GSK3β-SCFFBXW7α mediated phosphorylation and ubiquitination of IRF1 are required for its transcription-dependent turnover

IRF1 (Interferon Regulatory Factor-1) is the prototype of the IRF family of DNA binding transcription factors. IRF1 protein expression is regulated by transient up-regulation in response to external stimuli followed by rapid degradation via the ubiquitin-proteasome system. Here we report that DNA bound IRF1 turnover is promoted by GSK3β (Glycogen Synthase Kinase 3β) via phosphorylation of the T181 residue which generates a phosphodegron for the SCF (Skp-Cul-Fbox) ubiquitin E3-ligase receptor protein Fbxw7α (F-box/WD40 7). This regulated turnover is essential for IRF1 activity, as mutation of T181 results in an improperly stabilised protein that accumulates at target promoters but fails to induce RNA-Pol-II elongation and subsequent transcription of target genes. Consequently, the anti-proliferative activity of IRF1 is lost in cell lines expressing T181A mutant. Further, cell lines with dysfunctional Fbxw7 are less sensitive to IRF1 overexpression, suggesting an important co-activator function for this ligase complex. As T181 phosphorylation requires both DNA binding and RNA-Pol-II elongation, we propose that this event acts to clear " spent " molecules of IRF1 from transcriptionally engaged target promoters

The Cancer Research UK Stratified Medicine Programme as a model for delivering personalised cancer care

Genomic screening is routinely used to guide the treatment of cancer patients in many countries. However, several multi-layered factors make this effort difficult to deliver within a clinically relevant timeframe. Here we share the learnings from the CRUK-funded Stratified Medicine Programme for advanced NSCLC patients, which could be useful to better plan future studies

Expression of dystroglycan correlates with tumor grade and predicts survival in renal cell carcinoma.

The dystroglycan (DG) complex is a transmembrane glycoprotein that forms a continuous link from the extracellular matrix to the actin cytoskeleton. Deregulated expression of DG has been reported in a variety of human malignancies and related to tumor aggressiveness. In this study expression of the DG subunit was evaluated by immunostaining in a series of renal epithelial cancers and its relation with traditional prognostic indicators and with the clinical outcome of the patients was evaluated. alphaDG expression was undetectable in a significant fraction of tumors (54%). In renal cell carcinomas (RCC) loss of alpha-DG staining correlated with higher tumor grade (p = 0.02) but not with tumor stage nor tumor size. In clear cell RCC patients loss of alphaDG staining correlated with an increased risk of recurrence (p = 0.002 by log-rank test) and death (p = 0.004) also when patients with lower grade or stage tumors were analyzed separately. In a multivariate analysis loss of DG staining confirmed to be and independent predictor of shorter disease-free (p = 0.001; RR = 4.9) and overall (p = 0.009; RR = 4.9) survival stronger than tumor grade and size. These findings demonstrate that loss of alphaDG expression, which correspond to loss of a functional DG complex, is a frequent event in human renal tumorigenesis and is an independent predictor of early recurrence and death for patients with clear cell RCC

Gyrokinetic modelling of the Alfvén mode activity in ASDEX Upgrade with an isotropic slowing-down fast-particle distribution

In the present paper, the evolution of the Alfv\'en modes is studied in a realistic ASDEX Upgrade equilibrium by analysing the results of simulations with the global, electromagnetic, gyrokinetic particle-in-cell code ORB5. The energetic particles are modelled both via the newly implemented isotropic slowing-down and with Maxwellian distribution functions. The comparison of the numerical results shows that modelling the energetic particles with the equivalent Maxwellian rather than with the slowing-down, does not affect the frequency of the driven Alfv\'en mode, while its growth rate appears to be underestimated with a quantitative difference as large as almost 30 %. Additionally the choice of the isotropic slowing-down allows a better description of the nonlinear modification of the dominant Alfv\'en mode frequency, while an equivalent Maxwellian underestimates it. A good comparison with the experimental spectrogram is found

The tumor suppressor HINT1 regulates MITF and \u3b2-catenin transcriptional activity in melanoma cells

Histidine triad nucleotide-binding protein 1 (HINT1) is a haploinsufficient tumor suppressor gene that inhibits the Wnt/\u3b2-catenin pathway in colon cancer cells and Microphthalmia-associated transcription factor (MITF) activity in human mast cells. MITF and \u3b2-catenin play a central role in melanocyte and melanoma cell survival, and this study aimed to investigate the effects of HINT1 on the MITF and \u3b2-catenin pathways in malignant melanoma cells. We found that HINT1 inhibits MITF and \u3b2-catenin transcriptional activity, and both proteins can be co-immunoprecipitated with an anti-HINT1-specific antibody in melanoma cell lines. Stable, constitutive overexpression of the HINT1 protein in human melanoma cells significantly impaired cell proliferation in vitro and tumorigenesis in vivo. These effects were associated with a decreased expression of cyclin D1 and BCL2, well known MITF and \u3b2-catenin transcription targets, respectively. We also demonstrated that BCL2 and cyclin D1 can partially rescue the HINT1-driven phenotype. Moreover, we found in ChIP assays that HINT1 binds the chromatin at MITF and \u3b2-catenin sites in BCL2 and cyclin D1 promoters, respectively, and that mSIN3a and HDAC1, well known transcriptional repressors, can be co-immunoprecipitated with an anti-HINT1-specific antibody. These findings support the tumor suppressor activity of HINT1 gene in melanoma cells by promoting the formation of non-functional complexes with oncogenic transcription factors like MITF and \u3b2-catenin