Collagen4 fluorescent protein knock-in lines reveal remodeling of cardiovascular basement membranes

Basement membranes (BMs) are specialized extracellular matrix structures that provide structural support and regulate cellular behavior. Although BM composition and organization are dynamically remodeled during development and tissue regeneration, the remodeling of individual BM components in the cardiovascular system (CVS) remain incompletely characterized. Here, we focused on Collagen4 (Col4), a major structural component of BMs, to investigate its remodeling during cardiovascular development and regeneration. To monitor the remodeling of Col4 in vivo, the Venus fluorescent tag was integrated in frame into the zebrafish endogenous col4a1 and col4a2 genes, enabling live confocal imaging of expression. Our data reveal dynamic patterns of Col4a1 and Col4a2 within the developing CVS, with deposition progressively increasing as vascular and cardiac structures develop and mature during both development and regeneration. In the regenerating heart, Col4a2 accumulated at the injury site during early stages of regeneration and became increasingly associated with the newly regenerated myocardium. Together, these findings demonstrate that Col4 deposition is dynamically reorganized across developmental and regenerative stages of CVS and describe new tools for following Col4 dynamics in vivo.