A model to investigate the oncogenic activity of MLL-fusions in Acute Myeloid Leukaemia

The MLL gene, located on 11q23, is involved in a large number of chromosomal translocations, including t(9;11)(p22;q23) and t(11;19)(p22;q23). These translocations encode the MLL-AF9 and MLL-ENL fusion transcription factors and are prevalent in infant acute leukaemia and therapy-related leukaemia. Leukaemias associated with these translocations have a particularly poor outcome. In order to conditionally express the MLL-AF9 fusion oncogene in primary haematopoietic progenitor cells, retroviral delivery of the Tet-off expression system was used. Progenitors were purified from murine bone marrow and co-infected with MSCV-TRE-fMLL-AF9 and MSCV-tTA retroviral supernatants. Using this approach, eight independent cell lines with conditional expression of MLL-AF9 and three independent cell lines with constitutive MLL-AF9 expression were generated. Treatment of the conditional cells with Doxycycline caused a decrease in MLL-AF9 mRNA and protein expression, and resulted in terminal differentiation of the cells. By analysing global changes in gene expression after treatment of cells with Doxycycline, using Mouse genome Affymetrix Gene Chips (430 2.0), we have identified a number of potential transcriptional target genes of the MLL-AF9 and MLL-ENL fusion oncogenes. In order to examine the importance of target genes for MLL-fusion mediated transformation, up-regulated target genes were knocked down in vitro. Knock-down of a small proportion of the target genes analysed caused MLL-ENL and MLL-AF9 immortalised cells to die. These data illustrate novel approaches to interfering with MLL-fusion activity in leukaemia. In order to establish the importance of MLL-fusion activity for leukaemia in vivo, and hence its dependence on the transcriptional target genes identified, MLL-ENL immortalised cell lines were chosen to be injected into primary recipients. Conditionally MLL-ENL immortalised cell lines were found to induced leukaemia in vivo. Leukaemic cells isolated from primary recipient mice were shown to have acquired additional genetic abnormalities and, when transplanted into secondary recipients, induced leukaemia with shortened latencies. However, the leukaemic cells remained dependent on MLL-ENL expression in vitro and in vivo, and its ablation resulted in regression of established leukaemias

The pregnane xenobiotic receptor, a prominent liver factor, has actions in the midbrain for neurosteroid synthesis and behavioral/neural plasticity of female rats

A novel factor of interest for growth/plasticity in the brain is pregnane xenobiotic receptor (PXR). PXR is a liver factor known for its role in xenobiotic clearance and cholesterol metabolism. It is expressed in the brain, suggesting a potential role for plasticity, particularly involving cholesterol-based steroids and neurosteroids. Mating induces synthesis of neurosteroids in the midbrain Ventral Tegmental Area (VTA) of female rodents, as well as other “plastic” regions of the brain, including the hippocampus, that may be involved in the consolidation of the mating experience. Reducing PXR in the VTA attenuates mating-induced biosynthesis of the neurosteroid, 5α-pregnan-3α-ol-20-one (3α,5α-THP). The 18 kDA translocator protein (TSPO) is one rate-limiting factor for 3α,5α-THP neurosteroidogenesis. The hypothesis tested was that PXR is an upstream factor of TSPO for neurosteroidogenesis of 3α,5α-THP in the VTA for lordosis, independent of peripheral glands. First, proestrous rats were administered a TSPO blocker (PK11195) and/or 3α,5α-THP following infusions of PXR antisense oligonucleotides (AS-ODNs) or vehicle to the VTA. Inhibiting TSPO with PK11195 reduced 3α,5α-THP levels in the midbrain and lordosis, an effect that could be reversed with 3α,5α-THP administration, but not AS-ODN+3α,5α-THP. Second, proestrous, ovariectomized (OVX), or ovariectomized/adrenalectomized (OVX/ADX) rats were infused with a TSPO enhancer (FGIN 1-27) subsequent to AS-ODNs or vehicle to the VTA. PXR AS-ODNs blocked actions of FGIN 1–27 for lordosis and 3α,5α-THP levels among proestrous > OVX > OVX/ADX rats. Thus, PXR may be upstream of TSPO, involved in neurosteroidogenesis of 3α,5α-THP in the brain for plasticity. This novel finding of a liver factor involved in behavioral/neural plasticity substantiates future studies investigating factors known for their prominent actions in the peripheral organs, such as the liver, for modulating brain function and its augmentation

Neurosteroidogenesis Today: Novel Targets for Neuroactive Steroid Synthesis and Action and Their Relevance for Translational Research

Neuroactive steroids are endogenous neuromodulators synthesised in the brain that rapidly alter neuronal excitability by binding to membrane receptors, in addition to the regulation of gene expression via intracellular steroid receptors. Neuroactive steroids induce potent anxiolytic, antidepressant, anticonvulsant, sedative, analgesic and amnesic effects, mainly through interaction with the γ-amino-butyric type A (GABAA) receptor. They also exert neuroprotective, neurotrophic and antiapoptotic effects in several animal models of neurodegenerative diseases

