title: Heme deficiency causes apoptosis but does not increase ROS generation in HeLa cells.
abstract: Mitochondria provide cellular energy supply via respiration and are the major sites for the generation of reactive oxygen species (ROS). Mitochondria also play a fundamental role in apoptosis. Heme is a key factor in mitochondrial function. Defective heme synthesis or altered heme metabolism is associated with numerous diseases. Here we investigated the molecular mechanism by which heme promotes HeLa cell growth and survival. We found that heme deficiency-induced apoptosis involves the release of cytochrome c and the activation of caspase 3. However, heme deficiency-induced apoptosis appears to occur by a unique mechanism distinct from those known to mediate mitochondrial-dependent apoptosis. Specifically, our data show that heme deficiency causes apoptosis in a pathway that is independent of ROS generation and the collapse of mitochondrial membrane potential. These results provide insights into how defective heme synthesis or altered heme metabolism causes diseases and how heme may control cell growth and cell death.
authors.affiliation: Department of Environmental Health Sciences, Columbia University, Mailman School of Public Health, 60 Haven Avenue, B-1, New York, NY 10032, USA.
authors.forename: Weizhen
authors.initials: W
authors.lastname: Ye
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division; D002470:Cell Survival; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism*; D006418:Heme / Q000172:deficiency*; D006537:Heptanoates / Q000494:pharmacology; D006801:Humans; D020287:In Situ Nick-End Labeling; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D006537:Heptanoates; D017382:Reactive Oxygen Species; D006418:Heme; C020804:succinylacetone; D045304:Cytochromes c; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases