CREM and ICER are differentially implicated in trans-synaptic induction of tyrosine hydroxylase gene expression in adrenal medulla and sympathetic ganglia of rat

Reserpine treatment leads to a trans-synaptic increase of the tyrosine hydroxylase (TH) gene transcription rate, mRNA and protein levels in catecholaminergic tissues including the adrenal medulla (AM) and the superior cervical ganglia (SCG). The TPA-responsive element plays an important role in the trans-synaptically-induced transcription of the TH gene in the AM, whereas it does not appear to be involved in the SCG (Trocmé et al. [1997] J. Neurosci. Res. 48:489-498). In this study, we show that another regulatory sequence of the TH proximal promoter, the cAMP-responsive element (CRE), binds different factors in the AM and in the SCG. To elucidate the dynamics of promoter regulation a complete time course analysis was conducted. Reserpine treatment enhances, between 1 hr and 8 hr after the injection, the expression and the binding of the repressor ICER in the AM, whereas in the SCG it enhances the binding of CREM factors. These results suggest that the mechanisms mediating trans-synaptic induction of the TH gene are different in the AM and SCG. The interplay between positive and negative transcription factors and their kinetics of action are responsive of the long-term regulation of the TH gene.

Synaptic sprouting increases the uptake capacities of motoneurons in amyotrophic lateral sclerosis mice

Using adenoviruses encoding reporter genes as retrograde tracers, we assessed the capacity of motoneurons to take up and retrogradely transport adenoviral particles injected into the muscles of transgenic mice expressing the G93A human superoxide dismutase mutation, a model of amyotrophic lateral sclerosis. Surprisingly, transgene expression in the motoneurons was significantly higher in symptomatic mice than in control or presymptomatic mice. Using botulinum toxin to induce nerve sprouting at neuromuscular junctions, we showed that the unexpectedly high level of motoneurons retrograde transduction results, at least in part, from newly acquired uptake properties of the sprouts. These findings demonstrate the remarkable uptake properties of amyotrophic lateral sclerosis motoneurons in response to denervation and the rationale of using intramuscular injections of adenoviruses to overexpress therapeutic proteins in motor neuron diseases.

Primary adult human astrocytes as an ex vivo vehicle for beta-glucuronidase delivery in the brain

Astrocytes are a good candidate cell type for brain transplantation: They are endogenous to the CNS, they have efficient secretory machinery, and they play a major role in neuronal support. We assessed the potential of genetically modified primary adult human astrocytes as vehicles for the delivery of secreted molecules in the mammalian CNS. We report that such cells can be efficiently transduced by a recombinant adenoviral vector carrying the human beta-glucuronidase cDNA (Ad/CMV*beta-glu) and that the transduced astrocytes produce large amounts of the enzyme. Released beta-glucuronidase could be captured, in vitro, by primary neurons and astrocytes and by a neuroblastoma cell line and beta-glucuronidase-deficient fibroblasts. Following grafting into the mouse striatum, adult human astrocytes survived and expressed the transgene for at least 8 weeks. Moreover, the dosage of beta-glucuronidase activity within the grafted brains revealed high enzymatic levels at a long distance from the graft. These experiments document the grafting of engineered primary adult human astrocytes, allowing the release of a secreted therapeutic factor throughout the brain.

No evidence for linkage between COMT and schizophrenia in a French population

Catechol-O-methyltransferase is a candidate in the predisposition to schizophrenia both because of its function and the position of its gene. A multipoint non-parametric linkage analysis and a transmission disequilibrium test were performed on 42 multiplex families genotyped for Pml I and Bcl I polymorphisms using two definitions of the affected phenotype. Neither linkage nor preferential transmission of any allele or haplotype was detected, failing to replicate previous positive findings.