Effects and Mechanisms of 3α,5α,-THP on Emotion, Motivation, and Reward Functions Involving Pregnane Xenobiotic Receptor

Progestogens [progesterone (P4) and its products] play fundamental roles in the development and/or function of the central nervous system during pregnancy. We, and others, have investigated the role of pregnane neurosteroids for a plethora of functional effects beyond their pro-gestational processes. Emerging findings regarding the effects, mechanisms, and sources of neurosteroids have challenged traditional dogma about steroid action. How the P4 metabolite and neurosteroid, 3α-hydroxy-5α-pregnan-20-one (3α,5α-THP), influences cellular functions and behavioral processes involved in emotion/affect, motivation, and reward, is the focus of the present review. To further understand these processes, we have utilized an animal model assessing the effects, mechanisms, and sources of 3α,5α-THP. In the ventral tegmental area (VTA), 3α,5α-THP has actions to facilitate affective, and motivated, social behaviors through non-traditional targets, such as GABA, glutamate, and dopamine receptors. 3α,5α-THP levels in the midbrain VTA both facilitate, and/or are enhanced by, affective and social behavior. The pregnane xenobiotic receptor (PXR) mediates the production of, and/or metabolism to, various neurobiological factors. PXR is localized to the midbrain VTA of rats. The role of PXR to influence 3α,5α-THP production from central biosynthesis, and/or metabolism of peripheral P4, in the VTA, as well as its role to facilitate, or be increased by, affective/social behaviors is under investigation. Investigating novel behavioral functions of 3α,5α-THP extends our knowledge of the neurobiology of progestogens, relevant for affective/social behaviors, and their connections to systems that regulate affect and motivated processes, such as those important for stress regulation and neuropsychiatric disorders (anxiety, depression, schizophrenia, drug dependence). Thus, further understanding of 3α,5α-THP’s role and mechanisms to enhance affective and motivated processes is essential

Potentiale, Wirkungen und ökonomische Bewertung von hochwertigen Verkehrsinformationsdiensten

This paper analyzes the high-end range of traffic information systems for individual motorized traffic and for public transport. High value-added traffic services are characterized by dynamic, personalized information, including suggestions for alternative routing; they are supplied on a commercial basis, mainly by private enterprises. Based on a qualitative forecast of the diffusion of high value-added traffic information systems, we estimate their potential impact on the transport system as a whole, as well as on the environment. The approach also considers the strategies of the key actors (mainly enterprises) at each level of the value-added chain: Primary data collection and treatment, distribution of information services, data transfer, and the reception of information via specialized devices. The study concludes that high value-added traffic information systems will be much more widely diffused in the future, both in public transport and in individual motorized traffic. Traffic information services will also lead to a more efficient use of infrastructure. However, as regards economic policy, there seems to be no need for state intervention to remedy market failure. -- In diesem Beitrag werden hochwertige Verkehrsinformationsdienste für Nutzer des motorisierten Individualverkehrs (MIV) und des ÖPNV untersucht, die aus kommerziellen Interessen bereitgestellt werden und sich durch dynamische, personalisierte und empfehlende Verkehrsinformationen auszeichnen. Aufbauend auf einer qualitativen Prognose über die zukünftige Verbreitung hochwertiger Verkehrsinformationsdienste werden deren Auswirkungen auf das System Verkehr und die Umwelt ermittelt, um dann einen eventuellen wirtschaftspolitischen Handlungsbedarf abzuleiten. Dabei werden auch die Strategien der Schlüsselakteure auf den Märkten in die Überlegungen miteinbezogen. Bei der Analyse werden explizit die einzelnen Stufen der Wertschöpfungskette von Verkehrsinformationsdiensten betrachtet: Verkehrsdatenerhebung und -aufbereitung, Angebot und Vertrieb der Verkehrsinformationsdienste, Datenübertragung per Mobilfunk sowie Informationsausgabe auf Telematik-Endgeräten. Es wird festgestellt, dass zukünftig hochwertige Verkehrsinformationsdienste sowohl im ÖPNV wie auch im MIV eine weite Verbreitung erreichen und tendenziell zu einer effizienteren Nutzung der Infrastruktur beitragen werden. Ein wirtschaftspolitischer Handlungsbedarf im Markt für hochwertige Verkehrsinformationsdienste ergibt sich jedoch weder hieraus noch aus anderen Gründen.Telematics,Traffic Information Services,Market Failure,Market Development,Verkehrstelematik,Verkehrsinformationsdienste,Marktversagen,Marktentwicklung

The ontogeny of exploratory behavior in male and female adolescent rats (Rattus norvegicus)

