An NFATC4 phospho-switch links matrix stiffness to fibroblast fate
Rebecca Shelley Frabotta, Purushothama Rao Tata
Rebecca Shelley Frabotta, Purushothama Rao Tata
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Commentary

An NFATC4 phospho-switch links matrix stiffness to fibroblast fate

Abstract

Fibrosis is driven by the activation of quiescent fibroblasts into contractile, matrix-secreting myofibroblasts, a transition governed jointly by biochemical signals and by the mechanical properties of the ECM. How the physical stiffness of tissue is converted into a durable transcriptional cell fate decision has remained poorly understood. In this issue of the JCI, Kadri et al. used global phosphoproteomic profiling of primary human lung fibroblasts across a defined stiffness gradient to identify phosphorylation of NFATC4 at residues S213/S217 as a mechanosensitive switch that is both necessary and sufficient for the fibroblast-to-myofibroblast transition. They validated these predictions in an independent transcriptomic dataset from patients with idiopathic pulmonary fibrosis, showing that NFATC4 expression increased with disease severity. Prior work has implicated NFATC4 activation in cardiac and hepatic fibrosis, suggesting that this single modification may serve as a convergence point for mechanical and cytokine signals across fibrotic diseases.

Authors

Rebecca Shelley Frabotta, Purushothama Rao Tata

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Figure 1

Matrix stiffness activates an NFATC4 phospho-switch gating the fibroblast-to-myofibroblast transition.

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Matrix stiffness activates an NFATC4 phospho-switch gating the fibroblas...
Kadri et al. (10) used phosphoproteomic profiling in human lung fibroblasts cultured across a range of physiological matrix stiffnesses to identify mechanosensitive phosphosites involved in fibroblast differentiation. Among the candidates, NFATC4 emerged as a key regulator based on the strong association of its downstream targets with pathological fibrosis. (A) Increasing matrix stiffness promoted JNK-dependent phosphorylation of NFATC4 at S213/S217, enabling NFATC4 nuclear localization and induction of a fibrotic gene program. This stiffness-responsive switch drove CTHRC1+/ACTA2+ myofibroblast commitment, with TGF-β/SMAD2/3 signaling reinforcing the fibrotic state. (B) Kadri et al.’s study doubles as a resource for mechanosensitive phosphosites, adding substantially to those previously reported. This panel highlights select phosphosites spanning a range of roles, including cell adhesion, cytoskeletal reorganization, cell motility, and regulation of transcription.