Differential effects of high-fat diet on myocardial lipid metabolism in failing and nonfailing hearts with angiotensin II-mediated cardiac remodeling in mice.

Normal myocardium adapts to increase of nutritional fatty acid supply by upregulation of regulatory proteins of the fatty acid oxidation pathway. Because advanced heart failure is associated with reduction of regulatory proteins of fatty acid oxidation, we hypothesized that failing myocardium may not be able to adapt to increased fatty acid intake and therefore undergo lipid accumulation, potentially aggravating myocardial dysfunction. We determined the effect of high-fat diet in transgenic mice with overexpression of angiotensinogen in the myocardium (TG1306/R1). TG1306/R1 mice develop ANG II-mediated left ventricular hypertrophy, and at one year of age approximately half of the mice present heart failure associated with reduced expression of regulatory proteins of fatty acid oxidation and reduced palmitate oxidation during ex vivo working heart perfusion. Hypertrophied hearts from TG1306/R1 mice without heart failure adapted to high-fat feeding, similarly to hearts from wild-type mice, with upregulation of regulatory proteins of fatty acid oxidation and enhancement of palmitate oxidation. There was no myocardial lipid accumulation or contractile dysfunction. In contrast, hearts from TG1306/R1 mice presenting heart failure were unable to respond to high-fat feeding by upregulation of fatty acid oxidation proteins and enhancement of palmitate oxidation. This resulted in accumulation of triglycerides and ceramide in the myocardium, and aggravation of contractile dysfunction. In conclusion, hearts with ANG II-induced contractile failure have lost the ability to enhance fatty acid oxidation in response to increased fatty acid supply. The ensuing accumulation of lipid compounds may play a role in the observed aggravation of contractile dysfunction.

Helicase-defective RuvB(D113E) promotes RuvAB-mediated branch migration in vitro.

In Escherichia coli, the RuvA and RuvB proteins interact at Holliday junctions to promote branch migration leading to the formation of heteroduplex DNA. RuvA provides junction-binding specificity and RuvB drives ATP-dependent branch migration. Since RuvB contains sequence motifs characteristic of a DNA helicase and RuvAB exhibit helicase activity in vitro, we have analysed the role of DNA unwinding in relation to branch migration. A mutant RuvB protein, RuvB(D113E), mutated in helicase motif II (the DExx box), has been purified to homogeneity. The mutant protein forms hexameric rings on DNA similar to those formed by wild-type protein and promotes branch migration in the presence of RuvA. However, RuvB(D113E) exhibits reduced ATPase activity and is severely compromised in its DNA helicase activity. Models for RuvAB-mediated branch migration that invoke only limited DNA unwinding activity are proposed.

Proactive motivation and engagement in career behaviors: Investigating direct, mediated, and moderated effects

Proactive career behaviors become increasingly important in today's career environment, but little is known about how and when motivational patterns affect individual differences. In a six-month longitudinal study among German university students (Study 1; N = 289) it was demonstrated that motivation in terms of "can do" (self-efficacy and context beliefs), "reason to" (autonomous career goals), and "energized to" (positive affect) significantly predicted career behaviors. Contrary to expectation, negative context beliefs had a positive effect when combined with other motivational states. Study 2 replicated and extended those results by investigating whether "can do" motivation mediates the effect of proactive personality and whether those effects are conditional upon the degree of career choice decidedness. We tested a moderated multiple mediation model with a unique sample of 134 German students, assessed three times, each interval being 6 weeks apart. The results showed that effects of proactivity were partially carried through higher self-efficacy beliefs but not context beliefs. Supporting a moderation model, indirect effects through self-efficacy beliefs were not present for students with very low decidedness.

Recruitment of TNF receptor 1 to lipid rafts is essential for TNFalpha-mediated NF-kappaB activation.

Engagement of TNF receptor 1 by TNFalpha activates the transcription factor NF-kappaB but can also induce apoptosis. Here we show that upon TNFalpha binding, TNFR1 translocates to cholesterol- and sphingolipid-enriched membrane microdomains, termed lipid rafts, where it associates with the Ser/Thr kinase RIP and the adaptor proteins TRADD and TRAF2, forming a signaling complex. In lipid rafts, TNFR1 and RIP are ubiquitylated. Furthermore, we provide evidence that translocation to lipid rafts precedes ubiquitylation, which leads to the degradation via the proteasome pathway. Interfering with lipid raft organization not only abolishes ubiquitylation but switches TNFalpha signaling from NF-kappaB activation to apoptosis. We suggest that lipid rafts are crucial for the outcome of TNFalpha-activated signaling pathways.

