Neurocentre Magendie

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31 publications


* equal contribution
Les IF indiqués ont été collectés par le Web of Sciences en Juillet 2017

24/11/2017 | cell cycle
Regulation of RNA polymerase III transcription during transformation of human IMR90 fibroblasts with defined genetic elements.
Durrieu-Gaillard S, Dumay-Odelot H, Boldina G, Tourasse NJ, Allard D, Andre F, Macari F, Choquet A, Lagarde P, Drutel G, Leste-Lasserre T, Petitet M, Lesluyes T, Lartigue-Faustin L, Dupuy JW, Chibon F, Roeder RG, Joubert D, Vagner S, Teichmann M

Abstract:
RNA polymerase (Pol) III transcribes small untranslated RNAs that are essential for cellular homeostasis and growth. Its activity is regulated by inactivation of tumor suppressor proteins and overexpression of the oncogene c-MYC, but the concerted action of these tumor-promoting factors on Pol III transcription has not yet been assessed. In order to comprehensively analyse the regulation of Pol III transcription during tumorigenesis we employ a model system that relies on the expression of five genetic elements to achieve cellular transformation. Expression of these elements in six distinct transformation intermediate cell lines leads to the inactivation of TP53, RB1, and protein phosphatase 2A, as well as the activation of RAS and the protection of telomeres by TERT, thereby conducting to full tumoral transformation of IMR90 fibroblasts. Transformation is accompanied by moderately enhanced levels of a subset of Pol III-transcribed RNAs (7SK; MRP; H1). In addition, mRNA and/or protein levels of several Pol III subunits and transcription factors are upregulated, including increased protein levels of TFIIIB and TFIIIC subunits, of SNAPC1 and of Pol III subunits. Strikingly, the expression of POLR3G and of SNAPC1 is strongly enhanced during transformation in this cellular transformation model. Collectively, our data indicate that increased expression of several components of the Pol III transcription system accompanied by a 2-fold increase in steady state levels of a subset of Pol III RNAs is sufficient for sustaining tumor formation.





20/11/2017 | hepatology   IF 13.2
New insights into diagnosis and therapeutic options for proliferative hepatoblastoma.
Hooks KB, Audoux J, Fazli H, Lesjean S, Ernault T, Senant ND, Leste-Lasserre T, Hagedorn M, Rousseau B, Danet C, Branchereau S, Brugieres L, Taque S, Guettier C, Fabre M, Rullier A, Buendia MA, Commes T, Grosset CF, Raymond AA

Abstract:
Surgery and cisplatin-based treatment of hepatoblastoma (HB) currently guarantee the survival of 70-80% of patients. However, some important challenges remain in diagnosing high risk tumors and identifying relevant targetable pathways offering new therapeutic avenues. Previously, two molecular subclasses of hepatoblastoma tumors have been described, namely C1 and C2; C2 being the subgroup with the poorest prognosis, a more advanced tumor stage and the worst overall survival rate. An associated 16-gene signature to discriminate the two tumoral subgroups was proposed but it has not been transferred into clinical routine. To address these issues we performed RNA sequencing of 25 tumors and matched normal liver samples from patients. The transcript profiling separated HB into three distinct subgroups named C1, C2A and C2B, identifiable by a concise four-gene signature: HSD17B6, ITGA6, TOP2A and VIM, with TOP2A being characteristic for the proliferative C2A tumors. Differential expression of these genes was confirmed by RT-qPCR on an expanded cohort and by immunohistochemistry. We also revealed significant overexpression of genes involved in Fanconi Anemia (FA) pathway in the C2A subgroup. We then investigated the ability of several described FA inhibitors to block growth of HB cells in vitro and in vivo. We demonstrated that bortezomib, an FDA-approved proteasome inhibitor, strongly impairs the proliferation and survival of HB cell lines in vitro, blocks FA pathway associated double-strand DNA repair and significantly impedes HB growth in vivo. In conclusion, the highly proliferating C2A subtype is characterized by TOP2A gene up-regulation and FA pathway activation and HB therapeutic arsenal could include Bortezomib for the treatment of patients with the most aggressive tumors. This article is protected by copyright. All rights reserved.





