Cell geometry dictates TNFα-induced genome response

Area of Science:

• Cellular and Molecular Physiology
• Biophysics
• Systems Biology

Background:

• Cells integrate soluble and mechanical signals to control gene expression.
• The combined effects of chemical and physical signals on cellular responses are not fully understood.
• Tumor necrosis factor-alpha (TNFα) is a key cytokine involved in inflammation and immunity.

Purpose of the Study:

• To investigate the cross-talk between cellular geometry and TNFα signaling pathways.
• To determine how cell shape influences the nuclear translocation of transcription factors and gene expression.
• To assess the functional impact of geometry on TNFα-induced fibroblast proliferation.

Main Methods:

• NIH 3T3 fibroblasts were cultured in defined rectangular (anisotropic) and circular (isotropic) geometries.
• Cells were stimulated with TNFα, and nuclear translocation of NFκB (p65) and MKL was analyzed.
• Downstream gene expression patterns were profiled using transcriptomics; cell proliferation was measured.

Main Results:

• TNFα induced geometry-dependent actin depolymerization, affecting IκB degradation and p65 nuclear translocation.
• Cellular geometry modulated MKL nuclear exit and p65 sequestration at RNA-polymerase-II foci.
• Global transcription profiles revealed geometry-dependent gene expression patterns in response to TNFα.

Conclusions:

• Fibroblast cellular geometry significantly dictates cellular responses to TNFα signaling.
• Distinct geometric constraints lead to differential regulation of molecular pathways and gene expression.
• Cell shape is a critical factor influencing the functional outcomes of cytokine stimulation, such as cell proliferation.