Mitochondrial apoptosis is amplified through gap junctions.
The death of one cell can precipitate the death of nearby cells in a process referred to as the bystander effect. We investigated whether mitochondrial apoptosis generated a bystander effect and, if so, by which pathway. Microinjection with cytochrome c mimicked function of the mitochondrial apoptosis-induced channel MAC and caused apoptosis of both target and nearby osteoblasts. This effect was suppressed by inhibiting gap junction intercellular communication. A bystander effect was also observed after exogenous expression of tBid, which facilitates MAC formation and cytochrome c release. Interestingly, in connexin-43 deficient osteoblasts, microinjection of cytochrome c induced apoptosis only in the target cell. These findings indicate that a death signal was generated downstream of MAC function and was transmitted through gap junctions to amplify apoptosis in neighboring cells. This concept may have implications in development of new therapeutic approaches.
Peixoto
Pablo M
PM
Dept Basic Sciences, New York University College of Dentistry, New York, NY 10010, USA.
Ryu
Shin-Young
SY
Pruzansky
Dawn Pietkiewicz
DP
Kuriakose
Maria
M
Gilmore
Andrew
A
Kinnally
Kathleen W
KW
D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein / Q000096:biosynthesis; D024201:Bystander Effect; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000494:pharmacology; D017629:Gap Junctions / Q000502:physiology*; D006801:Humans; D008845:Microinjections; D008928:Mitochondria / Q000502:physiology*; D010006:Osteoblasts / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure
D051023:BH3 Interacting Domain Death Agonist Protein; D045304:Cytochromes c