Integrin-dependent activation of the JNK signaling pathway by mechanical stress

• Published in: PloS one 2011-12, Vol.6 (12), p.e26182-e26182
• Main Authors: Pereira, Andrea Maria, Tudor, Cicerone, Kanger, Johannes S, Subramaniam, Vinod, Martin-Blanco, Enrique
• Format: Article
• Language: English
• Subjects: Adhesion; Animals; Apoptosis; Biology; Biosensing Techniques; Biosensors; Cell adhesion; Cell adhesion & migration; Cell growth; Cell Line; Cell morphology; Cell Shape - drug effects; Cell size; Cell Survival; Confocal; Confocal microscopy; Cytology; Cytoskeleton; Cytoskeleton - drug effects; Cytoskeleton - metabolism; Detection equipment; Drosophila; Energy transfer; Fluorescence; Fluorescence microscopy; Fluorescence resonance energy transfer; Focal Adhesions - drug effects; Focal Adhesions - metabolism; Gene expression; In vitro methods and tests; Insects; Integrins; Integrins - metabolism; Ionizing radiation; JNK Mitogen-Activated Protein Kinases - antagonists & inhibitors; JNK Mitogen-Activated Protein Kinases - deficiency; JNK Mitogen-Activated Protein Kinases - genetics; JNK Mitogen-Activated Protein Kinases - metabolism; JNK protein; Kinases; MAP Kinase Signaling System - drug effects; Microscopy; Microscopy, Fluorescence; Nanotechnology; Permeability; Phosphorylation; Physiology; Plastics; Protein Kinase Inhibitors - pharmacology; Proteins; Regulators; RNA Interference; Rodents; Signal transduction; Signaling; Smooth muscle; Stress, Mechanical; Substrates; Talin; Tumor necrosis factor-TNF; Wound healing
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0026182

Mechanical force is known to modulate the activity of the Jun N-terminal kinase (JNK) signaling cascade. However, the effect of mechanical stresses on JNK signaling activation has previously only been analyzed by in vitro detection methods. It still remains unknown how living cells activate the JNK signaling cascade in response to mechanical stress and what its functions are in stretched cells.We assessed in real-time the activity of the JNK pathway in Drosophila cells by Fluorescence Lifetime Imaging Microscopy (FLIM), using an intramolecular phosphorylation-dependent dJun-FRET (Fluorescence Resonance Energy Transfer) biosensor. We found that quantitative FRET-FLIM analysis and confocal microscopy revealed sustained dJun-FRET biosensor activation and stable morphology changes in response to mechanical stretch for Drosophila S2R+ cells. Further, these cells plated on different substrates showed distinct levels of JNK activity that associate with differences in cell morphology, integrin expression and focal adhesion organization.These data imply that alterations in the cytoskeleton and matrix attachments may act as regulators of JNK signaling, and that JNK activity might feed back to modulate the cytoskeleton and cell adhesion. We found that this dynamic system is highly plastic; at rest, integrins at focal adhesions and talin are key factors suppressing JNK activity, while multidirectional static stretch leads to integrin-dependent, and probably talin-independent, Jun sensor activation. Further, our data suggest that JNK activity has to coordinate with other signaling elements for the regulation of the cytoskeleton and cell shape remodeling associated with stretch.