Lentiviral-mediated gene transfer of siRNAs for the treatment of Huntington's disease.

This chapter describes the potential use of viral-mediated gene transfer in the central nervous system for the silencing of gene expression using RNA interference in the context of Huntington's disease (HD). Protocols provided here describe the design of small interfering RNAs, their encoding in lentiviral vectors (LVs) and viral production, as well as procedures for their stereotaxic injection in the rodent brain.

Adenovirus-mediated gene transfer into selected liver segments using a vascular exclusion technique.

Adenovirus-mediated gene therapy is hampered by severe virus-related toxicity, especially to the liver. The aim of the present study was to test the ability of a vascular exclusion technique to achieve transgene expression within selected liver segments, thus minimizing both viral and transgene product toxicity to the liver. An E1-E3-deleted replication-deficient adenovirus expressing a green fluorescent protein (GFP) reporter gene was injected into the portal vein of BDIX rats, with simultaneous clamping of the portal vein tributaries to liver segments II, III, IV, V, and VIII. GFP expression and inflammatory infiltrate were measured in the different segments of the liver and compared with those of the livers of animals receiving the viral vector in the portal vein without clamping. The GFP expression was significantly higher in the selectively perfused segments of the liver as compared with the non-perfused segments (p < 0.0001) and with the livers of animals that received the vector in the portal vein without clamping (p < 0.0001). Accordingly, the inflammatory infiltrate was more intense in the selectively perfused liver segments as compared with all other groups (p < 0.0001). Fluorescence was absent in lungs and kidneys and minimal in spleen. The clinical usefulness of adenovirus-mediated gene transfer to the liver largely depends on the reduction of its liver toxicity. Clamping of selected portal vein branches during injection allows for delivery of genes of interest to targeted liver segments. Transgene expression confined to selected liver segments may be useful in the treatment of focal liver diseases, including metastases.

Selective neurodegeneration induced in rotation-mediated aggregate cell cultures by a transient switch to stationary culture conditions: a potential model to study ischemia-related pathogenic mechanisms.

Aggregating brain cell cultures at an advanced maturational stage (20-21 days in vitro) were subjected for 1-3 h to anaerobic (hypoxic) and/or stationary (ischemic) conditions. After restoration of the normal culture conditions, cell loss was estimated by measuring the release of lactate dehydrogenase as well as the irreversible decrease of cell type-specific enzyme activities, total protein and DNA content. Ischemia for 2 h induced significant neuronal cell death. Hypoxia combined with ischemia affected both neuronal and glial cells to different degrees (GABAergic neurons>cholinergic neurons>astrocytes). Hypoxic and ischemic conditions greatly stimulated the uptake of 2-deoxy-D-glucose, indicating increased glucose consumption. Furthermore, glucose restriction (5.5 mM instead of 25 mM) dramatically increased the susceptibility of neuronal and glial cells to hypoxic and ischemic conditions. Glucose media concentrations below 2 mM caused selective neuronal cell death in otherwise normal culture conditions. GABAergic neurons showed a particularly high sensitivity to glucose restriction, hypoxia, and ischemia. The pattern of ischemia-induced changes in vitro showed many similarities to in vivo findings, suggesting that aggregating brain cell cultures provide a useful in vitro model to study pathogenic mechanisms related to brain ischemia.

The role of transcription factories-mediated interchromosomal contacts in the organization of nuclear architecture.

Using numerical simulations, we investigate the underlying physical effects responsible for the overall organization of chromosomal territories in interphase nuclei. In particular, we address the following three questions: (i) why are chromosomal territories with relatively high transcriptional activity on average, closer to the centre of cell's nucleus than those with the lower activity? (ii) Why are actively transcribed genes usually located at the periphery of their chromosomal territories? (iii) Why are pair-wise contacts between active and inactive genes less frequent than those involving only active or only inactive genes? We show that transcription factories-mediated contacts between active genes belonging to different chromosomal territories are instrumental for all these features of nuclear organization to emerge spontaneously due to entropic effects arising when chromatin fibres are highly crowded.

Low dose endoluminal photodynamic therapy improves murine T cell-mediated colitis.

