Short Communication Distinct Expression Pattern of Two Related Human Proteins Containing Multiple Types of Protease-Inhibitory Modules WAP-domains were first identified in w hey a cidic p ro- teins (Hennighausen and Sippel, 1982; Beg et al., 1986). Related domains are found in a variety of proteins (an- tileukoproteinases, epididymal and ovulatory specific proteins, elafins) possessing protease inhibitory activity (Heinzel et al., 1986; Seemuller et al., 1986; Stetler et al., 1986; Wiedow et al., 1990; Kirchoff et al., 1991; Garczyn- ski and Goetz, 1997). The WAP-domain of elafin is a po- tent and specific inhibitor of elastin-degrading serine pro- teinases (leukocyte elastase, proteinase-3), whereas the antileukoprotease SLPI (secretory leucocyte proteinase inhibitor) inhibits many serine proteinases with a broad spectrum of substrates (Schalkwijk et al., 1999). The first WAP domain of SLPI is a trypsin inhibitory domain, the second WAP-domain is an elastase inhibitory domain. The WAP-domain of chelonianin (basic protease inhibitor, isolated from egg white of Red Sea turtle) inhibits subtil- isin (Kato and Tominaga, 1979). Members of the follistatin/Kazal/ovomucoid superfam- ily are also frequently involved in the inhibition of proteas- es. Ovomucoids and ovoinhibitors of avian egg whites are multidomain Kazal-type inhibitors with each domain con- taining a functional or putative reactive site for a serine proteinase (Stein et al., 1980; Scott et al., 1987; Saxena and Tayyab, 1997). Multivalent protease inhibitors con- taining several Kazal-type serine proteinase inhibitor do- mains are also present in mammalian blood, the pro- teinase inhibitor LEKTI contains 15 Kazal-type domains (Magert et al., 1999). As a rule, Kunitz-domains of multidomain proteins also function as inhibitors of serine proteases. For example, the Kunitz-domain of the precursor of Alzheimer’s dis- ease amyloid protein shows protease inhibitory activity (Kitaguchi et al., 1988; Schilling et al., 1991). The multiva- lent tissue factor pathway inhibitor (TFPI) regulates tissue factor-induced coagulation by inhibiting activated factor X and the factor VIIa/tissue factor catalytic complex. In this process the first Kunitz-domain of TFPI is bound to the active site of VII(a)/tissue factor and the second Ku- nitz domain binds to the active site of factor Xa (Girard et al. 1989; Broze, 1995; Petersen et al., 1996). In the case of the hepatocyte growth factor activator inhibitor HAI-2, mutational analysis has shown that the first Kunitz domain of this multidomain protein is mainly responsible for inhibition of HGF activator (Qin et al., 1998). The NTR-module is a novel domain-type present in netrins, complement proteins C3, C4, C5, secreted friz- Biol. Chem., Vol. 383, pp. 223 – 228, January 2002 · Copyright © by Walter de Gruyter · Berlin · New York Mária Trexler, László Bányai and László Patthy* Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary * Corresponding author We have recently identified a gene (the WFIKKN gene) on human chromosome 16 (16p13.3) that encodes a secreted protein containing W AP-type, F ollistatin/ Kazal type, K unitz-type and N TR-type protease-in- hibitory modules and an I mmunoglobulin domain [Trexler et al., Proc. Natl. Acad. Sci. USA 98 (2001), 3705 – 3709]. In the present work we show that a gene on chromosome 17 encodes a WFIKKN-related pro- tein (WFIKKNRP) that has the same domain organiza- tion as the WFIKKN protein. The exon-intron struc- ture of the two genes is also similar as both genes have a single phase 0 intron that splits their WAP do- mains in equivalent positions. In view of the presence of several protease inhibitory modules in these pro- teins it seems likely that they serve to control the ac- tion of multiple types of proteases. The tissue expres- sion pattern of the two proteins, however, is markedly different suggesting that they have distinct biological roles. Whereas the WFIKKN gene is expressed prima- rily in adult pancreas, liver and thymus but not in brain and ovary, significant expression of the WFIKKNRP gene is observed in ovary, testis and brain, but not in liver. Pronounced differences could also be seen in the case of fetal tissues: expression of the WFIKKN gene was highest in the lung, skeletal muscle and liv- er, whereas the WFIKKNRP gene was expressed pri- marily in brain, skeletal muscle, thymus and kidney. Key words: Expression pattern / Protease inhibitors / Serine proteinases / Tissue specificity / Zn-metalloproteinases. In our previous work (Trexler et al., 2001) we have de- scribed a novel secreted human protein (the WFIKKN protein) that consists of a WAP-domain, a follistatin/ Kazal domain, an immunoglobulin domain, two Kunitz- domains and an NTR-domain. Brought to you by | Tokyo Daigaku Authenticated Download Date | 5/20/15 6:55 PM