This SuperSeries is composed of the SubSeries listed below.
Epigenetic rejuvenation of mesenchymal stromal cells derived from induced pluripotent stem cells.
Specimen part, Subject
View SamplesStandardization of mesenchymal stromal cells (MSCs) remains a major obstacle in regenerative medicine. Starting material and culture expansion affect cell preparations and render comparison between studies difficult. In contrast, induced pluripotent stem cells (iPSCs) assimilate towards a ground-state and may therefore give rise to more standardized cell preparations. We reprogrammed bone marrow MSCs into iPSCs which were subsequently re-differentiated towards MSCs. These iPS-MSCs revealed similar morphology, immunophenotype, in vitro differentiation potential, and gene expression profiles as primary MSCs. DNA methylation (DNAm) profiles of iPSCs maintained some donor-specific characteristics, whereas tissue-specific, senescence-associated, and age-related DNAm patterns were erased during reprogramming. iPS-MSCs reacquired senescence-associated DNAm during culture expansion but they remained rejuvenated with regard to age-related DNAm. Overall, iPS-MSCs and MSCs are similar in function but differ in their epigenetic makeup.
Epigenetic rejuvenation of mesenchymal stromal cells derived from induced pluripotent stem cells.
Specimen part, Subject
View SamplesInduced pluripotent stem cells (iPSCs) are usually clonally derived. The selection of fully reprogrammed cells generally involves picking of individual colonies with morphology similar to embryonic stem cells (ESCs). However, successfully reprogrammed cells are highly proliferative and escape from cellular senescence - it is therefore conceivable that they outgrow non-pluripotent and partially reprogrammed cells during culture expansion without the need of clonal selection. In this study, we have reprogrammed human dermal fibroblasts (HDFs) with episomal plasmid vectors. Colony frequency and size was higher when using murine embryonic fibroblasts (MEFs) as stromal support instead of HDFs or human mesenchymal stromal cells (MSCs). We have then compared iPSCs which were either clonally derived by manual selection of a single colony, or derived from bulk-cultures of all initial colonies. After few passages their morphology, expression of pluripotency markers, and gene expression profiles did not reveal any significant differences. Furthermore, clonally-derived and bulk-cultured iPSCs had indistinguishable in vitro differentiation potential towards the three germ layers. Therefore, manual selection of individual colonies does not appear to be necessary for the generation of iPSCs this is of relevance for standardization and automation of cell culture procedures
To clone or not to clone? Induced pluripotent stem cells can be generated in bulk culture.
Sex, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Matrix elasticity, replicative senescence and DNA methylation patterns of mesenchymal stem cells.
Specimen part, Subject
View SamplesMatrix elasticity influences differentiation of mesenchymal stem cells (MSCs) but it is unclear if these effects are only transient - while the cells reside on the substrate - or if they reflect persistent lineage commitment. In this study, MSCs were continuously culture-expanded in parallel either on polydimethylsiloxane (PDMS) gels of different elasticity or on tissue culture plastic (TCP) to compare impact on replicative senescence, in vitro differentiation, gene expression, and DNA methylation (DNAm) profiles. The maximal number of cumulative population doublings was not affected by matrix elasticity. Differentiation towards adipogenic and osteogenic lineage was increased on soft and rigid biomaterials, respectively - but this propensity was no more evident if cells were transferred to TCP. Global gene expression profiles and DNAm profiles revealed relatively few differences in MSCs cultured on soft or rigid matrices. Furthermore, only moderate DNAm changes were observed upon culture on very soft hydrogels of human platelet lysate. Our results support the notion that matrix elasticity influences cellular differentiation while the cells are organized on the substrate, but it does not have major impact on cell-intrinsic lineage determination, replicative senescence or DNAm patterns.
Matrix elasticity, replicative senescence and DNA methylation patterns of mesenchymal stem cells.
Specimen part, Subject
View SamplesMouse embryonic fibroblasts (MEFs) were generated from 13.5-day-old embryos obtained from heterozygous PKBa mice intercrosses (Yang et al., 2003). Briefly, after dissection of head and visceral organs for genotyping, embryos were minced and trypsinized for 30 min at 37C. Embryonic fibroblasts were then plated and maintained in Dulbeccos Modified Eagle Medium (DMEM) with 10% foetal calf serum (FCS) (Life Technologies), 100 units/ml of penicillin and 100 mg/ml of streptomycin at 37C in an atmosphere of 5% CO2. All experiments were performed with wild-type and PKBa-/- MEFs between 15-20 passages. To induce adipocyte differentiation, 2-day-postconfluent cells (day 0) were treated with DMEM supplemented with 10% FCS, 8 mg/ml biotin, 4 mg/ml pantothenate, 0.5 mM 3-isobutyl-1-methylxanthine, 1 mM dexamethasone and 10 mg/ml insulin (all from Sigma). Total RNA was extracted from cells using TRIzol (Invitrogen) according to the manufacturers instructions.
