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Matrix Metalloproteinase‐2‐Mediated Inhibition of Na + ‐Dependent Ca2 + Uptake by Superoxide Radicals (O2. ‐ ) in Microsomes of Pulmonary Smooth Muscle

Matrix Metalloproteinase‐2‐Mediated Inhibition of Na + ‐Dependent Ca2 + Uptake by Superoxide... Treatment of microsomes (preferably enriched with endoplasmic reticulum) isolated from bovine pulmonary artery smooth muscle tissue with the O2. ‐‐generating system (hypoxanthine (HPX) plus xanthine oxidase (XO)), markedly stimulated matrix metalloproteinase‐2 (MMP‐2) activity and also enhanced Ca2 + ATPase activity and ATP‐dependent Ca2 + uptake. Pretreatment with superoxide dismutase (SOD) and tissue inhibitor of metalloproteinase (TIMP‐2) (50 μg ml‐1), preserved the increase in MMP‐2 activity, Ca2 + ATPase activity and also ATP‐dependent Ca2 + uptake in the microsomes. In contrast, Na +‐dependent Ca2 + uptake in the microsomes was found to be inhibited by the O2. ‐‐generating system. Additionally, O2. ‐ ‐induced inhibition of Na + ‐dependent Ca2 + uptake was reversed by SOD and TIMP‐2 (50 μg ml‐1). Electron microscopy revealed that treatment with the O2. ‐‐generating system did not cause any noticeable damage to the microsomes. O2. ‐ ‐induced changes in MMP‐2 activity, ATP‐dependent Ca2 + uptake and Na +‐dependent Ca2 + uptake, were not reversed upon pretreatment of the microsomes with a low dose (5 μg ml‐1) of TIMP‐2 which, on the contrary, reversed MMP‐2 (1 μg ml‐1)‐mediated alteration on these parameters. The inhibition of Na +‐dependent Ca2 + uptake by O2. ‐ and MMP‐2, overpowered the stimulation of ATP‐dependent Ca2 + uptake in the microsomes. Treatment of TIMP‐2 (5 μg ml‐1) with the O2. ‐‐generating system abolished the inhibitory effect of TIMP‐2 (5 μg ml‐1) on MMP‐2 (1 μg ml‐1) (measured by 14C‐gelatin degradation). Overall, the present study suggests that O2. ‐ inactivated TIMP‐2, the ambient inhibitor of MMP‐2, leading to activation of the ambient proteinase, MMP‐2, which subsequently stimulated Ca2 + ATPase activity and ATP‐dependent Ca2 + uptake, but inhibited Na +‐dependent Ca2 + uptake, resulting in a marked decrease in Ca2 + uptake in the smooth muscle microsomes. IUBMB Life, 56: 267‐276, 2004 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png IUBMB Life Wiley

Matrix Metalloproteinase‐2‐Mediated Inhibition of Na + ‐Dependent Ca2 + Uptake by Superoxide Radicals (O2. ‐ ) in Microsomes of Pulmonary Smooth Muscle

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References (58)

Publisher
Wiley Subscription Services, Inc., A Wiley Company
Copyright
Copyright © 2004 International Union of Biochemistry and Molecular Biology
ISSN
1521-6543
eISSN
1521-6551
DOI
10.1080/1521654041000171335
pmid
15370890
Publisher site
See Article on Publisher Site

Abstract

Treatment of microsomes (preferably enriched with endoplasmic reticulum) isolated from bovine pulmonary artery smooth muscle tissue with the O2. ‐‐generating system (hypoxanthine (HPX) plus xanthine oxidase (XO)), markedly stimulated matrix metalloproteinase‐2 (MMP‐2) activity and also enhanced Ca2 + ATPase activity and ATP‐dependent Ca2 + uptake. Pretreatment with superoxide dismutase (SOD) and tissue inhibitor of metalloproteinase (TIMP‐2) (50 μg ml‐1), preserved the increase in MMP‐2 activity, Ca2 + ATPase activity and also ATP‐dependent Ca2 + uptake in the microsomes. In contrast, Na +‐dependent Ca2 + uptake in the microsomes was found to be inhibited by the O2. ‐‐generating system. Additionally, O2. ‐ ‐induced inhibition of Na + ‐dependent Ca2 + uptake was reversed by SOD and TIMP‐2 (50 μg ml‐1). Electron microscopy revealed that treatment with the O2. ‐‐generating system did not cause any noticeable damage to the microsomes. O2. ‐ ‐induced changes in MMP‐2 activity, ATP‐dependent Ca2 + uptake and Na +‐dependent Ca2 + uptake, were not reversed upon pretreatment of the microsomes with a low dose (5 μg ml‐1) of TIMP‐2 which, on the contrary, reversed MMP‐2 (1 μg ml‐1)‐mediated alteration on these parameters. The inhibition of Na +‐dependent Ca2 + uptake by O2. ‐ and MMP‐2, overpowered the stimulation of ATP‐dependent Ca2 + uptake in the microsomes. Treatment of TIMP‐2 (5 μg ml‐1) with the O2. ‐‐generating system abolished the inhibitory effect of TIMP‐2 (5 μg ml‐1) on MMP‐2 (1 μg ml‐1) (measured by 14C‐gelatin degradation). Overall, the present study suggests that O2. ‐ inactivated TIMP‐2, the ambient inhibitor of MMP‐2, leading to activation of the ambient proteinase, MMP‐2, which subsequently stimulated Ca2 + ATPase activity and ATP‐dependent Ca2 + uptake, but inhibited Na +‐dependent Ca2 + uptake, resulting in a marked decrease in Ca2 + uptake in the smooth muscle microsomes. IUBMB Life, 56: 267‐276, 2004

Journal

IUBMB Life – Wiley

Published: May 1, 2004

Keywords: Oxidant; superoxide radical; antioxidant; superoxide dismutase; matrix metalloproteinase‐2; tissue inhibitor of metalloproteinase‐2; microsomes

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