The discovery of novel small molecules that induce stem cell reprogramming and give efficient access to pluripotent stem cells is of major importance for potential therapeutic applications and may ...reveal novel insights into the factors controlling pluripotency. Chemical reprogramming of mouse epiblast stem cells (EpiSCs) into cells corresponding to embryonic stem cells (cESCs) is an inefficient process. In order to identify small molecules that promote this cellular transition, we analyzed the LOPAC library in a phenotypic screen monitoring Oct4-GFP expression and identified triamterene (TR) as initial hit. Synthesis of a TR-derived compound collection and investigation for reprogramming of EpiSCs into cESCs identified casein kinases 1 (CK1) α/δ/ɛ as responsible cellular targets of TR and unraveled the structural parameters that determine reprogramming. Delineation of a structure-activity relationship led to the development of Epiblastin A, which engages CK1 isoenzymes in cell lysate and induces efficient conversion of EpiSCs into cESCs.
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•Triamterene induces reprogramming of epiblast stem cells•Triamterene targets casein kinases 1 (CK1) for stem cell reprogramming•Structure-based compound development yielded the novel CK1 inhibitor Epiblastin A•Epiblastin A displays high reprogramming activity
Ursu et al. identified Epiblastin A, which efficiently converts epiblast stem cells into embryonic stem cells by inhibition of casein kinase 1.
Syrbactins, a family of natural products belonging either to the syringolin or glidobactin class, are highly potent proteasome inhibitors. Although sharing similar structural features, they differ in ...their macrocyclic lactam core structure and exocyclic side chain. These structural variations critically influence inhibitory potency and proteasome subsite selectivity. Here, we describe the total synthesis of syringolin A and B, which together with enzyme kinetic and structural studies, allowed us to elucidate the structural determinants underlying the proteasomal subsite selectivity and binding affinity of syrbactins. These findings were used successfully in the rational design and synthesis of a syringolin A-based lipophilic derivative, which proved to be the most potent syrbactin-based proteasome inhibitor described so far. With a KFormula: see text' of 8.65 ± 1.13 nM for the chymotryptic activity, this syringolin A derivative displays a 100-fold higher potency than the parent compound syringolin A. In light of the medicinal relevance of proteasome inhibitors as anticancer compounds, the present findings may assist in the rational design and development of syrbactin-based chemotherapeutics.
Functional and molecular integrity of cardiomyocytes (CMs) derived from induced pluripotent stem (iPS) cells is essential for their use in tissue repair, disease modelling and drug screening. In this ...study we compared global transcriptomes of beating clusters (BCs) microdissected from differentiating human iPS cells and embryonic stem (ES) cells.
Hierarchical clustering and principal component analysis revealed that iPS-BCs and ES-BCs cluster together, are similarly enriched for cardiospecific genes and differ in expression of only 1.9% of present transcripts. Similarly, sarcomeric organization, electrophysiological properties and calcium handling of iPS-CMs were indistinguishable from those of ES-CMs. Gene ontology analysis revealed that among 204 genes that were upregulated in iPS-BCs vs ES-BCs the processes related to extracellular matrix, cell adhesion and tissue development were overrepresented. Interestingly, 47 of 106 genes that were upregulated in undifferentiated iPS vs ES cells remained enriched in iPS-BCs vs ES-BCs. Most of these genes were found to be highly expressed in fibroblasts used for reprogramming and 34% overlapped with the recently reported iPS cell-enriched genes.
These data suggest that iPS-BCs are transcriptionally highly similar to ES-BCs. However, iPS-BCs appear to share some somatic cell signature with undifferentiated iPS cells. Thus, iPS-BCs may not be perfectly identical to ES-BCs. These minor differences in the expression profiles may occur due to differential cellular composition of iPS-BCs and ES-BCs, due to retention of some genetic profile of somatic cells in differentiated iPS cell-derivatives, or both.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Bone tissue for transplantation therapies is in high demand in clinics. Osteodegenerative diseases, in particular, osteoporosis and osteoarthritis, represent serious public health issues affecting a ...respectable proportion of the elderly population. Furthermore, congenital indispositions from the spectrum of craniofacial malformations such as cleft palates and systemic disorders including osteogenesis imperfecta are further increasing the need for bone tissue. Additionally, the reconstruction of fractured bone elements after accidents and the consumption of bone parts during surgical tumor excisions represent frequent clinical situations with deficient availability of healthy bone tissue for therapeutic transplantations. Epigenetic reprogramming represents a powerful technology for the generation of healthy patient‐specific cells to replace or repair diseased or damaged tissue. The recent generation of induced pluripotent stem cells (iPSCs) is probably the most promising among these approaches dominating the literature of current stem cell research. It allows the generation of pluripotent stem cells from adult human skin cells from which potentially all cell types of the human body could be obtained. Another technique to produce clinically interesting cell types is direct lineage reprogramming (LR) with the additional advantage that it can be applied directly in vivo to reconstitute a damaged organ. Here, we want to present the two technologies of iPSCs and LR, to outline the current states of research, and to discuss possible strategies for their implementation in bone regeneration. STEM CELLS 2011;29:555–563
It has previously been reported that mouse epiblast stem cell (EpiSC) lines comprise heterogeneous cell populations that are functionally equivalent to cells of either early- or late-stage ...postimplantation development. So far, the establishment of the embryonic stem cell (ESC) pluripotency gene regulatory network through the widely known chemical inhibition of MEK and GSK3beta has been impractical in late-stage EpiSCs. Here, we show that chemical inhibition of casein kinase 1alpha (CK1alpha) induces the conversion of recalcitrant late-stage EpiSCs into ESC pluripotency. CK1alpha inhibition directly results in the simultaneous activation of the WNT signaling pathway, together with inhibition of the TGFbeta/SMAD2 signaling pathway, mediating the rewiring of the gene regulatory network in favor of an ESC-like state. Our findings uncover a molecular mechanism that links CK1alpha to ESC pluripotency through the direct modulation of WNT and TGFbeta signaling.
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•Inhibition of CK1alpha induces ESC conversion in EpiSCs recalcitrant to 2i/LIF•The ESC conversion acts via WNT activation and TGFbeta/SMAD2 inhibition•MEK inhibition stabilizes the conversion and restores germline competence•CK1 inhibition promotes activation and maintenance of the pluripotency network
Illich et al. convert late-stage EpiSCs recalcitrant to the 2i/LIF method into germline-competent ESC-like cells through inhibition of casein kinase 1 alpha (CK1a) with the small molecule Epiblastin A. Inhibition of CK1a leads to WNT activation and TGFbeta/SMAD2 inhibition, which promotes the establishment and maintenance of the pluripotency network.
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