title: Inner nuclear envelope protein SUN1 plays a prominent role in mammalian mRNA export.
abstract: Nuclear export of messenger ribonucleoproteins (mRNPs) through the nuclear pore complex (NPC) can be roughly classified into two forms: bulk and specific export, involving an nuclear RNA export factor 1 (NXF1)-dependent pathway and chromosome region maintenance 1 (CRM1)-dependent pathway, respectively. SUN proteins constitute the inner nuclear envelope component of the l I: nker of N: ucleoskeleton and C: ytoskeleton (LINC) complex. Here, we show that mammalian cells require SUN1 for efficient nuclear mRNP export. The results indicate that both SUN1 and SUN2 interact with heterogeneous nuclear ribonucleoprotein (hnRNP) F/H and hnRNP K/J. SUN1 depletion inhibits the mRNP export, with accumulations of both hnRNPs and poly(A)+RNA in the nucleus. Leptomycin B treatment indicates that SUN1 functions in mammalian mRNA export involving the NXF1-dependent pathway. SUN1 mediates mRNA export through its association with mRNP complexes via a direct interaction with NXF1. Additionally, SUN1 associates with the NPC through a direct interaction with Nup153, a nuclear pore component involved in mRNA export. Taken together, our results reveal that the inner nuclear envelope protein SUN1 has additional functions aside from being a central component of the LINC complex and that it is an integral component of the mammalian mRNA export pathway suggesting a model whereby SUN1 recruits NXF1-containing mRNP onto the nuclear envelope and hands it over to Nup153.
authors.affiliation: Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Strasse 52, 50931 Cologne, Germany.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Strasse 52, 50931 Cologne, Germany noegel@uni-koeln.de.
authors.forename: Angelika A
authors.initials: AA
authors.lastname: Noegel
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D006367:HeLa Cells; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism / Q000502:physiology*; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology*; D034443:RNA Transport; D012333:RNA, Messenger / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism
chemical_list: D034441:Heterogeneous-Nuclear Ribonucleoproteins; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C492666:NFX1 protein, human; C079377:NUP153 protein, human; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C506117:SUN1 protein, human