Reproductive isolation caused by colour pattern mimicry

Speciation is facilitated if ecological adaptation directly causes assortative mating, but few natural examples are known. Here we show that a shift in colour pattern mimicry was crucial in the origin of two butterfly species. The sister species Heliconius melpomene and Heliconius cydno recently diverged to mimic different model taxa, and our experiments show that their mimetic coloration is also important in choosing mates. Assortative mating between the sister species means that hybridization is rare in nature, and the few hybrids that are produced are non-mimetic, poorly adapted intermediates. Thus, the mimetic shift has caused both pre-mating and post-mating isolation. In addition, individuals from a population of H. melpomene allopatric to H. cydno court and mate with H. cydno more readily than those from a sympatric population. This suggests that assortative mating has been enhanced in sympatry.

The HIV-1 DNA flap stimulates HIV vector-mediated cell transduction in the brain

During HIV-1 reverse transcription, central initiation of the plus-strand DNA at the central polypurine tract (cPPT) and central termination at the central termination sequence (CTS) lead to the formation of a three-stranded DNA structure: the HIV-1 central DNA flap. We recently reported that the DNA flap acts as a cis-active determinant of HIV-1 genome nuclear import. Commonly employed HIV-1-derived vectors (HR vectors) lack the central DNA flap. Here we report that the insertion of this DNA flap sequence into HR vectors (TRIP vectors) improves gene transduction in neural cells, ex vivo and in vivo, in rat brain. When neural cells are exposed to increasing concentrations of TRIP vector particles, transgene expression correlates with the dose of vector. This effect contrasts with the plateau observed when using an HR vector. We further demonstrate that the increase of in vivo transduction efficiency obtained with TRIP vectors is due to the stimulation of their genome nuclear import.

The factor structure for positive and negative symptoms in South African Xhosa patients with schizophrenia

Most studies investigating the symptom dimensions of schizophrenia utilising the Scale for the Assessment of Negative Symptoms (SANS) and the Scale for the Assessment of Positive Symptoms (SAPS) favour a three factor model. This study sought to investigate the factor structure of both the global and individual items of the SANS and SAPS in a large sample of South African Xhosa patients with schizophrenia. A total of 422 subjects participated. Both principal components and factor analytical procedures were applied. For the global items, a two-factor solution representing positive and negative symptoms accounted for 59.9% of the variance. Alternatively, the three-dimensional model of negative, psychotic and disorganisation factors was supported by a five-factor solution if the more heterogeneous items of attention and alogia were ignored. Analysis of the individual items yielded a five-factor solution with the negative symptoms splitting into diminished expression and disordered relating, and the positive symptoms separating into factors for psychosis, thought disorder and bizarre behaviour. Our findings are very similar to those from other parts of the world, providing evidence that the factor structure for the symptoms of schizophrenia is relatively resistant to cultural influences. This is particularly true for negative symptoms.

Partial prevention of cisplatin-induced neuropathy by electroporation-mediated nonviral gene transfer

Cisplatin-induced sensory peripheral neuropathy is the dose-limiting factor for cisplatin chemotherapy. We describe the preventive effect of NT-3 delivery, using direct gene transfer into muscle by in vivo electroporation in a mouse model of cisplatin-induced neuropathy. Cisplatin-induced neuropathy was produced by weekly injections of cisplatin (five injections). Two doses of plasmid DNA encoding murine NT-3 (pCMVNT-3) were tested (5 and 50 microg/animal/injection). Cisplatin-treated mice were given two intramuscular injections. The first injection of pCMVNT-3 was given 2 days before the first injection of cisplatin and the second injection 2 weeks later. Six weeks after the start of the experiment, measurement of NT-3 levels (ELISA) demonstrated significant levels both in muscle and plasma. We observed a smaller cisplatin-related increase in the latency of the sensory nerve action potential of the caudal nerve in pCMVNT-3-treated mice than in controls (p < 0.0001). Mean sensory distal latencies were not different between the 5- and 50- microg/animal/injection groups. Treatment with gene therapy induced only a slight muscle toxicity and no general side effects. Therefore, neurotrophic factor delivery by direct gene transfer into muscle by electroporation is of potential benefit in the prevention of cisplatin-induced neuropathy and of peripheral neuropathies in general.

