title: Intracellular localization of protein C inhibitor (PCI) and urinary  plasminogen activator in renal tubular epithelial cells from  humans and human PCI gene transgenic mice.
abstract: Urinary plasminogen activator (uPA) is a serine protease that plays important roles in various extracellular proteolytic processes. In humans, protein C inhibitor (PCI) is known to regulate the activity of the serine proteases involved in blood coagulation, wound healing, and tumor metastasis, whereas PCI is not present in murine plasma or tissues other than the reproductive tissues. The large amount of uPA-PCI complexes found in human urine suggests that these complexes are formed in the kidneys. In the present study, we performed immunofluorescence double labeling and electron microscopic immunocytochemistry using renal tissues from humans and human PCI gene transgenic (PCI-TG) mice. In human renal tissues, PCI and uPA colocalized in the cytoplasm of renal proximal tubular epithelial cells (RPTECs), and juxtaposition of PCI and uPA immunoreactive particles was detected in the microvilli and lysosomes in the RPTECs. The intracellular distributions of PCI and uPA in the RPTECs from PCI-TG mice were similar to those observed in human RPTECs. These findings hint at the physiological roles of uPA and PCI in human kidneys, and also suggest that the PCI-TG mice will be useful for evaluating the roles of PCI in human physiological and pathological conditions.
authors.affiliation: Department of Molecular Pathobiology, Mie University Graduate School of Medicine, Tsu-city, Mie 514-8507, Japan.
authors.forename: Zhenhu
authors.initials: Z
authors.lastname: Song
authors.forename: Ning
authors.initials: N
authors.lastname: Ma
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Esteban C
authors.initials: EC
authors.lastname: Gabazza
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Sugimura
authors.forename: Koji
authors.initials: K
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D008822:Mice, Transgenic; D016253:Microscopy, Immunoelectron; D018046:Protein C Inhibitor / Q000235:genetics / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
chemical_list: D018046:Protein C Inhibitor; D014568:Urokinase-Type Plasminogen Activator