We purified human plasma lysophospholipase D that produces physiologically active lysophosphatidic acid and showed that it is a soluble form of autotaxin, an ecto-nucleotide pyrophosphatase/phosphodiesterase, originally found as a tumor cell motility-stimulating factor. Its lower K m value for a lysophosphatidylcholine than that for a synthetic substrate of nucleotide suggests that lysophosphatidylcholine is a more likely physiological substrate for autotaxin and that its predicted physiological and pathophysiological functions could be mediated by its activity to produce lysophosphate acid, an intercellular mediator. Recombinant autotaxin was found to have lysophospholipase D activity; its substrate specificity and metal ion requirement were the same as those of the purified plasma enzyme. The activity of lysophospholipase D for exogenous lysophosphatidylcholine in human serum was found to increase in normal pregnant women at the third trimester of pregnancy and to a higher extent in patients in threatened preterm delivery, suggesting its roles in induction of parturition.Recent rapid advance in research on phospholipidic mediators has revealed new members that have diverse sets of signaling through their specific G-protein-coupled receptors (1-3). Particularly, lysophosphatidic acid (LPA, 1 radyl-sn-glycerol-3-phosphate) has received interest because of its identification as an active component in platelet-aggregating activity and vasoactivity in incubated animal sera and plasma (4). Later, its principle effects were found to be growth-related; that is, cellular proliferation, alterations in differentiation, and suppression of apoptosis (2-5). Other important effects are its cytoskeletal response, cell aggregation, contraction, adhesion, or chemotaxis (1-5). Its diverse activities appear to be regulated by the relative distribution of its specific receptors in a family of endothelial differentiation genes (EDG), desensitization of the receptors, and the local concentration of LPA determined by balance between LPA-producing and -degrading enzyme activities (1-6). Although LPA is produced intracellularly in phospholipid biosynthesis and turnover, this should be differentiated from its actual pool as a first messenger unless there are efficient mechanisms for its release into extracellular fluid or leaflets of plasma membranes (3-6). In this sense, secretory or ecto-type LPA-producing enzymes can supply LPA directly to its receptors. The first study on extracellular production of LPA was our own, detecting lysophospholipase D (lysoPLD) activity that produces bioactive LPA from lysophosphatidylcholine (LPC) in rat plasma (7). Its distinct substrate specificity and cation requirement from known intracellular lysoPLD activity suggested that it is a hitherto uncharacterized metalloenzyme (7-9). To understand its physiological and pathological significance, the identity of lysoPLD activity in blood circulation should be clarified. Therefore we purified and characterized lysoPLD in human plasma and obtained strong evid...

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As reported in our previous paper1}, a new antitumor antibiotic, named ankinomycin, was found in the culture broth of Streptomyces sp. OCT. 1989 SF2587. The antibiotic belongs to oxabenzanthraquinone antibiotics and has potent antitumor activity. In this paper, we describe the in vitro cytotoxicity and in vivo antitumor activity of ankinomycin against various type of tumors. Six murine tumor cell lines and nineteen human tumor cell lines were used for the in vitro cytotoxicity test. The cytotoxicity test was carried out as follows: Cells were seeded to 96-well flat-bottomed microtiter plate (Falcon, No. 3002) 3,000 cells/well in 140/zl

We present evidence supporting novel collaborations between the serine protease inhibitor (serpin) and the trefoil factor during the budding stage of the tunicate Polyandrocarpa misakiensis . Using a maltose-binding protein/P-serpin fusion protein, two polypeptides of 40 kDa and 45 kDa were pulled down from Polyandrocarpa homogenates. Based on their partial amino acid sequence data, a single cDNA (928 bp) was cloned. It encodes a polypeptide that has five tandem repeats of a trefoil consensus motif. Thus, we termed the cDNA P-trefoil . Both P-trefoil and P-serpin were expressed exclusively by coelomic cells during budding. P-Trefoil was expressed mainly by coelomic cells throughout the asexual life cycle of Polyandrocarpa , while P-Serpin was localized particularly in coelomic cells and in the extracellular matrix in developing buds. The native PTrefoil protein showed aminopeptidase activity. It induced cell growth in cultured Polyandrocarpa cells at a concentration of 8 µ g/mL. P-Serpin reinforced this activity of P-Trefoil. Further, a mixture of P-Trefoil and P-Serpin exhibited the in vitro induction of a gut-specific alkaline phosphatase. These results show for the first time that a serpin can interact with a trefoil factor to play a role in the cellular growth and differentiation of the gastric epithelium.