Mechanical memory in cells emerges from mechanotransduction with transcriptional feedback and epigenetic plasticity

ABSTRACT Emerging evidence shows that cells are able to sense and store a memory of their past mechanical environment. Since existing mechanotransduction models are based on adhesion and cytoskeletal dynamics that occurs over seconds and minutes, they do not capture memory observed over days or weeks. We postulate that transcriptional activity and epigenetic plasticity, upstream of adhesion-based signaling, need to be invoked to explain long-term mechanical memory. Here, we present a theory for mechanical memory in cells governed by three key components. First, cells on a stiff matrix are primed by a transcriptional reinforcement of cytoskeletal signaling. Second, longer stiff-priming progressively produces more memory-regulating factors and reduces epigenetic plasticity. Third, when stiff-primed cells move to soft matrix, the reduced epigenetic plasticity blocks new transcription required for cellular adaptation to the new matrix. This stalled transcriptional state gives rise to memory. We validate this model against previous experimental findings of memory storage and decay in epithelial cell migration and stem cell differentiation. We also predict wide-ranging memory responses for different cell types of varying protein kinetics and priming conditions. This theoretical framework for mechanical memory expands the timescales of mechanotransduction captured by conventional models by integrating cytoskeletal signaling with transcriptional activity and epigenetic plasticity. Our model predictions explain mechanical memory and propose new experiments to test spatiotemporal regulation of cellular memory in diverse contexts ranging from cell differentiation to migration and growth.