title: Cytosol-dependent membrane fusion in ER, nuclear envelope and nuclear pore assembly: biological implications.
abstract: Endoplasmic reticulum and nuclear envelope rearrangements after mitosis are often studied in the reconstitution system based on Xenopus egg extract. In our recent work we partially replaced the membrane vesicles in the reconstitution mix with protein-free liposomes to explore the relative contributions of cytosolic and transmembrane proteins. Here we discuss our finding that cytosolic proteins mediate fusion between membranes lacking functional transmembrane proteins and the role of membrane fusion in endoplasmic reticulum and nuclear envelope reorganization. Cytosol-dependent liposome fusion has allowed us to restore, without adding transmembrane nucleoporins, functionality of nuclear pores, their spatial distribution and chromatin decondensation in nuclei formed at insufficient amounts of membrane material and characterized by only partial decondensation of chromatin and lack of nuclear transport. Both the mechanisms and the biological implications of the discovered coupling between spatial distribution of nuclear pores, chromatin decondensation and nuclear transport are discussed.
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, USA.
authors.forename: Elvira R
authors.initials: ER
authors.lastname: Rafikova
authors.forename: Kamran
authors.initials: K
authors.lastname: Melikov
authors.forename: Leonid V
authors.initials: LV
authors.lastname: Chernomordik
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002843:Chromatin / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008561:Membrane Fusion; D008938:Mitosis; D009685:Nuclear Envelope / Q000378:metabolism*; D022022:Nuclear Pore / Q000378:metabolism; D010063:Ovum; D014982:Xenopus laevis
chemical_list: D002843:Chromatin; D008081:Liposomes