CRC Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, B15 2TA, UK
Author for correspondence (e-mail: f.berditchevski{at}bham.ac.uk)
![]() |
SUMMARY |
---|
Key words: Tetraspanin, Integrin, Migration, Signalling
![]() |
Introduction |
---|
|
Tetraspanins are implicated in a variety of normal and pathological processes, such as tissue differentiation (Boismenu et al., 1996), egg-sperm fusion (Le Naour et al., 2000; Miyado et al., 2000), tumor-cell metastasis (Boucheix et al., 2001) and virus-induced syncytium formation (Fukudome et al., 1992). Nevertheless, the biochemical function of the tetraspanin proteins remains undefined. No membrane or soluble protein has yet been shown to be a physiological receptor/ligand for tetraspanins [except for the hepatitis C virus envelope glycoprotein E2 (Flint et al., 1999)]. The N- and C-termini of tetraspanins, although well preserved across vertebrate species, exhibit no similarities between the individual family members. Thus, despite their relatively short lengths, these regions might have distinct functions. Computer-assisted analysis of the cytoplasmic domains of tetraspanins does not reveal any homology to well defined structural modules or motifs [except for the tyrosine-based sorting motif (see below)]. Given no obvious clues to their biochemical function, tetraspanins are predicted to represent transmembrane scaffolds that control the presentation and spatial organisation of various membrane complexes (Maecker et al., 1997).
Here, I discuss recent work concerning the structural and functional aspects of the complexes of tetraspanins with integrins.
![]() |
The structural basis for integrin-tetraspanin complex assembly |
---|
|
Although the association of most tetraspanins with integrins can be observed only in the presence of so-called mild detergents, the CD151-3ß1, CD151-
6ß1 and CD81-
4ß1 complexes seem to be more stable given that they can withstand conditions (e.g. the presence of Triton X-100 and Digitonin) that disrupt all other integrin-tetraspanin and tetraspanin-tetraspanin interactions (Berditchevski et al., 1997a; Serru et al., 1999; Yauch et al., 1998). This suggests that the associations of CD151 and CD81 with their respective integrins are direct. Furthermore, by directly interacting with the integrins, these tetraspanins might bring other family members into integrin proximity. A recent report suggests that the tetraspanin Tspan-3 functions in a similar fashion, although a specific ß1-integrin partner has not been identified (Tiwari-Woodruff et al., 2001).
The relative stability of the CD151-3ß1 complex has allowed delineation of the interacting regions of the
3 integrin subunit and tetraspanin. In CD151, the sequence between residues Leu149 and Glu213 within the second half of the LECL is necessary and sufficient to confer stable association with
3ß1 integrin (Yauch et al., 2000; Berditchevski et al., 2001). This region includes all six cysteine residues present in the CD151 LECL, and mutation of the consecutive cysteine residues in the conserved CCG and PxxCC motifs precludes the direct association of CD151 with the integrin (Berditchevski et al., 2001). Hence, rather than being defined by a short linear sequence, the integrin-binding surface of CD151 is likely to be formed by various parts of the Leu149-Glu213 region, whose ternary fold is supported by the cysteine residues. It is not known whether this part of the CD151 LECL is also required for stabilisation of the CD151-
6ß1 complex. The CD151 LECL is not required for the heterotypic CD151-tetraspanin interactions, however, and, therefore, cannot be responsible for bringing more distal tetraspanins to the CD151-
3ß1 complex (Berditchevski et al., 2001).
Given the crucial role of the LECL in the CD151-3ß1 interaction, it is not surprising that the tetraspanin-binding site has been mapped to the extracellular portion of the
3 integrin subunit (Yauch et al., 1998; Yauch et al., 2000). Accordingly, substitution of the transmembrane and cytoplasmic domains of the
3 subunit with the corresponding regions of
5 does not affect its association with tetraspanins (Yauch et al., 1998). Using inter-integrin chimeras, Yauch and co-workers showed that part of the stalk region within the
3 extracellular domain (the sequence between residues 569-705) is required for stable association with CD151 (Yauch et al., 2000). Although the interaction between
4ß1 and the tetraspanin CD81 has not been examined in detail, an early study established that mutation of two metal-binding sites in the
4 integrin subunit diminished the stability of the complex (Mannion et al., 1996). Notably, corresponding mutations in
3 did not affect the association with CD151 (Yauch et al., 2000), which suggests that the interacting interfaces of the CD151-
3ß1 and CD81-
4ß1 complexes differ. Interestingly, homology modelling predicts that the
3ß1-interacting part of CD151 and the corresponding region of CD81 have different folds (Seigneuret et al., 2001).
A conformational change in integrin receptors is an important mechanism for controlling their ligand-binding activity (Humphries, 2000; Plow et al., 2000). As yet, there is no evidence demonstrating that their association with tetraspanins influences integrin conformation. Neither is there any indication that a particular conformational state favours the association of integrins with tetraspanins. The results of numerous studies indicate that various integrin-tetraspanin complexes can be immunoprecipitated equally well regardless of whether function-blocking, neutral or function-activating anti-integrin antibodies are used. Divalent cations, which activate (or inhibit) the ligand-binding function of integrins (e.g. Mg2+, Mn2+ and Ca2+), have no effect on integrin association with tetraspanins (Longhurst et al., 1999; Mannion et al., 1996; Yáñez-Mó et al., 2001a). Finally, ligand binding does not seem to influence the stability of various integrin-tetraspanin complexes (Israels et al., 2001; Longhurst et al., 1999; Yáñez-Mó et al., 2001a).
An interesting aspect of the integrin-tetraspanin complex formation has been described recently: Ono and co-workers found that the association of CD82 with 3ß1 and
5ß1 depends on the glycosylation state of both tetraspanin and integrins (Ono et al., 2000). Given that the degree of CD82 glycosylation varies in different cell types (White et al., 1998), this may represent a tissue-specific control mechanism that regulates the assembly of the CD82-
3ß1 and CD82-
5ß1 complexes.
