Identification of a novel anoikis signalling pathway using the fungal virulence factor gliotoxin
Haun, Florian ; Neumann, Simon ; Peintner, Lukas ; Wieland, Katrin ; Habicht, Juri ; Schwan, Carsten ; Ostevold, Kristine ; Koczorowska, Maria Magdalena ; Biniossek, Martin ; Kist, Matthias ... show 7 more
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Abstract
Anoikis is a form of apoptosis induced by cell detachment. Integrin inactivation plays a major role in the process but the exact signalling pathway is ill-defined. Here we identify an anoikis pathway using gliotoxin (GT), a virulence factor of the fungus Aspergillus fumigatus, which causes invasive aspergillosis in humans. GT prevents integrin binding to RGD-containing extracellular matrix components by covalently modifying cysteines in the binding pocket. As a consequence, focal adhesion kinase (FAK) is inhibited resulting in dephosphorylation of p190RhoGAP, allowing activation of RhoA. Sequential activation of ROCK, MKK4/MKK7 and JNK then triggers pro-apoptotic phosphorylation of Bim. Cells in suspension or lacking integrin surface expression are insensitive to GT but are sensitised to ROCK-MKK4/MKK7-JNK-dependent anoikis upon attachment to fibronectin or integrin upregulation. The same signalling pathway is triggered by FAK inhibition or inhibiting integrin alphaV/beta3 with Cilengitide. Thus, GT can target integrins to induce anoikis on lung epithelial cells.
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Nat Commun. 2018 Aug 30;9(1):3524. doi: 10.1038/s41467-018-05850-w. Link to article on publisher's site