of apico-basal polarity in epithelial cells and identify regions in JAM-A which are critical for this role.
Rehder
Daniela
D
Institute of Cell Biology, ZMBE, University of Münster, D-48149 Münster, Germany.
Iden
Sandra
S
Nasdala
Ines
I
Wegener
Joachim
J
Brickwedde
Maria-Katharina Meyer Zu
MK
Vestweber
Dietmar
D
Ebnet
Klaus
K
D020816:Amino Acid Motifs; D000818:Animals; D015815:Cell Adhesion Molecules / Q000737:chemistry* / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity / Q000502:physiology*; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology* / Q000502:physiology; D062726:Junctional Adhesion Molecules; D017434:Protein Structure, Tertiary; D019108:Tight Junctions / Q000502:physiology
D015815:Cell Adhesion Molecules; D062726:Junctional Adhesion Molecules