BACKGROUND AND STUDY AIMS: Low dose photodynamic therapy (LDPDT) may modify the mucosal immune response and may thus provide a therapy for Crohn's disease. We evaluated the efficacy and safety of this technique in a murine T cell-mediated colitis model. METHODS: The safety of LDPDT was first tested in BALB/c mice. Naïve T cells were used to induce colitis in mice with severe combined immunodeficiency, which were followed up endoscopically, and a murine endoscopic index of colitis (MEIC) was developed. The efficacy of LDPDT (10 J/cm (2); delta-aminolevulinic acid, 15 mg/kg bodyweight) was then tested on mice with moderate colitis, while a disease control group received no treatment. The MEIC, weight, length, and histology of the colon, cytokine expression indices, number of mucosal CD4 (+) T cells, percentage of apoptotic CD4 (+) T cells, body weight, and systemic side effects were evaluated. RESULTS: LDPDT improved the MEIC ( P = 0.011) and the histological score ( P = 0.025), diminished the expression indices of the proinflammatory cytokines, interleukin-6 ( P = 0.042), interleukin-17 ( P = 0.029), and interferon-gamma ( P = 0.014), decreased the number of mucosal CD4 (+) T cells, and increased the percentage of apoptotic CD4 (+) T cells compared with the disease control group. No local or systemic side effects occurred. CONCLUSION: LDPDT improves murine T cell-mediated colitis, decreases the proinflammatory cytokines interleukin-6, interleukin-17, and interferon-gamma, and decreases the number of CD4 (+) T cells. No adverse events were observed. Therefore, this technique is now being evaluated in patients with inflammatory bowel disease.

Whole genome analysis of p38 SAPK-mediated gene expression upon stress

Background: Cells have the ability to respond and adapt to environmental changes through activation of stress-activated protein kinases (SAPKs). Although p38 SAPK signalling is known to participate in the regulation of gene expression little is known on the molecular mechanisms used by this SAPK to regulate stress-responsive genes and the overall set of genes regulated by p38 in response to different stimuli.Results: Here, we report a whole genome expression analyses on mouse embryonic fibroblasts (MEFs) treated with three different p38 SAPK activating-stimuli, namely osmostress, the cytokine TNFα and the protein synthesis inhibitor anisomycin. We have found that the activation kinetics of p38α SAPK in response to these insults is different and also leads to a complex gene pattern response specific for a given stress with a restricted set of overlapping genes. In addition, we have analysed the contribution of p38α the major p38 family member present in MEFs, to the overall stress-induced transcriptional response by using both a chemical inhibitor (SB203580) and p38α deficient (p38α-/-) MEFs. We show here that p38 SAPK dependency ranged between 60% and 88% depending on the treatments and that there is a very good overlap between the inhibitor treatment and the ko cells. Furthermore, we have found that the dependency of SAPK varies depending on the time the cells are subjected to osmostress. Conclusions: Our genome-wide transcriptional analyses shows a selective response to specific stimuli and a restricted common response of up to 20% of the stress up-regulated early genes that involves an important set of transcription factors, which might be critical for either cell adaptation or preparation for continuous extra-cellular changes. Interestingly, up to 85% of the up-regulated genes are under the transcriptional control of p38 SAPK. Thus, activation of p38 SAPK is critical to elicit the early gene expression program required for cell adaptation to stress.

Motivational effects of cannabinoids are mediated by μ-opioid and k-opioid receptor

Repeated THC administration produces motivational and somaticadaptive changes leading to dependence in rodents. Toinvestigate the molecular basis for cannabinoid dependenceand its possible relationship with the endogenous opioid system,we explored Δ9-tetrahydrocannabinol (THC) activity in mice lacking μ-, δ- or κ-opioid receptor genes. Acute THCinduced hypothermia, antinociception, and ypolocomotion remained unaffected in these mice, whereas THC tolerance and withdrawal were minimally modified in mutant animals. In contrast, profound phenotypic changes are observed in several place conditioning protocols that reveal both THC rewarding and aversive properties. Absence of μ receptors abolishes THC place preference. Deletion of κ receptors ablates THC place aversion and furthermore unmasks THC place preference. Thus, an opposing activity of μ- and κ-opioid receptors in modulating reward pathways forms the basis for the dual euphoric–dysphoric activity of THC.

Apoptosis induced by death receptors.