![]() |
The role of tetraspanins in integrin-mediated cell adhesion and migration |
---|
In contrast, numerous reports describe the involvement of tetraspanins in both homotypic and heterotypic cell-cell adhesion (Barrett et al., 1991; Bradbury et al., 1992; Cao et al., 1997; Fitter et al., 1999; Lazo et al., 1997; Lagaudriere-Gesbert et al., 1997; Letarte et al., 1993; Masellis-Smith et al., 1990; Schick and Levy, 1993; Shibagaki et al., 1998; Skubitz et al., 1996; Toothill et al., 1990). The possible involvement of tetraspanins in intercellular adhesion has been a focus of a recent review (Yáñez-Mó et al., 2001b). It has to be emphasised that intercellular contacts are controlled by a diverse range of receptor-ligand interactions in which integrins play either a major (as in hematopoetic cells) or an auxiliary role. Given that tetraspanins can form complexes with various other transmembrane proteins, their role in regulating intercellular contacts may also involve non-integrin adhesion receptors (Lazo et al., 1997).
The involvement of tetraspanins in cell motility is well documented. Numerous reports published over the past ten years have demonstrated that tetraspanins are implicated in migration of monolayers (e.g. in wound closure), as well as in the random and chemotactic motility of various cell types (Ikeyama et al., 1993; Klein-Soyer et al., 2000; Miyake et al., 1991; Ono et al., 2000; Penas et al., 2000; Radford et al., 1997; Shaw et al., 1995; Sincock et al., 1999; Yáñez-Mó et al., 1998; Yáñez-Mó et al., 2001a). In addition, recent data indicate that tetraspanins are involved in more complex biological phenomena driven by integrin-ECM interactions. These include invasive migration of carcinoma cells within the 3D ECM (Sugiura and Berditchevski, 1999), collagen-gel contraction (Scherberich et al., 1998), morphogenetic re-organisation of monolayers of epithelial cells (Yáñez-Mó et al., 2001a) and neurite outgrowth (Stipp and Hemler, 2000).
Cell migration is a complex phenomenon that is controlled by highly regulated processes both at the leading edge and at the rear of the cell (Lauffenburger and Horwitz, 1996). In both stationary and migratory cells, tetraspanin-containing protein complexes are highly abundant at the outermost cell periphery (Berditchevski and Odintsova, 1999; Berditchevski et al., 1997b). These highly dynamic parts of the cell are engaged in transient interactions with the substrate and trigger the initial set of biochemical signals that leads to the assembly of more stable attachment structures (e.g. focal adhesions). Two recent reports indicate that tetraspanin-containing adhesion complexes may control the protrusion activity in migrating cells. Firstly, antibody-interference experiments have demonstrated that in keratinocytes, tetraspanins regulate lamellipodia formation (Baudoux et al., 2000). Secondly, elongation of the invasive protrusions of breast carcinoma cells embedded into the 3D ECM can be stimulated by antibodies to various tetraspanins and the 3 integrin subunit (Sugiura and Berditchevski, 1999). Detailed time-lapse analysis has shown that antibody treatment attenuates retraction of the extending protrusions (Sugiura and Berditchevski, 1999).
Current data suggest that the pro- or anti-migratory activities of tetraspanins are not limited to a particular ECM ligand (Shaw et al., 1995, Domanico et al., 1997). Furthermore, binding of the tetraspanins can affect integrin-mediated cell migration in both a ligand-dependent and a ligand-independent fashion (Domanico et al., 1997). In most cells, the tetraspanin-containing peripheral adhesion complexes are devoid of cytoskeletal and signalling components typically found in more stable adhesion structures, such as focal adhesions and Rac-dependent focal complexes (e.g. vinculin, paxilin and FAK) (Berditchevski and Odintsova, 1999; Penas et al., 2000). In contrast, tetraspanins are colocalised with MARCKS (myristoylated alanine-rich C kinase substrate), one of the prominent substrates for different members of the protein kinase C (PKC) family (Berditchevski and Odintsova, 1999). One of the proposed functions of MARCKS is regulation of cortical cytoskeleton dynamics during cell spreading and migration (Wiederkehr et al., 1997). Given that certain tetraspanins can associate with PKC enzymes (Zhang, et al., 2001a), it is conceivable that the tetraspanin-containing adhesion complexes affect the actin-reorganising activity of MARCKS.
In sections of normal skin and cultured keratinocytes, the anti-CD151 antibody (but not several other anti-tetraspanin antibodies) label hemidesmosomes specialised junctional complexes that mediate stable attachment of cells to the basement membrane (Sterk et al., 2000). Thus, CD151 might have opposing functions in cell migration: in non-transformed epithelial cells, it could be involved in the stabilization of cell attachment, but in carcinomas, the elevated expression of CD151 potentiates their pro-migratory phenotype (Testa et al., 1999).
Finally, in some cells (epithelia and endothelia), integrin-tetraspanin complexes are enriched at cell-cell contact sites (Nakamura et al., 1995; Penas et al., 2000; Yáñez-Mó et al., 2001b), where they may affect migration indirectly by regulating the dynamics of intercellular communication.
