Complete microtubule–kinetochore occupancy favours the segregation of merotelic attachments

Kinetochores are multi-protein complexes that power chromosome movements by tracking microtubules plus-ends in the mitotic spindle. Human kinetochores bind up to 20 microtubules, even though single microtubules can generate sufficient force to move chromosomes. Here, we show that high microtubule occupancy at kinetochores ensures robust chromosome segregation by providing a strong mechanical force that favours segregation of merotelic attachments during anaphase. Using low doses of the microtubules-targeting agent BAL27862 we reduce microtubule occupancy and observe that spindle morphology is unaffected and bi-oriented kinetochores can still oscillate with normal intra-kinetochore distances. Inter-kinetochore stretching is, however, dramatically reduced. The reduction in microtubule occupancy and inter-kinetochore stretching does not delay satisfaction of the spindle assembly checkpoint or induce microtubule detachment via Aurora-B kinase, which was so far thought to release microtubules from kinetochores under low stretching. Rather, partial microtubule occupancy slows down anaphase A and increases incidences of lagging chromosomes due to merotelically attached kinetochores

Differential responses to kinase inhibition in FGFR2-addicted triple negative breast cancer cells: a quantitative phosphoproteomics study

Fibroblast Growth Factor (FGF) dependent signalling is frequently activated in cancer by a variety of different mechanisms. However, the downstream signal transduction pathways involved are poorly characterised. Here a quantitative differential phosphoproteomics approach, SILAC, is applied to identify FGF-regulated phosphorylation events in two triple- negative breast tumour cell lines, MFM223 and SUM52, that exhibit amplified expression of FGF receptor 2 (FGFR2) and are dependent on continued FGFR2 signalling for cell viability. Comparative Gene Ontology proteome analysis revealed that SUM52 cells were enriched in proteins associated with cell metabolism and MFM223 cells enriched in proteins associated with cell adhesion and migration. FGFR2 inhibition by SU5402 impacts a significant fraction of the observed phosphoproteome of these cells. This study expands the known landscape of FGF signalling and identifies many new targets for functional investigation. FGF signalling pathways are found to be flexible in architecture as both shared, and divergent, responses to inhibition of FGFR2 kinase activity in the canonical RAF/MAPK/ERK/RSK and PI3K/AKT/PDK/mTOR/S6K pathways are identified. Inhibition of phosphorylation-dependent negative-feedback pathways is observed, defining mechanisms of intrinsic resistance to FGFR2 inhibition. These findings have implications for the therapeutic application of FGFR inhibitors as they identify both common and divergent responses in cells harbouring the same genetic lesion and pathways of drug resistance

Three Types of Coexistence of Pagan and Christian Elements in the Late Roman Intellectuals’ Mentality

The paper considers three types of coexistence of pagan and Christian elements in the consciousness of Late antique intellectuals who were Latin writers in the period from of the 4th to 6th centuries, representatives of the upper stratum, Christians such as Ausonius, Paulinus of Nola, Sidonius Apollinaris, and others. The authors come to the conclusion that the attitude to the pagan heritage combined in the minds of Late Latin intellectuals with Christian ideas in three versions: passive-eclectic, contrast-nihilistic and respectful-condescending, which was conditioned both by life circumstances and chronologically

Narrative-based computational modelling of the Gp130/JAK/STAT signalling pathway.

BACKGROUND: Appropriately formulated quantitative computational models can support researchers in understanding the dynamic behaviour of biological pathways and support hypothesis formulation and selection by "in silico" experimentation. An obstacle to widespread adoption of this approach is the requirement to formulate a biological pathway as machine executable computer code. We have recently proposed a novel, biologically intuitive, narrative-style modelling language for biologists to formulate the pathway which is then automatically translated into an executable format and is, thus, usable for analysis via existing simulation techniques. RESULTS: Here we use a high-level narrative language in designing a computational model of the gp130/JAK/STAT signalling pathway and show that the model reproduces the dynamic behaviour of the pathway derived by biological observation. We then "experiment" on the model by simulation and sensitivity analysis to define those parameters which dominate the dynamic behaviour of the pathway. The model predicts that nuclear compartmentalisation and phosphorylation status of STAT are key determinants of the pathway and that alternative mechanisms of signal attenuation exert their influence on different timescales. CONCLUSION: The described narrative model of the gp130/JAK/STAT pathway represents an interesting case study showing how, by using this approach, researchers can model biological systems without explicitly dealing with formal notations and mathematical expressions (typically used for biochemical modelling), nevertheless being able to obtain simulation and analysis results. We present the model and the sensitivity analysis results we have obtained, that allow us to identify the parameters which are most sensitive to perturbations. The results, which are shown to be in agreement with existing mathematical models of the gp130/JAK/STAT pathway, serve us as a form of validation of the model and of the approach itself

Antioxidant effects of resveratrol in cardiovascular, cerebral and metabolic diseases.

Resveratrol-a natural polyphenolic compound-was first discovered in the 1940s. Although initially used for cancer therapy, it has shown beneficial effects against most cardiovascular and cerebrovascular diseases. A large part of these effects are related to its antioxidant properties. Here we review: a) the sources, the metabolism, and the bioavailability of resveratrol; b) the ability of resveratrol to modulate redox signalling and to interact with multiple molecular targets of diverse intracellular pathways; c) its protective effects against oxidative damage in cardio-cerebro-vascular districts and metabolic disorders such as diabetes; and d) the evidence for its efficacy and toxicity in humans. The overall aim of this review is to discuss the frontiers in the field of resveratrol's mechanisms, bioactivity, biology, and health-related use

