title: Role of matrix metalloprotease-2 in oxidant activation of Ca2+ ATPase by hydrogen peroxide in pulmonary vascular smooth muscle plasma membrane.
abstract: Exposure of bovine pulmonary artery smooth muscle plasma membrane suspension with the oxidant H2O2 (1 mM) stimulated Ca2+ATPase activity. We sought to determine the role of matrix metalloprotease-2 (MMP-2) in stimulating Ca2+ATPase activity by H2O2 in the smooth muscle plasma membrane. The smooth muscle membrane possesses a Ca2+-dependent protease activity in the gelatin containing zymogram having an apparent molecular mass of 72 kDa. The 72 kDa protease activity was found to be inhibited by EGTA, 1 : 10-phenanthroline, a2-macroglobulin and tissue inhibitor of metalloprotease-2 (TIMP-2) indicating that the Ca2+-dependent 72 kDa protease is the MMP-2. Western immunoblot studies of the membrane suspension with polyclonal antibodies of MMP-2 and TIMP-2 revealed that MMP-2 and TIMP-2, respectively, are the ambient matrix metalloprotease and the corresponding tissue inhibitor of metalloprotease in the membrane. In addition to increasing the Ca2+ATPase activity, H2O2 also enhanced the activity of the smooth muscle plasma membrane associated protease activity as evidenced by its ability to degrade 14C-gelatin. The protease activity and the Ca2+ATPase activity were prevented by the antioxidant, vitamin E, indicating that the effect produced by H2O2 was due to reactive oxidant species(es). Both basal and H2O2 stimulated MMP-2 activity and Ca2+ATPase activity were inhibited by the general inhibitors of matrix metalloproteases: EGTA, 1 : 10-phenanthroline, a2-macroglobulin and also by TIMP-2 (the specific inhibitor of MMP-2) indicating that H2O2 increased MMP-2 activity and that subsequently stimulated Ca2+ATPase activity in the plasma membrane. This was further confirmed by the following observations: (i) adding low doses of MMP-2 or H2O2 to the smooth muscle membrane suspension caused submaximal increase in Ca2+ATPase activity, and pretreatment with TIMP-2 prevents the increase in Ca2+ATPase activity; (ii) combined treatment of the membrane with low doses of MMP-2 and H2O2 augments further the Ca2+ATPase activity caused by the respective low doses of either H2O2 or MMP-2; and (iii) pretreatment with TIMP-2 prevents the increase in Ca2+ATPase activity in the membrane caused by the combined treatment of MMP-2 and H2O2.
authors.affiliation: Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741 235, India.
authors.forename: Malay
authors.initials: M
authors.lastname: Mandal
authors.forename: Sudip
authors.initials: S
authors.lastname: Das
authors.forename: Tapati
authors.initials: T
authors.lastname: Chakraborti
authors.forename: Amritlal
authors.initials: A
authors.lastname: Mandal
authors.forename: Sajal
authors.initials: S
authors.lastname: Chakraborti
mesh_terms: D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008168:Lung / Q000098:blood supply*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology
chemical_list: D006861:Hydrogen Peroxide; D020778:Matrix Metalloproteinase 2; D000252:Calcium-Transporting ATPases