Collagen processing is essential for germ cell identity.

The extracellular matrix (ECM) is a critical component of embryonic development, providing both structural support and a dynamic signaling environment for cell migration, adhesion, and tissue organization. Collagen, the most abundant protein in the ECM, is crosslinked by the enzyme lysyl oxidase (LOX), and that activity plays a pivotal role in creating support throughout the ECM. Dysregulated LOX activity disrupts the mechanical integrity of the ECM. Sea urchins offer a robust model for studying LOX function and ECM dynamics in embryonic development due to their rapid, transparent development and traceable cell lineages. Previous studies using the pan-monoamine oxidase/LOX inhibitor β-aminopropionitrile suggested an essential role of LOX activity in sea urchin gastrulation and maintenance of ECM integrity. Here, we integrate newly developed and traditional LOX inhibitors, with a translation blocking morpholino antisense oligonucleotide to a specific lysyl oxidase, and chemoselective fluorescent probes to LOX oxidation products, all to test the role of the ECM in development and germ cell formation. The primordial germ cells in this animal are believed to be committed at the fifth cell division as small micromeres by inheritance of yet unknown molecular constituency. We find that LOX activity is essential for an instructive environment in the development of a germ line, even though the fate of that germ line in the sea urchin is predetermined. Our findings provide insight into the dynamic interplay between ECM remodeling, gene expression, and metabolism, offering a more profound understanding of the role of the ECM in development and germ cell identity.