Kunitz-type trypsin inhibitor prevents LPS-induced increase of cytosolic free Ca2+ in human neutrophils and HUVEC cells.
The protease inhibitor part of inter-alpha trypsin inhibitor is identical to urinary trypsin inhibitor (UTI). Preincubation of neutrophils and HUVEC cells with UTI inhibited increase of cytosolic free Ca2+ induced by LPS. Increase of cytosolic free Ca2+ induced by LPS in the presence of EGTA was also inhibited by UTI. In contrast, UTI did not inhibit increase of cytosolic free Ca2+ in cells stimulated by Ca2+ ionophore with or without EGTA. The effects of nine synthetic peptides of UTI on the concentration of cytosolic free Ca2+ in the neutrophils induced by LPS were examined. Preincubation with a peptide of UTI domain 2, NLPIVRGPCRAFIQL (83-97), was completely inhibited by the increase of cytosolic free Ca2+ in neutrophils. This region is identical to the trypsin inhibitor site of UTI. We propose that a function of UTI other than as a protease inhibitor is in regulation of intracellular Ca2+ and that this is due to its trypsin inhibitor region.
Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Japan.
N
N
Kanayama
A
A
Halim
K
K
Maehara
Y
Y
Kajiwara
M
M
Fujie
T
T
Terao
D000595:Amino Acid Sequence; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D006023:Glycoproteins / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry; D017433:Protein Structure, Secondary; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000737:chemistry / Q000494:pharmacology*; D014361:Trypsin Inhibitors / Q000494:pharmacology; D014471:Umbilical Veins
D006023:Glycoproteins; D008070:Lipopolysaccharides; D010455:Peptides; D014361:Trypsin Inhibitors; D000001:Calcimycin; D004533:Egtazic Acid; D014360:Trypsin Inhibitor, Kunitz Soybean; C028665:urinastatin; D002118:Calcium