Virus Res. 2000 Jul;68(2):161-73. Unique Identifier : AIDSLINE
HIV-1 Vpr induces cell cycle G2 arrest, morphological changes and cell
death in human and fission yeast cells. The cellular targets for G2
arrest were expected to be the inhibitory phosphorylation sites of Cdc2,
as G2 arrest correlates with hyperphosphorylation and decreased activity
of Cdc2 in both human and fission yeast cells. In this study, we present
direct evidence of genetic suppression of Vpr-induced G2 arrest by cdc2
mutations. Mutations in cdc2 (cdc2-1w and cdc2-3w) reduce the ability of
Vpr to induce G2 arrest. A strain with a mutation changing the Tyr15 of
Cdc2 to the non-phosphorylated Phe (Y15F) eliminated Vpr-induced G2
arrest indicating that Tyr15 of Cdc2 is the sole target for induction of
G2 arrest by Vpr. Although the G2 arrest induced by DNA damage also
proceeds through phosphorylation of Tyr15, the rad1, rad3, rad9 and
rad17 mutations, which eliminate the G2 checkpoint for DNA damage, did
not block the G2 arrest induced by Vpr. Furthermore, Vpr expression did
not alter sensitivity of these rad mutants to UV radiation. Thus, the
pathways for the induction of G2 arrest by DNA damage and Vpr are not
identical. Interestingly, Vpr still induces cell death and morphological
changes in the Y15F Cdc2 strain indicating that G2 arrest is not
required for morphological changes and cell death. This conclusion was
further supported by the observation that mutations in Vpr, which have
lost their ability to induce G2 arrest, retained the ability to kill
cells.
JOURNAL ARTICLE *Cell Death Cell Division *DNA Damage Gene Products,
vpr/GENETICS/*PHYSIOLOGY G2 Phase Human *HIV-1 Mutagenesis
Phosphorylation Protein p34cdc2/GENETICS/METABOLISM
Schizosaccharomyces/*CYTOLOGY/GENETICS *Signal Transduction Support,
Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Tyrosine/METABOLISM
Ultraviolet Rays