       Document 0567
 DOCN  M9620567
 TI    The roles of nucleolar structure and function in the subcellular
       location of the HIV-1 Rev protein.
 DT    9602
 AU    Dundr M; Leno GH; Hammarskjold ML; Rekosh D; Helga-Maria C; Olson MO;
       Department of Biochemistry, University of Mississippi Medical; Center,
       Jackson 39216, USA.
 SO    J Cell Sci. 1995 Aug;108 ( Pt 8):2811-23. Unique Identifier : AIDSLINE
       MED/96034319
 AB    The human immunodeficiency virus 1 (HIV-1) Rev transactivator protein
       plays a critical role in the regulation of expression of structural
       proteins by controlling the pathway of mRNA transport. The Rev protein
       is located predominantly in the nucleoli of HIV-1 infected or
       Rev-expressing cells. Previous studies demonstrated that the Rev protein
       forms a specific complex in vitro with protein B23 which is suggested to
       be a nucleolar receptor and/or carrier for the Rev protein. To study the
       role of the nucleolus and nucleolar proteins in Rev function,
       transfected COS-7 or transformed CMT3 cells expressing the Rev protein
       were examined for subcellular locations of Rev and other proteins using
       indirect immunofluorescence and immunoelectron microscopy. One day after
       transfection the Rev protein was found in most cells only in the
       nucleolar dense fibrillar and granular components where it colocalized
       with protein B23. These were designated class 1 cells. In a second class
       of cells Rev and B23 accumulated in the nucleoplasm as well as in
       nucleoli. Treatment of class 1 cells with actinomycin D (AMD) under
       conditions that blocked only RNA polymerase I transcription caused Rev
       to completely redistribute from nucleoli to the cytoplasm.
       Simultaneously, protein B23 was partially released from nucleoli, mostly
       into the nucleoplasm, with detectable amounts in the cytoplasm. In cells
       recovering from AMD treatment in the presence of cycloheximide Rev and
       B23 showed coincident relocation to nucleoli. Class 2 cells were
       resistant to AMD-induced Rev redistribution. Selective inhibition of RNA
       polymerase II transcription by alpha-amanitin or by DRB did not cause
       Rev to be released into the cytoplasm suggesting that active
       preribosomal RNA transcription is required for the nucleolar location of
       Rev. However, treatment with either of the latter two drugs at higher
       doses and for longer times caused partial disruption of nucleoli
       accompanied by translocation of the Rev protein to the cytoplasm. These
       results suggest that the nucleolar location of Rev depends on continuous
       preribosomal RNA transcription and a substantially intact nucleolar
       structure.
 DE    Animal  Antibodies  Antibodies, Monoclonal  Cell Line  Cell
       Nucleolus/*PHYSIOLOGY/*ULTRASTRUCTURE  Cercopithecus aethiops
       Dactinomycin/PHARMACOLOGY  Gene Products, rev/ANALYSIS/DRUG
       EFFECTS/*METABOLISM  Human  HIV-1/*METABOLISM  Microscopy, Fluorescence
       Microscopy, Immunoelectron  Support, U.S. Gov't, P.H.S.  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