Supported by Wellcome Trust grant 078405/Z/05/ZDuring adolescence, rats gain independence from their mothers and disperse from the natal burrow, with males typically dispersing further than females. We predicted that, if dispersal patterns are associated with responsiveness to novelty, exploratory behavior in novel environments would increase across adolescence, and males would explore more than females. Alternatively, females might explore more than males, if females are more motivated than males to learn about the immediate environment or if females have poorer spatial abilities than males. Twenty-five male and 21 female rats were exposed to two novel environments (open field and elevated plus-maze) during early, mid-, or late adolescence. Total locomotion and amount of exploration directed towards aversive areas increased across adolescence, even when body weight was included as a covariate. Female adolescents locomoted more and spent more time exploring aversive areas than males. Developmental changes in neural function potentially underlie age and sex differences in exploratory, behavior (C) 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 513-520, 2009.Publisher PDFPeer reviewe

Identification of a c-MYB-directed therapeutic for acute myeloid leukemia

A significant proportion of patients suffering from acute myeloid leukemia (AML) cannot be cured by conventional chemotherapy, relapsed disease being a common problem. Molecular targeting of essential oncogenic mediators is an attractive approach to improving outcomes for this disease. The hematopoietic transcription factor c-MYB has been revealed as a central component of complexes maintaining aberrant gene expression programs in AML. We have previously screened the Connectivity Map database to identify mebendazole as an anti-AML therapeutic targeting c-MYB. In the present study we demonstrate that another hit from this screen, the steroidal lactone withaferin A (WFA), induces rapid ablation of c-MYB protein and consequent inhibition of c-MYB target gene expression, loss of leukemia cell viability, reduced colony formation and impaired disease progression. Although WFA has been reported to have pleiotropic anti-cancer effects, we demonstrate that its anti-AML activity depends on c-MYB modulation and can be partially reversed by a stabilized c-MYB mutant. c-MYB ablation results from disrupted HSP/HSC70 chaperone protein homeostasis in leukemia cells following induction of proteotoxicity and the unfolded protein response by WFA. The widespread use of WFA in traditional medicines throughout the world indicates that it represents a promising candidate for repurposing into AML therapy

The Steroidogenesis Inhibitor Finasteride Reduces the Response to Both Stressful and Rewarding Stimuli

This work is licensed under a Creative Commons Attribution 4.0 International License.Finasteride (FIN) is the prototypical inhibitor of steroid 5α-reductase (5αR), the enzyme that catalyzes the rate-limiting step of the conversion of progesterone and testosterone into their main neuroactive metabolites. FIN is clinically approved for the treatment of benign prostatic hyperplasia and male baldness; while often well-tolerated, FIN has also been shown to cause or exacerbate psychological problems in vulnerable subjects. Evidence on the psychological effects of FIN, however, remains controversial, in view of inconsistent clinical reports. Here, we tested the effects of FIN in a battery of tests aimed at capturing complementary aspects of mood regulation and stress reactivity in rats. FIN reduced exploratory, incentive, prosocial, and risk-taking behavior; furthermore, it decreased stress coping, as revealed by increased immobility in the forced-swim test (FST). This last effect was also observed in female and orchiectomized male rats, suggesting that the mechanism of action of FIN does not primarily reflect changes in gonadal steroids. The effects of FIN on FST responses were associated with a dramatic decrease in corticotropin release hormone (CRH) mRNA and adrenocorticotropic hormone (ACTH) levels. These results suggest that FIN impairs stress reactivity and reduces behavioral activation and impulsive behavior by altering the function of the hypothalamus–pituitary–adrenal (HPA) axis

A Dominant Negative ERβ Splice Variant Determines the Effectiveness of Early or Late Estrogen Therapy after Ovariectomy in Rats

The molecular mechanisms for the discrepancy in outcome of initiating estrogen therapy (ET) around peri-menopause or several years after menopause in women are unknown. We hypothesize that the level of expression of a dominant negative estrogen receptor (ER) β variant, ERβ2, may be a key factor determining the effectiveness of ET in post-menopausal women. We tested this hypothesis in ovariectomized nine month-old (an age when irregular estrous cycles occur) female Sprague Dawley rats. Estradiol treatment was initiated either 6 days (Early ET, analogous to 4 months post-menopause in humans), or 180 days (Late ET, analogous to 11 years post-menopause in humans) after ovariectomy. Although ERβ2 expression increased in all OVX rats, neurogenic and neuroprotective responses to estradiol differed in Early and Late ET. Early ET reduced ERβ2 expression in both hippocampus and white blood cells, increased the hippocampal cell proliferation as assessed by Ki-67 expression, and improved mobility in the forced swim test. Late ET resulted in either no or modest effects on these parameters. There was a close correlation between the degree of ERβ2 expression and the preservation of neural effects by ET after OVX in rats, supporting the hypothesis that persistent elevated levels of ERβ2 are a molecular basis for the diminished effectiveness of ET in late post-menopausal women. The correlation between the expression of ERβ2 in circulating white blood cells and brain cells suggests that ERβ2 expression in peripheral blood cells may be an easily accessible marker to predict the effective window for ET in the brain