![]() |
Signal transduction by integrin-tetraspanin protein complexes |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The contribution of tetraspanins to adhesion-dependent signalling might be linked with their ability to recruit certain signalling enzymes into the integrin complexes (Hemler, 1998). A number of tetraspanins, including CD9, CD63, CD81, A15/Talla-1 and CD151 (but not CD82, CD37, CD53 or NAG-2/Tspan-4), are associated with type II phosphatidylinositol 4-kinase (PtdIns 4-K), one of the key enzymes in synthesis of C-4 phosphoinositides (Berditchevski et al., 1997b; Yauch and Hemler, 2000). Furthermore, the association with CD151 seems to be critical for tethering of PtdIns 4-K to 3ß1 integrin (Yauch and Hemler, 2000). Given the lack of apparent similarity between the cytoplasmic portions of the PtdIns 4-K-linked tetraspanins, the association is probably mediated by another part(s) of the protein. Although the interaction of PtdIns 4-K with tetraspanins does not require their association with integrins, not all tetraspanin-linked integrins (e.g.
4ß1 and
6ß1) are associated with the PtdIns 4-K activity (Yauch and Hemler, 2000). This suggests that additional mechanisms (or protein components) that control the association of the enzyme with integrins exist. Whether or not binding of the
3ß1 integrin to ECM ligands regulates the activity of the enzyme within the complex is not known.
Treatment of cells with phorbol ester (PMA) induces association of various tetraspanins (e.g. CD9, CD53, CD81, CD82 and CD151) with two members of the PKC family, and ßII (Zhang et al., 2001a). The specificity of the tetraspanin-PKC interaction is further strengthened by the fact that other PKC enzymes, including PKC
, PKC
and PKCµ, are not associated with the tetraspanin complexes (Zhang et al., 2001a). An interaction with integrins is not required for the association of tetraspanins with PKC, which suggests that tetraspanins play a critical role in recruiting PKC into the integrin complexes (
3ß1 and
6ß1). Furthermore, PKC-dependent phosphorylation of the
3 integrin subunit is critical for cell migration and for the adhesion-dependent signalling mediated by
3ß1 (Zhang et al., 2001b).
Two Src family tyrosine kinases, Lyn and Hck, and unspecified serine/threonine kinase activities, are associated with the ß2-integrinCD63 complex and might play an important role in the CD63-induced upregulation and activation of ß2 integrins in human neutrophils (Skubitz et al., 1996).
The ability to associate simultaneously with one another and various classes of transmembrane proteins might mean that tetraspanins can transmit lateral signals between integrins and other surface receptors. This could further diversify the contribution of tetraspanin proteins to adhesion-dependent signalling. For example, in B cells, the network of tetraspanins may juxtapose 4ß1 and
5ß1 integrins with the CD21-CD19-Leu13 complex, so that antibody-induced crosslinking of integrins or tetraspanins induces phosphorylation of CD19 (Horvath et al., 1998; Xiao et al., 1996). Conversely, clustering of CD19 complexes induces tyrosine-kinase-dependent adhesion of B cells to cell-deposited fibronectin, a process mediated by
4ß1 integrin (Behr and Schriever, 1995).
![]() |
The role of tetraspanins in integrin maturation and trafficking |
---|
Immunoelectron microscopy and immunofluorescence studies have demonstrated that tetraspanins are abundant on various types of intracellular vesicles (Escola et al., 1998; Hamamoto et al., 1994; Hotchin et al., 1995; Peters et al., 1991; Sincock et al., 1999). These data point to a possible role for tetraspanins in turnover and/or sorting of integrins. Several tetraspanins contain a tyrosine-based sorting motif (Tyr-X-X-) at their C-termini (Table 2) that might recruit clathrin adapter proteins to the integrin complexes and thereby direct them along various trafficking routes (Bonifacino and DellAngelica, 1999). The tetraspanin-associated PtdIns 4-K and PKC can also contribute to this sorting function of tetraspanins (Fig. 2). Indeed, activation of PKC
in mammary epithelial cells facilitates internalisation of ß1 integrins (Ng et al., 1999).
|
|
![]() |
Integrin-tetraspanin complexes and lipid rafts |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
Perspectives |
---|
The function of tetraspanins is clearly important in integrin-driven cell migration. Given the distinct composition of integrin-tetraspanin adhesion complexes, it will be crucial to identify specific proximal targets for the activated integrin-tetraspanin complexes. Tetraspanin-associated PtdIns 4-K can enhance synthesis of phosphoinositides in proximity to integrins (Fig. 2). This may affect the actin-binding properties of a number of integrin-associated cytoskeletal proteins (e.g. -actinin, talin and filamin). Alternatively, locally generated phosphoinositides may function as anchors for the recruitment of cytoplasmic proteins (e.g. MARCKS) into the integrin vicinity (Fig. 2). Similarly, the activity of the tetraspanin-associated PKC may be directed towards various protein targets (both cytoskeletal and signalling). Identification of new components within integrin-tetraspanin complexes and studying their involvement in PKC-dependent signalling should become a focus of future experiments. Another important aspect of future work will be to examine the spatial dynamics of the complexes in migrating cells, particularly in relation to cytoskeleton and adhesion-related signalling proteins. These experiments should place tetraspanin-dependent processes into a specific signalling context and answer the question of whether there is a functional link between tetraspanin-containing adhesion complexes and the more stable focal adhesions.
It is currently recognised that targeted delivery of integrins to the leading edge of migrating cells and their recycling may help to perpetuate lamellipodial extensions (Fabbri et al., 1999; Lauffenburger and Horwitz, 1996; Pierini et al., 2000). Certainly, the occurrence of the tyrosine-based sorting signal in some tetraspanins equips them with the potential to serve as navigators that direct integrin trafficking during the migration. A comparative real-time analysis of integrin trafficking in cells expressing tetraspanins in which the sorting signal is obliterated should establish whether this potential is indeed realised.
![]() |
ACKNOWLEDGMENTS |
---|
![]() |
Footnotes |
---|
The LECLs of the tetraspanins rom-1 and RDS have an additional cysteine, which precedes the CCG-sequence (Bascom et al., 1992; Travis et al., 1989). The LECL of Tspan-5 has an additional pair of cysteines (Todd et al., 1998).
