OVEREXPRESSED MITOCHONDRIAL HINGE PROTEIN, A CYTOCHROME C-BINDING PROTEIN, ACCELERATES APOPTOSIS BY ENHANCING THE RELEASE OF CYTOCHROME-C FROM MITOCHONDRIA
M. Okazaki et al., OVEREXPRESSED MITOCHONDRIAL HINGE PROTEIN, A CYTOCHROME C-BINDING PROTEIN, ACCELERATES APOPTOSIS BY ENHANCING THE RELEASE OF CYTOCHROME-C FROM MITOCHONDRIA, Biochemical and biophysical research communications, 243(1), 1998, pp. 131-136
Holocytochrome c released from mitochondria has been revealed to be on
e of the contributors of apoptosis. To investigate how the cytochrome
c protein is released from mitochondria, we examined the effects of ov
erexpression of the hinge protein, a cytochrome c-binding protein, or
cytochrome c on apoptosis by introducing their cDNAs under a constitut
ive promoter. Overexpression of the cytochrome c and hinge protein mRN
As was confirmed by Northern blotting, although marked accumulation of
the cytochrome c protein was not observed. In transfectants of the hi
nge protein gene as well as cytochrome c gene, apoptosis was accelerat
ed as judged by FITC-conjugated Annexin V binding to the cell surface
and DNA fragmentation. In addition, enhancement of the release of cyto
chrome c into cytosol was demonstrated in these transfectants by a sub
cellular fractionation experiment, followed by Western blotting. These
findings suggest that the release of the cytochrome c protein from mi
tochondria is regulated by the hinge protein involved in the respirato
ry chain in the apoptotic process. (C) 1998 Academic Press.