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Matrix Metalloproteinase‐2‐Mediated Inhibition of Na + ‐Dependent Ca2 + Uptake by Superoxide Radicals (O2. ‐ ) in Microsomes of Pulmonary Smooth Muscle
Author(s) -
Mandal Amritlal,
Chakraborti Tapati,
Das Sudip,
Ghosh Biswarup,
Ghosh Amarnath,
Chakraborti Sajal
Publication year - 2004
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/1521654041000171335
Subject(s) - microsome , xanthine oxidase , chemistry , endoplasmic reticulum , superoxide dismutase , hypoxanthine , superoxide , biochemistry , oxidase test , enzyme
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