Filamin A Mediates Wound Closure by Promoting Elastic Deformation and Maintenance of Tension in the Collagen Matrix

Abstract

Cell-mediated remodeling and wound closure are critical for efficient wound healing, but the contribution of actin-binding proteins to contraction of the extracellular matrix is not defined. We examined the role of filamin A (FLNa), an actin filament cross-linking protein, in wound contraction and maintenance of matrix tension. Conditional deletion of FLNa in fibroblasts in mice was associated with ~ 4 day delay of full-thickness skin wound contraction compared with wild-type (WT) mice. We modeled the healing wound matrix using cultured fibroblasts plated on grid-supported collagen gels that create lateral boundaries, which are analogues to wound margins. In contrast to WT cells, FLNa knockdown (KD) cells could not completely maintain tension when matrix compaction was resisted by boundaries, which manifested as relaxed matrix tension. Similarly, WT cells on cross-linked collagen, which requires higher levels of sustained tension, exhibited approximately fivefold larger deformation fields and approximately twofold greater fiber alignment compared with FLNa KD cells. Maintenance of boundary-resisted tension markedly influenced the elongation of cell extensions: in WT cells, the number (~50%) and length (~300%) of cell extensions were greater than FLNa KD cells. We conclude that FLNa is required for wound contraction, in part by enabling elastic deformation and maintenance of tension in the matrix.

Filamin A regulates the organization and remodeling of the pericellular collagen matrix

“…The actin-binding protein filamin A (FLNa) contributes to the organization, function, stability, and signaling functions of the actin cytoskeletal network (20)(21)(22). FLNa cross-links actin filaments into orthogonal arrays and interacts with a large number of proteins that regulate cell-directed, adhesion-dependent processes, including the stabilization of focal adhesions (FAs), mechanoprotection, and wound healing (23)(24)(25)(26)(27)(28)(29). As a result of competition with the actin-binding protein talin for binding to integrins (30), FLNa strongly affects the activation state of integrins and, as a result, the affects the binding of collagen fibrils to b1 integrin-containing collagen adhesions.…”

Mass spectrometry‐based proteomics reveals the distinct nature of the skin proteomes of photoaged compared to intrinsically aged skin

“…Keratin 6A mRNA expression has been shown to be increased with age in sun‐protected human skin , though we did not find a concurrent increase in its binding partner keratin 16 with age. Filamin A is an actin‐binding protein and is known to be important in the pericellular organization of collagen and providing tension to the ECM . Alterations in this protein with age in the skin have not to our knowledge been reported previously, though it is known that mutations in filamin A can lead to cutaneous alterations including fibromas and pigmentary changes .…”

Establishment of in vitro model of corneal scar pathophysiology

“…These mainly included the expression of proteins related to cytoskeletal remodeling and wound healing. For example, FLNA that mediates actin polymerization leading to increased contraction (Mohammadi et al, ) and further activation of P13/Akt (phosphatidylinositol 3/Akt) cell survival pathway (Gurtner & Bhatt, ) possibly leading to persistent proliferation of myofibroblasts. Further expression of other actin crosslinking proteins like Spectrin, MACF1, and Alpha‐actinin‐4 might be leading to a spread morphology (Metral et al, ) and stress fiber formation (Leung, Sun, Zheng, Knowles, & Liem, ; Welch, Odland, & Clark, ) in the in vitro CS model as validated by the expression of α‐SMA in immunofluorescence analysis (Figure i,k).…”