Human cytochrome c enters murine J774 cells and causes G1 and G2/M cell cycle arrest and induction of apoptosis.
Cytochrome c is well known as a carrier of electrons during respiration. Current evidence indicates that cytochrome c also functions as a major component of apoptosomes to induce apoptosis in eukaryotic cells as well as an antioxidant. More recently, a prokaryotic cytochrome c, cytochrome c(551) from Pseudomonas aeruginosa, has been shown to enter in mammalian cells such as the murine macrophage-like J774 cells and causes inhibition of cell cycle progression. Much less is known about such functions by mammalian cytochromes c, particularly the human cytochrome c. We now report that similar to P. aeruginosa cytochrome c(551), the purified human cytochrome c protein can enter J774 cells and induce cell cycle arrest at the G(1) to S phase, as well as at the G(2)/M phase at higher concentrations. Unlike P. aeruginosa cytochrome c(551) which had no effect on the induction of apoptosis, human cytochrome c induces significant apoptosis and cell death in J774 cells, presumably through inhibition of the cell cycle at the G(2)/M phase. When incubated with human breast cancer MCF-7 and normal mammary epithelial cell line MCF-10A1 cells, human cytochrome c entered in both types of cells but induced cell death only in the normal MCF-10A1 cells. The ability of human cytochrome c to enter J774 cells was greatly reduced at 4 degrees C, suggesting energy requirement in the entry process.
Hiraoka
Yoshinori
Y
Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL, USA.
Granja
Ana Teresa
AT
Fialho
Arsenio M
AM
Schlarb-Ridley
Beatrix G
BG
Das Gupta
Tapas K
TK
Chakrabarty
Ananda M
AM
Yamada
Tohru
T
D017209:Apoptosis; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000493:pharmacokinetics*; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology*; D016193:G1 Phase; D016195:G2 Phase; D006801:Humans
D045304:Cytochromes c