Interaction between the shuttling mRNA export factor Gle1 and the nucleoporin hCG1: a conserved mechanism in the export of Hsp70 mRNA.
Translocation of messenger RNAs through the nuclear pore complex (NPC) requires coordinated physical interactions between stable NPC components, shuttling transport factors, and mRNA-binding proteins. In budding yeast (y) and human (h) cells, Gle1 is an essential mRNA export factor. Nucleocytoplasmic shuttling of hGle1 is required for mRNA export; however, the mechanism by which hGle1 associates with the NPC is unknown. We have previously shown that the interaction of hGle1 with the nucleoporin hNup155 is necessary but not sufficient for targeting hGle1 to NPCs. Here, we report that the unique C-terminal 43 amino acid region of the hGle1B isoform mediates binding to the C-terminal non-FG region of the nucleoporin hCG1/NPL1. Moreover, hNup155, hGle1B, and hCG1 formed a heterotrimeric complex in vitro. This suggested that these two nucleoporins were required for the NPC localization of hGle1. Using an siRNA-based approach, decreased levels of hCG1 resulted in hGle1 accumulation in cytoplasmic foci. This was coincident with inhibition of heat shock-induced production of Hsp70 protein and export of the Hsp70 mRNA in HeLa cells. Because this closely parallels the role of the hCG1 orthologue yNup42/Rip1, we speculate that hGle1-hCG1 function in the mRNA export mechanism is highly conserved.
Kendirgi
Frederic
F
Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232-8240, USA.
Rexer
Deborah J
DJ
Alcázar-Román
Abel R
AR
Onishko
Halina M
HM
Wente
Susan R
SR
D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D017930:Genes, Reporter; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; C474082:Gle1 protein, human; D018840:HSP70 Heat-Shock Proteins; C080427:NUP155 protein, human; C119720:NUP42 protein, human; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins