EWI-2 is a new component of the tetraspanin web in hepatocytes and lymphoid cells.
Several tetraspanins bind directly to a few molecular partners to form primary complexes, which might assemble through tetraspanin-tetraspanin interactions to form a network of molecular interactions, the tetraspanin web. We have produced a monoclonal antibody directed to a 63 kDa molecule (determined under non-reducing conditions) associated with CD9. This molecule was first identified by MS as a molecule with four Ig domains, EWI-2. Like the related molecule CD9P-1, EWI-2 was found to be a partner not only for CD9, but also for CD81, a tetraspanin required for hepatic infection by the parasite responsible for malaria, and also a putative hepatitis C virus receptor. Using chimaeric CD9/CD82 molecules, two separate regions of CD9 of 40 and 47 amino acids were demonstrated to confer the ability to interact with EWI-2. Both EWI-2 and CD9P-1 were detected in the human liver at the surface of hepatocytes and were found to associate with CD81 on freshly isolated hepatocytes. EWI-2 also co-localized with CD81 in the liver. CD9P-1 was not detected on most peripheral blood cells, whereas EWI-2 was expressed on the majority of B-, T- and natural killer cells and was not detected on monocytes, polynuclear cells or platelets. This distribution is identical to that of CD81. Finally, EWI-2 associated with all tetraspanins studied after lysis under conditions preserving tetraspanin-tetraspanin interactions, showing that EWI-2 is a new component of the tetraspanin web.
Charrin
Stéphanie
S
INSERM U268, Institut André Lwoff, Hôpital Paul Brousse, 14 Av Paul Vaillant Couturier, Villejuif 94807 Cedex, France.
Le Naour
François
F
Labas
Valérie
V
Billard
Martine
M
Le Caer
Jean-Pierre
JP
Emile
Jean-François
JF
Petit
Marie-Anne
MA
Boucheix
Claude
C
Rubinstein
Eric
E
D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000378:metabolism*; D016466:CHO Cells; D006224:Cricetinae; D017931:DNA Primers; D005455:Fluorescent Antibody Technique; D022781:Hepatocytes / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007136:Immunoglobulins / Q000276:immunology / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D060225:Tetraspanin 28; D060245:Tetraspanin 29; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C554798:CD81 protein, human; C554869:CD9 protein, human; C554799:Cd81 protein, mouse; C554870:Cd9 protein, mouse; D017931:DNA Primers; C440028:IGSF8 protein, human; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D060225:Tetraspanin 28; D060245:Tetraspanin 29