PKBalpha is required for adipose differentiation of mouse embryonic fibroblasts.
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View SamplesThe thymus constitutes the primary lymphoid organ for the majority of T cells. The phosphatidyl-inositol 3 kinase (PI3K) signaling pathway is involved in lymphoid development. Defects in single components of this pathway prevent thymocytes from progressing beyond early T cell developmental stages. Protein kinase B (PKB) is the main effector of the PI3K pathway. To determine whether PKB mediates PI3K signaling in early T cell development, we characterized PKB knockout thymi. Our results reveal a significant thymic hypocellularity in PKBalpha-/- neonates and an accumulation of early thymocyte subsets in PKBalpha-/- adult mice. The latter finding is specifically attributed to the lack of PKBalpha within the lymphoid component of the thymus. Microarray analyses show that the absence of PKBalpha in early thymocyte subsets modifies the expression of genes known to be involved in pre-TCR signaling, in T cell activation, and in the transduction of interferon-mediated signals. This report highlights the specific requirements of PKBalpha for thymic development.
Deletion of PKBalpha/Akt1 affects thymic development.
Sex, Age, Specimen part
View SamplesGlioblastoma multiforme (GBM) is the most malignant and most common tumor of the central nervous system characterized by rapid growth and extensive tissue infiltration. GBM results in more years of life lost than any other cancer type. Notch signaling has been implicated in GBM pathogenesis through several modes of action. Inhibition of Notch leads to a reduction of cancer-initiating cells in gliomas and reduces proliferation and migration. Deltex1 (DTX1) is part of an alternative Notch signaling pathway distinct from the canonical MAML1/RBPJ-mediated cascade. In this study, we show that DTX1 activates both the RTK/PI3K/PKB as well as the MAPK/ERK pathway. Moreover, we found the anti-apoptotic factor Mcl-1 to be induced by DTX1. In accordance with this, the clonogenic potential and proliferation rates of glioma cell lines correlated with DTX1 levels. DTX1 knock down mitigated the tumorigenic potential in vivo, and overexpression of DTX1 increased cell migration and invasion of tumor cells accompanied by an elevation of the pro-migratory factors PKB and Snail1. Microarray gene expression analysis identified a DTX1-specific transcriptional program - including microRNA-21 - which is distinct from the canonical Notch signaling. We propose the alternative Notch pathway via DTX1 as oncogenic factor in malignant glioma and found low DTX1 expression levels to correlate with prolonged survival of GBM and early breast cancer patients in open source databases.
Deltex-1 activates mitotic signaling and proliferation and increases the clonogenic and invasive potential of U373 and LN18 glioblastoma cells and correlates with patient survival.
Specimen part, Cell line
View SamplesTo identify signaling pathways that are differentially regulated in human gliomas, a microarray analysis on 30 brain tumor samples (12 primary glioblastomas (GBM), 3 secondary glioblastomas (GBM-2), 8 astrocytomas (Astro) and 7 oligodendrogliomas (Oligo)) and on 5 glioblastoma cell lines (LN018, LN215, LN229, LN319 and BS149) was performed. Normal brain tissue (NB) and normal human astrocytes (NHA) were used as a control. Kinase expression in each tumor was compared to expression in normal brain and expression values from normal human astrocytes were used as an additional control.
MAP kinase-interacting kinase 1 regulates SMAD2-dependent TGF-β signaling pathway in human glioblastoma.
Sex, Age, Specimen part, Disease stage, Cell line
View SamplesTwist1 variants including wildtype Twist1, a non-phosphorylatable mutant Twist1/S42A and a phospho-mimicking mutant Twist1/S42D were expressed in 4T1 cells in which the endogenous Twist1 was depleted.
Akt/PKB-mediated phosphorylation of Twist1 promotes tumor metastasis via mediating cross-talk between PI3K/Akt and TGF-β signaling axes.
Specimen part
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