Abstract
Loss of the tumour-suppressor gene TSC1 is responsible for hamartoma development in tuberous sclerosis complex (TSC), which renders several organs susceptible to benign tumours. Hamartin, the protein encoded by TSC1, contains a coiled-coil domain and is expressed in most adult tissues, although its function is unknown. Here we show that hamartin interacts with the ezrin-radixin-moesin (ERM) family of actin-binding proteins. Inhibition of hamartin function in cells containing focal adhesions results in loss of adhesion to the cell substrate, whereas overexpression of hamartin in cells lacking focal adhesions results in activation of the small GTP-binding protein Rho, assembly of actin stress fibres and formation of focal adhesions. Interaction of endogenous hamartin with ERM-family proteins is required for activation of Rho by serum or by lysophosphatidic acid (LPA). Our data indicate that disruption of adhesion to the cell matrix through loss of hamartin may initiate the development of TSC hamartomas and that a Rho-mediated signalling pathway regulating cell adhesion may constitute a rate-limiting step in tumour formation.
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References
Gomez, M. R., Sampson, J. R. & Whittemore, V. H. Tuberous Sclerosis 3rd edn (Oxford Univ. Press, 1999).
van Slegtenhorst M. et al. Identification of the tuberous sclerosis gene TSC1 on chromosome 9q34. Science 277, 805– 808 (1997).
The European Chromosome 16 Tuberous Sclerosis Consortium. Identification and characterization of the tuberous sclerosis gene on chromosome 16. Cell 75, 1305–1315 (1993).
Kandt, R. S. et al. Linkage of an important gene locus for tuberous sclerosis to a chromosome 16 marker for polycystic kidney disease. Nature Genet. 2, 37–41 ( 1992).
Povey, S. et al. Two loci for tuberous sclerosis: one on 9q34 and one on 16p13 . Ann. Hum. Genet. 58, 107– 127 (1994).
Ito, N. & Rubin, G. M. Gigas, a Drosophila homolog of tuberous sclerosis gene product-2, regulates the cell cycle. Cell 96, 529–539 (1999).
Jin, F. et al. Suppression of tumorigenicity by the wild-type tuberous sclerosis 2 (Tsc2) gene and its C-terminal region. Proc. Natl Acad. Sci. USA 93, 9154–9159 (1996).
Jones, A. C. et al. Molecular genetic and phenotypic analysis reveals differences between TSC1 and TSC2 associated familial and sporadic tuberous sclerosis . Hum. Mol. Genet. 6, 2155– 2161 (1997).
Bretscher, A., Reczek, D. & Berryman, M. Ezrin: a protein requiring conformational activation to link microfilaments to the plasma membrane in the assembly of cell surface structures. J. Cell Sci. 110, 3011– 3018 (1997).
Gary, R. & Bretscher, A. Ezrin self-association involves binding of an N-terminal domain to a normally masked C-terminal domain that includes the F actin binding site. Mol. Biol. Cell 6, 1061–1075 (1995).
Pietromonaco, S. F., Simons, P. C., Altman, A. & Elias, L. Protein kinase C-theta phosphorylation of moesin in the actin-binding sequence . J. Biol. Chem. 273, 7594– 7603 (1998).
Matsui, T. et al. Rho-kinase phosphorylates COOH-terminal threonines of ezrin/radixin/moesin (ERM) proteins and regulates their head-to-tail association. J. Cell Biol. 140, 647–657 (1998).
Hirao, M. et al. Regulation mechanism of ERM (Ezrin/Radixin/Moesin) protein/plasma membrane association; possible involvement of phosphatidylinositol turnover and Rho-dependent signalling pathway. J. Cell Biol. 135, 37–51 (1996).
Ridley, A. J. & Hall, A. The small GTP-binding protein rho regulates the assembly of focal adhesions and actin stress fibers in response to growth factors. Cell 70, 389–399 (1992).
McKay, D. J. G., Esch, F., Furthmayr, H. & Hall, A. Rho- and rac-dependent assembly of focal adhesion complexes and actin filaments in permeabilized fibroblasts: an essential role for ezrin/radixin/moesin proteins. J. Cell Biol. 138, 927–938 (1997).
Takahashi, K. et al. Direct interaction of the Rho GDP dissociation inhibitor with ezrin/radixin/moesin initiates the activation of the Rho small G protein. J. Biol. Chem. 272, 23371–23375 (1997).
Takahashi, K. et al. Interaction of radixin with rho small G protein GDP/GTP exchange factor Dbl. Oncogene 16, 3279– 3284 (1998).
Trofatter, J. A. et al. A novel moesin-, ezrin-, radixin-like gene is a candidate for the neurifibromatosis 2 tumour suppressor. Cell 72, 791–800 (1993).
Tacheuchi, K. et al. Perturbation of cell adhesion and microvilli formation by antisense oligonucleotides to ERM family members. J. Cell Biol. 125, 1371–1384 (1994).
Lamb, R. F. et al. Essential functions of ezrin in maintenance of cell shape and lamellipodial extension in normal and transformed fibroblasts. Curr. Biol. 7, 682–688 (1997).
Robertson, D., Paterson, H., Adamson, P., Hall, A. & Monaghan, P. Ultrastructural localization of ras-related proteins using epitope-tagged plasmids. J. Histochem. Cytochem. 43, 471–480 ( 1995).
Franck, Z., Gary, R. & Bretscher, A. Moesin, like ezrin, colocalizes with actin in the cortical cytoskeleton in cultured cells, but its expression is more variable. J. Cell Sci. 105, 219–231 (1993).