* Some of the discrepancies observed in the literature may reflect differences in the purification conditions used in the immunoprecipitation experiments.
![]() |
REFERENCES |
---|
Barrett, T. B., Shu, G. and Clark, E. A. (1991). CD40 signaling activates CD11a/CD18 (LFA-1)-mediated adhesion in B cells. J. Immunol. 146, 1722-1729.
Bascom, R. A., Manara, S., Collins, L., Molday, R. S., Kalnins, V. I. and McInnes, R. R. (1992). Cloning of the cDNA for a novel photoreceptor membrane protein (rom-1) identifies a disk rim protein family implicated in human retinopathies. Neuron 8, 1171-1184.[Medline]
Baudoux, B., Castanares-Zapatero, D., Leclercq-Smekens, M., Berna, N. and Poumay, Y. (2000). The tetraspanin CD9 associates with the integrin alpha6beta4 in cultured human epidermal keratinocytes and is involved in cell motility. Eur. J. Cell Biol. 79, 41-51.[Medline]
Behr, S. and Schriever, F. (1995). Engaging CD19 or target of an antiproliferative antibody 1 on human B lymphocytes induces binding of B cells to the interfollicular stroma of human tonsils via integrin 4/ß1 and fibronectin. J. Exp. Med. 182, 1191-1199.[Abstract]
Berditchevski, F. and Odintsova, E. (1999). Characterization of integrin/tetraspanin adhesion complexes: role of tetraspanins in integrin signaling. J. Cell Biol. 146, 477-492.
Berditchevski, F., Zutter, M. M. and Hemler, M. E. (1996). Characterization of novel complexes on the cell surface between integrins and proteins with 4 transmembranes (TM4 proteins). Mol. Biol. Cell 7, 193-207.[Abstract]
Berditchevski, F., Chang, S., Bodorova, J. and Hemler, M. E. (1997a). Generation of monoclonal antibodies to integrin-associated proteins. Evidence that alpha3beta1 complexes with EMMPRIN/basigin/OX47/M6. J. Biol. Chem. 272, 29174-29180.
Berditchevski, F., Tolias, K. F., Wong, K., Carpenter, C. L. and Hemler, M. E. (1997b). Novel link between integrins, TM4SF proteins (CD63, CD81) and phosphatidylinositol 4-kinase. J. Biol. Chem. 272, 2595-2598.
Berditchevski, F., Gilbert, E., Griffiths, M. R., Fitter, S., Ashman, L. and Jenner, S. J. (2001). Analysis of the CD151-3ß1 integrin and CD151-tetraspanin interactions by mutagenesis. J. Biol. Chem. (in press).
Boismenu, R., Rhein, M., Fischer, W. H. and Havran, W. L. (1996). A role for CD81 in early T cell development. Science 271, 198-200.[Abstract]
Bonifacino, J. S. and DellAngelica, E. C. (1999). Molecular bases for the recognition of tyrosine-based sorting signals. J. Cell Biol. 145, 923-926.
Boucheix, C., Huynh Thien Duc, G., Jasmin, C. and Rubinstein, E. (2001). Tetraspanins and malignancy. Exp. Rev. Mol. Med. 31 January, http://www-ermm.cbcu.cam.ac.uk/01002381h.htm
Bradbury, L. E., Kansas, G. S., Levy, S., Evans, R. L. and Tedder, T. F. (1992). The CD19/CD21 signal transducing complex of human B lymphocytes includes the target of antiproliferative antibody-1 and Leu-13 molecules. J. Immunol. 149, 2841-2850.
Cao, L., Yoshino, T., Kawasaki, N., Sakuma, I., Takahashi, K. and Akagi, T. (1997). Anti-CD53 monoclonal antibody induced LFA-1/ICAM-1-dependent and independent lymphocyte homotypic cell aggregation. Immunobiol. 197, 70-81.[Medline]
Claas, C., Seiter, S., Claas, A., Savelyeva, L., Schwab, M. and Zöller, M. (1998). Association between the rat homologue of CO-029, a metastasis-associated tetraspanin molecule and consumption coagulopathy. J. Cell Biol. 141, 267-280.
Claas, C., Stipp, C. S. and Hemler, M. E. (2001). Evaluation of prototype transmembrane 4 superfamily protein complexes and their relation to lipid rafts. J. Biol. Chem. 276, 7974-7984.
Crosbie, R. H., Heighway, J., Venzke, D. P., Lee, J. C. and Campbell, K. P. (1997). Sarcospan, the 25-kDa transmembrane component of the dystrophin-glycoprotein complex. J. Biol. Chem. 272, 31221-31224.
Dorahy, D. J., Lincz, L. F., Meldrum, C. J. and Burns, G. F. (1996). Biochemical isolation of a membrane microdomain from resting platelets highly enriched in the plasma membrane glycoprotein CD36. Biochem. J. 319, 67-72.[Medline]
Domanico, S. Z., Pelletier, A. J., Havran, W. L. and Quaranta, V. (1997). Integrin alpha 6A beta 1 induces CD81-dependent cell motility without engaging the extracellular matrix migration substrate. Mol. Biol. Cell 8, 2253-2265.
Escola, J.-M., Kleijmeer, M. J., Stoorvogel, W., Griffith, J., Yoshie, O. and Geuze, H. J. (1998). Selective enrichment of tetraspan proteins on the internal vesicles of multivesicular endosomes and exosomes secreted by human B-lymphocytes. J. Biol. Chem. 273, 20121-20127.
Fabbri, M., Fumagalli, L., Bossi, G., Bianchi, E., Bender, J. R. and Pardi, R. (1999). A tyrosine-based sorting signal in the beta2 integrin cytoplasmic domain mediates its recycling to the plasma membrane and is required for ligand-supported migration. EMBO J. 18, 4815-4925.
