A systems-based analysis of feedback structure and characteristic timescales in turnover-mediated mechanical adaptation.

Mechanical adaptation underlies mechanical homeostasis by enabling living systems to maintain characteristic mechanical states under sustained perturbations. Turnover-mediated remodeling contributes to this process by renewing or reorganizing internal structures under load across biological scales. While substantial advances have been made in understanding remodeling mechanisms, reduced-order system-level interpretations that relate feedback structure to characteristic timescales remain limited. Here, we develop a systems-based reduced-order formulation that provides a feedback representation for turnover-mediated mechanical adaptation processes. We first formulate a minimal actin-based model as a concrete starting point for linking turnover-mediated remodeling with mechanical response and identifying three system-level elements: a disturbance input, a remodeling state, and a regulated mechanical quantity. In the resulting local linearized representation, turnover-mediated remodeling dynamics can be represented in an integral-equivalent closed-loop form, yielding a local characteristic timescale determined by the local turnover and mechanical gains. A literature-based descriptive comparison shows that reported adaptation times lie near or above the corresponding turnover-related timescale ranges in representative multiscale systems. The present formulation provides a reduced-order system-level representation that relates turnover-mediated mechanical adaptation to feedback structure and characteristic timescales.