Multiple complexes involved in tyrosine hydroxylase mRNA stability in rat adrenal medulla, after reserpine stimulation

A 28-nucleotide sequence within the 3'-untranslated region (3'UTR) of tyrosine hydroxylase (TH) mRNA has been suggested to influence the turnover rate of the TH messenger in vitro (W. R. Paulding and M. F. Czyzyk-Krzeska, 1999, J. Biol. Chem. 274, 2532-2538). In this study, we show that treatment with reserpine, a catecholamine-depleting drug which increases the stability of TH mRNA, allows the binding of a cytosolic protein to this 28-mer site in the TH 3'UTR in the rat adrenal medulla. An ex vivo kinetic analysis shows that the resulting 54-kDa ribonucleoprotein is early induced by reserpine. However, the formation of this complex is not coupled with the upregulation of TH mRNA, indicating that this 54-kDa complex could not be the unique factor accountable for the long-term stabilization of the TH messenger. Following this result we found that several other cis-acting elements, located in single-stranded stem loops within the secondary structure of TH 3'UTR, formed multiple complexes (43, 54, and 105 kDa) with cytosolic, polysome-associated, and also nuclear proteins. Our findings demonstrate that the messenger stability does not depend solely on the formation of a unique RNA-protein complex, but involves mechanisms with higher complexity implicating the interactions between posttranscriptional, nuclear RNA export, and translational processes.

Efficient transduction of neural cells in vitro and in vivo by a baculovirus-derived vector

Gene delivery to the central nervous system is central to the development of gene therapy for neurological diseases. We developed a baculovirus-derived vector, the Bac-CMV-GFP vector, containing a reporter gene encoding for the green fluorescent protein (GFP) under the control of the cytomegalovirus (CMV) promoter. Two neuroblastomal cell lines and three human primary neural cultures could be efficiently transduced. In all cases, addition of butyrate, an inhibitor of histone deacetylase, increased the level of expression in terms of the number of GFP-expressing cells and the intensity of fluorescence. The level of expression in a human telencephalic culture was over 50% of transduced cells with a multiplicity of infection of 25. GFP expression was demonstrated to be genuine expression and not pseudotransduction of the reporter protein. Most interestingly, Bac-CMV-GFP could transduce neural cells in vivo when directly injected into the brain of rodents and was not inactivated by the complement system. Thus, baculovirus is a promising tool for gene transfer into the central nervous system both for studies of the function of foreign genes and the development of gene therapy strategies.

Evidence for linkage by transmission disequilibrium test analysis of a chromosome 22 microsatellite marker D22S278 and bipolar disorder in a Palestinian Arab population

A number of linkage studies suggest a schizophrenia susceptibility locus on chromosome 22, particularly with microsatellite marker D22S278 (22q12). In addition to some evidence for linkage to schizophrenia in this region, linkage to bipolar disorder using this marker has also been reported. We tested a group of 60 Bipolar I triads and an expanded group of 79 Bipolar I and Bipolar II triads recruited from a Palestinian Arab population for linkage with the D22S278 marker. Significant linkage was observed using the extended transmission disequilibrium test for multiallelic markers (ETDT) for both Bipolar I (P = 0.031) and the expanded group of Bipolar I and Bipolar II (P = 0.041). These weakly positive results are at least consistent with the hypothesis that this region of chromosome 22 might harbor a susceptibility locus for both major psychoses and should be considered for more intensive study. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:836-838, 2000.

