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Arg-Gly-Asp–Containing Domains of Fibrillins-1 and -2 Distinctly Regulate Lung Fibroblast Migration

¹ Department of Veterans Affairs Research Service and University of Iowa Carver College of Medicine, Iowa City, Iowa; ² Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri; and ³ Department of Orthopaedics and Rehabilitation, Pennsylvania State University School of Medicine, Hershey, Pennsylvania

Correspondence and requests for reprints should be addressed to Stephen E. McGowan, M.D., Division of Pulmonary, Critical Care, and Occupational Medicine, Department of Internal Medicine, C33B GH, University of Iowa Hospital, 200 Hawkins Dr., Iowa City, IA 52242. E-mail: Stephen-mcgowan{at}uiowa.edu

Development of the extracellular matrix is a critical feature of alveolar formation and actively involves pulmonary interstitial fibroblasts. The elastic fiber network is an interconnected system of load-bearing fibers that also influences the behavior of adjacent cells, particularly the interstitial lung fibroblasts (LF). We hypothesized that discrete domains of fibrillins-1 and -2 interact with LF integrins and direct their migration in the presence of platelet-derived growth factor (PDGF)-A. Surfaces coated with recombinant peptides lacking or including an arginine-glycine-aspartic acid (RGD) motif were used to study LF migration across porous filters and on protein-coated glass. Exon 24 of fibrillin-2 (Fib2 24), which encodes for an RGD-containing transforming growth factor-β–binding (TB) domain, stimulated migration with greater directional persistence and more effectively stimulated trans-filter migration at low concentrations. Exons 36–44 of fibrillin-1 (Fib1 36–44), which include epidermal growth factor–like domains and an RGD-containing TB domain, induce more lamlellipodia and more widespread remodeling of the leading edge, resulting in greater migration velocity than did Fib2 24. Distinct structural features in regions that surround the RGD motifs may differentially regulate how the PDGF receptor- promotes integrin distribution and actin filament remodeling at the cell's leading edge. Understanding how fibrillins regulate LF migration may help elucidate how the elastic fiber system could be restored as an interconnected unit, which fails to occur in emphysematous lungs.

Key Words: alveolus • fibrillin • elastin • integrin • cell migration

CLINICAL RELEVANCE This research defines interactions between proteins in the elastic fiber and lung fibroblasts that may be involved in the alveolar septation process. The findings foster the development of new treatments for emphysema.