08/09/2017 | Sci Rep   IF 4.3
Spinal miRNA-124 regulates synaptopodin and nociception in an animal model of bone cancer pain.
Elramah S, Lopez-Gonzalez MJ, Bastide M, Dixmerias F, Roca-Lapirot O, Wielanek-Bachelet AC, Vital A, Leste-Lasserre T, Brochard A, Landry M, Favereaux A

Abstract:
Strong breakthrough pain is one of the most disabling symptoms of cancer since it affects up to 90% of cancer patients and is often refractory to treatments. Alteration in gene expression is a known mechanism of cancer pain in which microRNAs (miRNAs), a class of non-coding regulatory RNAs, play a crucial role. Here, in a mouse model of cancer pain, we show that miR-124 is down-regulated in the spinal cord, the first relay of the pain signal to the brain. Using in vitro and in vivo approaches, we demonstrate that miR-124 is an endogenous and specific inhibitor of synaptopodin (Synpo), a key protein for synaptic transmission. In addition, we demonstrate that Synpo is a key component of the nociceptive pathways. Interestingly, miR-124 was down-regulated in the spinal cord in cancer pain conditions, leading to an up-regulation of Synpo. Furthermore, intrathecal injections of miR-124 mimics in cancerous mice normalized Synpo expression and completely alleviated cancer pain in the early phase of the cancer. Finally, miR-124 was also down-regulated in the cerebrospinal fluid of cancer patients who developed pain, suggesting that miR-124 could be an efficient analgesic drug to treat cancer pain patients.





23/06/2017 | hepatology   IF 13.2
Argininosuccinate synthase 1 (ASS1): A marker of unclassified hepatocellular adenoma and high bleeding risk.
Henriet E, Hammoud AA, Dupuy JW, Dartigues B, Ezzoukry Z, Dugot-Senant N, Leste-Lasserre T, Pallares-Lupon N, Nikolski M, Le Bail B, Blanc JF, Balabaud C, Bioulac-Sage P, Raymond AA, Saltel F

Abstract:
Hepatocellular adenomas (HCA) are rare benign tumors divided into three main subgroups defined by patho-molecular features, HNF1A (H-HCA), mutated beta-catenin (b-HCA) and inflammatory (IHCA). In the case of unclassified HCA (UHCA), which are currently identified by default, a high risk of bleeding remains a clinical issue. The objective of this study was to explore UHCA proteome with the aim to identify specific biomarkers. Following dissection of the tumoral (T) and non-tumoral (NT) tissue on formalin-fixed paraffin-embedded (FFPE) from HCA tissue sections using laser capture methodology, we performed mass spectrometry analysis to compare T and NT protein expression levels in HCA, H-HCA, IHCA, b-HCA, UHCA and focal nodular hyperplasia. Using this methodology, we searched for proteins, which are specifically deregulated in UHCA. We demonstrate that proteomic profiles allow discriminating known HCA subtypes through the identification of classical biomarkers in each HCA subgroup. We observed specific upregulation of the arginine synthesis pathway associated with overexpression of argininosuccinate synthase (ASS1) and arginosuccinate lyase (ASL) in UHCA. ASS1 immunohistochemistry identified all the UHCA, of which 64.7% presented clinical bleeding manifestations. Interestingly, we demonstrated that the significance of ASS1 was not restricted to UHCA but also encompassed certain hemorrhagic cases in other HCA subtypes, particularly inflammatory HCA. CONCLUSION: ASS1+ HCA combined with a typical hematoxylin and eosin stain aspect defined a new HCA subgroup at a high risk of bleeding. This article is protected by copyright. All rights reserved.





05/2017 | Eur J Neurosci   IF 2.9
Species-specific diversity in the anatomical and physiological organisation of the BNST-VTA pathway.
Kaufling J, Girard D, Maitre M, Leste-Lasserre T, Georges F

Abstract:
The anteromedial part of the bed nucleus of the stria terminalis (amBNST) is a limbic structure innervating the ventral tegmental area (VTA) that is remarkably constant across species. The amBNST modulates fear and anxiety, and activation of VTA dopamine (DA) neurons by amBNST afferents seems to be the way by which stress controls motivational states associated with reward or aversion. Because fear learning and anxiety states can be expressed differently between rats and mice, we compared the functional connectivity between amBNST and the VTA-DA neurons in both species using consistent methodological approaches. Using a combination of in vivo electrophysiological, neuroanatomical tracing and laser capture approaches we explored the BNST influences on VTA-DA neuron activity. First, we characterised in rats the molecular phenotype of the amBNST neurons projecting to the VTA. We found that this projection is complex, including both GABAergic and glutamatergic neurons. Then, VTA injections of a conventional retrograde tracer, the beta-sub-unit of the cholera toxin (CTB), revealed a stronger BNST-VTA projection in mice than in rats. Finally, electrical stimulations of the BNST during VTA-DA neuron recording demonstrated a more potent excitatory influence of the amBNST on VTA-DA neuron activity in rats than in mice. These data illustrate anatomically, but also functionally, a significant difference between rats and mice in the amBNST-VTA pathway. More generally, together with previous findings, our research highlights the importance of species differences for the interpretation and the generalisation of research data.