Sensitive and quantitative co-detection of two mRNA species by double radioactive in situ hybridization

A better understanding of biological phenomena involving modulations of gene expression requires quantitative analysis of the expression of several genes in the same structure. For this purpose, we have developed a novel in situ hybridization method to quantify two different mRNA species in the same tissue section simultaneously. Two probes labeled with radioelements of significantly different energies ((3)H and (33)P or (35)S) were used to detect the mRNA species. Radioactive images corresponding to the detected mRNA species were acquired with a Micro Imager, a real-time, high-resolution digital autoradiography system. An algorithm was used to process the data such that the initial radioactive image acquired was filtered into two subimages, each representative of the hybridization result specific to one probe. This novel method allows local discrimination and quantification of the respective contributions of each label to each pixel and can therefore be used for quantitative analysis of two mRNAs with a resolution of 15-20 microm.

Is RE1/NRSE a common cis-regulatory sequence for ChAT and VAChT genes?

Choline acetyltransferase (ChAT), the biosynthetic enzyme of acetylcholine, and the vesicular acetylcholine transporter (VAChT) are both required for cholinergic neurotransmission. These proteins are encoded by two embedded genes, the VAChT gene lying within the first intron of the ChAT gene. In the nervous system, both ChAT and VAChT are synthesized only in cholinergic neurons, and it is therefore likely that the cell type-specific expression of their genes is coordinately regulated. It has been suggested that a 2336-base pair genomic region upstream from the ChAT and VAChT coding sequences drives ChAT gene expression in cholinergic structures. We investigated whether this region also regulates VAChT gene transcription. Transfection assays showed that this region strongly represses the activity of the native VAChT promoters in non-neuronal cells, but has no major effect in neuronal cells whether or not they express the endogenous ChAT and VAChT genes. The silencer activity of this region is mediated solely by a repressor element 1 or neuron-restrictive silencer element (RE1/NRSE). Moreover, several proteins, including RE1-silencing transcription factor or neuron-restrictive silencer factor, are recruited by this regulatory sequence. These data suggest that this upstream region and RE1/NRSE co-regulate the expression of the ChAT and VAChT genes.

Rat alpha-synuclein interacts with Tat binding protein 1, a component of the 26S proteasomal complex

The alpha-synuclein gene, which encodes a brain presynaptic nerve terminal protein of unknown function, is linked to familial early-onset Parkinson's disease (PD). The finding that alpha-synuclein forms the major fibrillary component of Lewy bodies in brains of PD patients suggests that the two point mutations in alpha-synuclein (Ala(53)Thr, Ala(30)Pro) may promote the aggregation of alpha-synuclein into filaments. To address the role of alpha-synuclein in neurodegenerative diseases, we performed a yeast two-hybrid screen of a rat adult brain cDNA library using rat alpha-synuclein 2 (alphaSYN2). Here we report that alphaSYN2 interacts specifically with Tat binding protein 1, a subunit of the 700-kDa proteasome activator (PA700), the regulatory complex of the 26S proteasome and of the modulator complex, which enhances PA700 activation of the proteasome.

Overexpression of glutathione peroxidase increases the resistance of neuronal cells to Abeta-mediated neurotoxicity

Senile plaques are neuropathological manifestations in Alzheimer's disease (AD) and are composed mainly of extracellular deposits of amyloid beta-peptide (Abeta). Various data suggest that the accumulation of Abeta may contribute to neuronal degeneration and that Abeta neurotoxicity could be mediated by oxygen free radicals. Removal of free radicals by antioxidant scavengers or enzymes was found to protect neuronal cells in culture from Abeta toxicity. However, the nature of the free radicals involved is still unclear. In this study, we investigated whether the neuronal overexpression of glutathione peroxidase (GPx), the major hydrogen peroxide (H2O2)-de-grading enzyme in neurons, could increase their survival in a cellular model of Abeta-induced neurotoxicity. We infected pheochromocytoma (PC12) cells and rat embryonic cultured cortical neurons with an adenoviral vector encoding GPx (Ad-GPx) prior to exposure to toxic concentrations of Abeta(25-35) or (1-40). Both PC12 and cortical Ad-GPx-infected cells were significantly more resistant to Abeta-induced injury. These data strengthen the hypothesis of a role of H2O2 in the mechanism of Abeta toxicity and highlight the potential of Ad-GPx to reduce Abeta-induced damage to neurons. These findings may have applications in gene therapy for AD.