Aspenstrom, P. & Olsen, M. F. Yeast two-hybrid system to detect protein–protein interactions with Rho GTPases. Methods Enzymol. 256, 228–241 (1995).
Chishti, A. H. et al. The FERM domain: a unique module involved in the linkage of cytoplasmic proteins to the membrane. Trends Biochem. Sci. 23, 281–282 (1998).
van Slegtenhorst, M. et al. Interaction between hamartin and tuberin, the TSC1 and TSC2 gene products. Hum. Mol. Genet. 7, 1053– 1057 (1998).
Reczek, D., Berryman, M. & Bretscher, A. Identification of EBP50: A PDZ-containing phosphoprotein that associates with members of the ezrin-radixin-moesin family. J. Cell Biol. 139, 169–179 (1997).
Wang, F-S. & Jay, D. G. Chromophore-assisted laser inactivation (CALI): probing protein function in situ with a high degree of spatial and temporal resolution. Trends Cell Biol. 6, 442–445 (1996).
Liao, J. C., Berg, L. J. & Jay, D. G. Chromophore-assisted laser inactivation of subunits of the T-cell receptor in living cells is spatially restricted. Photochem. Photobiol. 62, 923–929 (1995).
Ren, X-D., Kiosses, W. B. & Schwartz, M. A. Regulation of the small GTP-binding protein Rho by cell adhesion and the cytoskeleton. EMBO J. 18, 578–585 (1999).
Bretscher, A. Regulation of cortical structure by the ezrin-radixin-moesin protein family . Curr. Opin. Cell Biol. 11, 109– 116 (1999).
Hart, M. J. et al. Direct stimulation of the guanine nucleotide exchange activity of p115 RhoGEF by Ga13. Science 280, 2112 –2114 (1998).
Assoian, R. K. & Zhu, X. Cell anchorage and the cytoskeleton as partners in growth factor dependent cell cycle progression . Curr. Opin.Cell Biol. 9, 93– 98 (1997).
Frisch, S. M. & Ruoslahti, E. Integrins and anoikis. Curr. Opin.Cell Biol. 9, 701–706 (1997).
Tlsty, T. D. Cell-adhesion-dependent influences on genomic instability and carcinogenesis . Curr. Opin. Cell Biol. 10, 647– 653 (1998).
Huynh, D. P. & Pulst, S. M. Neurofibromatosis 2 antisense oligodeoxynucleotides induce reversible inhibition of schwannomin synthesis and cell adhesion in STS26T and T98G cells. Oncogene 13, 73– 84 (1996).
McClatchey, A. I. et al. Mice heterozygous for a mutation at the Nf2 tumor suppressor locus develop a range of highly metastatic tumors. Genes Dev. 12, 1121–1133 (1998).
Koga, H. et al. Impairment of cell adhesion by expression of the mutant neurofibromatosis type 2 (NF2) genes which lack exons in the ERM-homology domain. Oncogene 17, 801–810 (1998).
Guilford, P. et al. E-cadherin germline mutations in familial gastric cancer. Nature 392, 402–405 (1998).
Self, A. J. & Hall, A. Purification of recombinant Rho/Rac/G25K from Escherichia coli. Methods Enzymol. 256, 3–10 (1995).
Dransfield, D. T. et al. Ezrin is a cyclic AMP-dependent protein kinase anchoring protein . EMBO J. 16, 35–43 (1997).
Roy, C., Martin, M. & Mangeat, P. A dual involvement of the amino-terminal domain of ezrin in F- and G-actin binding. J. Biol. Chem. 272, 20088–20095 (1997).
Johnson, M. W., Emelin, J. K., Park, S-H. & Vinters, H. V. Co-localization of TSC1 and TSC2 gene products in tubers of patients with tuberous sclerosis. Brain Pathol. 1, 45–54 (1999 ).
Nobes, C. D. & Hall, A. Rho, rac, and cdc42 GTPases regulate the assembly of multimolecular focal complexes associated with actin stress fibers, lamellipodia, and filopodia. Cell 81, 53-62 (1995).
Hill, C. S., Wynne, J. & Treisman, R. The Rho family GTPases RhoA, Rac1, and CDC42Hs regulate transcriptional activation by SRF. Cell 81, 1159–1170 (1995).
Acknowledgements
We thank J. Cheadle for full-length human hamartin cDNA, N. Ito and G. Rubin for Drosophila hamartin cDNA, P. Mangeat for anti-ezrin antibody and pGEX human ERM constructs, J. Gusella and V. Ramesh for the pGEX construct of human NF2 isoform 1, S. Tsukita for mouse anti-chick ERM monoclonal antibody, P. van der Sluijs for pGADGH giantin cDNA and M. Schwartz for pGEX RBD of Rhotekin. R.F.L. thanks H. Paterson for help with preliminary micro-CALI experiments, V. Bragga for the L63 Rho protein, S. Povey, J. Sampson, M. Nellist, J. Connolly and C. Nobes for discussion and technical advice and M. Marsh for critical reading of the manuscript. This work was supported by an MRC Project Grant (to R.F.L.) and grants from NINDS and NCI (to D.G.J.). M.W.J. is supported in part by a USPHS/NIH Molecular and Cellular Neurobiology training grant.
Correspondence and requests for materials should be addressed to R.F.L.
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Lamb, R., Roy, C., Diefenbach, T. et al. The TSC1 tumour suppressor hamartin regulates cell adhesion through ERM proteins and the GTPase Rho . Nat Cell Biol 2, 281–287 (2000). https://doi.org/10.1038/35010550
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DOI: https://doi.org/10.1038/35010550
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