Self-assembly of Laminin Isoforms*
- Yi-Shan Cheng‡,
- Marie-France Champliaud§,
- Robert E. Burgeson§,
- M. Peter Marinkovich¶‖ and
- Peter D. Yurchenco‡**
- From the ‡Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, the ¶Division of Dermatology, Palo Alto Veterans Affairs Health Care System, Palo Alto, California 94061, the‖Department of Dermatology, Stanford University School of Medicine, Stanford, California 94305, and the§Cutaneous Biology Research Center, Massachusetts General Hospital-East, Harvard Medical School, Charlestown, Massachusetts 02129
Abstract
The α, β, and γ subunits of basement membrane laminins can combine into different heterotrimeric molecules with either three full short arms (e.g. laminins-1–4), or molecules containing one (laminins-6–9) or more (laminin-5) short arm truncations. Laminin-1 (α1β1γ1), self-assembles through a calcium-dependent thermal gelation requiring binding interactions between N-terminal short arm domains, forming a meshwork polymer thought to contribute to basement membrane architecture (Yurchenco, P. D., and Cheng, Y. S. (1993) J. Biol. Chem. 268, 17286–17299). However, it has been unclear whether other isoforms share this property, and if so, which ones. To begin to address this, we evaluated laminin-2 (α2β1γ1), laminin-4 (α2β2γ1), laminin-5 (α3Aβ3γ2), and laminin-6 (α3Aβ1γ1). The first two isoforms were found to self-aggregate in a concentration- and temperature-dependent manner and a close self-assembly relationship among laminins-1, -2, and -4 were demonstrated by: (a) polymerization of all three proteins was inhibited by EDTA and laminin-1 short arm fragments, (b) polymerization of laminin-1 was inhibited by fragments of laminins-2 and -4, (c) laminin-2 and, to a lesser degree, laminin-4, even well below their own critical concentration, co-aggregated with laminin-1, evidence for co-polymerization. Laminin-5, on the other hand, neither polymerized nor co-polymerized with laminin-1. Laminin-6 failed to co-aggregate with laminin-1 at all concentrations evaluated, evidence for a lack of a related self-assembly activity. The data support the hypothesis that all three short arms are required for self-assembly and suggest that the short arm domain structure of laminin isoforms affect their architecture-forming properties in basement membranes.
Footnotes
-
↵* This work was supported by National Institutes of Health Grants R01-DK36425 (to Y. S. C. and P. D. Y.), R01-AR 35689 (to M. F. C. and R. E. B.), and P01-AR-44012 (to M. P. M.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵** To whom correspondence should be addressed: Dept. Pathology & Laboratory Medicine, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854. Tel.: 732-235-4674; Fax: 732-235-4825; E-mail:yurchenc{at}rwja.umdnj.edu.
-
↵1 The abbreviations used are: EHS, Engelbreth-Holm-Swarm; HMB, p-hydroxymecuribenzoic acid; PMSF, phenylmethylsulfonyl fluoride; HPLC, high performance liquid chromatography; PAGE, polyacrylamide gel electrophoresis; BSA, bovine serum albumin.
-
↵2 Calculated from the product of the slope andx axis intercept given that the predicted slope for a pure polymerizing protein that follows nucleation-propagation thermodynamics is one. Thus 70% of the laminin-2/4 preparation is active.
-
↵3 As evidenced by a measurable critical concentration.
-
↵4 H. Colognato and P. D. Yurchenco, unpublished results.
-
- Received April 11, 1997.
- Revision received October 1, 1997.
