Generation of spinocerebellar ataxia type 2 patient-derived iPSC line H271

AbstractSpinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease primarily affecting the cerebellum. Very little is known about the molecular mechanisms underlying the disease and, to date, no cure or treatment is available. Here, we demonstrate the generation of an induced pluripotent stem cell (iPSC) line of a SCA2 patient. The selected clone has been proven to be a bona fide iPSC line, which retains a normal karyotype. Due to its differentiation potential into neurons, this iPSC line will be a valuable tool in studying a disease-specific phenotype of SCA2

Generation of spinocerebellar ataxia type 2 patient-derived iPSC line H266

AbstractSpinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease primarily affecting the cerebellum. Very little is known about the molecular mechanisms underlying the disease and, to date, no cure or treatment is available. Here, we demonstrate the generation of an induced pluripotent stem cell (iPSC) line of a SCA2 patient. The selected clone has been proven to be a bona fide iPSC line, which retains a normal karyotype. Due to its differentiation potential into neurons, this iPSC line will be a valuable tool in studying a disease-specific phenotype of SCA2

Dissecting the role of distinct OCT4-SOX2 heterodimer configurations in pluripotency

The transcription factors OCT4 and SOX2 are required for generating induced pluripotent stem cells (iPSCs) and for maintaining embryonic stem cells (ESCs). OCT4 and SOX2 associate and bind to DNA in different configurations depending on the arrangement of their individual DNA binding elements. Here we have investigated the role of the different OCT4-SOX2-DNA assemblies in regulating and inducing pluripotency. To this end, we have generated SOX2 mutants that interfere with specific OCT4-SOX2 heterodimer configurations and assessed their ability to generate iPSCs and to rescue ESC self-renewal. Our results demonstrate that the OCT4-SOX2 configuration that dimerizes on a Hoxb1-like composite, a canonical element with juxtaposed individual binding sites, plays a more critical role in the induction and maintenance of pluripotency than any other OCT4-SOX2 configuration. Overall, the results of this study provide new insight into the protein interactions required to establish a de novo pluripotent network and to maintain a true pluripotent cell fate.Link_to_subscribed_fulltex

Generation of an isogenic, gene-corrected control cell line of the spinocerebellar ataxia type 2 patient-derived iPSC line H271

AbstractSpinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease primarily affecting the cerebellum. Very little is known about the molecular mechanisms underlying the disease and, to date, no cure or treatment is available. We have successfully generated bona fide induced pluripotent stem cell (iPSC) lines of SCA2 patients in order to study a disease-specific phenotype. Here, we demonstrate the gene correction of the iPSC line H271 clone 1 where we have exchanged the expanded CAG repeat of the ATXN2 gene with the normal length found in healthy alleles. This gene corrected cell line will provide the ideal control to model SCA2 by iPSC technology

Epigenetic Aberrations Are Not Specific to Transcription Factor-Mediated Reprogramming

Somatic cells can be reprogrammed to pluripotency using different methods. In comparison with pluripotent cells obtained through somatic nuclear transfer, induced pluripotent stem cells (iPSCs) exhibit a higher number of epigenetic errors. Furthermore, most of these abnormalities have been described to be intrinsic to the iPSC technology. Here, we investigate whether the aberrant epigenetic patterns detected in iPSCs are specific to transcription factor-mediated reprogramming. We used germline stem cells (GSCs), which are the only adult cell type that can be converted into pluripotent cells (gPSCs) under defined culture conditions, and compared GSC-derived iPSCs and gPSCs at the transcriptional and epigenetic level. Our results show that both reprogramming methods generate indistinguishable states of pluripotency. GSC-derived iPSCs and gPSCs retained similar levels of donor cell-type memory and exhibited comparable numbers of reprogramming errors. Therefore, our study demonstrates that the epigenetic abnormalities detected in iPSCs are not specific to transcription factor-mediated reprogramming

Counteracting Activities of OCT4 and KLF4 during Reprogramming to Pluripotency

Differentiated cells can be reprogrammed into induced pluripotent stem cells (iPSCs) after overexpressing four transcription factors, of which Oct4 is essential. To elucidate the role of Oct4 during reprogramming, we investigated the immediate transcriptional response to inducible Oct4 overexpression in various somatic murine cell types using microarray analysis. By downregulating somatic-specific genes, Oct4 induction influenced each transcriptional program in a unique manner. A significant upregulation of pluripotent markers could not be detected. Therefore, OCT4 facilitates reprogramming by interfering with the somatic transcriptional network rather than by directly initiating a pluripotent gene-expression program. Finally, Oct4 overexpression upregulated the gene Mgarp in all the analyzed cell types. Strikingly, Mgarp expression decreases during the first steps of reprogramming due to a KLF4-dependent inhibition. At later stages, OCT4 counteracts the repressive activity of KLF4, thereby enhancing Mgarp expression. We show that this temporal expression pattern is crucial for the efficient generation of iPSCs