Comprehensive Endogenous Tagging of Basement Membrane Components Reveals Dynamic Movement within the Matrix Scaffolding

Basement membranes (BMs) are supramolecular matrices built on laminin and type IV collagen networks that provide structural and signaling support to tissues. BM complexity, however, has hindered an understanding of its formation, dynamics, and regulation. Using genome editing, we tagged 29 BM matrix components and receptors in C. elegans with mNeonGreen. Here, we report a common template that initiates BM formation, which rapidly diversifies during tissue differentiation. Through photobleaching studies, we show that BMs are not static—surprisingly, many matrix proteins move within the laminin and collagen scaffoldings. Finally, quantitative imaging, conditional knockdown, and optical highlighting indicate that papilin, a poorly studied glycoprotein, is the most abundant component in the gonadal BM, where it facilitates type IV collagen removal during BM expansion and tissue growth. Together, this work introduces methods for holistic investigation of BM regulation and reveals that BMs are highly dynamic and capable of rapid change to support tissues. [Display omitted] •In vivo visualization of 29 basement membrane (BM) proteins fused with mNeonGreen•Embryonic BMs share a common template but diversify greatly during development•Stable BM proteins form a scaffold that supports movement of dynamic BM components•Papilin promotes local BM collagen removal by limiting GON-1 protease localization Basement membranes (BMs) are complex extracellular structures that are difficult to study in vivo. Keeley et al. use CRISPR-Cas9 genome editing to fluorescently tag 29 BM components in C. elegans and discover that BMs are not static—many matrix proteins move within a stable laminin and collagen IV-based scaffold.