Export of Precursor tRNAIle from the Nucleus to the Cytoplasm in Human Cells.
In the current concept, tRNA maturation in vertebrate cells, including splicing of introns, trimming of 5' leader and 3' trailer, and adding of CCA, is thought to occur exclusively in the nucleus. Here we provide evidence to challenge this concept. Unspliced intron-containing precursor tRNAIle was identified in Human Immunodeficiency Virus type 1 (HIV-1) virions, which are synthesized in the cytoplasm. Northern blot, confocal microscopy and quantitative RT-PCR further verified enrichment of this unspliced tRNAIle within the cytoplasm in human cells. In addition to containing an intron, the cytoplasmic precursor tRNAIle also contains a short incompletely processed 5´ leader and a 3´ trailer, which abundance is around 1000 fold higher than the nuclear precursor tRNAIle with long 5' leader and long 3' trailer. In vitro data also suggest that the cytoplasmic unspliced end-immature precursor tRNAIle could be processed by short isoform of RNase Z, but not long isoform of RNase Z. These data suggest that precursor tRNAs could export from the nucleus to the cytoplasm in human cells, instead of be processed only in the nucleus.
School of Medicine, Nankai University, Tianjin, China.|Lady Davis Institute, Jewish General Hospital, McGill University, Canada.
Min
M
Wei
Lady Davis Institute, Jewish General Hospital, McGill University, Canada.
Xia
X
Zhao
State Key Laboratory for Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
Mi
M
Liu
Lady Davis Institute, Jewish General Hospital, McGill University, Canada.
Meijuan
M
Niu
Lady Davis Institute, Jewish General Hospital, McGill University, Canada.
Elias
E
Seif
Lady Davis Institute, Jewish General Hospital, McGill University, Canada.
Lawrence
L
Kleiman
D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D005814:Genes, Viral; D015497:HIV-1 / Q000235:genetics; D006801:Humans; D007438:Introns; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012355:RNA, Transfer, Ile / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014771:Virion / Q000235:genetics
D012322:RNA Precursors; D012355:RNA, Transfer, Ile