Coordinate effects of human immunodeficiency virus type 1 protein Tat and cellular protein Purα on DNA replication initiated at the JC virus origin

Purα Is Essential for Postnatal Brain Development and Developmentally Coupled Cellular Proliferation As Revealed by Genetic Inactivation in the Mouse

“…Rather, Pur␣ may be required for the developmental replication of selective classes of cells at specific times. Previous studies have described a stimulation of JCV DNA replication at low Pur␣ levels (9) and an inhibition of replication at higher Pur␣ levels (5,9). Ectopic overexpression of Pur␣ in cells has been reported to inhibit DNA replication (1), cell cycle progression (1,44), and oncogenic transformation (1, 11).…”

“…In this regard, reports of interactions of Pur␣ with cell cycle regulatory proteins such as Rb (25) or cyclin/Cdk complexes (1, 23) warrant further investigation. At this time, it remains to be determined whether effects of Pur␣ on cellular DNA replication are through interaction with the replication apparatus, as they are in the JCV model (5,7,9), or whether they are mediated by effects on transcription or translation.…”

“…Work on viruses has suggested a common mechanism in Pur␣ interactions with proteins and nucleic acids. It was found that at low levels Pur␣ stimulates initiation of JCV DNA replication, whereas at high levels Pur␣ is inhibitory (9). Earlier studies have revealed that while Pur␣ stimulates JCV early gene transcription, it suppresses the regulatory activity of T antigen when the two proteins are bound (15).…”

Detecção do DNA do Poliomavírus Humano JC em amostras de líquido cefalorraquidiano de pacientes com AIDS e lesões não expansivas de substância branca do sistema nervoso central

“…Aparentemente, devido à persistência do vírus JC por longos períodos em um indivíduo, variações, especialmente da região regulatória (hipervariável) podem ocorrer in vivo, com amplificação e seleção de variantes ao longo do tempo (GRINELL et al, 1983;BERGER et al, 2001). Estas variações ou rearranjos da região regulatória ocorreriam devido à imunossupressão, levando a viremia do VJC e conseqüente disseminação hematogênica para o sistema nervoso central (KORALNICK et al, 1999).Segundo DANIEL e col (2001), a região regulatória do vírus JC arquetípico, é menos suscetível a ativação da replicação do que o VJC tipo LEMP (DANIEL et al, 2001). …”

“…Segundo DANIEL e col (2001), a região regulatória do vírus JC arquetípico, é menos suscetível a ativação da replicação do que o VJC tipo LEMP (DANIEL et al, 2001). …”