Scarface, a secreted serine protease-like protein, regulates polarized localization of laminin A at the basement membrane of the Drosophila embryo.

Cell-matrix interactions brought about by the activity of integrins and laminins maintain the polarized architecture of epithelia and mediate morphogenetic interactions between apposing tissues. Although the polarized localization of laminins at the basement membrane is a crucial step in these processes, little is known about how this polarized distribution is achieved. Here, in Drosophila, we analyse the role of the secreted serine protease-like protein Scarface in germ-band retraction and dorsal closure-morphogenetic processes that rely on the activity of integrins and laminins. We present evidence that scarface is regulated by c-Jun amino-terminal kinase and that scarface mutant embryos show defects in these morphogenetic processes. Anomalous accumulation of laminin A on the apical surface of epithelial cells was observed in these embryos before a loss of epithelial polarity was induced. We propose that Scarface has a key role in regulating the polarized localization of laminin A in this developmental context.