O2-sensing after carotid chemodenervation: hypoxic ventilatory responsiveness and upregulation of tyrosine hydroxylase mRNA in brainstem catecholaminergic cells

Ventilatory responses to acute and long-term hypoxia are classically triggered by carotid chemoreceptors. The chemosensory inputs are carried within the carotid sinus nerve to the nucleus tractus solitarius and the brainstem respiratory centres. To investigate whether hypoxia acts directly on brainstem neurons or secondarily via carotid body inputs, we tested the ventilatory responses to acute and long-term hypoxia in rats with bilaterally transected carotid sinus nerves and in sham-operated rats. Because brainstem catecholaminergic neurons are part of the chemoreflex pathway, the ventilatory response to hypoxia was studied in association with the expression of tyrosine hydroxylase (TH). TH mRNA levels were assessed in the brainstem by in situ hybridization and hypoxic ventilatory responses were measured in vivo by plethysmography. After long-term hypoxia, TH mRNA levels in the nucleus tractus solitarius and ventrolateral medulla increased similarly in chemodenervated and sham-operated rats. Ventilatory acclimatization to hypoxia developed in chemodenervated rats, but to a lesser extent than in sham-operated rats. Ventilatory response to acute hypoxia, which was initially low in chemodenervated rats, was fully restored within 21 days in long-term hypoxic rats, as well as in normoxic animals which do not overexpress TH. Therefore, activation of brainstem catecholaminergic neurons and ventilatory adjustments to hypoxia occurred independently of carotid chemosensory inputs. O2-sensing mechanisms unmasked by carotid chemodenervation triggered two ventilatory adjustments: (i) a partial acclimatization to long-term hypoxia associated with TH upregulation; (ii) a complete restoration of acute hypoxic responsivity independent of TH upregulation.

A preliminary study of patients' perceptions of routine follow-up after treatment for breast cancer

Early detection and longer survival have led to increasing numbers of patients requiring follow-up after treatment for breast cancer, yet there is little consensus as to how this should be achieved. Breast cancer patients have needs that change over time but the current system of follow-up is traditionally routinized and lacks an individualized approach. This preliminary study was designed to ascertain patients' perceptions of routine follow-up care after completion of treatment for breast cancer. A cross-sectional survey of a stratified systematic sample of patients was utilized. Data were collected using semi-structured, taped interviews. The tapes were inductively analysed and coded to ascertain predominant themes. Twenty-four patients were recruited. Analysis indicated that follow-up examinations were hurried (18 patients), investigations were not reassuring (11) and that the lack of continuity was unacceptably poor (22). Many patients (19) felt uncomfortable expressing emotional concerns or asking questions. The majority (18) stated that they would prefer to receive all or part of their follow-up from a breast care nurse. These findings have implications for service provision in terms of quality and cost-effectiveness. On the basis of these results a patient-focused, nurse-led intervention is being evaluated against traditional medical follow-up for patients with breast cancer.

Multicenter linkage study of schizophrenia candidate regions on chromosomes 5q, 6q, 10p, and 13q: schizophrenia linkage collaborative group III

