Basement Membrane Sliding and Targeted Adhesion Remodels Tissue Boundaries During Uterine-vulval Attachment in C. elegans

Large gaps in basement membrane (BM) occur at sites of cell invasion and tissue remodelling in development and cancer. Though never followed directly in vivo, BM dissolution or reduced synthesis have been postulated to create these gaps. Using landmark photobleaching and optical highlighting of laminin and type IV collagen, we find that a new mechanism, BM sliding, underlies BM gap enlargement during uterine-vulval attachment in C. elegans. Laser ablation and mutant analysis reveal that the invaginating vulval cells promote BM movement. Further, an RNA interference and expression screen identify the integrin INA-1/PAT-3 and VAB-19, homolog of the tumour suppressor Kank, as regulators of BM opening. Both concentrate within vulval cells at the BM gap boundary and halt expansion of the shifting BM. BM sliding followed by targeted adhesion represents a new mechanism for creating precise BM breaches that can be used by cells to break down compartment boundaries.