Membrane lipid peroxidation and its conflict of interest: the two faces of oxidative stress

Membranes are the most vital structure for all organisms which not only control molecular trafficking but also perceive environmental cues and transduce it in response. Membrane lipid peroxidation, which is normally associated with natural course of ageing, senescence and environmental stresses, is mechanistically important as it is one of the very few examples of carbon-centered radical production in cell. Chemically, it involves the formation and propagation of lipid radicals, the uptake of molecular oxygen and arrangement of double bonds in the unsaturated lipids and eventually their destruction, with subsequent production of a variety of breakdown products, including alcohol, ketones, alkanes, aldehydes and ethers. The process is considered as the main event involved in oxidative damage to cell, which may eventually Cause cell death. A significant proportion of oxidized lipids are electrophilic in nature. Recent studies suggest that reactive lipid species formed through lipid peroxidation can benefit cells in a number of ways. There are strong evidences in support of the view that reactive lipid species-mediated signalling participates in several physiological pathways including apoptosis, induction of antioxidative defence, membrane repair, proteosomal pathway, etc. The activation of cell signalling pathways by reactive lipid species is hierarchical and largely depends on intrinsic chemical reactivity of electrophiles, thiol-containing signalling domains and the subsequent signalling cascades. An effort has been made to provide an update on membrane lipid peroxidation while addressing the conflicting roles of membrane lipid peroxidation in deteriorative oxidative damage and adaptive cell signalling.