title: Cubic membranes: a structure-based design for DNA uptake.
abstract: Cubic membranes are soft three-dimensional crystals found within cell organelles in a variety of living systems, despite the aphorism of Fedorov: 'crystallization is death'. They consist of multi-bilayer lipid-protein stacks, folded onto anticlastic surfaces that resemble triply periodic minimal surfaces, forming highly swollen crystalline sponges. Although cubic membranes have been observed in numerous cell types and under different pathophysiological conditions, knowledge about the formation and potential function(s) of non-lamellar, cubic structures in biological systems is scarce. We report that mitochondria with this cubic membrane organization isolated from starved amoeba Chaos carolinense interact sufficiently with short segments of phosphorothioate oligonucleotides (PS-ODNs) to give significant ODNs uptake. ODNs condensed within the convoluted channels of cubic membrane by an unknown passive targeting mechanism. Moreover, the interaction between ODNs and cubic membrane is sufficient to retard electrophoretic mobility of the ODN component in the gel matrix. These ODN-cubic membrane complexes are readily internalized within the cytoplasm of cultured mammalian cells. Transmission electron microscopic analysis confirms ODNs uptake by cubic membranes and internalization of ODN-cubic membrane complexes into the culture cells. Cubic membranes thus may offer a new, potentially benign medium for gene transfection.
authors.affiliation: Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117597, Republic of Singapore.
authors.forename: Zakaria
authors.initials: Z
authors.lastname: Almsherqi
authors.forename: Stephen
authors.initials: S
authors.lastname: Hyde
authors.forename: Malarmathy
authors.initials: M
authors.lastname: Ramachandran
authors.forename: Yuru
authors.initials: Y
authors.lastname: Deng
mesh_terms: D000656:Amoeba / Q000737:chemistry*; D000818:Animals; D045744:Cell Line, Tumor; D004247:DNA / Q000008:administration & dosage / Q000737:chemistry*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D051336:Mitochondrial Membranes / Q000737:chemistry*; D054735:Phosphorothioate Oligonucleotides / Q000008:administration & dosage / Q000737:chemistry*; D014162:Transfection
chemical_list: D054735:Phosphorothioate Oligonucleotides; D004247:DNA