Substrate stiffness regulates temporary NF-κB activation via actomyosin contractions

Area of Science:

• Cell biology
• Biophysics
• Mechanobiology

Background:

• The extracellular matrix (ECM) influences cell behavior through mechanotransduction.
• The role of transcription factors in mechanotransduction is not fully understood.
• NF-κB is a key regulator in immune responses and cancer.

Purpose of the Study:

• To investigate the influence of substrate stiffness on NF-κB activity.
• To elucidate the molecular mechanisms linking substrate stiffness to NF-κB activation.
• To determine the role of NF-κB in substrate-dependent cell morphology.

Main Methods:

• Culturing H1299 lung adenocarcinoma cells on substrates of varying stiffness.
• Assessing NF-κB activation.
• Analyzing the role of actomyosin contractions and MRLC phosphorylation.
• Using Rho kinase inhibitor Y27632.
• Observing cell morphology.

Main Results:

• NF-κB activation was induced by stiff substrates but not soft substrates.
• NF-κB activation was dependent on actomyosin contractions and MRLC phosphorylation, independent of integrin β1.
• Inhibition of MRLC phosphorylation reduced NF-κB activity.
• Cell morphology (rounded vs. spread) was substrate-dependent and modulated by NF-κB activity.

Conclusions:

• Substrate stiffness regulates NF-κB activity through actomyosin contractions.
• NF-κB signaling plays a role in substrate-dependent cell morphology.
• These findings link physical cues to a critical transcription factor involved in immunity and cancer.