Schizophrenia candidate regions 33-51 cM in length on chromosomes 5q, 6q, 10p, and 13q were investigated for genetic linkage with mapped markers with an average spacing of 5.64 cM. We studied 734 informative multiplex pedigrees (824 independent affected sibling pairs [ASPs], or 1,003 ASPs when all possible pairs are counted), which were collected in eight centers. Cases with diagnoses of schizophrenia or schizoaffective disorder (DSM-IIIR criteria) were considered affected (n=1,937). Data were analyzed with multipoint methods, including nonparametric linkage (NPL), ASP analysis using the possible-triangle method, and logistic-regression analysis of identity-by-descent (IBD) sharing in ASPs with sample as a covariate, in a test for intersample heterogeneity and for linkage with allowance for intersample heterogeneity. The data most supportive for linkage to schizophrenia were from chromosome 6q; logistic-regression analysis of linkage allowing for intersample heterogeneity produced an empirical P value <.0002 with, or P=.0004 without, inclusion of the sample that produced the first positive report in this region; the maximum NPL score in this region was 2.47 (P=.0046), the maximum LOD score (MLS) from ASP analysis was 3.10 (empirical P=.0036), and there was significant evidence for intersample heterogeneity (empirical P=.0038). More-modest support for linkage was observed for chromosome 10p, with logistic-regression analysis of linkage producing an empirical P=. 045 and with significant evidence for intersample heterogeneity (empirical P=.0096).

Dysfunctional regulation of alphaCaMKII and syntaxin 1B transcription after induction of LTP in the aged rat

Syntaxin 1B and alphaCaMKII are two genes that are upregulated after the induction of LTP and appear to underlie different mechanisms of synaptic plasticity. alphaCaMKII is directly implicated in strengthening the synapses that have been modified, whereas syntaxin 1B has been implicated in a mechanism for the propagation of synaptic plasticity within neural circuits. In these experiments we have investigated whether the regulation of these genes is altered after the induction of LTP in aged rats. We found, three hours after the induction of LTP in the dentate gyrus, that aged rats could be subgrouped into those in which LTP was maintained and those in which LTP had decayed back to basal levels. Both genes were upregulated in young adult rats, whereas there was a differential pattern of LTP-induced expression in the aged rats. Dendritic alphaCaMKII was upregulated in aged rats only when LTP was maintained. In contrast, regulation of syntaxin 1B and alphaCaMKII was absent in the granule cell bodies of the aged rats regardless of whether LTP was maintained or not. These results suggest that molecular mechanisms implicated in two aspects of hippocampal synaptic plasticity malfunction during normal ageing and therefore may have some contributory role in the decline in memory function routinely observed in ageing.

A constrained Gauss-Seidel method for correction of point spread function effect in MR spectroscopic imaging

Magnetic resonance spectroscopic imaging is limited by a low signal-to-noise ratio, so a compromise between spatial resolution and examination time is needed in clinical application. The reconstruction of truncated signal introduces a Point Spread Function that considerably affects the spatial resolution. In order to reduce spatial contamination, three methods, applied after Fourier transform image reconstruction, based on deconvolution or iterative techniques are tested to decrease Point Spread Function contamination. A Gauss-Seidel (GS) algorithm is used for iterative techniques with and without a non-negative constraint (GS+). Convergence and noise dependence studies of the GS algorithm have been done. The linear property of contamination was validated on a point sample phantom. A significant decrease of contamination without broadening the spatial resolution was obtained with GS+ method compared to a conventional apodization. This post-processing method can provide a contrast enhancement of clinical spectroscopic images without changes in acquisition time.

Association between bipolar disorder and monoamine oxidase A gene polymorphisms: results of a multicenter study

OBJECTIVE

Although genetic factors have been implicated in the etiology of bipolar disorder, no specific gene has been conclusively identified. Given the link between abnormalities in serotonergic neurotransmission and bipolar disorder, a candidate gene association approach was applied to study the involvement of the monoamine oxidase A (MAOA) gene, which codes for a catabolic enzyme of serotonin, in the susceptibility to bipolar disorder.

METHOD

In France and Switzerland, 272 patients with bipolar disorder and 122 healthy subjects were typed for three polymorphic markers of the MAOA gene: the MAOA-CA repeat, the MAOA restriction fragment length polymorphism (RFLP), and a repeat directly adjacent to the variable number of tandem repeats (VNTR) locus.

RESULTS

A significant difference in the distribution of the alleles for the MAOA-CA repeat was observed between the female bipolar patients and comparison group.

CONCLUSIONS

The results obtained in the French and Swiss population confirm findings from two studies conducted in the United Kingdom.