Stathmin Regulates Keratinocyte Proliferation and Migration during Cutaneous Regeneration

Sabrina Schmitt,Ute Müller,Peter Angel,Niels Grabe,Peter Schirmacher,Günter Germann,Stefan Holland-Cunz,Nathalie Harder,Manuel Hrabowski,Kathi Westphal,Volker Ehemann,Benedikt Müller,Damian Stichel,Karl Rohr,Lars Wiechert,Franziska Matthäus,Kai Breuhahn,Kai Safferling,Christophe Egles

doi:10.1371/journal.pone.0075075

Abstract

Cutaneous regeneration utilizes paracrine feedback mechanisms to fine-tune the regulation of epidermal keratinocyte proliferation and migration. However, it is unknown how fibroblast-derived hepatocyte growth factor (HGF) affects these mutually exclusive processes in distinct cell populations. We here show that HGF stimulates the expression and phosphorylation of the microtubule-destabilizing factor stathmin in primary human keratinocytes. Quantitative single cell- and cell population-based analyses revealed that basal stathmin levels are important for the migratory ability of keratinocytes in vitro; however, its expression is moderately induced in the migration tongue of mouse skin or organotypic multi-layered keratinocyte 3D cultures after full-thickness wounding. In contrast, clearly elevated stathmin expression is detectable in hyperproliferative epidermal areas. In vitro, stathmin silencing significantly reduced keratinocyte proliferation. Automated quantitative and time-resolved analyses in organotypic cocultures demonstrated a high correlation between Stathmin/phospho-Stathmin and Ki67 positivity in epidermal regions with proliferative activity. Thus, activation of stathmin may stimulate keratinocyte proliferation, while basal stathmin levels are sufficient for keratinocyte migration during cutaneous regeneration.

Highlights

Binding of growth factors, cytokines, and chemokines to their respective receptors and subsequent activation of signaling pathways play a pivotal role in the regulation of cellular responses under physiological and pathophysiological conditions
This tightly regulated process partly depends on a double paracrine feedback mechanism initiated by active secretion of keratinocyte-derived interleukin-1 (IL-1), which in turn induces the expression of fibroblast-derived growth factors including keratinocyte growth factor (KGF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and hepatocyte growth factor (HGF; synonym: scatter factor) in an AP-1-dependent manner [4,5,6]
Because the HGF/c-Met signaling axis affects the activity of the MT-destabilizing protein Stathmin in different tumor cell lines [16,17], the effects of HGF on Stathmin expression and phosphorylation were analyzed in primary human keratinocytes

Summary

Introduction

Cytokines, and chemokines to their respective receptors and subsequent activation of signaling pathways play a pivotal role in the regulation of cellular responses under physiological and pathophysiological conditions. After wounding, proliferating epidermal keratinocytes are located in very close proximity to migrating keratinocytes, which is essential for efficient production of new epidermis and fast wound closure [3] This tightly regulated process partly depends on a double paracrine feedback mechanism initiated by active secretion of keratinocyte-derived interleukin-1 (IL-1), which in turn induces the expression of fibroblast-derived growth factors including keratinocyte growth factor (KGF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and hepatocyte growth factor (HGF; synonym: scatter factor) in an AP-1-dependent manner [4,5,6]. The central role of this paracrine feedback communication between fibroblasts and keratinocytes has been documented in genetically modified animals, demonstrating that KGF-, GM-CSF-, or HGF-induced signaling is of pivotal importance for proper reepithelialization during wound closure [7,8,9]

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