2017 | front mol neurosci   IF 5.1
Differential Alteration in Expression of Striatal GABAAR Subunits in Mouse Models of Huntington's Disease.
Du Z, Tertrais M, Courtand G, Leste-Lasserre T, Cardoit L, Masmejean F, Halgand C, Cho YH, Garret M

Abstract:
Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive motor symptoms that are preceded by cognitive deficits and is considered as a disorder that primarily affects forebrain striatal neurons. To gain a better understanding of the molecular and cellular mechanisms associated with disease progression, we analyzed the expression of proteins involved in GABAergic neurotransmission in the striatum of the R6/1 transgenic mouse model. Western blot, quantitative PCR and immunohistochemical analyses were conducted on male R6/1 mice and age-matched wild type littermates. Analyses were performed on 2 and 6 month-old animals, respectively, before and after the onset of motor symptoms. Expression of GAD 67, GAD 65, NL2, or gephyrin proteins, involved in GABA synthesis or synapse formation did not display major changes. In contrast, expression of alpha1, alpha3 and alpha5 GABAAR subunits was increased while the expression of delta was decreased, suggesting a change in tonic- and phasic inhibitory transmission. Western blot analysis of the striatum from 8 month-old Hdh Q111, a knock-in mouse model of HD with mild deficits, confirmed the alpha1 subunit increased expression. From immunohistochemical analyses, we also found that alpha1 subunit expression is increased in medium-sized spiny projection neurons (MSN) and decreased in parvalbumin (PV)-expressing interneurons at 2 and 6 months in R6/1 mice. Moreover, alpha2 subunit labeling on the PV and MSN cell membranes was increased at 2 months and decreased at 6 months. Alteration of gene expression in the striatum and modification of GABAA receptor subtypes in both interneurons and projection neurons suggested that HD mutation has a profound effect on synaptic plasticity at an early stage, before the onset of motor symptoms. These results also indicate that cognitive and other behavioral deficits may be associated with changes in GABAergic neurotransmission that consequently could be a relevant target for early therapeutic treatment.





30/11/2016 | Diabetes   IF 8.7
Inhibiting Microglia Expansion Prevents Diet-induced Hypothalamic and Peripheral Inflammation.
Andre C, Guzman-Quevedo O, Rey C, Remus-Borel J, Clark S, Castellanos-Jankiewicz A, Ladeveze E, Leste-Lasserre T, Nadjar A, Abrous DN, Laye S, Cota D

Abstract:
Cell proliferation and neuroinflammation in the adult hypothalamus may contribute to the pathogenesis of obesity. Here we tested whether the intertwining of these two processes has a role in the metabolic changes caused by three weeks of saturated high-fat diet (HFD) consumption.As compared to chow, HFD-fed mice rapidly increased body weight and fat mass, and specifically showed increased microglia number in the arcuate nucleus (ARC) of the hypothalamus. Microglia expansion required the adequate presence of fats and carbohydrates in the diet, since feeding mice a very high-fat, very low-carbohydrate diet did not affect cell proliferation. Blocking HFD-induced cell proliferation by central delivery of the antimitotic drug arabinofuranosyl cytidine (AraC) blunted food intake, body weight gain and adiposity. AraC treatment completely prevented the increase in the number of activated microglia in the ARC, the expression of the pro-inflammatory cytokine TNFalpha in microglia and the recruitment of the NF-kappaB pathway, while restoring hypothalamic leptin sensitivity. Central blockade of cell proliferation also normalized circulating levels of the cytokines leptin and IL-1beta and decreased peritoneal pro-inflammatory CD86-IR macrophages number.These findings suggest that inhibition of diet-dependent microglia expansion hinders body weight gain while preventing central and peripheral inflammatory responses due to caloric overload.





12/11/2016 | Brain Behav Immun   IF 6
Selective dentate gyrus disruption causes memory impairment at the early stage of experimental multiple sclerosis.
Planche V, Panatier A, Hiba B, Ducourneau EG, Raffard G, Dubourdieu N, Maitre M, Leste-Lasserre T, Brochet B, Dousset V, Desmedt A, Oliet SH, Tourdias T

