Keratin isoform shifts modulate motility signals during wound healing

Abstract

Keratin intermediate filaments form strong mechanical scaffolds that confer structural stability to epithelial tissues, but the reason this function requires a protein family with fifty-four isoforms is not understood. During skin wound healing, a shift in keratin isoform expression alters the composition of keratin filaments. How this change modulates cellular function to support epidermal remodeling remains unclear. We report an unexpected effect of keratin isoform variation on kinase signal transduction. Increased expression of wound-associated keratin 6A, but not of steady-state keratin 5, potentiated keratinocyte migration and wound closure without compromising epidermal stability by activating myosin motors. This pathway depended on isoform-specific interaction between intrinsically disordered keratin head domains and non-filamentous vimentin shuttling myosin-activating kinases. These results substantially expand the functional repertoire of intermediate filaments from their canonical role as mechanical scaffolds to include roles as signaling scaffolds that spatiotemporally organize signal transduction cascades depending on isoform composition.

A general algorithm for consensus 3D cell segmentation from 2D segmented stacks

“…We adapted an epidermal organoid culture model from existing protocols 86,101,102 . Polycarbonate filters with 0.4μm pore size (0.47cm 2 area, Nunc #140620) were placed in larger tissue culture dishes using sterile forceps.…”

“…Human keratinocyte Ker-CT cells (ATCC #CRL-4048) were a kind gift from Dr. Jerry Shay (UT Southwestern Medical Center). A keratinocyte cell line stably expressing mNeonGreen-tagged keratin 5 (K5) to label intermediate filaments was created as previously described 86 .…”

“…Epidermal organoid culture. We adapted an epidermal organoid culture model from existing protocols 86,101,102 .…”

“…For one view, this is conceptually similar to the stitching across xy slices. Looking top-to-bottom through an epidermal organoid culture 86 (Methods), cells are initially spherical, becoming increasingly irregular and elongated (Fig. 4a).…”