Regulation of cellular interactions with laminin by integrin cytoplasmic domains: the A and B structural variants of the alpha 6 beta 1 integrin differentially modulate the adhesive strength, morphology, and migration of macrophages

LM Shaw and AM Mercurio

Program in Cell and Developmental Biology, Harvard Medical School, Boston, Massachusetts 02115.

Several integrin alpha subunits have structural variants that are identical in their extracellular and transmembrane domains but that differ in their cytoplasmic domains. The functional significance of these variants, however, is unknown. In the present study, we examined the possibility that the A and B variants of the alpha 6 beta 1 integrin laminin receptor differ in function. For this purpose, we expressed the alpha 6A and alpha 6B cDNAs, as well as a truncated alpha 6 cDNA (alpha 6-delta CYT) in which the cytoplasmic domain sequence was deleted after the GFFKR pentapeptide, in P388D1 cells, an alpha 6 deficient macrophage cell line. Populations of stable alpha 6A, alpha 6B, and alpha 6-delta CYT transfectants that expressed equivalent levels of cell surface alpha 6 were obtained by fluorescence-activated cell sorter and shown to form heterodimers with endogenous beta 1 subunits. Upon attachment to laminin, the alpha 6A transfectants extended numerous pseudopodia. In contrast, the alpha 6B transfectants remained rounded and extended few processes. The transfectants were also examined for their ability to migrate toward a laminin substratum using Transwell chambers. The alpha 6A transfectants were three- to fourfold more migratory than the alpha 6B transfectants. The alpha 6- delta CYT transfectants did not attach to laminin in normal culture medium, but they did attach in the presence of Mn2+. The alpha 6-delta CYT transfectants migrated to a lesser extent than either the alpha 6A or alpha 6B transfectants in the presence of Mn2+. The alpha 6 transfectants differed significantly in the concentration of substratum bound laminin required for half-maximal adhesion in the presence of Mn2+:alpha 6A (2.1 micrograms/ml), alpha 6B (6.3 micrograms/ml), and alpha 6-delta CYT (8.8 micrograms/ml). Divalent cation titration studies revealed that these transfectants also differed significantly in both the [Ca2+] and [Mn2+] required to obtain half-maximal adhesion to laminin. These data demonstrate that the A and B variants of the alpha 6 cytoplasmic domain can differentially modulate the function of the alpha 6 beta 1 extracellular domain.

Volume 5, Issue 6, pp. 679-690, 06/01/1994
Copyright © 1994 by The American Society for Cell Biology

This article has been cited by other articles:

				D. Segat, R. Comai, E. Di Marco, A. Strangio, R. Cancedda, A. T. Franzi, and C. Tacchetti Integrins alpha 6Abeta 1 and alpha 6Bbeta 1 Promote Different Stages of Chondrogenic Cell Differentiation J. Biol. Chem., August 23, 2002; 277(35): 31612 - 31622. [Abstract] [Full Text] [PDF]

				X. A. Zhang, A. L. Bontrager, C. S. Stipp, S.-K. Kraeft, G. Bazzoni, L. B. Chen, and M. E. Hemler Phosphorylation of a Conserved Integrin {alpha}3 QPSXXE Motif Regulates Signaling, Motility, and Cytoskeletal Engagement Mol. Biol. Cell, February 1, 2001; 12(2): 351 - 365. [Abstract] [Full Text]

				C. S. Buensuceso and T. E. O'Toole The Association of CRKII with C3G Can be Regulated by Integrins and Defines a Novel Means to Regulate the Mitogen-activated Protein Kinases J. Biol. Chem., April 21, 2000; 275(17): 13118 - 13125. [Abstract] [Full Text] [PDF]

				D Nath, P. Slocombe, A Webster, P. Stephens, A. Docherty, and G Murphy Meltrin gamma(ADAM-9) mediates cellular adhesion through alpha(6)beta(1 )integrin, leading to a marked induction of fibroblast cell motility J. Cell Sci., January 6, 2000; 113(12): 2319 - 2328. [Abstract] [PDF]

				M.S. Chen, E.A.C. Almeida, A.-P.J. Huovila, Y. Takahashi, L.M. Shaw, A.M. Mercurio, and J.M. White Evidence that Distinct States of the Integrin alpha 6beta 1 Interact with Laminin and an ADAM J. Cell Biol., February 8, 1999; 144(3): 549 - 561. [Abstract] [Full Text] [PDF]

