Hackl, Hubert*
Dotaz
Zobrazit nápovědu
Filamentous green algae of the genus Zygnema (Zygnematophyceae, Streptophyta) are key components of polar hydro-terrestrial mats where they face various stressors including UV irradiation, freezing, desiccation and osmotic stress. Their vegetative cells can develop into pre-akinetes, i.e. reserve-rich, mature cells. We investigated lipid accumulation and fatty acid (FA) composition upon pre-akinete formation in an Arctic and an Antarctic Zygnema strain using transmission electron microscopy and gas chromatography coupled with mass spectrometry. Pre-akinetes formed after 9 weeks of cultivation in nitrogen-free medium, which was accompanied by massive accumulation of lipid bodies. The composition of FAs was similar in both strains, and α-linolenic acid (C18:3) dominated in young vegetative cells. Pre-akinete formation coincided with a significant change in FA composition. Oleic (C18:1) and linoleic (C18:2) acid increased the most (up to 17- and 8-fold, respectively). Small amounts of long-chain polyunsaturated FAs were also detected, e.g. arachidonic (C20:4) and eicosapentaenoic (C20:5) acid. Pre-akinetes exposed to desiccation at 86% relative humidity were able to recover maximum quantum yield of photosystem II, but desiccation had no major effect on FA composition. The results are discussed with regard to the capability of Zygnema spp. to thrive in extreme conditions.
- MeSH
- dusík metabolismus MeSH
- fotosystém II (proteinový komplex) genetika metabolismus MeSH
- lipidová tělíska metabolismus MeSH
- mastné kyseliny chemie metabolismus MeSH
- osmotický tlak MeSH
- Streptophyta chemie genetika metabolismus účinky záření MeSH
- ultrafialové záření MeSH
- vysoušení MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Antarktida MeSH
- Arktida MeSH
Vav3 is a key modulator of GTP-hydrolases of the Rho/Rac family, which are crucially involved in cell proliferation. Vav3 is alternatively spliced in full-length Vav3-alpha and N-terminal truncated Vav3.1 lacking its self-regulatory domains. The aim of our study was to estimate the clinical impact of Vav3 and all other Vav family members in ovarian cancer. Purification of a stem-cell like side-population (SP) from ovarian cancer cell lines was performed by flow cytometry/FACS. Differences in gene expression between SP and NSP were assessed by Gene Array analysis and confirmed by RT-PCR and immunoblot. In addition, Vav mRNA expression was determined in 150 epithelial ovarian cancers. Clinicopathological parameters, platinum-sensitivity and survival were analyzed and associated with Vav expression. SP fractions of ovarian cancer cell lines exhibited marked overexpression of Vav3.1 (p < 0.001). Vav1 and Vav2 did not prove to be of clinicopathologic relevance in ovarian cancer. High Vav3.1 expression correlated with higher FIGO stage and residual disease. Furthermore, Vav3.1 overexpression was associated with poor progression-free (HR = 2.820, p = 0.0001) and overall survival (HR = 2.842, p = 0.0001). Subgroup analyses revealed an impact of Vav3.1 on survival in Type-II but not in Type-I cancers. Notably, platinum-refractory cancers showed marked overexpression of Vav3.1 compared to other subsets of platinum-sensitivity (15.848 vs. 6.653, p = 0.0001). In conclusion, Vav3.1 is over-expressed in stem-cell like SP fractions and is clinically relevant in the pathophysiology of ovarian cancer. The N-terminal truncated Vav3.1 may be decisively involved in mechanisms causing genuine multi-drug resistance.
- MeSH
- fosforylace účinky léků MeSH
- lidé středního věku MeSH
- lidé MeSH
- messenger RNA metabolismus MeSH
- nádorové buněčné linie MeSH
- nádorové kmenové buňky účinky léků metabolismus MeSH
- nádory vaječníků farmakoterapie genetika metabolismus MeSH
- organoplatinové sloučeniny terapeutické užití MeSH
- přežití bez známek nemoci MeSH
- prognóza MeSH
- protein - isoformy metabolismus MeSH
- protoonkogenní proteiny c-vav metabolismus MeSH
- regulace genové exprese u nádorů účinky léků MeSH
- senioři MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The product of the ecotropic virus integration site 1 (EVI1) gene, whose overexpression is associated with a poor prognosis in myeloid leukemias and some epithelial tumors, regulates gene transcription both through direct DNA binding and through modulation of the activity of other sequence specific transcription factors. Previous results from our laboratory have shown that EVI1 influenced transcription regulation in response to the myeloid differentiation inducing agent, all-trans retinoic acid (ATRA), in a dual manner: it enhanced ATRA induced transcription of the RARβ gene, but repressed the ATRA induction of the EVI1 gene itself. In the present study, we asked whether EVI1 would modulate the ATRA regulation of a larger number of genes, as well as biological responses to this agent, in human myeloid cells. U937 and HL-60 cells ectopically expressing EVI1 through retroviral transduction were subjected to microarray based gene expression analysis, and to assays measuring cellular proliferation, differentiation, and apoptosis. These experiments showed that EVI1 modulated the ATRA response of several dozens of genes, and in fact reinforced it in the vast majority of cases. A particularly strong synergy between EVI1 and ATRA was observed for GDF15, which codes for a member of the TGF-β superfamily of cytokines. In line with the gene expression results, EVI1 enhanced cell cycle arrest, differentiation, and apoptosis in response to ATRA, and knockdown of GDF15 counteracted some of these effects. The potential clinical implications of these findings are discussed.
