Expression of multidrug resistance ABC transporters has been suggested as a functional marker and chemoprotective element in early human progenitor cell types. In this study we examined the expression and function of the key multidrug-ABC transporters, ABCB1, ABCC1 and ABCG2 in two human embryonic stem (HuES) cell lines. We detected a high level ABCG2 expression in the undifferentiated HuES cells, while the expression of this protein significantly decreased during early cell differentiation. ABCG2 in HuES cells provided protection against mitoxantrone toxicity, with a drug-stimulated overexpression of the transporter. No significant expression of ABCB1/ABCC1 was found either in the undifferentiated or partially differentiated HuES cells. Examination of the ABCG2 mRNA in HuES cells indicated the use of selected promoter sites and a truncated 3' untranslated region, suggesting a functionally distinct regulation of this transporter in undifferentiated stem cells. The selective expression of the ABCG2 multidrug transporter indicates that ABCG2 can be applied as a marker for undifferentiated HuES cells. Moreover, protection of embryonic stem cells against xenobiotics and endobiotics may depend on ABCG2 expression and regulation.

Human embryonic stem (HuES) cells represent a new potential tool for cell-therapy and gene-therapy applications. However, these approaches require the development of efficient, stable gene delivery, and proper progenitor cell and tissue separation methods. In HuES cell lines, we have generated stable, enhanced green fluorescent protein (EGFP)-expressing clones using a transposon-based (Sleeping Beauty) system. This method yielded high percentage of transgene integration and expression. Similarly to a lentiviral expression system, both the undifferentiated state and the differentiation pattern of the HuES cells were preserved. By using the CAG promoter, in contrast to several other constitutive promoter sequences (such as CMV, elongation factor 1a, or phosphoglycerate kinase), an exceptionally high EGFP expression was observed in differentiated cardiomyocytes. This phenomenon was independent of the transgene sequence, methods of gene delivery, copy number, and the integration sites. This ''doublefeature'' promoter behavior, that is providing a selectable marker for transgene expressing undifferentiated stem cells, and also specifically labeling differentiated cardiomyocytes, was assessed by transcriptional profiling. We found a positive correlation between CAG promoter-driven EGFP transcription and expression of cardiomyocyte-specific genes. Our experiments indicate an efficient applicability of transposon-based gene delivery into HuES cells and provide a novel approach to identify differentiated tissues by exploiting a nontypical behavior of a constitutively active promoter, thereby avoiding invasive drug selection methods.

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Background: ATP-binding cassette (ABC) transporters have key roles in various physiological functionsas well as providing chemical defense and stress tolerance in human tissues. In this study, we have examined the expression pattern of all ABC proteins in pluripotent human embryonic stem cells (hESCs) and in their differentiated progenies. We paid special attention to the cellular expression and localization of multidrug transporter ABC proteins.Methods: Stem cell differentiation was carried out without chemical induction or cell sorting, and specialized cell types were separated mechanically. Cellular features regarding pluripotency and tissue identity, as well as ABC transporter expression were studied by flow cytomtery, immuno-microscopy, and qPCR-based low-density arrays.Results: Pluripotent hESCs and differentiated cell types (cardiomyocytes, neuronal cells, and mesenchymal stem cells) were distinguished by morphology, immunostaining markers, and selected mRNA expression patterns. We found that the mRNA expression levels of the 48 human ABC proteins also clearly distinguished the pluripotent and the respective differentiated cell types. When multidrug and lipid transporter ABC protein expression was examined by using well characterized specific antibodies by flow cytometry and confocal microscopy, the protein expression data corresponded well to the mRNA expression results. Moreover, the cellular localization of these important human ABC transporter proteins could be established in the pluripotent and differentiated hESC derived samples.Conclusions: These studies provide valuable information regarding ABC protein expression in human stem cells and their differentiated offspring. The results may also help to obtain further information concerning the specialized cellular functions of selected ABC transporters. V C 2014 International Clinical Cytometry Society

Background: ATP-binding Cassette (ABC) transporters have key roles in various physiological functions as well as providing chemical defense and stress tolerance in human tissues. In this study we have examined the expression pattern of all ABC proteins in pluripotent human embryonic stem cells (hESCs) and in their differentiated progenies. We paid special attention to the cellular expression and localization of multidrug transporter ABC proteins.Methods: Stem cell differentiation was carried out without chemical induction or cell sorting, and specialized cell types were separated mechanically. Cellular features regarding pluripotency and tissue identity, as well as ABC transporter expression were studied by flow cytomtery, immuno-microscopy and qPCR-based low-density arrays.Results: Pluripotent hESCs and differentiated cell types (cardiomyocytes, neuronal cells and mesenchymal stem cells) were distinguished by morphology, immunostaining markers and selected mRNA expression patterns. We found that the mRNA expression levels of the 48 human ABC proteins also clearly distinguished the pluripotent and the respective differentiated cell types. When multidrug and lipid transporter ABC protein expression was examined by using well characterized specific antibodies by flow cytometry and confocal microscopy, the protein expression data corresponded well to the mRNA expression results.Moreover, the cellular localization of these important human ABC transporter proteins could be established in the pluripotent and differentiated hESC derived samples. Conclusions:These studies provide valuable information regarding ABC protein expression in human stem cells and their differentiated offspring. The results may also help to obtain further information concerning the specialized cellular functions of selected ABC transporters.

Background De novo mutations (DNMs) have been implicated in the etiology of schizophrenia (SZ), a chronic debilitating psychiatric disorder characterized by hallucinations, delusions, cognitive dysfunction, and decreased community functioning. Several DNMs have been identified by examining SZ cases and their unaffected parents; however, in most cases, the biological significance of these mutations remains elusive. To overcome this limitation, we have developed an approach of using induced pluripotent stem cell (iPSC) lines from each member of a SZ case-parent trio, in order to investigate the effects of DNMs in cellular progenies of interest, particularly in dentate gyrus neuronal progenitors. Methods We identified a male SZ patient characterized by early disease onset and negative symptoms, who is a carrier of 3 non-synonymous DNMs in genes LRRC7, KHSRP, and KIR2DL1. iPSC lines were generated from his and his parents’ peripheral blood mononuclear cells using Sendai virus-based reprogramming and differentiated into neuronal progenitor cells (NPCs) and hippocampal dentate gyrus granule cells. We used RNASeq to explore transcriptomic differences and calcium (Ca2+) imaging, cell proliferation, migration, oxidative stress, and mitochondrial assays to characterize the investigated NPC lines. Results NPCs derived from the SZ patient exhibited transcriptomic differences related to Wnt signaling, neuronal differentiation, axonal guidance and synaptic function, and decreased Ca2+ reactivity to glutamate. Moreover, we could observe increased cellular proliferation and alterations in mitochondrial quantity and morphology. Conclusions The approach of reprograming case-parent trios represents an opportunity for investigating the molecular effects of disease-causing mutations and comparing these in cell lines with reduced variation in genetic background. Our results are indicative of a partial overlap between schizophrenia and autism-related phenotypes in the investigated family. Limitations Our study investigated only one family; therefore, the generalizability of findings is limited. We could not derive iPSCs from two other siblings to test for possible genetic effects in the family that are not driven by DNMs. The transcriptomic and functional assays were limited to the NPC stage, although these variables should also be investigated at the mature neuronal stage.

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