Antioxidant Function of the Mitochondrial Protein SP-22 in the Cardiovascular System

These findings indicate that SP-22 functions as an antioxidant in mitochondria of the cardiovascular system

Masaru Araki; Hiroki Nanri; Kuniaki Ejima; Yoshinobu Murasato; Toshiyuki Fujiwara; Yasuhide Nakashima; Masaharu Ikeda


Scholarcy highlights

  • Mitochondria play an important role in aerobic energy metabolism of living cells
  • To test the hypothesis that SP-22 functions as an antioxidant system in mitochondria, which are the major site of cellular reactive oxygen intermediates generation, we investigated the oxidant-induced expression of SP-22 using cultured bovine aortic endothelial cells and an in vivo model of experimental myocardial infarction
  • When cultured KB cells were stained with the anti-SP-22 antibody, the signals of immunoreactive SP-22 exhibited the mitochondrial staining pattern characterized by a reticular staining appearance
  • These results indicate that SP-22 protein is located in mitochondria of culture cells, which is consistent with the results of the biochemical analysis by Watabe et al
  • The mitochondrial electron transport system consumes a great deal of oxygen and produces ROIs
  • ROI generation in submitochondrial particles treated with antimycin A and rotenone showed 40 –100% increase compared with untreated SMP
  • It is well known that respiratory chain inhibitors increase ROIs in mitochondria by blocking electron transport, and we confirmed that antimycin A and rotenone increased superoxide production in submitochondrial particles of BAEC
  • With the progression of ischemia, reactive oxygen intermediates such as superoxide, hydrogen peroxide, and hydroxyl radical are generated through several pathways, including the leakage of electrons from mitochondria, which are especially abundant in the heart , the metabolism of arachidonic acid released by activated phospholipases , and the increase in xanthine oxidase activity, which produces superoxide

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