Prolactin in man: a tale of two promoters

The pituitary hormone prolactin (PRL) is best known for its role in the regulation of lactation. Recent evidence furthermore indicates PRL is required for normal reproduction in rodents. Here, we report on the insertion of two transposon-like DNA sequences in the human prolactin gene, which together function as an alternative promoter directing extrapituitary PRL expression. Indeed, the transposable elements contain transcription factor binding sites that have been shown to mediate PRL transcription in human uterine decidualised endometrial cells and lymphocytes. We hypothesize that the transposon insertion event has resulted in divergent (pituitary versus extrapituitary) expression of prolactin in primates, and in differential actions of pituitary versus extrapituitary prolactin in lactation versus pregnancy respectively. Importantly, the TE insertion might provide a context for some of the conflicting results obtained in studies of PRL function in mice and man. BioEssays 28: 1051–1055, 2006. © 2006 Wiley Periodicals, Inc

Social, educational and vocational outcomes in patients with childhood-onset and young-adult-onset growth hormone deficiency

Pfizer, Inc

A highly selective, label-free, homogenous luminescent switch-on probe for the detection of nanomolar transcription factor NF-kappaB

Transcription factors are involved in a number of important cellular processes. The transcription factor NF-κB has been linked with a number of cancers, autoimmune and inflammatory diseases. As a result, monitoring transcription factors potentially represents a means for the early detection and prevention of diseases. Most methods for transcription factor detection tend to be tedious and laborious and involve complicated sample preparation, and are not practical for routine detection. We describe herein the first label-free luminescence switch-on detection method for transcription factor activity using Exonuclease III and a luminescent ruthenium complex, [Ru(phen)2(dppz)]2+. As a proof of concept for this novel assay, we have designed a double-stranded DNA sequence bearing two NF-κB binding sites. The results show that the luminescence response was proportional to the concentration of the NF-κB subunit p50 present in the sample within a wide concentration range, with a nanomolar detection limit. In the presence of a known NF-κB inhibitor, oridonin, a reduction in the luminescence response of the ruthenium complex was observed. The reduced luminescence response of the ruthenium complex in the presence of small molecule inhibitors allows the assay to be applied to the high-throughput screening of chemical libraries to identify new antagonists of transcription factor DNA binding activity. This will allow the rapid and low cost identification and development of novel scaffolds for the treatment of diseases caused by the deregulation of transcription factor activity

Genetic regulation of pituitary gland development in human and mouse

Normal hypothalamopituitary development is closely related to that of the forebrain and is dependent upon a complex genetic cascade of transcription factors and signaling molecules that may be either intrinsic or extrinsic to the developing Rathke’s pouch. These factors dictate organ commitment, cell differentiation, and cell proliferation within the anterior pituitary. Abnormalities in these processes are associated with congenital hypopituitarism, a spectrum of disorders that includes syndromic disorders such as septo-optic dysplasia, combined pituitary hormone deficiencies, and isolated hormone deficiencies, of which the commonest is GH deficiency. The highly variable clinical phenotypes can now in part be explained due to research performed over the last 20 yr, based mainly on naturally occurring and transgenic animal models. Mutations in genes encoding both signaling molecules and transcription factors have been implicated in the etiology of hypopituitarism, with or without other syndromic features, in mice and humans. To date, mutations in known genes account for a small proportion of cases of hypopituitarism in humans. However, these mutations have led to a greater understanding of the genetic interactions that lead to normal pituitary development. This review attempts to describe the complexity of pituitary development in the rodent, with particular emphasis on those factors that, when mutated, are associated with hypopituitarism in humans

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

Nucleosome Chiral Transition under Positive Torsional Stress in Single Chromatin Fibers

Using magnetic tweezers to investigate the mechanical response of single chromatin fibers, we show that fibers submitted to large positive torsion transiently trap positive turns, at a rate of one turn per nucleosome. A comparison with the response of fibers of tetrasomes (the (H3-H4)2 tetramer bound with ~50 bp of DNA) obtained by depletion of H2A-H2B dimers, suggests that the trapping reflects a nucleosome chiral transition to a metastable form built on the previously documented righthanded tetrasome. In view of its low energy, <8 kT, we propose this transition is physiologically relevant and serves to break the docking of the dimers on the tetramer which in the absence of other factors exerts a strong block against elongation of transcription by the main RNA polymerase.Comment: 33 pages (double spacing), 7 figure

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

Cancer risks in patients treated with growth hormone in childhood: the SAGhE European cohort study.

Context: Growth hormone (GH) is prescribed for an increasing range of indications, but there has been concern that it might raise cancer risk. Published data are limited. Objective: To examine cancer risks in relation to GH treatment. Design: Cohort study. Setting: Population-based. Patients: Cohort of 23,984 patients treated with recombinant human GH (r-hGH) in eight European countries since this treatment was first used in 1984. Cancer expectations from country-specific national population statistics. Main Outcome Measures: Cancer incidence and cancer mortality. Results: Incidence and mortality risks in the cohort were raised for several cancer sites, largely consequent on second primary malignancies in patients given r-hGH after cancer treatment. There was no clear raised risk in patients with growth failure without other major disease. Only for bone and bladder cancers was incidence significantly raised in GH-treated patients without previous cancer. Cancer risk was unrelated to duration or cumulative dose of r-hGH treatment, but for patients treated after previous cancer, cancer mortality risk increased significantly with increasing daily r-hGH dose (P trend < 0.001). Hodgkin lymphoma (HL) incidence increased significantly with longer follow-up (P trend = 0.001 for patients overall and 0.002 for patients without previous cancer). Conclusions: Our results do not generally support a carcinogenic effect of r-hGH, but the unexplained trend in cancer mortality risk in relation to GH dose in patients with previous cancer, and the indication of possible effects on bone cancer, bladder cancer, and HL risks, need further investigation