tailieunhanh - Báo cáo Y học: Identification of ectopic anionic trypsin I in rat lungs potentiating pneumotropic virus infectivity and increased enzyme level after virus infection

Extracellular cleavage of virus envelope fusionglycoproteins by host cellular proteases is a prerequisite for the infectivity of mammalian and nonpathogenic avian influenza viruses, and Sendai virus. In search of such target processing pro-teases in the airway, we recently found a new candidate trypsin-like processing protease in rat lungs, which was induced by Sendai virus infection, and identified as ectopic rat anionic trypsin I. | Eur. J. Biochem. 269 2613-2621 2002 FEBS 2002 doi Identification of ectopic anionic trypsin I in rat lungs potentiating pneumotropic virus infectivity and increased enzyme level after virus infection Takae Towatari Mikiko Ide Kumiko Ohba Yuusuke Chiba Meiko Murakami Mayumi Shiota Miki Kawachi Hiroshi Yamada and Hiroshi Kido Division of Enzyme Chemistry Institute for Enzyme Research University of Tokushima Japan Extracellular cleavage of virus envelope fusion glycoproteins by host cellular proteases is a prerequisite for the infectivity of mammalian and nonpathogenic avian influenza viruses and Sendai virus. In search of such target processing proteases in the airway we recently found a new candidate trypsin-like processing protease in rat lungs which was induced by Sendai virus infection and identified as ectopic rat anionic trypsin I. On SDS PAGE under reducing and nonreducing conditions the purified enzyme gave protein bands corresponding to 29 and 22 kDa respectively . at the same positions as rat pancreatic anionic trypsin I. It exhibited an apparent molecular mass of 31 kDa on molecular sieve chromatography and its isoelectric point was pH . The amino-acid sequences of the N-terminus and proteolytic digest peptides of the purified enzyme were consistent with those of rat pancreatic anionic trypsin I. Its substrate specificities and inhibitor sensitivities were the same as those of the pancreatic enzyme. The purified enzyme efficiently processed the fusion glycoprotein precursor of Sendai virus and hemagglutinin of human influenza A virus and potentiated the infectivity of Sendai virus in the same dose-dependent manner as the pancreatic one. Immunohistochemical studies revealed that this protease is located in the stromal cells in peri-bronchiolar regions. These results suggest that ectopic anionic trypsin I in rat lungs induced by virus infection may trigger virus spread in rat lungs. Keywords anionic trypsin I processing