Fitter, S., Sincock, P. M., Jolliffe, C. N. and Ashman, L. K. (1999). The transmembrane 4 superfamily (TM4SF) protein CD151 (PETA-3) associates with ß1 and IIbß3 integrins in haematopoetic cells and modulates cell-cell adhesion. Biochem. J. 338, 61-70.[Medline]
Flint, M., Maidens, C., Loomis-Price, L. D., Shotton, C., Dubuisson, J., Monk, P., Higginbottom, A., Levy, S. and McKeating, J. A. (1999). Characterization of hepatitis C virus E2 glycoprotein interaction with a putative cellular receptor, CD81. J. Virol. 73, 6235-6244.
Fukudome, K., Furuse, M., Imai, T., Nishimura, M., Takagi, S., Hinuma, Y. and Yoshie, O. (1992). Identification of membrane antigen C33 recognized by monoclonal antibodies inhibitory to human T-cell leukemia virus type 1 (HTLV- 1)-induced syncytium formation: altered glycosulation of C33 antigen in HTLV-1-positive T cells. J. Virol. 66, 1394-1401.[Abstract]
Hadjiargyrou, M., Kaprielian, Z., Kato, N. and Patterson, P. H. (1996). Association of the tetraspan protein CD9 with integrins on the surface of S-16 Schwann cells. J. Neurochem. 6, 2505-2513.
Hamamoto, K., Ohga, S., Nomura, S. and Yasunaga, K. (1994). Cellular distribution of CD63 antigen in platelets and in three megakaryocytic cell lines. Haematology 72, 184-190.
Hasegawa, H., Nomura, T., Kishimoto, K., Yanagisawa, K. and Fujita, S. (1998). SFA-1/PETA-3 (CD151), a member of the transmembrane 4 superfamily, associates preferentially with alpha 5 beta 1 integrin and regulates adhesion of human T cell leukemia virus type 1-infected T cells to fibronectin. J. Immunol. 161, 3087-3095.
Hemler, M. E. (1998). Integrin associated proteins. Curr. Opin. Cell Biol. 10, 578-585.[Medline]
Hirano, T., Higuchi, T., Ueda, M., Inoue, T., Kataoka, N., Maeda, M., Fujiwara, H. and Fujii, S. (1999). CD9 is expressed in extravillous trophoblasts in association with integrin alpha3 and integrin alpha5. Mol. Hum. Reprod. 2, 162-167.
Horvath, G., Serru, V., Clay, D., Billard, M., Boucheix, C. and Rubinstein, E. (1998). CD19 is linked to the integrin-associated tetraspans CD9, CD81, and CD82. J. Biol. Chem. 273, 30537-30543.
Hotchin, N. A., Gandarillas, A. and Watt, F. M. (1995). Regulation of cell surface beta 1 integrin levels during keratinocyte terminal differentiation. J. Cell Biol. 128, 1209-1219.[Abstract]
Hotta, H., Ross, A. H., Huebner, K., Isobe, M., Wendeborn, S., Chao, M. V., Ricciardi, R. P., Tsujimoto, Y., Croce, C. M. and Koprowski, H. (1988). Molecular cloning and characterization of an antigen associated with early stages of melanoma tumor progression. Cancer Res. 48, 2955-2962.[Abstract]
Humphries, M. J. (2000). Integrin structure. Biochem. Soc. Trans. 28, 311-339.[Medline]
Ikeyama, S., Koyama, M., Yamaoko, M., Sasada, R. and Miyake, M. (1993). Suppression of cell motility and metastasis by transfection with human motility-related protein (MRP-1/CD9) DNA. J. Exp. Med. 177, 1231-1237.[Abstract]
Israels, S. J., McMillan-Ward, E. M., Easton, J., Robertson, C. and McNicol, A. (2001). CD63 associates with the alphaIIb beta3 integrin-CD9 complex on the surface of activated platelets. Thrombos. Hemostas. 85, 134-141.
Jennings, L. K., Crossno, J. T., Fox, C. F., White, M. M. and Green, C. A. (1994). Platelet p24/CD9, a member of the tetraspanin family of proteins. Ann. NY Acad. Sci. 714, 175-184.[Medline]
Jones, P. H., Bishop, L. A. and Watt, F. M. (1996). Functional significance of CD9 association with beta 1 integrins in human epidermal keratinocytes. Cell Adhes. Commun. 4, 297-305.[Medline]
Kauffmann-Zeh, A., Klinger, R., Endemann, G., Waterfield, M. D., Wetzker, R. and Hsuan, J. J. (1994). Regulation of human type II phosphatidylinositol kinase activity by epidermal growth factor-dependent phosphorylation and receptor association. J. Biol. Chem. 269, 31243-31251.
Klein-Soyer, C., Azorsa, D. O., Cazenave, J. P. and Lanza, F. (2000). CD9 participates in endothelial cell migration during in vitro wound repair. Arterioscler. Thromb. Vasc. Biol. 20, 360-369.
Kurzchalia, T. V. and Parton, R. G. (1999). Membrane microdomains and caveolae. Curr. Opin. Cell Biol. 11, 424-431.[Medline]
Lagaudriere-Gesbert, C., Le Naour, F., Lebel-Binay, S., Billard, M., Lemichez, E., Boquet, P., Boucheix, C., Conjeaud, H. and Rubinstein, E. (1997). Functional analysis of four tetraspans, CD9, CD53, CD81, and CD82, suggests a common role in costimulation, cell adhesion, and migration: only CD9 upregulates HB-EGF activity. Cell. Immunol. 182, 105-112.[Medline]
Lauffenburger, D. A. and Horwitz, A. F. (1996). Cell migration: a physically integrated molecular process. Cell 84, 359-369.[Medline]
Lazo, P. A., Cuevas, L., Gutierrez del Arroyo, A. and Orue, E. (1997). Ligation of CD53/OX44, a tetraspan antigen, induces homotypic adhesion mediated by specific cell-cell interactions. Cell. Immunol. 178, 132-140.[Medline]
Le Naour, F., Rubinstein, E., Jasmin, C., Prenant, M. and Boucheix, C. (2000). Severely reduced female fertility in CD9-deficient mice. Science 287, 319-321.
