The active role of biomaterials in the regeneration of tissues and their ability to modulate the behavior of stem cells in terms of their differentiation is highly advantageous. Here, polypyrrole, as a representantive of electro-conducting materials, is found to modulate the behavior of embryonic stem cells. Concretely, the aqueous extracts of polypyrrole induce neurogenesis within embryonic bodies formed from embryonic stem cells. This finding ledto an effort to determine the physiological cascade which is responsible for this effect. The polypyrrole modulates signaling pathways of Akt and ERK kinase through their phosphorylation. These effects are related to the presence of low-molecular-weight compounds present in aqueous polypyrrole extracts, determined by mass spectroscopy. The results show that consequences related to the modulation of stem cell differentiation must also be taken into account when polypyrrole is considered as a biomaterial.

• Klíčová slova
• biocompatibility, conducting polymer, neurogenesis, polypyrrole, stem cells,
• MeSH
• buněčná diferenciace účinky léků   genetika   MeSH
• buněčné linie MeSH
• embryoidní tělíska cytologie   účinky léků   MeSH
• exprese genu účinky léků   MeSH
• molekulární struktura MeSH
• myší embryonální kmenové buňky cytologie   účinky léků   metabolismus   MeSH
• myši MeSH
• nervové kmenové buňky cytologie   účinky léků   metabolismus   MeSH
• neurogeneze účinky léků   genetika   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• polymery chemie   farmakologie   MeSH
• pyrroly chemie   farmakologie   MeSH
• transkripční faktor PAX6 genetika   MeSH
• transkripční faktory bHLH genetika   MeSH
• transkripční faktory SOXB1 genetika   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Ascl1 protein, mouse MeSH Prohlížeč
• polymery MeSH
• polypyrrole MeSH Prohlížeč
• pyrroly MeSH
• transkripční faktor PAX6 MeSH
• transkripční faktory bHLH MeSH
• transkripční faktory SOXB1 MeSH

The potentiation of the naturally limited regenerative capacity of the heart is dependent on an understanding of the mechanisms that are activated in response to pathological conditions such as hypoxia. Under these conditions, the expression of genes suggested to support cardiomyocyte survival and heart adaptation is triggered. Particularly important are changes in the expression of myosin heavy chain (MHC) isoforms. We propose here that alterations in the expression profiles of MHC genes are induced in response to hypoxia and are primarily mediated by hypoxia inducible factor (HIF). In in vitro models of mouse embryonic stem cell-derived cardiomyocytes, we showed that hypoxia (1% O2) or the pharmacological stabilization of HIFs significantly increased MHCbeta (Myh7) gene expression. The key role of HIF-1alpha is supported by the absence of these effects in HIF-1alpha-deficient cells, even in the presence of HIF-2alpha. Interestingly, ChIP analysis did not confirm the direct interaction of HIF-1alpha with putative HIF response elements predicted in the MHCalpha and beta encoding DNA region. Further analyses showed the significant effect of the mTOR signaling inhibitor rapamycin in inducing Myh7 expression and a hypoxia-triggered reduction in the levels of antisense RNA transcripts associated with the Myh7 gene locus. Overall, the recognized and important role of HIF in the regulation of heart regenerative processes could be highly significant for the development of novel therapeutic interventions in heart failure.

• Klíčová slova
• fetal gene program, heart, hypoxia, mouse, myosin heavy chain,
• Publikační typ
• časopisecké články MeSH

Hypoxia is involved in the regulation of stem cell fate, and hypoxia-inducible factor 1 (HIF-1) is the master regulator of hypoxic response. Here, we focus on the effect of hypoxia on intracellular signaling pathways responsible for mouse embryonic stem (ES) cell maintenance. We employed wild-type and HIF-1α-deficient ES cells to investigate hypoxic response in the ERK, Akt, and STAT3 pathways. Cultivation in 1% O2 for 24 h resulted in the strong dephosphorylation of ERK and its upstream kinases and to a lesser extent of Akt in an HIF-1-independent manner, while STAT3 phosphorylation remained unaffected. Downregulation of ERK could not be mimicked either by pharmacologically induced hypoxia or by the overexpression. Dual-specificity phosphatases (DUSP) 1, 5, and 6 are hypoxia-sensitive MAPK-specific phosphatases involved in ERK downregulation, and protein phosphatase 2A (PP2A) regulates both ERK and Akt. However, combining multiple approaches, we revealed the limited significance of DUSPs and PP2A in the hypoxia-mediated attenuation of ERK signaling. Interestingly, we observed a decreased reactive oxygen species (ROS) level in hypoxia and a similar phosphorylation pattern for ERK when the cells were supplemented with glutathione. Therefore, we suggest a potential role for the ROS-dependent attenuation of ERK signaling in hypoxia, without the involvement of HIF-1.

• MeSH
• down regulace MeSH
• faktor 1 indukovatelný hypoxií - podjednotka alfa metabolismus   MeSH
• mitogenem aktivované proteinkinasy kinas metabolismus   MeSH
• myší embryonální kmenové buňky metabolismus   MeSH
• myši MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• faktor 1 indukovatelný hypoxií - podjednotka alfa MeSH
• mitogenem aktivované proteinkinasy kinas MeSH
• reaktivní formy kyslíku MeSH