Mycolactone activation of Wiskott-Aldrich syndrome proteins underpins Buruli ulcer formation
Laure Guenin-Macé, … , Marie-France Carlier, Caroline Demangel
Laure Guenin-Macé, … , Marie-France Carlier, Caroline Demangel
Published March 15, 2013
Citation Information: J Clin Invest. 2013;123(4):1501-1512. https://doi.org/10.1172/JCI66576.
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Research Article Infectious disease

Mycolactone activation of Wiskott-Aldrich syndrome proteins underpins Buruli ulcer formation

Abstract

Mycolactone is a diffusible lipid secreted by the human pathogen Mycobacterium ulcerans, which induces the formation of open skin lesions referred to as Buruli ulcers. Here, we show that mycolactone operates by hijacking the Wiskott-Aldrich syndrome protein (WASP) family of actin-nucleating factors. By disrupting WASP autoinhibition, mycolactone leads to uncontrolled activation of ARP2/3-mediated assembly of actin in the cytoplasm. In epithelial cells, mycolactone-induced stimulation of ARP2/3 concentrated in the perinuclear region, resulting in defective cell adhesion and directional migration. In vivo injection of mycolactone into mouse ears consistently altered the junctional organization and stratification of keratinocytes, leading to epidermal thinning, followed by rupture. This degradation process was efficiently suppressed by coadministration of the N-WASP inhibitor wiskostatin. These results elucidate the molecular basis of mycolactone activity and provide a mechanism for Buruli ulcer pathogenesis. Our findings should allow for the rationale design of competitive inhibitors of mycolactone binding to N-WASP, with anti–Buruli ulcer therapeutic potential.

Authors

Laure Guenin-Macé, Romain Veyron-Churlet, Maria-Isabel Thoulouze, Guillaume Romet-Lemonne, Hui Hong, Peter F. Leadlay, Anne Danckaert, Marie-Thérèse Ruf, Serge Mostowy, Chiara Zurzolo, Philippe Bousso, Fabrice Chrétien, Marie-France Carlier, Caroline Demangel

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Figure 6

Mycolactone impairs directed migration of epithelial cells.

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Mycolactone impairs directed migration of epithelial cells. (A) Represen...
(A) Representative image of the wound area after 24 hours of cell migration in the presence of 25 nM mycolactone or methanol (control). Dashed line denotes wound edges at 0 hours. (B) Mean ± SEM cell speed and x displacement (n > 170), and time-dependent representation of cell trajectories. ***P < 0.001, Mann-Whitney test. (C) Mean ± SEM speed and x displacement of more than 200 HeLa cells transfected with an expression vector encoding WASP CR1 24 hours before assessment of cell migration in the presence or absence of 25 nM mycolactone. Controls are cells transfected with empty vector and treated with vehicle. *P < 0.05, ***P < 0.001, Kruskal Wallis with Dunn post-test. (D) Representative images of the wound area after 24 hours of cell migration. HeLa cells were transfected with an expression vector encoding WASP CR1, or an empty vector (no WASP CR1) 24 hours prior to wound formation and cell migration in the presence of 25 nM mycolactone or vehicle control. Dashed lines denote wound edges at 0 hours. Wound-healing assays were repeated twice with similar results. Scale bars: 100 μm (A and D); 50 μm (B).