title: Role of MMP-2 in inhibiting Na+ dependent Ca2+ uptake by H2O2 in microsomes isolated from pulmonary smooth muscle.
abstract: Treatment of microsomes (preferentially enriched with endoplasmic reticulum) isolated from bovine pulmonary artery smooth muscle tissue with H2O2 (1 mM) markedly stimulated matrix metalloproteinase activity and also inhibited Na+ dependent Ca2+ uptake. Electron micrograph revealed that H2O2 (1 mM) does not cause any damage to the microsomes. MMP-2 and TIMP-2 were determined to be the ambient protease and corresponding antiprotease of the microsomes. Pretreatment with vitamin E (1 mM) and TIMP-2 (50 microg/ml) reversed the effect produced by H2O2 (1 mM) on Na+ dependent Ca2+ uptake in the microsomes. However, H2O2 (1 mM) caused changes in MMP-2 activity and Na+ dependent Ca2+ uptake were not reversed upon pretreatment of the microsomes with a low concentration of 5 microg/ml of TIMP-2 which otherwise reversed MMP-2 (1 microg/ml) mediated increase in 14C-gelatin degradation and inhibition of Na+ dependent Ca2+ uptake. Combined treatment of the microsomes with a low dose of MMP-2 (0.5 microg/ml) and H2O2 (0.5 mM) inhibited Na+ dependent Ca2+ uptake in the microsomes compared to the respective low dose of either of them. Direct treatment of TIMP-2 (5 microg/ml) with H2O2 (1 mM) abolished the inhibitory effect of the inhibitor on 14C-gelatinolytic activity elicited by 1 microg/ml of MMP-2. Thus, one of the mechanisms by which H2O2 activates MMP-2 could be due to inactivation of TIMP-2 by the oxidant. The resulting activation of MMP-2 subsequently inhibits Na+ dependent Ca2+ uptake in the microsomes.
authors.affiliation: Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal, India.
authors.forename: Amritlal
authors.initials: A
authors.lastname: Mandal
authors.forename: Tapati
authors.initials: T
authors.lastname: Chakraborti
authors.forename: Rajdeep
authors.initials: R
authors.lastname: Choudhury
authors.forename: Biswarup
authors.initials: B
authors.lastname: Ghosh
authors.forename: Amar Nath
authors.initials: AN
authors.lastname: Ghosh
authors.forename: Sudip
authors.initials: S
authors.lastname: Das
authors.forename: Sajal
authors.initials: S
authors.lastname: Chakraborti
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D005780:Gelatin / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008168:Lung / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism / Q000502:physiology*; D008854:Microscopy, Electron; D008861:Microsomes / Q000201:enzymology* / Q000378:metabolism; D009130:Muscle, Smooth / Q000201:enzymology* / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D011651:Pulmonary Artery / Q000201:enzymology* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D013997:Time Factors; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism / Q000494:pharmacology; D014810:Vitamin E / Q000378:metabolism / Q000494:pharmacology
chemical_list: D016877:Oxidants; D019716:Tissue Inhibitor of Metalloproteinase-2; D014810:Vitamin E; D005780:Gelatin; D012964:Sodium; D006861:Hydrogen Peroxide; D020778:Matrix Metalloproteinase 2; D002118:Calcium