TY - JOUR
T1 - Cardiolipin or MTCH2 can serve as tBID receptors during apoptosis
AU - Raemy, E.
AU - Montessuit, S.
AU - Pierredon, S.
AU - van Kampen, A.H.
AU - Vaz, F.M.
AU - Martinou, J.C.
N1 - With supplementary information
PY - 2016
Y1 - 2016
N2 - During apoptosis, proapoptotic BAX and BAK trigger mitochondrial outer membrane (MOM) permeabilization by a mechanism that is not yet fully understood. BH3-only proteins such as tBID, together with lipids of the MOM, are thought to play a key role in BAX and BAK activation. In particular, cardiolipin (CL) has been shown to stimulate tBID-induced BAX activation in vitro. However, it is still unclear whether this process also relies on CL in the cell, or whether it is more dependent on MTCH2, a proposed receptor for tBID present in the MOM. To address this issue, we deleted both alleles of cardiolipin synthase in human HCT116 cells by homologous recombination, which resulted in a complete absence of CL. The CL-deficient cells were fully viable in glucose but displayed impaired oxidative phosphorylation and an inability to grow in galactose. Using these cells, we found that CL was not required for either tBID-induced BAX activation, or for apoptosis in response to treatment with TRAIL. Downregulation of MTCH2 in HCT116 cells also failed to prevent recruitment of tBID to mitochondria in apoptotic conditions. However, when both CL and MTCH2 were depleted, a significant reduction in tBID recruitment was observed, suggesting that in HCT116 cells, CL and MTCH2 can have redundant functions in this process.
AB - During apoptosis, proapoptotic BAX and BAK trigger mitochondrial outer membrane (MOM) permeabilization by a mechanism that is not yet fully understood. BH3-only proteins such as tBID, together with lipids of the MOM, are thought to play a key role in BAX and BAK activation. In particular, cardiolipin (CL) has been shown to stimulate tBID-induced BAX activation in vitro. However, it is still unclear whether this process also relies on CL in the cell, or whether it is more dependent on MTCH2, a proposed receptor for tBID present in the MOM. To address this issue, we deleted both alleles of cardiolipin synthase in human HCT116 cells by homologous recombination, which resulted in a complete absence of CL. The CL-deficient cells were fully viable in glucose but displayed impaired oxidative phosphorylation and an inability to grow in galactose. Using these cells, we found that CL was not required for either tBID-induced BAX activation, or for apoptosis in response to treatment with TRAIL. Downregulation of MTCH2 in HCT116 cells also failed to prevent recruitment of tBID to mitochondria in apoptotic conditions. However, when both CL and MTCH2 were depleted, a significant reduction in tBID recruitment was observed, suggesting that in HCT116 cells, CL and MTCH2 can have redundant functions in this process.
UR - https://pure.uva.nl/ws/files/2716696/174969_Cardiolipin_or_MTCH2_can_serve_suppl._1.jpg
UR - https://pure.uva.nl/ws/files/2716698/174972_Cardiolipin_or_MTCH2_can_serve_suppl._2_1_.jpg
UR - https://pure.uva.nl/ws/files/2716700/174971_Cardiolipin_or_MTCH2_can_serve_suppl._3.pdf
U2 - https://doi.org/10.1038/cdd.2015.166
DO - https://doi.org/10.1038/cdd.2015.166
M3 - Article
C2 - 26794447
SN - 1350-9047
VL - 23
SP - 1165
EP - 1174
JO - Cell Death & Differentiation
JF - Cell Death & Differentiation
IS - 7
ER -