Membrane Curvature’s Pore Relation
ER membrane–bending proteins are necessary for de novo nuclear pore formation
T. Renee Dawson1, Michelle D. Lazarus1, Martin W. Hetzer2, and Susan R. Wente1
1 Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232
2 Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037
Correspondence to Susan R. Wente: susan.wente@vanderbilt.edu
Nucleocytoplasmic transport occurs exclusively through nuclearpore complexes (NPCs) embedded in pores formed by inner andouter nuclear membrane fusion. The mechanism for de novo poreand NPC biogenesis remains unclear. Reticulons (RTNs) and Yop1/DP1are conserved membrane protein families required to form andmaintain the tubular endoplasmic reticulum (ER) and the postmitoticnuclear envelope. In this study, we report that members of theRTN and Yop1/DP1 families are required for nuclear pore formation.Analysis of Saccharomyces cerevisiae prp20-G282S and nup133NPC assembly mutants revealed perturbations in Rtn1–greenfluorescent protein (GFP) and Yop1-GFP ER distribution and colocalizationto NPC clusters. Combined deletion of RTN1 and YOP1 resultedin NPC clustering, nuclear import defects, and synthetic lethalitywith the additional absence of Pom34, Pom152, and Nup84 subcomplexmembers. We tested for a direct role in NPC biogenesis usingXenopus laevis in vitro assays and found that anti-Rtn4a antibodiesspecifically inhibited de novo nuclear pore formation. We hypothesizethat these ER membrane–bending proteins mediate earlyNPC assembly steps.