title: Trimethylguanosine capping selectively promotes expression of Rev-dependent HIV-1 RNAs.
abstract: 5'-mRNA capping is an early modification that affects pre-mRNA synthesis/splicing, RNA cytoplasmic transport, and mRNA translation and turnover. In eukaryotes, a 7-methylguanosine (m7G) cap is added to newly transcribed RNA polymerase II (RNAP II) transcripts. A subset of RNAP II-transcribed cellular RNAs, including small nuclear RNA (snRNA), small nucleolar RNA (snoRNA), and telomerase RNA, is further hypermethylated at the exocyclic N2 of the guanosine to create a trimethylguanosine (TMG)-capped RNA. Some of these TMG-capped RNAs are transported within the nucleus and from the nucleus to the cytoplasm by the CRM-1 (required for chromosome region maintenance) protein. CRM-1 is also used to export Rev/RRE-dependent unspliced/ partially spliced HIV-1 RNAs. Here we report that like snRNAs and snoRNAs, some Rev/RRE-dependent HIV-1 RNAs are TMG-capped. The methyltransferase responsible for TMG modification of HIV-1 RNAs is the human PIMT (peroxisome proliferator-activated receptor-interacting protein with methyltransferase) protein. TMG capping of unspliced/partially spliced HIV-1 RNAs represents a new regulatory mechanism for selective expression.
authors.affiliation: Molecular Virology Section, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0460, USA.
authors.forename: Venkat S R K
authors.initials: VS
authors.lastname: Yedavalli
authors.forename: Kuan-Teh
authors.initials: KT
authors.lastname: Jeang
mesh_terms: D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D015967:Gene Expression Regulation, Viral; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006151:Guanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D009154:Mutation; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000235:genetics / Q000378:metabolism; D012315:RNA Caps / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014779:Virus Replication / Q000187:drug effects; D054321:rev Gene Products, Human Immunodeficiency Virus / Q000235:genetics* / Q000378:metabolism
chemical_list: D012315:RNA Caps; D012367:RNA, Viral; D054321:rev Gene Products, Human Immunodeficiency Virus; C422952:telomerase RNA; D006151:Guanosine; D049452:Green Fluorescent Proteins; C016578:7-methylguanosine; D012313:RNA; C435725:PCMT1 protein, human; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase; D019098:Telomerase