The extracellular matrix (ECM) is a polymer network hypothesized to form a stable cellular scaffold. While the ECM can undergo acute remodeling during embryogenesis, it is experimentally difficult to determine whether basal turnover is also important. Most studies of homeostatic turnover assume an initial steady-state balance of production and degradation and measure half-life by quantifying the rate of decay after experimental intervention (e.g., pulse labeling). Here, we present an intervention-free approach to mathematically model basal ECM turnover during embryogenesis by exploiting our ability to live image de novo ECM development in Drosophila to quantify production from initiation to homeostasis. This reveals rapid turnover (half-life ∼7–10 h), which we confirmed by in vivo pulse-chase experiments. Moreover, ECM turnover is partially dependent on proteolysis and network interactions, and slowing turnover affects tissue morphogenesis. These data demonstrate that embryonic ECM undergoes constant replacement, which is likely necessary to maintain network plasticity to accommodate growth and morphogenesis.

细胞外基质 (ECM) 是一种聚合物网络，被假设为形成稳定的细胞支架。虽然 ECM 在胚胎发生过程中会发生急性重塑，但在实验上很难确定基础周转是否也很重要。大多数关于稳态周转的研究假设生产和降解的初始稳态平衡，并通过量化实验干预（例如脉冲标记）后的衰减率来测量半衰期。在这里，我们提出了一种无需干预的方法，通过利用我们在果蝇中实时成像从头ECM 发育的能力来量化从起始到稳态的生产，从而对胚胎发生过程中的基础 ECM 周转进行数学建模。这揭示了快速周转（半衰期~7-10小时），我们证实了这一点体内脉冲追踪实验。此外，ECM 周转部分依赖于蛋白水解和网络相互作用，减缓周转会影响组织形态发生。这些数据表明，胚胎 ECM 不断更换，这可能是维持网络可塑性以适应生长和形态发生所必需的。