The Myb/SANT domain of the telomere-binding protein TRF2 alters chromatin structure

Eukaryotic DNA is packaged into chromatin, which regulates genome activities such as telomere maintenance. This study focuses on the interactions of a myb/SANT DNA-binding domain from the telomere-binding protein, TRF2, with reconstituted telomeric nucleosomal array fibers. Biophysical characteristics of the factor-bound nucleosomal arrays were determined by analytical agarose gel electrophoresis (AAGE) and single molecules were visualized by atomic force microscopy (AFM). The TRF2 DNA-binding domain (TRF2 DBD) neutralized more negative charge on the surface of nucleosomal arrays than histone-free DNA. Binding of TRF2 DBD at lower concentrations increased the radius and conformational flexibility, suggesting a distortion of the fiber structure. Additional loading of TRF2 DBD onto the nucleosomal arrays reduced the flexibility and strongly blocked access of micrococcal nuclease as contour lengths shortened, consistent with formation of a unique, more compact higher-order structure. Mirroring the structural results, TRF2 DBD stimulated a strand invasion-like reaction, associated with telomeric t-loops, at lower concentrations while inhibiting the reaction at higher concentrations. Full-length TRF2 was even more effective at stimulating this reaction. The TRF2 DBD had less effect on histone-free DNA structure and did not stimulate the t-loop reaction with this substrate, highlighting the influence of chromatin structure on the activities of DNA-binding proteins

Granulocyte-Colony Stimulating Factor Reactivates Human Cytomegalovirus in a Latently Infected Humanized Mouse Model

Human cytomegalovirus (HCMV) continues to be a significant cause of morbidity and mortality in organ transplant recipients despite the availability of antiviral therapy. Considerable controversy exists regarding the use of granulocyte-colony stimulating factor (G-CSF) mobilized blood products from HCMV seropositive donors during stem cell transplantation (SCT) and in patients receiving granulocyte transfusions to treat neutropenia. In order to understand mechanisms of HCMV transmission to patients receiving G-CSF mobilized blood products, we generated a novel NOD-scid IL2Rγcnull humanized mouse model in which HCMV establishes a latent infection in human hematopoietic lineage cells. In this model, G-CSF induces the reactivation of latent HCMV in monocytes/macrophages that have migrated into organ tissues. These results suggest that the use of G-CSF mobilized blood products from seropositive donors pose an elevated risk for HCMV transmission to recipients

Risk of Meningioma in European Patients Treated With Growth Hormone in Childhood: Results From the SAGhE Cohort.

Context:There has been concern that GH treatment of children might increase meningioma risk. Results of published studies have been inconsistent and limited. Objective:To examine meningioma risks in relation to GH treatment. Design:Cohort study with follow-up via cancer registries and other registers. Setting:Population-based. Patients:A cohort of 10,403 patients treated in childhood with recombinant GH in five European countries since this treatment was first used in 1984. Expected rates from national cancer registration statistics. Main Outcome Measures:Risk of meningioma incidence. Results:During follow-up, 38 meningiomas occurred. Meningioma risk was greatly raised in the cohort overall [standardized incidence ratio (SIR) = 75.4; 95% CI: 54.9 to 103.6], as a consequence of high risk in subjects who had received radiotherapy for underlying malignancy (SIR = 658.4; 95% CI: 460.4 to 941.7). Risk was not significantly raised in patients who did not receive radiotherapy. Risk in radiotherapy-treated patients was not significantly related to mean daily dose of GH, duration of GH treatment, or cumulative dose of GH. Conclusions:Our data add to evidence of very high risk of meningioma in patients treated in childhood with GH after cranial radiotherapy, but suggest that GH may not affect radiotherapy-related risk, and that there is no material raised risk of meningioma in GH-treated patients who did not receive radiotherapy

Population biology of establishment in New Zealand hedgehogs inferred from genetic and historical data: conflict or compromise?

The crucial steps in biological invasions, related to the shaping of genetic architecture and the current evolution of adaptations to a novel environment, usually occur in small populations during the phases of introduction and establishment. However, these processes are difficult to track in nature due to invasion lag, large geographic and temporal scales compared with human observation capabilities, the frequent depletion of genetic variance, admixture and other phenomena. In this study, we compared genetic and historical evidence related to the invasion of the West European hedgehog to New Zealand to infer details about the introduction and establishment. Historical information indicates that the species was initially established on the South Island. A molecular assay of populations from Great Britain and New Zealand using mitochondrial sequences and nuclear microsatellite loci was performed based on a set of analyses including approximate Bayesian computation, a powerful approach for disentangling complex population demographies. According to these analyses, the population of the North Island was most similar to that of the native area and showed greatest reduction in genetic variation caused by founder demography and/or drift. This evidence indicated the location of the establishment phase. The hypothesis was corroborated by data on climate and urbanization. We discuss the contrasting results obtained by the molecular and historical approaches in the light of their different explanatory power and the possible biases influencing the description of particular aspects of invasions, and we advocate the integration of the two types of approaches in invasion biology

Genetic Analysis of GHR Should Contain Sequencing of All Coding Exons and Specific Intron Sequences, and Screening for Exon Deletions

Epidemiology in Pediatrics and Child Healt