Death receptors belong to the TNF receptor family and are characterised by an intracellular death domain that serves to recruit adapter proteins such as TRADD and FADD and cysteine proteases such as Caspase-8. Activation of Caspase-8 on the aggregated receptor leads to apoptosis. Triggering of death receptors is mediated through the binding of specific ligands of the TNF family, which are homotrimeric type-2 membrane proteins displaying three receptor binding sites. There are various means of modulating the activation of death receptors. The status of the ligand (membrane-bound vs. soluble) is critical in the activation of Fas and of TRAIL receptors. Cleavage of membrane-bound FasL to a soluble form (sFasL) does not affect its ability to bind to Fas but drastically decreases its cytotoxic activity. Conversely, cross-linking epitope-tagged sFasL with anti-tag antibodies to mimic membrane-bound ligand results in a 1000-fold increase in cytotoxicity. This suggests that more than three Fas molecules need to be aggregated to efficiently signal apoptosis. Death receptors can also be regulated by decoy receptors. The cytotoxic ligand TRAIL interacts with five receptors, only two of which (TRAIL-R1 and -R2) have a death domain. TRAIL-R3 is anchored to the membrane by a glycolipid and acts as a dominant negative inhibitor of TRAIL-mediated apoptosis when overexpressed on TRAIL-sensitive cells. Intracellular proteins interacting with the apoptotic pathway are potential modulators of death receptors. FLIP resembles Caspase-8 in structure but lacks protease activity. It interacts with both FADD and Caspase-8 to inhibits the apoptotic signal of death receptors and, at the same time, can activate other signalling pathways such as that leading to NF-kappa B activation.

FIST/HIPK3: a Fas/FADD-interacting serine/threonine kinase that induces FADD phosphorylation and inhibits fas-mediated Jun NH(2)-terminal kinase activation.

Fas is a cell surface death receptor that signals apoptosis. Several proteins have been identified that bind to the cytoplasmic death domain of Fas. Fas-associated death domain (FADD), which couples Fas to procaspase-8, and Daxx, which couples Fas to the Jun NH(2)-terminal kinase pathway, bind independently to the Fas death domain. We have identified a 130-kD kinase designated Fas-interacting serine/threonine kinase/homeodomain-interacting protein kinase (FIST/HIPK3) as a novel Fas-interacting protein. Binding to Fas is mediated by a conserved sequence in the COOH terminus of the protein. FIST/HIPK3 is widely expressed in mammalian tissues and is localized both in the nucleus and in the cytoplasm. In transfected cell lines, FIST/HIPK3 causes FADD phosphorylation, thereby promoting FIST/HIPK3-FADD-Fas interaction. Although Fas ligand-induced activation of Jun NH(2)-terminal kinase is impaired by overexpressed active FIST/HIPK3, cell death is not affected. These results suggest that Fas-associated FIST/HIPK3 modulates one of the two major signaling pathways of Fas.

Transcriptional activation of the macrophage migration-inhibitory factor gene by the corticotropin-releasing factor is mediated by the cyclic adenosine 3',5'- monophosphate responsive element-binding protein CREB in pituitary cells.

Macrophage migration-inhibitory factor (MIF) has recently been identified as a pituitary hormone that functions as a counterregulatory modulator of glucocorticoid action within the immune system. In the anterior pituitary gland, MIF is expressed in TSH- and ACTH-producing cells, and its secretion is induced by CRF. To investigate MIF function and regulation within pituitary cells, we initiated the characterization of the MIF 5'-regulatory region of the gene. The -1033 to +63 bp of the murine MIF promoter was cloned 5' to a luciferase reporter gene and transiently transfected into freshly isolated rat anterior pituitary cells. This construct drove high basal transcriptional activity that was further enhanced after stimulation with CRF or with an activator of adenylate cyclase. These transcriptional effects were associated with a concomitant rise in ACTH secretion in the transfected cells and by an increase in MIF gene expression as assessed by Northern blot analysis. A cAMP-responsive element (CRE) was identified within the MIF promoter region which, once mutated, abolished the cAMP responsiveness of the gene. Using this newly identified CRE, DNA-binding activity was detected by gel retardation assay in nuclear extracts prepared from isolated anterior pituitary cells and AtT-20 corticotrope tumor cells. Supershift experiments using antibodies against the CRE-binding protein CREB, together with competition assays and the use of recombinant CREB, allowed the detection of CREB-binding activity with the identified MIF CRE. These data demonstrate that CREB is the mediator of the CRF-induced MIF gene transcription in pituitary cells through an identified CRE in the proximal region of the MIF promoter.