The riddle of mitochondrial caspase-3 from liver.
Caspase-3 is one of the main executors of apoptosis. Its zymogen procaspase-3 was localized to cytosol, mitochondria and nuclei. The subcellular location of procaspase-3 in liver was reported by several studies to be either cytosolic or cytosolic and mitochondrial. Our aim was to investigate these separate procaspase-3 pools to differentiate the pathways of their activation. By cell fractionation, immunocytochemistry, and confocal microscopy we report that there is a single procaspase-3 pool located to the cytosol in primary hepatocytes and in fractions of rat liver. In contrast, it depends on the isolation purity whether procaspase-3 is located in mitochondria of non-parenchymal liver cells, or not. All preparations with mitochondrial procaspase-3 fractions contain traces of haemoglobin, indicating the presence of some erythrocytes, which are the source of mitochondrial procaspase-3. Since erythrocytes migrate with mitochondria in subcellular fractionations, it is important to check for haemoglobin, before localizing the protein to mitochondria.
Milisav
Irina
I
Institute of Pathophysiology, University of Ljubljana, Zaloska, Slovenia. irina.milisav@mf.uni-lj.si
Nipic
Damijan
D
Suput
Dusan
D
D000818:Animals; D053148:Caspase 3 / Q000378:metabolism*; D002458:Cell Fractionation; D003600:Cytosol / Q000201:enzymology; D004912:Erythrocytes / Q000166:cytology / Q000201:enzymology / Q000648:ultrastructure; D006454:Hemoglobins / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000201:enzymology / Q000648:ultrastructure; D008099:Liver / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar
D006454:Hemoglobins; D053148:Caspase 3