Abstract:
Memory impairment is an early and disabling manifestation of multiple sclerosis whose anatomical and biological substrates are still poorly understood. We thus investigated whether memory impairment encountered at the early stage of the disease could be explained by a differential vulnerability of particular hippocampal subfields. By using experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, we identified that early memory impairment was associated with selective alteration of the dentate gyrus as pinpointed in vivo with diffusion-tensor-imaging (DTI). Neuromorphometric analyses and electrophysiological recordings confirmed dendritic degeneration, alteration in glutamatergic synaptic transmission and impaired long-term synaptic potentiation selectively in the dentate gyrus, but not in CA1, together with a more severe pattern of microglial activation in this subfield. Systemic injections of the microglial inhibitor minocycline prevented DTI, morphological, electrophysiological and behavioral impairments in EAE-mice. Furthermore, daily infusions of minocycline specifically within the dentate gyrus were sufficient to prevent memory impairment in EAE-mice while infusions of minocycline within CA1 were inefficient. We conclude that early memory impairment in EAE is due to a selective disruption of the dentate gyrus associated with microglia activation. These results open new pathophysiological, imaging, and therapeutic perspectives for memory impairment in multiple sclerosis.





01/08/2016 | Proc Natl Acad Sci U S A   IF 9.7
Reducing C-terminal truncation mitigates synucleinopathy and neurodegeneration in a transgenic model of multiple system atrophy.
Bassil F, Fernagut PO, Bezard E, Pruvost A, Leste-Lasserre T, Hoang QQ, Ringe D, Petsko GA, Meissner WG

Abstract:
Multiple system atrophy (MSA) is a sporadic orphan neurodegenerative disorder. No treatment is currently available to slow down the aggressive neurodegenerative process, and patients die within a few years after disease onset. The cytopathological hallmark of MSA is the accumulation of alpha-synuclein (alpha-syn) aggregates in affected oligodendrocytes. Several studies point to alpha-syn oligomerization and aggregation as a mediator of neurotoxicity in synucleinopathies including MSA. C-terminal truncation by the inflammatory protease caspase-1 has recently been implicated in the mechanisms that promote aggregation of alpha-syn in vitro and in neuronal cell models of alpha-syn toxicity. We present here an in vivo proof of concept of the ability of the caspase-1 inhibitor prodrug VX-765 to mitigate alpha-syn pathology and to mediate neuroprotection in proteolipid protein alpha-syn (PLP-SYN) mice, a transgenic mouse model of MSA. PLP-SYN and age-matched wild-type mice were treated for a period of 11 wk with VX-765 or placebo. VX-765 prevented motor deficits in PLP-SYN mice compared with placebo controls. More importantly, VX-765 was able to limit the progressive toxicity of alpha-syn aggregation by reducing its load in the striatum of PLP-SYN mice. Not only did VX-765 reduce truncated alpha-syn, but it also decreased its monomeric and oligomeric forms. Finally, VX-765 showed neuroprotective effects by preserving tyrosine hydroxylase-positive neurons in the substantia nigra of PLP-SYN mice. In conclusion, our results suggest that VX-765, a drug that was well tolerated in a 6 wk-long phase II trial in patients with epilepsy, is a promising candidate to achieve disease modification in synucleinopathies by limiting alpha-syn accumulation.





20/05/2016 | Neuroscience   IF 3.3
Early GABAergic transmission defects in the external globus pallidus and rest/activity rhythm alteration in a mouse model of Huntington's disease.
Du Z, Chazalon M, Bestaven E, Leste-Lasserre T, Baufreton J, Cazalets JR, Cho YH, Garret M

Abstract:
Huntington's disease (HD) is characterized by progressive motor symptoms preceded by cognitive deficits and is regarded as a disorder that primarily affects the basal ganglia. The external globus pallidus (GPe) has a central role in the basal ganglia, projects directly to the cortex, and is majorly modulated by GABA. To gain a better understanding of the time course of HD progression and gain insight into the underlying mechanisms, we analysed GABAergic neurotransmission in the GPe of the R6/1 mouse model at purportedly asymptomatic and symptomatic stages (i.e., 2 and 6 months). Western blot and quantitative PCR analyses revealed alterations in the GPe of male R6/1 mice compared with wild type littermates. Expression of proteins involved in pre- and post-synaptic GABAergic compartments as well as synapse number were severely decreased at 2 and 6 months. At both ages, patch clamp electrophysiological recordings showed a decrease of spontaneous and miniature inhibitory post-synaptic currents suggesting that Huntington's disease mutation has an early effect on the GABA signalling in the brain. Therefore, we performed continuous locomotor activity recordings from 2 to 4 months of age. Actigraphy analyses revealed rest/activity fragmentation alterations that parallel GABAergic system impairment at 2 months, while the locomotor deficit is evident only at 3 months in R6/1 mice. Our results reveal early deficits in Huntington's disease and support growing evidence for a critical role played by the GPe in physiological and pathophysiological states. We suggest that actimetry may be used as a non-invasive tool to monitor early disease progression.