Letarte, M., Seehafer, J. G., Greaves, A., Masellis-Smith, A. and Shaw, A. R. (1993). Homotypic aggregation of pre-B leukemic cell lines by antibodies to VLA integrins correlates with their expression of CD9. Leukemia 7, 93-103.[Medline]
Levy, S., Nguyen, V. Q., Andria, M. L. and Takahashi, S. (1991). Structure and membrane topology of TAPA-1. J. Biol. Chem. 266, 14597-14602.
Longhurst, C. M., White, M. M., Wilkinson, D. A. and Jennings, L. K. (1999). A CD9, IIbß3, integrin-associated protein, and GPIb/v/IX complex on the surface of human platelets is influenced by
IIbß3 conformational states. Eur. J. Biochem. 263, 104-111.
Lozahic, S., Christiansen, D., Manie, S., Gerlier, D., Billard, M., Boucheix, C. and Rubinstein, E. (2000). CD46 (membrane cofactor protein) associates with multiple beta1 integrins and tetraspans. Eur. J. Immunol. 30, 900-907.[Medline]
Maecker, H. T., Todd, S. C. and Levy, S. (1997). The tetraspanin superfamily: molecular facilitators. FASEB J. 11, 428-442.
Mannion, B. A., Berditchevski, F., Kraeft, S.-K., Chen, L. B. and Hemler, M. E. (1996). TM4SF proteins CD81 (TAPA-1), CD82, CD63 and CD53 specifically associate with 4ß1 integrin. J. Immunol. 157, 2039-2047.[Abstract]
Marken, J. S., Schieven, G. L., Hellstrom, I., Hellstrom, E. and Aruffo, A. (1992). Cloning and expression of the tumor-associated antigen L6. Proc. Natl. Acad. Sci. USA 89, 3503-3507.[Abstract]
Masellis-Smith, A., Jensen, G. S., Seehafer, J. G., Slupsky, J. R. and Shaw, A. R. (1990). Anti-CD9 monoclonal antibodies induce homotypic adhesion of pre-B cell lines by a novel mechanism. J. Immunol. 144, 1607-1613.
Miyado, K., Yamada, G., Yamada, S., Hasuwa, H., Nakamura, Y., Ryu, F., Suzuki, K., Kosai, K., Inoue, K., Ogura, A., Okabe, M. and Mekada, E. (2000). Requirement of CD9 on the egg plasma membrane for fertilization. Science 287, 321-324.
Miyake, M., Koyama, M., Seno, M. and Ikeyama, S. (1991). Identification of the motility-related protein (MRP-1), recognized by monoclonal antibody M31-15, which inhibits cell motility. J. Exp. Med. 174, 1347-1354.[Abstract]
Nakamura, K., Iwamoto, R. and Mekada, E. (1995). Membrane-anchored heparin-binding EGF-like growth factor (HB-EGF) and diptheria toxin receptor-associated protein (DRAP27)/CD9 form a complex with integrin 3ß1 at cell-cell contact sites. J. Cell Biol. 129, 1691-1705.[Abstract]
Ng, T., Shima, D., Squire, A., Bastienns, P. I., Gschmeissner, S., Humphries, M. J. and Parker, P. J. (1999). PKCalpha regulates beta1 integrin-dependent cell motility through association and control of integrin traffic. EMBO J. 18, 3909-3923.
Odintsova, E., Sugiura, T. and Berditchevski, F. (2000). Attenuation of EGF receptor signaling by a metastasis suppressor tetraspanin KAI-1/CD82. Curr. Biol. 10, 1009-1012.[Medline]
Ono, M., Handa, K., Withers, D. A. and Hakomori, S. (2000). Glycosylation effect on membrane domain (GEM) involved in cell adhesion and motility: a preliminary note on functional alpha3, alpha5-CD82 glycosylation complex in ldlD 14 cells. Biochem. Biophys. Res. Commun. 279, 744-750.[Medline]
Park, K. R., Inoue, T., Ueda, M., Hirano, T., Higuchi, T., Maeda, M., Konishi, I., Fujiwara, H. and Fujii, S. (2000). CD9 is expressed on human endometrial epithelial cells in association with integrins alpha(6), alpha(3) and beta(1). Mol. Hum. Reprod. 3, 252-257.
Penas, P. F., Garcia-Diaz, A., Sanchez-Madrid, F. and Yanez-Mo, M. (2000). Tetraspanins are localized at motility-related structures and involved in normal human keratinocyte wound healing migration. J. Invest. Derm. 114, 1126-1135.
Peters, P. J., Borst, J., Oorschot, V., Fukuda, M., Krahenbuhl, O., Tschopp, J., Slot, J. W. and Geuze, H. J. (1991). Cytotoxic T lymphocyte granules are secretory lysosomes, comtaining both perforin and granzymes. J. Exp. Med. 173, 1099-1109.[Abstract]
Pierini, L. M., Lawson, M. A., Eddy, R., Hendey, B. and Maxfield, F. R. (2000). Oriented endocytic recycling of alpha5beta1 in motile neutrophils. Blood 95, 2471-2480.
Plow, E. F., Haas, T. A., Zhang, L., Loftus, J. and Smith, J. W. (2000). Ligand binding to integrins. J. Biol. Chem. 275, 21785-21788.
