Cytoskeletal Prestress Regulates RIG-I-Mediated Innate Immunity

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• Innate immunity provides crucial antiviral defense via signaling pathways like retinoic acid-inducible gene I (RIG-I).
• The influence of cytoskeletal prestress, a key aspect of cellular mechanotransduction, on RIG-I signaling and innate immunity is not well understood.

Purpose of the Study:

• To investigate the role of cytoskeletal prestress in regulating RIG-I signaling and type-I interferon (IFN) gene expression.
• To determine how substrate stiffness affects innate immune responses.

Main Methods:

• Cells were cultured on soft (0.6 kPa) and stiff (8.5 kPa) substrates to alter cellular traction and prestress.
• Poly(I:C), a viral dsRNA mimic, was used to stimulate the RIG-I pathway.
• Expression of IFN-β1 and IFN-stimulated genes (ISGs) was measured.
• The activation and localization of TANK Binding Kinase 1 (TBK1) and Yes-associated protein (YAP) were assessed.

Main Results:

• Cells on soft substrates exhibited minimal RIG-I signaling activation and low IFN-β1 and ISG expression.
• On soft substrates, YAP localized to the cytoplasm, inhibiting TBK1 activation.
• Cells on stiff substrates showed enhanced RIG-I signaling, elevated TBK1 activation, and increased IFN and ISG expression due to nuclear YAP localization.

Conclusions:

• Cytoskeletal prestress significantly influences the activation of RIG-I signaling and subsequent innate immune responses.
• Substrate stiffness, by modulating cytoskeletal prestress and YAP localization, acts as a critical biophysical regulator of antiviral signaling.