title: Keratinocyte-specific mesotrypsin contributes to the desquamation process via kallikrein activation and LEKTI degradation.
abstract: Kallikrein-related peptidases (KLKs) have critical roles in corneocyte desquamation and are regulated by lymphoepithelial Kazal-type inhibitor (LEKTI). However, it is unclear how these proteases are activated and how activated KLKs are released from LEKTI in the upper cornified layer. Recently, we reported cloning of a PRSS3 gene product, keratinocyte-specific mesotrypsin, from a cDNA library. We hypothesized that mesotrypsin is involved in the desquamation process, and the aim of the present study was to test this idea by examining the effects of mesotrypsin on representative desquamation-related enzymes pro-KLK5 and pro-KLK7. Incubation of mesotrypsin and these zymogens resulted in generation of the active forms. KLK activities were effectively inhibited by recombinant LEKTI domains D2, D2-5, D2-6, D2-7, D5, D6, D6-9, D7, D7-9, and D10-15, whereas mesotrypsin activity was not susceptible to these domains, and in fact degraded them. Immunoelectron microscopy demonstrated that mesotrypsin was localized in the cytoplasm of granular cells and intercellular spaces of the cornified layer. Proximity ligation assay showed close association between mesotrypsin and KLKs in the granular to cornified layers. Age-dependency analysis revealed that mesotrypsin was markedly downregulated in corneocyte extract from donors in their sixties, compared with younger donors. Collectively, our findings suggest that mesotrypsin contributes to the desquamation process by activating KLKs and degrading the intrinsic KLKs' inhibitor LEKTI.
authors.affiliation: Shiseido Research Center, Kanazawa-ku, Yokohama, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyai
authors.affiliation: Shiseido Research Center, Kanazawa-ku, Yokohama, Japan.
authors.forename: Yuuko
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Shiseido Research Center, Kanazawa-ku, Yokohama, Japan.
authors.forename: Haruyo
authors.initials: H
authors.lastname: Yamanishi
authors.affiliation: Shiseido Research Center, Kanazawa-ku, Yokohama, Japan; Department of Dermatology, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan.
authors.forename: Mami
authors.initials: M
authors.lastname: Yamamoto-Tanaka
authors.affiliation: Department of Dermatology, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan.
authors.forename: Ryoji
authors.initials: R
authors.lastname: Tsuboi
authors.affiliation: Shiseido Research Center, Kanazawa-ku, Yokohama, Japan. Electronic address: toshihiko.hibino1@to.shiseido.co.jp.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Hibino
mesh_terms: D000906:Antibodies / Q000737:chemistry; D001665:Binding Sites; D018076:DNA, Complementary / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism; D015723:Gene Library; D006801:Humans; D007610:Kallikreins / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology*; D017434:Protein Structure, Tertiary; D053491:Proteinase Inhibitory Proteins, Secretory / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D000074163:Serine Peptidase Inhibitor Kazal-Type 5; D014357:Trypsin / Q000378:metabolism*
chemical_list: D000906:Antibodies; D018076:DNA, Complementary; D053491:Proteinase Inhibitory Proteins, Secretory; D011994:Recombinant Proteins; C120650:SPINK5 protein, human; D000074163:Serine Peptidase Inhibitor Kazal-Type 5; C400147:KLK5 protein, human; C082472:KLK7 protein, human; D007610:Kallikreins; C040749:PRSS3 protein, human; D014357:Trypsin