Identification of novel components in fibroblast growth factor signalling

Fibroblast growth factor receptors play many roles in development, cell proliferation and differentiation. They possess intrinsic tyrosine kinase activity which enables activation of other signalling proteins, formation of multiprotein signalling complexes and activation of downstream cascades. The goal of this project was to identify novel FGFR1 interacting proteins. The strategy employed for mapping novel partners on the basis of peptide-protein interaction was peptide pull-down. Using synthetic pairs of phosphorylated and unphosphorylated peptides, pull down experiments were performed to enrich phospho-specific binding partners which then were identified by mass spectrometry. Experiments carried out using FGFR1 peptides revealed novel proteins associated with receptor. Signal transducer and activator of transcription 3 (STAT3) was identified as a phospho-dependent partner for Tyr677 of FGFR1. Mutation of this tyrosine to phenylalanine eliminated the binding of STAT3 to FGFR1. Furthermore, it was presented that STAT3 tyrosine phosphorylation required over-expression of FGFRs, as shown in the breast cancer cell line, SUM-52PE. The inhibition of Src and Janus non receptor tyrosine kinases decreased FGF1-induced tyrosine STAT3 phosphorylation. The findings suggested that FGFR kinase activity was mandatory for physical association between FGFR and STAT3 and its subsequent tyrosine activation by Src and Jak kinases. Moreover, Src and Jak2 were demonstrated to form a complex with kinase active FGFR1. Finally, STAT3 was serine phosphorylated by JNK and ERK kinases, which were activated by FGF1 stimulation. Since over-expression of FGFRs is correlated with tumour development and STAT3 is a well known oncogene, it is possible that the FGFRSTAT3 signalling pathway is up regulated in cancer cells and therefore merits consideration as a therapeutic target

The analysis of fungal flora in people with clinical changes occurring on skin and nails.

Zakażenia grzybicze skóry i jej przydatków, pomimo postępu w diagnostyce oraz leczeniu, stanowią poważny, ciągle aktualny problem zdrowotny, epidemiologiczny, jak i społeczny. Celem niniejszej pracy była ocena częstości występowania grzybów w materiałach pobranych z klinicznie zmienionych paznokci oraz ze zmian na skórze, od pacjentów zgłaszających się do pracowni mikologicznej.Materiał do badań stanowiło 100 próbek klinicznych, pobranych z ognisk chorobowo zmienionych, od 76 pacjentów, w tym 36 kobiet (47,4%) oraz 40 mężczyzn (52,6%). Diagnostykę mikologiczną przeprowadzono zgodnie z aktualnie obowiązującymi metodami laboratoryjnymi.Zakażenie grzybicze rozpoznano u 36 chorych. Z badanych próbek wyhodowano 52 szczepy grzybów. 23 (44,22%) zidentyfikowano jako dermatofity, 23 (44,22%) jako grzyby pleśniowe oraz 6 jako grzyby drożdżopodobne (11,52%). Najczęściej izolowano Trichophyton rubrum (34,6%), Penicillium spp. (19,2%), Scopulariopsis brevicaulis (9,6%).Najczęstszym miejscem zakażenia były paznokcie stóp. Głównymi patogenami wywołującymi grzybice paznokci są grzyby pleśniowe (46,2%), następnie dermatofity (41,4%) oraz grzyby drożdżopodobne (12,1%). Wśród grzybów pleśniowych izolowano głównie Penicillium spp. (14,6%) oraz S. brevicaulis (12,2%), wśród dermatofitów – T. rubrum (31,7%), natomiast wśród grzybów drożdżopodobnych – Candida spp. (7,3%).Although there has been progress in diagnostics and treatment, fungal infections of skin and its appendages are a serious and still current health problem, epidemiological problem as well as a social problem.The aim of this dissertation was the evaluation of frequency of fungal occurrence in materials obtained from clinically altered nails and changes on skin, which were received from patients who reported themselves to the mycological laboratory.100 clinical specimens were the material for research. They were obtained from altered lesions of 76 patients, 36 women (47,4%) and 40 men (52,6%). The mycological diagnostics was conducted in accordance with currently valid laboratory methods. Fungal infection was diagnosed in 36 patients. From the examined specimens 52 fungal strains were cultivated. 23 (44,22%) were identified as dermatophytes, 23 (44,22%) as molds and 6 (11,52%) as yeast-like fungi. Trichophyton rubrum (34,6%), Penicillium spp. (19,2%), Scopulariopsis brevicaulis (9,6%) were isolated most commonly. The most frequent place of infection was toenails. The main pathogens causing fungal infections on nails are molds (46,2%), then dermatophytes (41,4%) and yeast-like fungi (12,1%). Among molds Penicillium spp. (14,6%) oraz S. brevicaulis (12,2%) were mostly isolated; in dermatophytes—T. rubrum (31,7%); whereas in yeast-like fungi—Candida spp. (7,3%)

Signal transducers and activators of transcription-3 binding to the fibroblast growth factor receptor is activated by receptor amplification.

Fibroblast growth factor receptors (FGFRs) are cell surface tyrosine kinases that function in cell proliferation and differentiation. Aberrant FGFR signaling occurs in diverse cancers due to gene amplification, but the associated oncogenic mechanisms are poorly understood. Using a proteomics approach, we identified STAT3 as a receptor binding partner that is mediated by Tyr677 phosphorylation on FGFR. Binding to activated FGFR was essential for subsequent tyrosine phosphorylation and nuclear translocation of STAT3, along with activation of its downstream target genes. Tyrosine phosphorylation of STAT3 was also dependent upon concomitant FGFR-dependent activity of SRC and JAK kinases. Lastly, tyrosine (but not serine) phosphorylation of STAT3 required amplified FGFR protein expression, generated either by enforced overexpression or as associated with gene amplification in cancer cells. Our findings show that amplified FGFR expression engages the STAT3 pathway, and they suggest therapeutic strategies to attack FGFR-overexpressing cancers