title: Promotion of cell adhesion by single-stranded and triple-helical peptide models of basement membrane collagen alpha 1(IV)531-543. Evidence for conformationally dependent and conformationally independent type IV collagen cell adhesion sites.
abstract: Several regions within the triple-helical domain of type IV collagen function as cellular recognition sites. We have demonstrated previously that melanoma cell activities promoted by the alpha 1(IV)1263-1277 sequence are enhanced by triple helicity (Fields, C. G., Mickelson, D. J., Drake, S.L., McCarthy, J.B., and Fields, G.B. (1993) J. Biol. Chem. 268, 14153-14160), whereas Eble et al. reached similar conclusions for alpha 1 beta 1 integrin-mediated fibrosarcoma cell adhesion to [alpha 1(IV)]2 alpha 2(IV)434-472 (Eble, J. A., Golbik, R., Mann, K., and Kühn, K. (1993) EMBO J. 12, 4795-4802). In the present study, we have examined the cell adhesion activities of a third region in type IV collagen. A single-stranded peptide (SSP) incorporating the alpha 1(IV)531-543 sequence promoted the adhesion of melanoma, ovarian carcinoma, and Jurkat cells in a dose-dependent manner, with 40% cell adhesion observed at [SSP] = 1.8, 11.5, and 42.2 microM, respectively. Nearly identical results were obtained for cell adhesion to an all-D-enantiomer of the SSP, suggesting that the cell surface receptor(s) for this site do not discriminate based on chirality. The alpha 1(IV)531-543 sequence maintained its cell adhesion promoting activity when incorporated into a homotrimeric triple-helical polypeptide, although relative levels of adhesion were either slightly enhanced or slightly diminished compared with the SSP. Triple-helical conformation was thus not critical for cellular recognition of the alpha 1(IV)531-543 sequence. Single-site substitution experiments of the SSP showed no overall correlation between the biological effects of substitutions and SSP conformation. The SSP, D-SSP, triple-helical polypeptide, and SSP substitution results suggest that cell recognition of the alpha 1(IV)531-543 sequence is generally independent of substrate conformation. The present and prior studies indicate that "conformationally dependent" and "conformationally independent" cellular recognition sites exist within the triple-helical domain of type IV collagen.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis 55455.
authors.forename: A J
authors.initials: AJ
authors.lastname: Miles
authors.forename: A P
authors.initials: AP
authors.lastname: Skubitz
authors.forename: L T
authors.initials: LT
authors.lastname: Furcht
authors.forename: G B
authors.initials: GB
authors.lastname: Fields
mesh_terms: D000595:Amino Acid Sequence; D001485:Basement Membrane / Q000378:metabolism; D002448:Cell Adhesion; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D024141:Collagen Type IV; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D024141:Collagen Type IV; D010446:Peptide Fragments; C065384:collagen type IV alpha1 (531-543); D003094:Collagen