Radford, K. J., Thorne, R. F. and Hersey, P. (1997). Regulation of tumor cell motility and migration by CD63 in a human melanoma cell line. J. Immunol. 158, 3353-3358.[Abstract]
Rubinstein, E., Le Naour, F., Billard, M., Prenant, M. and Boucheix, C. (1994). CD9 antigen is an accessory subunit of the VLA integrin complexes. Eur. J. Immunol. 12, 3005-3013.
Rubinstein, E., Le Naour, F., Lagaudriere-Gesbert, C., Billard, M., Conjeaud, H. and Boucheix, C. (1996). CD9, CD63, CD81, and CD82 are components of a surface tetraspan network connected to HLA-DR and VLA integrins. Eur. J. Immunol. 26, 2657-2665.[Medline]
Rubinstein, E., Poindessous-Jazat, V., Le Naour, F., Billard, M. and Boucheix, C. (1997). CD9, but not other tetraspans, associates with the beta1 integrin precursor. Eur. J. Immunol. 27, 1919-1927.[Medline]
Scherberich, A., Moog, S., Haan-Archipoff, G., Azorsa, D. O., Lanza, F. and Beretz, A. (1998). Tetraspanin CD9 is associated with very late-acting integrins in human vascular smooth muscle cells and modulates collagen matrix reorganization. Arterioscler. Thromb. Vasc. Biol. 18, 1691-1697.
Schick, M. and Levy, S. (1993). The TAPA-1 molecule is associated on the surface of B cells with HLA-DR molecules. J. Immunol. 151, 4090-4097.
Schlegel, A., Volonte, D., Engelman, J. A., Galbiati, F., Mehta, P., Zhang, X. L., Scherer, P. E. and Lisanti, M. P. (1998). Crowded little caves: structure and function of caveolae. Cell Signal. 10, 457-463.[Medline]
Seehafer, J. G., Tang, S. C., Slupsky, J. R. and Shaw, A. R. (1988). The functional glycoprotein CD9 is variably acylated: localization of the variably acylated region to a membrane-associated peptide containing the binding site for the agonistic monoclonal antibody 50H.19. Biochim. Biophys. Acta 957, 399-410.[Medline]
Seehafer, J. G., Slupsky, J. R., Tang, S. C., Masellis-Smith, A. and Shaw, A. R. (1990). Myristic acid is incorporated into the two acylatable domains of the functional glycoprotein CD9 in ester, but not in amide bonds. Biochim. Biophys. Acta 1039, 218-226.[Medline]
Seigneuret, M., Delaguillaumie, A., Lagaudrière-Gesbert, C. and Conjeaud, H. (2001). Structure of the tetraspanin main extracellular domain: a partially conserved fold with a structurally variable domain insertion. J. Biol. Chem. (in press).
Serru, V., Le Naour, F., Billard, M., Azorsa, D. O., Lanza, F., Boucheix, C. and Rubinstein, E. (1999). Selective tetraspan-integrin complexes (CD81/4ß1, CD151/
3ß1, D151/
6ß1) under conditions disrupting tetraspan interactions. Biochem. J. 340, 103-111.[Medline]
Shaw, A. R. E., Domanska, A., Mak, A., Gilchrist, A., Dobler, K., Visser, L., Poppema, S., Fliegel, L., Letarte, M. and Willett, B. J. (1995). Ectopic expression of human and feline CD9 in a human B cell line confers ß1 integrin-dependent motility on fibronectin and laminin substrates and enhanced tyrosine phosphorylation. J. Biol. Chem. 270, 24092-24099.
Shibagaki, N., Hanada, K., Yamaguchi, S., Yamashita, H., Shimada, S. and Hamada, H. (1998). Functional analysis of CD82 in the early phase of T cell activation: roles in cell adhesion and signal transduction. Eur. J. Immunol. 28, 1125-1133.[Medline]
Simons, K. and Toomre, D. (2000). Lipid rafts and signal transduction. Nat. Rev. Mol. Cell. Biol. 1, 31-39.[Medline]
Sincock, P. M., Fitter, S., Parton, R. G., Berndt, M., Gamble, J. R. and Ashman, L. K. (1999). PETA-3/CD151, a member of the transmembrane 4 superfamily, is localised to the plasma membrane and endocytic system of endothelial cells, associates with multiple integrins and modulates cell function. J. Cell Sci. 112, 833-844.
Skubitz, K. M., Campbell, K. D., Iida, J. and Skubitz, A. P. N. (1996). CD63 associates with tyrosine kinase activity and CD11/CD18, and transmits an activation signal in neutrophils. J. Immunol. 157, 3617-3626.[Abstract]
Slupsky, J. R., Seehafer, J. G., Tang, S.-C., Masellis-Smith, A. and Shaw, A. R. E. (1989). Evidence that monoclonal antibodies against CD9 antigen induce specific association between CD9 and the platelet glycoprotein IIb-IIIa complex. J. Biol. Chem. 264, 12289-12293.
Sterk, L. M., Geuijen, C. A., Oomen, L. C., Calafat, J., Janssen, H. and Sonnenberg, A. (2000). The tetraspan molecule CD151, a novel constituent of hemidesmosomes, associates with the integrin alpha6beta4 and may regulate the spatial organization of hemidesmosomes. J. Cell Biol. 149, 969-982.
Stipp, C. S. and Hemler, M. E. (2000). Transmembrane-4-superfamily proteins CD151 and CD81 associate with alpha 3 beta 1 integrin, and selectively contribute to alpha 3 beta 1-dependent neurite outgrowth. J. Cell Sci. 113, 1871-1882.
Sugiura, T. and Berditchevski, F. (1999). Function of 3ß1tetraspanin protein complexes in tumor cell invasion. Evidence for the role of the complexes in production of Matrix Metalloproteinase 2 (MMP-2). J. Cell Biol. 146, 1375-1389.
