Controlled extracellular proteolysis is catalyzed in part by the secretion of plasminogen activators. As a step in the study of the expression of these enzymes in mouse tissues, we have isolated five cDNAs encoding the mouse urokinase-type plasminogen activator from a cDNA library prepared with size-selected mRNA from MSVtransformed 3T3 cells. The longest cDNA insert contains the entire coding region of mouse urokinase, 58 base pairs of the 5' non-coding region, and the entire 3' non-coding region, which is 942 base pairs long. The deduced protein sequence, which starts with a signal peptide of 20 amino acids, shows extensive homology to that of human and porcine urokinase. However, in contrast to these enzymes, mouse urokinase contains no N-glycosylation site. Bacteria harbouring one of the recombinant plasmids synthesize and secrete into their periplasm a protease indistinguishable from mouse urokinase.Plasminogen activators (PAS) are serine proteases of trypsin-like specificity, which convert plasminogen, an inactive zymogen present in plasma and most other extracellular fluids, into plasmin, a neutral protease of broad specificity PAS are synthesized by a number of cell types, usually under a strict and cell-specific hormonal control. Enzyme production has been correlated with several processes involving cell migration and tissue remodeling [9]. PA induction can result from a selective increase in either urokinase [lo, 111 or TA [12] mRNA content. In addition, PA activity can be modulated at post-translational levels, which include the secretion of the enzyme [l 11 and the concomitant production of PA-specific protease inhibitors [13, 141. In the mouse, PA production has been studied in a variety of physiological and pathological situations, including embryonic development [4, 151 and inflammation [ 161. However, no information has been available as to the primary structure of the mouse enzymes, and the probes required to study the expression of the mouse PA genes have not yet been described. We report here the isolation and characterization of cDNA clones containing the entire coding sequence of mouse urokinase mRNA.

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Serpins, a superfamily of protease inhibitors, control proteolytic cascades in many physiological processes. Genomic studies have revealed the presence of a high number of serpinencoding genes in Drosophila melanogaster, but their functions remain largely unknown. In a biochemical screen designed to detect protease inhibitors that may be implicated in early Drosophila development, we identified in embryos a ligand that forms a 67 kDa SDS-stable complex with the broad spectrum protease trypsin. Characterization of this ligand revealed it to be the recently described serpin, Spn5. Expression analysis by in situ and Northern blot hybridization indicated maternal transmission of the transcript as well as zygotic expression in many larval, pupal and adult tissues. Targeted repression by RNA interference did not alter early embryogenesis but resulted in a complete defect in the unfolding and expansion of the wings of freshly eclosed mutant flies, without other detectable effects on development.

The serpin superfamily of serine protease inhibitors is implicated in the regulation of numerous physiological processes. In mice, Spi3/Serpinb6 has a broad tissue distribution. We have investigated the expression of Serpinb6 family members in embryonic and adult gonads. In male and female mice, Spi3/Serpinb6 and NK13/Serpinb6b were expressed in developing gonads and in both somatic and germ cells of adult gonads. By contrast, gonadal expression of Spi3C/Serpinb6c was sexually dimorphic and restricted to male germ cells and female somatic cells. These observations raise the question of the possible role(s) of the Serpinb6 family members in gonad development, gametogenesis, and/or fertilization.

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