Nup153 Recruits the Nup107-160 Complex to the Inner Nuclear Membrane for Interphasic Nuclear Pore Complex Assembly

Abstract

In metazoa, nuclear pore complexes (NPCs) are assembled from constituent nucleoporins by two distinct mechanisms: in the re-forming nuclear envelope at the end of mitosis and into the intact nuclear envelope during interphase. Here, we show that the nucleoporin Nup153 is required for NPC assembly during interphase but not during mitotic exit. It functions in interphasic NPC formation by binding directly to the inner nuclear membrane via an N-terminal amphipathic helix. This binding facilitates the recruitment of the Nup107-160 complex, a crucial structural component of the NPC, to assembly sites. Our work further suggests that the nuclear transport receptor transportin and the small GTPase Ran regulate the interaction of Nup153 with the membrane and, in this way, direct pore complex assembly to the nuclear envelope during interphase.

Perforating the nuclear boundary – how nuclear pore complexes assemble

“…Of note, in mitotic NPC assembly, as discussed above, recruitment of the Y-complex is executed by MEL28, which directs the Y-complex to the decondensing chromatin. Consistent with this division of function, MEL28 is essential for mitotic but not interphase NPC assembly, whereas Nup153 is crucially required for interphase but not mitotic NPC assembly (Doucet et al, 2010;Vollmer et al, 2015). Two nuclear basket nucleoporins in S. cerevisiae, Nup1 and Nup60, contain an N-terminal amphipathic helix, which binds the inner nuclear membrane and might play a similar role to Nup153 in yeast NPC assembly (Meszaros et al, 2015).…”

“…In the case of nucleoporins, this allows for initiation of NPC assembly at the nuclear envelope with the chromatinbinding nucleoporin MEL28 being one of the relevant regulatory Ran targets (Franz et al, 2007;Rotem et al, 2009). The importance of this spatial information is underscored by the aberrant assembly of ectopic NPC as cytoplasmic annulate lamellae that has been observed upon disruption of the Ran-GTP gradient (Walther et al, 2003b;Franz et al, 2007;Vollmer et al, 2015).…”

Nuclear Reformation at the End of Mitosis

“…New evidences suggest that the function of MEL28/ELYS as initiating assembly point is taken over by Nup153 in interphase NPC assembly. Nup153 would then direct the Nup107-160 complex to the INM and pore assembly sites 207 . This functional difference in initiation, on the chromatin at the end of mitosis and on the nuclear membranes during interphase, might be an indication that, in contrast to interphase NPC assembly, NPC reassembly at the end of mitosis follows an enclosure pathway.…”

The lysine demethylase LSD1 is required for nuclear envelope formation at the end of mitosis

“…With the exception of the mAB414 (used to detect Nup62), Ku70 (H3H10,Abcam,ab3114) and CoREST (Millipore, antibodies, which were employed for western blotting, antibodies raised against Xenopus proteins were employed in immunoblotting and immunofluorescence in assays based on Xenopus egg extract. Antibodies against Xenopus laevis GP210 (Antonin et al, 2005), NDC1 (Mansfeld et al, 2006), POM121 and RTN4 (Vollmer et al, 2015) have been described previously. For the anti-MEL28 antibody, a construct comprising amino acids 2290-2408 was expressed from a pET28a vector and used for antibody production in rabbits.…”