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. 2011 Sep 2;6(9):e24412. doi: 10.1371/journal.pone.0024412

Figure 2. HIV-1 Tat inhibited endogenous Cdk5 kinase activity and mRNA production.

Figure 2

(A) Cdk5 kinase activity in DRG neurons in response to exposure of HIV-1 Tat or Gag. Primary DRG neurons from rats were treated with 20 µM of HIV-1 Tat or Gag for various time intervals ranging from 15 min to 60 min, and were then subjected to Cdk5 kinase assays. Treatment with PBS was included to obtain the baseline of Cdk5 kinase activity. Open, solid gray, and solid black bars represent treatments of PBS, Tat, and Gag, respectively. Cdk5 kinase activity obtained from all conditions was normalized to PBS-treated controls. (B), (C) and (D) Direct effects of HIV-1 Tat and Gag on the regulation of Cdk5 mRNA and p35 mRNA levels in DRG neurons. DRG neurons were treated with 20 µM of HIV-1 Tat or Gag, or PBS for 4 h, and then subjected to analysis of Cdk5 or p35 mRNA production using (B) semi-quantitative RT-PCR and (C) and (D) real-time qPCR assays. Bars represent SD on the mean of three individual experiments. Asterisk indicates statistically significant (*p<0.05; **p<0.01) associations between PBS and Tat treatments.