title: Mammalian phospholipid homeostasis: evidence that membrane curvature elastic stress drives homeoviscous adaptation in vivo.
abstract: Several theories of phospholipid homeostasis have postulated that cells regulate the molecular composition of their bilayer membranes, such that a common biophysical membrane parameter is under homeostatic control. Two commonly cited theories are the intrinsic curvature hypothesis, which states that cells control membrane curvature elastic stress, and the theory of homeoviscous adaptation, which postulates cells control acyl chain packing order (membrane order). In this paper, we present evidence from data-driven modelling studies that these two theories correlate in vivo. We estimate the curvature elastic stress of mammalian cells to be 4-7 × 10(-12) N, a value high enough to suggest that in mammalian cells the preservation of membrane order arises through a mechanism where membrane curvature elastic stress is controlled. These results emerge from analysing the molecular contribution of individual phospholipids to both membrane order and curvature elastic stress in nearly 500 cellular compositionally diverse lipidomes. Our model suggests that the de novo synthesis of lipids is the dominant mechanism by which cells control curvature elastic stress and hence membrane order in vivo These results also suggest that cells can increase membrane curvature elastic stress disproportionately to membrane order by incorporating polyunsaturated fatty acids into lipids.
authors.affiliation: Division of Chemistry, School of Pharmacy and Biological Sciences, University of Brighton, Brighton BN2 4GL, UK m.dymond@brighton.ac.uk.
authors.forename: Marcus K
authors.identifier: 0000-0002-9903-4993
authors.initials: MK
authors.lastname: Dymond
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D004548:Elasticity; D018922:HL-60 Cells; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D010743:Phospholipids / Q000096:biosynthesis*; D013312:Stress, Physiological
chemical_list: D010743:Phospholipids
keywords: data-driven modelling; homeoviscous adaptation; intrinsic curvature hypothesis; lipid spontaneous curvature; membrane curvature elastic stress; membrane order