HERV transcription activity in different human brain cell lines after treatment with valproic acid.

<p>15 representative examples of false-color microarray data sets representing untreated and treated (1 or 5 mM VPA) samples from different cell lines were aligned. For detailed information about the identity of microarray capture probes see references <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030054#pone.0030054-Seifarth2" target="_blank">[19]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030054#pone.0030054-Frank1" target="_blank">[20]</a>. Each positive spot on the microarray represents multiple HERV loci assigned to one subgroup of multicopy HERV elements with sufficient sequence homology that they cannot be distinguished on an individual basis. The housekeeping gene HPRT served as an internal control. Quantitative RT-PCRs were performed for a subset of six differentially active taxa (HERV-W, ERV9, HERV-F, HML-2, Seq26, and HERV-KC4 indicated by red boxes.</p

Quantification of HERV transcription in 56 postmortem brain samples by qRT-PCR.

<p>Transcriptional activities of ERV9 (<b>A</b>), HERV-W (<b>B</b>), and HML-2 (<b>C</b>) were analyzed in a subset of 18 schizophrenia-derived brain samples and 20 samples of patients with bipolar disorders with regard to VPA treatment, and compared to 18 healthy individuals. The level of HERV transcripts in each sample was normalized to RPII levels and represents the mean value of at least triplicate experiments. Significant deviation between patient groups according to the Student's t-test is denoted for each HERV taxon by * p≤0.05, ** p≤0.01, *** p≤0.001).</p

Influence of antipsychotic medication on HERV activity in human brain cell lines.

<p>Two glioblastoma cell lines (U-138MG and U-251MG), two neuroblastoma cell lines (SK-N-SH and SK-N-MC) and the human neural stem cell line HNSC.100 were treated with 5 mM VPA and compared to untreated cells. U-138MG, SK-N-SH and HNSC.100 were also treated with 10 µM haloperidol, risperidone, or clozapine. Data were obtained from at least two microarray experiments of each of two independent antipsychotic drug treatments. Varying results for the two treatments are indicated by a backslash.</p><p>− no expression; 0 no influence; + weak influence; ++ strong influence.</p><p>Abbreviations: U138 (U-138 MG), U251 (U-251 MG), SKNSH (SK-N-SH), SKNMC (SK-N-MC), HNSC (HNSC.100).</p><p>*HERV subgroups selected for quantification by qRT-PCR.</p

Relative transcriptional activity of selected HERV taxa in human brain cell lines.

<p>Cells were treated with (<b>A</b>) 5 mM VPA and (<b>B</b>) 10 µM haloperidol, risperidone, or clozapine, and compared to untreated cells. QRT-PCR experiments were performed on RNA samples that were obtained from two independent treatments with VPA, haloperidol, risperidone, or clozapine previously used for the retrovirus-specific microarray. Relative transcription levels were quantified according to Pfaffl et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030054#pone.0030054-Pfaffl1" target="_blank">[41]</a>. For amplification of HERV-K(HML-2) transcripts primers derived from the <i>gag</i> region were used. Transcription of other HERV subgroups was analyzed using <i>pol</i> specific primers overlapping with the capture probes of the microarray. The level of HERV transcripts was normalized to RPII and represents the mean value of at least triplicate qRT-PCR experiments. Numbers on the Y-axis show the fold up-regulation. A less than 2.5-fold increase of transcript levels is not considered as a significant transcriptional activation.</p