Nup358 binds to AGO proteins through its SUMO ‐interacting motifs and promotes the association of target mRNA with miRISC

Abstract

MicroRNA (miRNA)-guided mRNA repression, mediated by the miRNA-induced silencing complex (miRISC), is an important component of post-transcriptional gene silencing. However, how miRISC identifies the target mRNA in vivo is not well understood. Here, we show that the nucleoporin Nup358 plays an important role in this process. Nup358 localizes to the nuclear pore complex and to the cytoplasmic annulate lamellae (AL), and these structures dynamically associate with two mRNP granules: processing bodies (P bodies) and stress granules (SGs). Nup358 depletion disrupts P bodies and concomitantly impairs the miRNA pathway. Furthermore, Nup358 interacts with AGO and GW182 proteins and promotes the association of target mRNA with miRISC. A well-characterized SUMO-interacting motif (SIM) in Nup358 is sufficient for Nup358 to directly bind to AGO proteins. Moreover, AGO and PIWI proteins interact with SIMs derived from other SUMO-binding proteins. Our study indicates that Nup358-AGO interaction is important for miRNA-mediated gene silencing and identifies SIM as a new interacting motif for the AGO family of proteins. The findings also support a model wherein the coupling of miRISC with the target mRNA could occur at AL, specialized domains within the ER, and at the nuclear envelope.

Nup358 regulates microridge length by controlling SUMOylation-dependent activity of aPKC in zebrafish epidermis

“…We identified the cytoplasmic structures called AL, which contain Nup358, as potential sites of aPKC regulation. As mentioned above, AL are specific subdomains of endoplasmic reticulum, which were recently shown to be associating with messenger ribonucleoprotein granules and playing a role in microRNA (miRNA)-dependent translation regulation of mRNAs (Sahoo et al, 2017). The finding from this study, showing the association of aPKC with Nup358-positive AL structures in zebrafish cells, points towards other unidentified processes mediated by AL.…”

“…This is particularly interesting, given that Nup358 primarily resides in the nuclear membrane as a part of NPC and aPKC is mostly present at the apical junctions of epithelial cells. Nup358, along with a subset of nucleoporins, is also found in the cytoplasm as a part of the AL structure (Sahoo et al, 2017). To analyze the distribution of Nup358 and other nucleoporins in zebrafish, we resorted to fluorescence microscopy using specific antibodies.…”

“…Nup358 is a nucleoporin present on the cytoplasmic side of the nuclear pore complex, and in the cytoplasm as a component of annulate lamellae (AL), which represent specific subdomains of the endoplasmic reticulum (ER) (Sahoo et al, 2017). Although Nup358 is involved in cargo-specific and receptor-specific nucleo-cytoplasmic transport, it appears to be dispensable for general transport (Wälde et al, 2012).…”

ROCK ‐dependent phosphorylation of NUP 62 regulates p63 nuclear transport and squamous cell carcinoma proliferation

“…In parallel, this elevated ΔNp63α in the nucleus modulated the level of transcript of ΔNp63α target genes (Fig EV5A). Both WT and Amt NUP62 proteins co‐localized with another NPC molecule RanBP2 , suggesting those ectopic NUP properly localized on the nuclear envelope (Fig EV5B). Concordantly, we observed increased proliferative ability of SCC cells expressing Amt NUP62 compared to WT NUP62 based on both short‐term proliferation assays and foci formation assays (Figs D, and EV5C and D).…”

miRNA targeting and alternative splicing in the stress response – events hosted by membrane-less compartments

“…2). The nuclear pore, which also exhibits features of a hydrogel (Frey et al, 2006), dynamically associates with PBs and SGs; in particular, the nucleoporin Nup358 (also known as RANBP2) interacts with Argonaute (Ago) and GW182 proteins, and its depletion disrupts PBs and impairs the miRNA pathway (Sahoo et al, 2017). In the cytoplasm, the pre-miRNAs are further processed by Dicer to form mature, ∼22-nucleotide miRNAs.…”