An ECM-to-Nucleus Signaling Pathway Activates Lysosomes for C. elegans Larval Development.

Lysosomes degrade macromolecular cargos, recycle catabolites, and serve as signaling platforms to maintain cell homeostasis, but their role at the tissue level is unclear. Here, we investigate lysosome regulation and function during C. elegans molting, a specialized extracellular matrix (ECM) remodeling process essential for larval development. We found that lysosomes are specifically activated in the epidermis at molt when the apical ECM (cuticle) is being replaced. Impaired lysosome function affects endocytic cargo degradation, suppresses elevated protein synthesis at molt, and causes molting defects. Disturbance of ECM-epidermis attachments triggers lysosomal activation and induces expression of the vacuolar H+-ATPase (V-ATPase), which is mediated by the GATA transcription factor ELT-3 and the STAT family protein STA-2. Our study reveals an ECM-to-nucleus signaling pathway that activates lysosomes to facilitate ECM remodeling essential for larval development.