title: Vesicular PtdIns(3,4,5)P3 and Rab7 are key effectors of sea urchin zygote nuclear membrane fusion.
abstract: Regulation of nuclear envelope dynamics is an important example of the universal phenomena of membrane fusion. The signalling molecules involved in nuclear membrane fusion might also be conserved during the formation of both pronuclear and zygote nuclear envelopes in the fertilised egg. Here, we determine that class-I phosphoinositide 3-kinases (PI3Ks) are needed for in vitro nuclear envelope formation. We show that, in vivo, PtdIns(3,4,5)P3is transiently located in vesicles around the male pronucleus at the time of nuclear envelope formation, and around male and female pronuclei before membrane fusion. We illustrate that class-I PI3K activity is also necessary for fusion of the female and male pronuclear membranes. We demonstrate, using coincidence amplified Förster resonance energy transfer (FRET) monitored using fluorescence lifetime imaging microscopy (FLIM), a protein-lipid interaction of Rab7 GTPase and PtdIns(3,4,5)P3that occurs during pronuclear membrane fusion to create the zygote nuclear envelope. We present a working model, which includes several molecular steps in the pathways controlling fusion of nuclear envelope membranes.
authors.affiliation: Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biofísika Instituto (UPV/EHU, CSIC), University of the Basque Country, Areatza Hiribidea, 47, 48620 Plentzia, Spain.|Biofísika Instituto (UPV/EHU, CSIC) and Departamento de Bioquímica, University of the Basque Country, Barrio Sarriena s/n, Leioa 48940, Spain.|Cell Biophysics Laboratory, Research Centre for Experimental Marine Biology and Biotechnology (PiE), Biofisika Instituto (UPV/EHU,CSIC) and, University of the Basque Country, Leioa 48940, Spain.
authors.forename: Marta G
authors.initials: MG
authors.lastname: Lete
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London NW7 1AA, UK.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Byrne
authors.affiliation: Biofísika Instituto (UPV/EHU, CSIC) and Departamento de Bioquímica, University of the Basque Country, Barrio Sarriena s/n, Leioa 48940, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Alonso
authors.affiliation: Department of Biology, Amherst College, Amherst, MA 01002, USA.
authors.forename: Dominic
authors.initials: D
authors.lastname: Poccia
authors.affiliation: Cell Biophysics Laboratory, Research Centre for Experimental Marine Biology and Biotechnology (PiE), Biofisika Instituto (UPV/EHU,CSIC) and, University of the Basque Country, Leioa 48940, Spain banafshe.larijani@ikerbasque.org.
authors.forename: Banafshé
authors.identifier: 0000-0003-4735-1169
authors.initials: B
authors.lastname: Larijani
mesh_terms: D000818:Animals; D005260:Female; D005306:Fertilization; D008297:Male; D008561:Membrane Fusion; D008954:Models, Biological; D009685:Nuclear Envelope / Q000378:metabolism*; D047328:Paracentrotus / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D022161:Transport Vesicles / Q000378:metabolism*; D015053:Zygote / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000090802:rab7 GTP-Binding Proteins
chemical_list: D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020691:rab GTP-Binding Proteins; D000090802:rab7 GTP-Binding Proteins; C060974:phosphatidylinositol 3,4,5-triphosphate
keywords: FRET–FLIM; Membrane fusion; Nuclear envelope; Phosphoinositide 3-kinase; Phosphoinositides; Rab GTPases; Src kinase; Zygote formation