The Ca2+ threshold for the mitochondrial permeability transition and the content of proteins related to Bcl-2 in rat liver and Zajdela hepatoma mitochondria.
Zajdela hepatoma mitochondria were able to accumulate two to five times more Ca2+ than rat liver mitochondria before the permeability transition was induced. Pulses of Ca2+ were given in series to determine the Ca2+ threshold by recording changes in [Ca2+] and membrane potential, the permeability transition causing the release of accumulated Ca2+ and collapse of the membrane potential. Hepatoma mitochondria had lower Ca2+ efflux rates, higher net Ca2+ uptake rates and lower phosphorylation rates than liver mitochondria. Since the differences in regard to induction of the permeability transition might be due to higher expression of the Bcl-2 protein in hepatoma cells than in hepatocytes, the transcription of Bcl-2 and the proteins reacting with a Bcl-2 polyclonal antiserum were estimated by Northern and Western blotting, respectively. Hepatoma cells had two Bcl-2 specific mRNA bands of 7 and 2.4 kb, and substantial amounts of the Bcl-2 protein, whereas in liver cells and mitochondria these were not detected. Both cell lines had a reactive band at 19-20 kDa, and hepatocytes a small band at 31-32 kDa. Bcl-2 antibodies stimulated the permeability transition potently in hepatoma mitochondria.
Evtodienko
Y V
YV
Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino.
Teplova
V V
VV
Azarashvily
T S
TS
Kudin
A
A
Prusakova
O
O
Virtanen
I
I
Saris
N E
NE
D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D017931:DNA Primers; D008114:Liver Neoplasms, Experimental / Q000378:metabolism* / Q000648:ultrastructure; D008928:Mitochondria / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats
D017931:DNA Primers; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D002118:Calcium