				I Ozaki, K Yamamoto, T Mizuta, S Kajihara, N Fukushima, Y Setoguchi, F Morito, and T Sakai Differential expression of laminin receptors in human hepatocellular carcinoma Gut, December 1, 1998; 43(6): 837 - 842. [Abstract] [Full Text] [PDF]

				C. Gimond, C. Baudoin, R. van der Neut, D. Kramer, J. Calafat, and A. Sonnenberg Cre-loxP-mediated Inactivation of the alpha 6A Integrin Splice Variant In Vivo: Evidence for a Specific Functional Role of alpha 6A in Lymphocyte Migration but Not in Heart Development J. Cell Biol., October 5, 1998; 143(1): 253 - 266. [Abstract] [Full Text] [PDF]

				J. Wei, L. M. Shaw, and A. M. Mercurio Regulation of Mitogen-activated Protein Kinase Activation by the Cytoplasmic Domain of the alpha 6 Integrin Subunit J. Biol. Chem., March 6, 1998; 273(10): 5903 - 5907. [Abstract] [Full Text] [PDF]

				R. B. Wesley II, X. Meng, D. Godin, and Z. S. Galis Extracellular Matrix Modulates Macrophage Functions Characteristic to Atheroma : Collagen Type I Enhances Acquisition of Resident Macrophage Traits by Human Peripheral Blood Monocytes In Vitro Arterioscler. Thromb. Vasc. Biol., March 1, 1998; 18(3): 432 - 440. [Abstract] [Full Text] [PDF]

				S. Z. Domanico, A. J. Pelletier, W. L. Havran, and V. Quaranta Integrin alpha 6Abeta 1 Induces CD81-dependent Cell Motility without Engaging the Extracellular Matrix Migration Substrate Mol. Biol. Cell, November 1, 1997; 8(11): 2253 - 2265. [Abstract] [Full Text]

				S Tavella, G Bellese, P Castagnola, I Martin, D Piccini, R Doliana, A Colombatti, R Cancedda, and C Tacchetti Regulated expression of fibronectin, laminin and related integrin receptors during the early chondrocyte differentiation J. Cell Sci., January 9, 1997; 110(18): 2261 - 2270. [Abstract] [PDF]

				C.-C. Yao, B. L. Ziober, R. M. Squillace, and R. H. Kramer alpha 7 Integrin Mediates Cell Adhesion and Migration on Specific Laminin Isoforms J. Biol. Chem., October 11, 1996; 271(41): 25598 - 25603. [Abstract] [Full Text] [PDF]

				C. Yao, B. Ziober, A. Sutherland, D. Mendrick, and R. Kramer Laminins promote the locomotion of skeletal myoblasts via the alpha 7 integrin receptor J. Cell Sci., January 12, 1996; 109(13): 3139 - 3150. [Abstract] [PDF]

				T. Lallier, C. Whittaker, and D. DeSimone Integrin alpha 6 expression is required for early nervous system development in Xenopus laevis Development, January 8, 1996; 122(8): 2539 - 2554. [Abstract] [PDF]

				L. M. Shaw, C. E. Turner, and A. M. Mercurio The alpha6Abeta1 and alpha6Bbeta1 Integrin Variants Signal Differences in the Tyrosine Phosphorylation of Paxillin and Other Proteins J. Biol. Chem., October 6, 1995; 270(40): 23648 - 23652. [Abstract] [Full Text] [PDF]

				F. Berditchevski, G. Bazzoni, and M. E. Hemler Specific Association Of CD63 with the VLA-3 and VLA-6 Integrins J. Biol. Chem., July 28, 1995; 270(30): 17784 - 17790. [Abstract] [Full Text] [PDF]

				O Behrendtsen, C. Alexander, and Z Werb Cooperative interactions between extracellular matrix, integrins and parathyroid hormone-related peptide regulate parietal endoderm differentiation in mouse embryos Development, January 12, 1995; 121(12): 4137 - 4148. [Abstract] [PDF]

				A Cattelino, R Longhi, and I de Curtis Differential distribution of two cytoplasmic variants of the alpha 6 beta 1 integrin laminin receptor in the ventral plasma membrane of embryonic fibroblasts J. Cell Sci., January 9, 1995; 108(9): 3067 - 3078. [Abstract] [PDF]

				T. T. Tani and A. M. Mercurio PDZ Interaction Sites in Integrin alpha Subunits. TIP-2/GIPC BINDS TO A TYPE I RECOGNITION SEQUENCE IN alpha 6A/alpha 5 AND A NOVEL SEQUENCE IN alpha 6B J. Biol. Chem., September 21, 2001; 276(39): 36535 - 36542. [Abstract] [Full Text] [PDF]