title: Ultradonut topology of the nuclear envelope.
abstract: The nuclear envelope is a unique topological structure formed by lipid membranes in eukaryotic cells. Unlike other membrane structures, the nuclear envelope comprises two concentric membrane shells fused at numerous sites with toroid-shaped pores that impart a "geometric" genus on the order of thousands. Despite the intriguing architecture and vital biological functions of the nuclear membranes, how they achieve and maintain such a unique arrangement remains unknown. Here, we used the theory of elasticity and differential geometry to analyze the equilibrium shape and stability of this structure. Our results show that modest in- and out-of-plane stresses present in the membranes not only can define the pore geometry, but also provide a mechanism for destabilizing membranes beyond a critical size and set the stage for the formation of new pores. Our results suggest a mechanism wherein nanoscale buckling instabilities can define the global topology of a nuclear envelope-like structure.
authors.affiliation: Department of Mechanical Engineering, University of Houston, Houston, TX 77204.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Torbati
authors.affiliation: Department of Chemical Engineering, University of Florida, Gainesville, FL 32611.
authors.forename: Tanmay P
authors.initials: TP
authors.lastname: Lele
authors.affiliation: Department of Mechanical Engineering, University of Houston, Houston, TX 77204; ashutosh@uh.edu.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Agrawal
mesh_terms: D002467:Cell Nucleus / Q000737:chemistry / Q000648:ultrastructure; D004548:Elasticity; D008051:Lipid Bilayers / Q000737:chemistry*; D008962:Models, Theoretical; D009685:Nuclear Envelope / Q000737:chemistry* / Q000648:ultrastructure; D022022:Nuclear Pore / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D008051:Lipid Bilayers
keywords: buckling instability; lipid membranes; nuclear envelope; topology