title: Bcl-2 sensitive mitochondrial potassium accumulation and swelling in apoptosis.
abstract: During etoposide-induced apoptosis in HL-60 cells, cytochrome c release was associated with mitochondrial swelling caused by increased mitochondrial potassium uptake. The mitochondrial permeability transition was also observed; however, it was not the primary cause of mitochondrial swelling. Potassium uptake and swelling of mitochondria were blocked by bcl-2 overexpression. As a result, cytochrome c release was reduced, and apoptosis delayed. Residual cytochrome c release in the absence of swelling in bcl-2 expressing cells could be due to observed Bax translocation into mitochondria. This study suggests several novel aspects of apoptotic signaling: (1) potassium related swelling of mitochondria; (2) inhibition of mitochondrial potassium uptake by bcl-2; (3) co-existence within one system of multiple mechanisms of cytochrome c release: mitochondrial swelling and swelling-independent permeabilization of the outer mitochondrial membrane.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, NY, USA.
authors.forename: Roman A
authors.initials: RA
authors.lastname: Eliseev
authors.forename: Karlene K
authors.initials: KK
authors.lastname: Gunter
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Gunter