Tachibana, I., Bodorova, J., Berditchevski, F., Zutter, M. M. and Hemler, M. E. (1997). NAG-2, a novel transmembrane-4 superfamily (TM4SF) protein that complexes with integrins and other TM4SF proteins. J. Biol. Chem. 272, 29181-29189.
Tachibana, I. and Hemler, M. E. (1999). Role of transmembrane 4 superfamily (TM4SF) proteins CD9 and CD81 in muscle cell fusion and myotube maintenance. J. Cell Biol. 146, 893-904.
Testa, J. E., Brooks, P. C., Lin, J. M. and Quigley, J. P. (1999). Eukaryotic expression cloning with an antimetastatic monoclonal antibody identifies a tetraspanin (PETA-3/CD151) as an effector of human tumor cell migration and metastasis. Cancer Res. 59, 3812-3820.
Tiwari-Woodruff, S. K., Buznikov, A. G., Vu, T. Q., Micevych, P. E., Chen, K., Kornblum, H. I. and Bronstein, J. M. (2001). OSP/claudin-11 forms a complex with a novel member of the tetraspanin super family and beta1 integrin and regulates proliferation and migration of oligodendrocytes. J. Cell Biol. 153, 295-305.
Todd, S. C., Doctor, V. S. and Levy, S. (1998). Sequences and expression of six new members of the tetraspanin/TM4SF family. Biochim. Biophys. Acta 1399, 101-104.[Medline]
Toothill, V. J., van Mourik, J. A., Nieuwenhuis, H. K., Metzelaar, M. J. and Pearson, J. D. (1990). Characterization of the enhanced adhesion of neutrophil leukocytes to thrombin-stimulated endothelial cells. J. Immunol. 145, 283-291.
Tordes, E., Nardi, J. B. and Robertson, H. M. (2000). The tetraspanin superfamily in insects. Insect Mol. Biol. 9, 581-590.[Medline]
Travis, G. H., Brennan, M. B., Danielson, P. E., Kozak, C. A. and Sutcliffe, J. G. (1989). Identification of a photoreceptor-specific mRNA encoded by the gene responsible for retinal degeneration slow (rds). Nature 338, 70-73.[Medline]
White, A., Lamb, P. W. and Barret, J. C. (1998). Frequent downregulation of the KAI1(CD82) metastasis suppressor protein in human cancer cell lines. Oncogene 16, 3143-3149.[Medline]
Wice, B. M. and Gordon, J. I. (1995). A tetraspan membrane glycoprotein produced in the human intestinal epitheliul and liver that can regulate cell density-dependent proliferation. J. Biol. Chem. 270, 21907-21918.
Wiederkehr, A., Staple, J. and Caroni, P. (1997). The motility-associated proteins GAP-43, MARCKS, and CAP-23 share unique targeting and surface activity-inducing properties. Exp. Cell Res. 236, 103-116.[Medline]
Wright, M. D. and Tomlinson, M. G. (1994). The ins and outs of the transmembrane 4 superfamily. Immunol. Today 15, 588-594.[Medline]
Xavier, R. and Seed, B. (1999). Membrane compartmentation and the response to antigen. Curr. Opin. Immunol. 11, 265-269.[Medline]
Xiao, J., Messinger, Y., Jin, J., Myers, D. E., Bolen, J. B. and Uckun, F. M. (1996). Signal transduction through the beta1 integrin family surface adhesion molecules VLA-4 and VLA-5 of human B-cell precursors activates CD19 receptor-associated protein-tyrosine kinases. J. Biol. Chem. 271, 7659-7664.
Yauch, R. L., Berditchevski, F., Harler, M. B., Reichner, J. and Hemler, M. E. (1998). Highly stoichiometric, stable, and specific association of integrin 3ß1 with CD151 provides a major link to phosphatidylinositol 4-kinase, and may regulate cell migration. Mol. Biol. Cell 9, 2751-2765.
Yauch, R. L. and Hemler, M. (2000). Specific interactions among transmembrane 4 superfamily (TM4SF) proteins and phosphoinositide 4-kinase. Biochem. J. 351, 629-637.[Medline]
Yauch, R. L., Kazarov, A. R., Desai, B., Lee, R. T. and Hemler, M. E. (2000). Direct extracellular contact between integrin 3ß1 and TM4SF protein CD151. J. Biol. Chem. 275, 9230-9238.
Yáñez-Mó, M., Alfranca, A., Cabañas, C., Marazuela, M., Tejedor, R., Ursa, A., Ashman, L. K., De Landázuri, M. O. and Sanchez-Madrid, F. (1998). Regulation of endothelial cell motility by complexes of tetraspan molecules CD81/TAPA-1 and CD151/PETA-3 with 3ß 1 integrin localized at endothelial lateral junctions. J. Cell Biol. 141, 791-804.
Yáñez-Mó, M., Tejedor, R., Rousselle, P. and Sanchez-Madrid, F. (2001a). Tetraspanins in intercellular adhesion of polarized epithelial cells: spatial and functional relationship to integrins and cadherins. J. Cell Sci. 114, 577-587.
Yáñez-Mó, M., Mittelbrunn, M. and Sanchez-Madrid, F. (2001b). Tetraspanins and intercellular interactions. Microcirculation 8, 153-169.[Medline]
Zhang, X. A., Bontrager, A. L. and Hemler, M. E. (2001a). TM4SF proteins associate with activated PKC and Link PKC to specific beta1 integrins. J. Biol. Chem. 276, 25005-25013.
Zhang, X. A., Bontrager, A. L., Stipp, C. S., Kraeft, S.-K., Bazzoni, G., Chen, L. B. and Hemler, M. E. (2001b). Phosphorylation of a conserved integrin alpha 3 QPSXXE motif regulates signaling, motility, and cytoskeletal engagement. Mol. Biol. Cell 12, 351-365.