title: Oxidative stress inhibits nuclear protein export by multiple mechanisms that target FG nucleoporins and Crm1.
abstract: Nuclear transport of macromolecules is regulated by the physiological state of the cell and thus sensitive to stress. To define the molecular mechanisms that control nuclear export upon stress, cells were exposed to nonlethal concentrations of the oxidant diethyl maleate (DEM). These stress conditions inhibited chromosome region maintenance-1 (Crm1)-dependent nuclear export and increased the association between Crm1 and Ran. In addition, we identified several repeat-containing nucleoporins implicated in nuclear export as targets of oxidative stress. As such, DEM treatment reduced Nup358 levels at the nuclear envelope and redistributed Nup98. Furthermore, oxidative stress led to an increase in the apparent molecular masses of Nup98, Nup214, and Nup62. Incubation with phosphatase or beta-N-acetyl-hexosaminidase showed that oxidative stress caused the phosphorylation of Nup98, Nup62, and Nup214 as well as O-linked N-acetylglucosamine modification of Nup62 and Nup214. These oxidant-induced changes in nucleoporin modification correlated first with the increased binding of Nup62 to the exporter Crm1 and second with the reduced interaction of Nup62 with other FxFG-containing nucleoporins. Together, oxidative stress up-regulated the binding of Crm1 to Ran and affected multiple repeat-containing nucleoporins by changing their localization, phosphorylation, O-glycosylation, or interaction with other transport components. We propose that the combination of these events contributes to the stress-dependent regulation of Crm1-mediated protein export.
authors.affiliation: Department of Physiology, McGill University, Montreal, QC, Canada.
authors.forename: Noah
authors.initials: N
authors.lastname: Crampton
authors.forename: Mohamed
authors.initials: M
authors.lastname: Kodiha
authors.forename: Sanhita
authors.initials: S
authors.lastname: Shrivastava
authors.forename: Rehan
authors.initials: R
authors.lastname: Umar
authors.forename: Ursula
authors.initials: U
authors.lastname: Stochaj
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins / Q000378:metabolism*; D008298:Maleates / Q000494:pharmacology; D008954:Models, Biological; D009685:Nuclear Envelope / Q000187:drug effects / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry* / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D020449:Repetitive Sequences, Amino Acid; D013312:Stress, Physiological / Q000187:drug effects; D000097606:Exportin 1 Protein
chemical_list: D028884:Karyopherins; D008298:Maleates; D028861:Nuclear Pore Complex Proteins; D016877:Oxidants; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein; C014476:diethyl maleate