Dataset Information

Comparative gene expression profiling of pig‐derived iPSC‐like cells: Effects of induced pluripotency on expression of porcine endogenous retrovirus (PERV)

ABSTRACT: Background: Porcine induced pluripotent stem cells (piPSCs) offer an alternative strategy in xenotransplantation (XTx). As human endogenous retroviruses (HERV), particularly HERV‐K, are highly expressed in natural human stem cells, we compared the expression of porcine endogenous retroviruses (PERV) and retrotransposon LINE‐1 (L1) open reading frames 1 and 2 (pORF1 and pORF2) in different piPSC‐like cell lines with their progenitors (porcine fetal fibroblasts, pFF). Methods: Cells reprogrammed via Sleeping Beauty‐transposed transcription factors were cultured and analyzed on a custom‐designed microarray representing the reference pig genome. Data were complemented by qRT‐PCR and reverse transcriptase (RT) assay. Results: The expression profiles revealed that 8515 of 26967 targets were differentially expressed. A total of 4443 targets showed log2 expression ratio >1, and 4072 targets showed log2 expression ratio less than −1 with 0.05 P‐value threshold. Approximately ten percent of the targets showed highly significant expression ratios with log2 ≥4 or ≤−4. Besides this general switch in cellular gene expression that was accompanied by an altered morphology, expression of both PERV and L1 pORF1/pORF2 was significantly enhanced. piPSC‐like cells revealed a 10‐fold to 100‐fold higher transcription of the viral PERV‐A and PERV‐B envelope genes (env), viral protease/polymerase (prt/pol), and L1 elements. No functional retrovirus could be detected under these conditions. Conclusion: Epigenetic reprogramming has functional impact on retrotransposons. Thus, the induction of pig‐derived pluripotent cells influences their PERV expression profile. Data emphasize the necessity to focus on animals, which show non‐functional endogenous viral background to ensure virological safety.

ORGANISM(S): Sus scrofa

PROVIDER: GSE119664 | GEO | 2018/09/08

REPOSITORIES: GEO

ACCESS DATA

Shared Molecules

Only show the datasets with similarity scores above: 0.5

Threshold

0.5

Similar Datasets

Project description:Understanding essential signaling network requirements and adjustment the culture conditions for porcine pluripotent stem cells (pPSC) that allow its full potential are necessary. Here we compared culture conditions of various cytokine and kinase inhibitor combinations by deriving porcine induced pluripotent stem cells (piPSC) and porcine embryonic stem cell (pESC)-like cells. We modified the naïve-type human PSC condition by replacing TGFB1 with TGFB inhibitor and developed a so-called FL6i condition, consisting of FGF2, LIF, p38i, JNKi, TGFBi, GSK3i, MEKi, and BMPi. In such conditions, the primed type lentiviral reprogrammed piPSC (Lv-piPSC) was converted into naïve-like state demonstrating increased expression of endogenous pluripotent genes. By using the FL6i condition, new piPSC lines were generated with non-integrative episomal plasmids (Epi-piPSC). While concurrently generated piPSC in condition with FGF2 and LIF only, and without inhibitors lost the pluripotency within a couple passages of the culture, piPSC in FL6i were successfully established stable lines (> 45 passages) with pluripotent phenotypes. The Epi-piPSC-FL6i lines expressed higher endogenous pPOU5F1, and pSOX2 expressions than Lv-piPSC, however, variable transgene expressions were detected with consistent presence of POU5F1. The teratomas generated from Epi-piPSC-FL6i that developed fully differentiated teratomas while those from Lv-piPSC lines and Epi-piPSC derived in a different condition were limited in differentiation range, suggesting the beneficial role of the FL6i condition supporting elevated pluripotent phenotypes. FL6i conditions were also able to maintain the embryo derived cells with dome-shaped phenotype and extended the culture period that cells showed undifferentiated phenotype than the ones cultured with FGF2 alone. But neither conditions established stable pESC lines. RNAseq analysis with the piPSC and pESC-like cells revealed elevated expressions of early differentiation markers in the lines derived without inhibitors. The pathway analysis suggested that the activation of TGFB and BMP signaling pathways may be responsible for losing pluripotent state in porcine cells.

Project description:Human Endogenous Retroviruses (HERVs) are exogenous viral elements that integrated into the germline millions of years ago. They comprise 8% of the human genome and play a critical role in cellular differentiation during development. HERV-K(HML-2) is the most recently integrated and actively transcribed HERV. It is found to be highly expressed in pluripotent stem cells and strongly downregulated during cellular differentiation. Moreover, expression of HERV-K in terminally differentiated neurons results in cytotoxicity. Expression of HERVs has been implicated in carcinogenesis and is suggested to confer stem cell like features important for cell growth. Atypical Teratoid / Rhabdoid Tumor (AT/RT) is a rare pediatric brain cancer that results from incomplete neuronal differentiation during embryonic development. In this paper, we investigated the cytopathic effect of Ouabain, a cardiac glycoside that induces cytotoxicity in stem cells, on AT/RT cells. We characterized four AT/RT cell lines by immunostaining and observed variable levels of stem cell, Oct4 and Pax6, and neuronal differentiation markers, TUBB3 and MAP2, as well as HERV-K envelope (env), polymerase (pol), and gag transcripts. We stained formalin-fixed brain tissues from 20 AT/RT patients and 5 unaffected controls for HERV-K ENV protein expression. 40% of AT/RT patient tissues showed ENV expression. In contrast, no ENV immunostaining was observed in all 5 control brain tissues. We used Ouabain, known to be cytotoxic to stem cells, observed up to 50% toxicity at 24 hr and 80% toxicity at 48 hr after treatment. While AT/RT primarily exist as large cell aggregates in suspension, Ouabain treatment downregulated HERV-K ENV protein and caused disruption of cell-to-cell interactions. Similarly, when AT/RT cells were transfected with a CRISPR/Cas9 construct designed to repress HERV-K promotor activity, cell aggregates separated and cell viability decreased significantly. Using a luciferase reporter construct under the control of a HERV-K promotor, we observed a significant decrease in HERV-K promotor activity at 8 to 72 hr post treatment with 0.5 uM Ouabain. Given that downregulation of HERV-K alone was sufficient to cause cytotoxicity in the cells, HERV-K expression may be essential for AT/RT growth and survival. Ouabain and other compounds that modulate HERV expression may provide an alternative or adjunctive therapeutic option for treatment of embryonal tumors.