A novel role for Vpr of human immunodeficiency virus type 1 as a regulator of the splicing of cellular pre-mRNA.
Vpr, one of the accessory gene products of human immunodeficiency virus type 1 (HIV-1), affects aspects of both viral and cellular proliferation, being involved in long terminal repeat (LTR) activation, arrest of the cell cycle at the G2 phase, and apoptosis. We have discovered a novel role for Vpr as a regulator of the splicing of pre-mRNA both in vivo and in vitro. We found, by RT-PCR and RNase protection analysis, that Vpr caused the accumulation of incompletely spliced forms of alpha-globin 2 and beta-globin pre-mRNAs in cells that had been transiently transfected with a Vpr expression vector. We postulated that this novel effect of Vpr might occur via a pathway that is distinct from arrest of the cell cycle at G2. By analyzing splicing reactions in vitro, we showed that Vpr inhibited the splicing of beta-globin pre-mRNA in vitro. The splicing of intron 1 of alpha-globin 2 pre-mRNA was modestly inhibited by Vpr but the splicing of intron 2 was unaffected. Interestingly, an experimental infection system which utilizes high-titered HIV-1/vesticular stomatitis virus G protein showed that Vpr expressed from an HIV-1 provirus was sufficient to accumulate endogenous alpha-globin 2 pre-mRNA. Thus, it is likely that Vpr contributes to selective inhibition of the splicing of cellular pre-mRNA.
Kuramitsu
Madoka
M
Retrovirus Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Hashizume
Chieko
C
Yamamoto
Norio
N
Azuma
Akihiko
A
Kamata
Masakazu
M
Yamamoto
Naoki
N
Tanaka
Yoshimasa
Y
Aida
Yoko
Y
D015153:Blotting, Western; D002460:Cell Line; D016336:Gene Products, vpr / Q000502:physiology*; D005914:Globins / Q000032:analysis / Q000235:genetics; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D007438:Introns / Q000235:genetics; D023282:Nuclease Protection Assays; D012322:RNA Precursors / Q000378:metabolism*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054325:vpr Gene Products, Human Immunodeficiency Virus
D016336:Gene Products, vpr; D012322:RNA Precursors; D012333:RNA, Messenger; D054325:vpr Gene Products, Human Immunodeficiency Virus; D005914:Globins