ORC interacts with THSC/TREX-2 and its subunits promote Nxf1 association with mRNP and mRNA export inDrosophila

Abstract

The origin recognition complex (ORC) of eukaryotes associates with the replication origins and initiates the pre-replication complex assembly. In the literature, there are several reports of interaction of ORC with different RNAs. Here, we demonstrate for the first time a direct interaction of ORC with the THSC/TREX-2 mRNA nuclear export complex. The THSC/TREX-2 was purified from the Drosophila embryonic extract and found to bind with a fraction of the ORC. This interaction occurred via several subunits and was essential for Drosophila viability. Also, ORC was associated with mRNP, which was facilitated by TREX-2. ORC subunits interacted with the Nxf1 receptor mediating the bulk mRNA export. The knockdown of Orc5 led to a drop in the Nxf1 association with mRNP, while Orc3 knockdown increased the level of mRNP-bound Nxf1. The knockdown of Orc5, Orc3 and several other ORC subunits led to an accumulation of mRNA in the nucleus, suggesting that ORC participates in the regulation of the mRNP export.

Nonreplicative functions of the origin recognition complex

“…Moreover, ORC interacts with TREX-2, the complex of general mRNA nuclear export [17,108]. Besides that, we have shown an interaction between the ORC subunits and the Nxf1 protein, the mRNA transport receptor [17]. Most likely, TREX-2 facilitates ORC binding to mRNP, which, in turn, promotes the Nxf1 recruitment.…”

“…However, recently we have shown, that the ORC complex interacts with coding mRNAs and participates in mRNA export in D. melanogaster . Moreover, ORC interacts with TREX-2, the complex of general mRNA nuclear export [17,108]. Besides that, we have shown an interaction between the ORC subunits and the Nxf1 protein, the mRNA transport receptor [17].…”

“…In the last few decades, involvement of ORC in numerous highly diverse cellular functions was discovered, e. g. the formation of heterochromatin, chromosome condensation and segregation, centrosome duplication, cytokinesis and mRNA nuclear export [14–17]. The sub-complexes or the individual subunits of ORC are localized not only in nuclei and on the mitotic chromosomes, but in the cytoplasm as well [18–21].…”

Novel candidate biomarkers of origin recognition complex 1, 5 and 6 for survival surveillance in patients with hepatocellular carcinoma

“…Phosphorylation of ORC2 by polo-like kinase 1 promotes DNA replication under stress conditions [14]. Knockdown of ORC3 increased the level of mRNP-bound Nxf1, while knockdown of ORC5 decreased the association between Nxf1 and mRNP [15]. ORC6 is crucial for the formation of pre-replicative complex interactions with ORC chaperone proteins that promote chromatin binding of ORC [16].…”

Spermatogenesis in Drosophila melanogaster: Key Features and the Role of the NXF1 (Nuclear Export Factor) Protein

“…In addition, the source of specialized functions may be the presence of functionally significant sequences in the SBR protein, responsible for interaction with the certain partners. As a result, SBR may be involved in other processes than the nuclear-cytoplasmic export of mRNAs [36,37]. A mutant product that disrupts the system of macromolecular interactions can have a dominant negative effect, in this case heterozygosity at the null allele will be better than the presence of a mutant protein along with the normal product [38].…”