Robustness of dead Cas9 activators in human pluripotent and mesenchymal stem cells

Human pluripotent stem cells (hPSCs) and mesenchymal stromal/stem cells (hMSCs) are clinically relevant sources for cellular therapies and for modeling human development and disease. Many stem cell-based applications rely on the ability to activate several endogenous genes simultaneously to modify cell fate. However, genetic intervention of these cells remains challenging. Several catalytically dead Cas9 (dCas9) proteins fused to distinct activation domains can modulate gene expression when directed to their regulatory regions by a specific single-guide RNA (sgRNA). In this study, we have compared the ability of the first-generation dCas9-VP64 activator and the second-generation systems, dCas9-SAM and dCas9-SunTag, to induce gene expression in hPSCs and hMSCs. Several stem cell lines were tested for single and multiplexed gene activation. When the activation of several genes was compared, all three systems induced specific and potent gene expression in both single and multiplexed settings, but the dCas9-SAM and dCas9-SunTag systems resulted in the highest and most consistent level of gene expression. Simultaneous targeting of the same gene with multiple sgRNAs did not result in additive levels of gene expression in hPSCs nor hMSCs. We demonstrate the robustness and specificity of second-generation dCas9 activators as tools to simultaneously activate several endogenous genes in clinically relevant human stem cells.We thank CERCA/Generalitat de Catalunya and Fundació Josep Carreras-Obra Social la Caixa for their institutional support. We thank Jose Luis Sardina (IJC, Barcelona) for technical assistance with the teratoma assays. Financial support for this work was obtained from the Catalunya Goverment (SGR330 and PERIS 2017-2019), the Spanish Ministry of Economy and Competitiveness (SAF2016-80481-R), the European Research Council (CoG-2014-646903), and the Fundación Leo Messi to P.M.; the Spanish Association against Cancer (AECC-CI-2015) and the Health Institute Carlos III (ISCIII/FEDER, PI17/01028) to C.B.; the Biotechnology and Biological Sciences Research Council (BBRSC) to L.M.F. and A.F.; and the Spanish National Research and Development Plan (ISCIII/FEDER, PI17/02303) and the AEI/MICIU EXPLORA Project (BIO2017-91272-EXP) to S.R.-P. P.M. is an investigator of the Spanish Cell Therapy Cooperative Network (TERCEL). R.T.-R. is supported by a postdoctoral fellowship from the Asociación Española Contra el Cáncer (AECC).S

The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect

Discovery of widespread transcription initiation at microsatellites predictable by sequence-based deep neural network

Using the Cap Analysis of Gene Expression (CAGE) technology, the FANTOM5 consortium provided one of the most comprehensive maps of transcription start sites (TSSs) in several species. Strikingly, ~72% of them could not be assigned to a specific gene and initiate at unconventional regions, outside promoters or enhancers. Here, we probe these unassigned TSSs and show that, in all species studied, a significant fraction of CAGE peaks initiate at microsatellites, also called short tandem repeats (STRs). To confirm this transcription, we develop Cap Trap RNA-seq, a technology which combines cap trapping and long read MinION sequencing. We train sequence-based deep learning models able to predict CAGE signal at STRs with high accuracy. These models unveil the importance of STR surrounding sequences not only to distinguish STR classes, but also to predict the level of transcription initiation. Importantly, genetic variants linked to human diseases are preferentially found at STRs with high transcription initiation level, supporting the biological and clinical relevance of transcription initiation at STRs. Together, our results extend the repertoire of non-coding transcription associated with DNA tandem repeats and complexify STR polymorphism

HOXB4 can enhance the differentiation of embryonic stem cells by modulating the haematopoietic niche

Haematopoietic differentiation of embryonic stem (ES) cells in vitro has been used as a model to study early haematopoietic development and it is well documented that haematopoietic differentiation can be enhanced by over-expression of HOXB4. HOXB4 is expressed in haematopoietic progenitor cells (HPC) where it promotes self-renewal, but it is also expressed in the primitive streak of the gastrulating embryo. This led us to hypothesise that HOXB4 might modulate gene expression in pre-haematopoietic mesoderm and that this property might contribute to its pro-haematopoietic effect in differentiating ES cells. To test our hypothesis we developed a conditionally activated HOXB4 expression system using the mutant oestrogen receptor (ER(T2)) and showed that a pulse of HOXB4 prior to HPC emergence in differentiating ES cells led to an increase in haematopoietic differentiation. Expression profiling revealed an increase in the expression of genes associated with paraxial mesoderm that gives rise to the haematopoietic niche. We therefore considered that HOXB4 might modulate the formation of the haematopoietic niche as well as the production of haematopoietic cells per se. Cell mixing experiments supported this hypothesis demonstrating that HOXB4 activation can generate a paracrine as well as a cell autonomous effect on haematopoietic differentiation. We provide evidence to demonstrate that this activity is partly mediated by the secreted protein FRZB

Robustness of Catalytically Dead Cas9 Activators in Human Pluripotent and Mesenchymal Stem Cells

Altres ajuts: We thank Fundació Josep Carreras-Obra Social la Caixa for their institutional support. We thank Jose Luis Sardina (IJC, Barcelona) for technical assistance with the teratoma assays. Financial support for this work was obtained from the Fundación Leo Messi to P.M.; the Spanish Association against Cancer (AECC-CI-2015) ; and A.F. P.M. is an investigator of the Spanish Cell Therapy Cooperative Network (TERCEL). R.T.-R. is supported by a postdoctoral fellowship from the Asociación Española Contra el Cáncer (AECC).Human pluripotent stem cells (hPSCs) and mesenchymal stromal/stem cells (hMSCs) are clinically relevant sources for cellular therapies and for modeling human development and disease. Many stem cell-based applications rely on the ability to activate several endogenous genes simultaneously to modify cell fate. However, genetic intervention of these cells remains challenging. Several catalytically dead Cas9 (dCas9) proteins fused to distinct activation domains can modulate gene expression when directed to their regulatory regions by a specific single-guide RNA (sgRNA). In this study, we have compared the ability of the first-generation dCas9-VP64 activator and the second-generation systems, dCas9-SAM and dCas9-SunTag, to induce gene expression in hPSCs and hMSCs. Several stem cell lines were tested for single and multiplexed gene activation. When the activation of several genes was compared, all three systems induced specific and potent gene expression in both single and multiplexed settings, but the dCas9-SAM and dCas9-SunTag systems resulted in the highest and most consistent level of gene expression. Simultaneous targeting of the same gene with multiple sgRNAs did not result in additive levels of gene expression in hPSCs nor hMSCs. We demonstrate the robustness and specificity of second-generation dCas9 activators as tools to simultaneously activate several endogenous genes in clinically relevant human stem cells