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J. Cell Biol.,
Volume 141, Number 3, May 4, 1998 791-804
3
1 Integrin Localized at Endothelial Lateral Junctions


* Servicio de Inmunología and Cell-to-cell junction structures play a key
role in cell growth rate control and cell polarization. In
endothelial cells (EC), these structures are also involved in regulation of vascular permeability and leukocyte extravasation. To identify novel components in
EC intercellular junctions, mAbs against these cells
were produced and selected using a morphological
screening by immunofluorescence microscopy. Two
novel mAbs, LIA1/1 and VJ1/16, specifically recognized a 25-kD protein that was selectively localized at
cell-cell junctions of EC, both in the primary formation
of cell monolayers and when EC reorganized in the
process of wound healing. This antigen corresponded to
the recently cloned platelet-endothelial tetraspan antigen CD151/PETA-3 (platelet-endothelial tetraspan antigen-3), and was consistently detected at EC cell-cell
contact sites. In addition to CD151/PETA-3, two other
members of the tetraspan superfamily, CD9 and CD81/
TAPA-1 (target of antiproliferative antibody-1), localized at endothelial cell-to-cell junctions. Biochemical
analysis demonstrated molecular associations among
tetraspan molecules themselves and those of CD151/
PETA-3 and CD9 with
Servicio de Endocrinología, Hospital de la Princesa, Universidad Autónoma de Madrid; § Departamento de Bioquímica, Facultad de Medicina, Universidad Complutense, Madrid, Spain; and
Division of Haematology,
Institute of Medical and Veterinary Science, University of Adelaide, SA 5000, Australia
3
1 integrin. Interestingly,
mAbs directed to both CD151/PETA-3 and CD81/
TAPA-1 as well as mAb specific for
3 integrin, were
able to inhibit the migration of ECs in the process of
wound healing. The engagement of CD151/PETA-3
and CD81/TAPA-1 inhibited the movement of individual ECs, as determined by quantitative time-lapse
video microscopy studies. Furthermore, mAbs against
the CD151/PETA-3 molecule diminished the rate of
EC invasion into collagen gels. In addition, these mAbs
were able to increase the adhesion of EC to extracellular matrix proteins. Together these results indicate that
CD81/TAPA-1 and CD151/PETA-3 tetraspan molecules are components of the endothelial lateral junctions implicated in the regulation of cell motility, either
directly or by modulation of the function of the associated integrin heterodimers.
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