Phospholipid scramblase 3 controls mitochondrial structure, function, and apoptotic response.
Phospholipid scramblase 3 (PLS3) is a newly recognized member of a family of proteins responsible for phospholipid translocation between two lipid compartments. To study PLS3 function in mitochondria, we disrupted its conserved calcium-binding motif yielding an inactive mutant PLS3(F258V). Cells transfected with PLS3(F258V) exhibited reduced proliferative capacity. Mitochondrial analysis revealed that PLS3(F258V)-expressing cells have decreased mitochondrial mass shown by lower cytochrome c and cardiolipin (CL) content, poor mitochondrial respiration, and reduced oxygen consumption and intracellular ATP; whereas wild-type PLS3-transfected cells exhibit increased mitochondrial mass and enhanced respiration. Electron microscopic examination revealed that the mitochondria in PLS3(F258V)-expressing cells have densely packed cristae and are fewer in number and larger than those in control cells. The abnormal mitochondrial metabolism and structure in PLS3(F258V)-expressing cells were associated with decreased sensitivity to UV- and tBid-induced apoptosis and diminished translocation of CL to the mitochondrial outer membrane. In contrast, wild-type PLS3-transfected cells displayed increased sensitivity to apoptosis and enhanced CL translocation. These studies identify PLS3 as a critical regulator of mitochondrial structure and respiration, and CL transport in apoptosis.
Liu
Jihua
J
Huntsman Cancer Institute,, University of Utah, Salt Lake City, UT 84112, USA.
Dai
Qiang
Q
Chen
Jun
J
Durrant
David
D
Freeman
Angela
A
Liu
Tong
T
Grossman
Douglas
D
Lee
Ray M
RM
D017209:Apoptosis / Q000502:physiology*; D002308:Cardiolipins / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008854:Microscopy, Electron; D008928:Mitochondria / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D009154:Mutation; D049294:Phospholipid Transfer Proteins; D016133:Polymerase Chain Reaction; D013997:Time Factors; D015854:Up-Regulation
D002308:Cardiolipins; D002352:Carrier Proteins; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins; D045304:Cytochromes c