Régulation transcriptionnelle par l'AMP cyclique et les acides gras du gène codant la carnitine palmitoyltransférase I de foie

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

The Coactivator PGC-1 Is Involved in the Regulation of the Liver Carnitine Palmitoyltransferase I Gene Expression by cAMP in Combination with HNF4α and cAMP-response Element-binding Protein (CREB)

International audienceLiver carnitine palmitoyltransferase I catalyzes the transfer of long-chain fatty acids into mitochondria. L-CPT I is considered the rate-controlling enzyme in fatty acid oxidation. Expression of the L-CPT I gene is induced by starvation in response to glucagon secretion from the pancreas, an effect mediated by cAMP. Here, the molecular mechanisms underlying the induction of L-CPT I gene expression by cAMP were characterized. We demonstrate that the cAMP response unit of the L-CPT I gene is composed of a cAMP-response element motif and a DR1 sequence located 3 kb upstream of the transcription start site. Our data strongly suggest that the coactivator PGC-1 is involved in the regulation of this gene expression by cAMP in combination with HNF4α and cAMP-response element-binding protein (CREB). Indeed, (i) cotransfection of CREB or HNF4α dominant negative mutants completely abolishes the effect of cAMP on the L-CPT I promoter, and (ii) the cAMP-responsive unit binds HNF4α and CREB through the DR1 and the cAMP-response element sequences, respectively. Moreover, cotransfection of PGC-1 strongly activates the L-CPT I promoter through HNF4α bound at the DR1 element. Finally, we show that the transcriptional induction of the PGC-1 gene by glucagon through cAMP in hepatocytes precedes that of L-CPT-1. In addition to the key role that PGC-1 plays in glucose homeostasis, it may also be critical for lipid homeostasis. Taken together these observations suggest that PGC-1 acts to coordinate the process of metabolic adaptation in the liver

Impact of Clipping on EVM of the Predistorted Non-Linear Amplified Multicarrier Signals

International audienceIn this paper, we analyse the impact of the clipping technique on EVM of multicarrier signals, assuming that the transmitter is equipped with a linearization stage before the PA. Therefore, the expression of the Error Vector Magnitude (EVM) of the output signal is analytically derived with and without the use of the predistortion and/or the clipping technique. We provide analytical expressions of the EVM in the form of a series expansion that depends on the transition factors of the PA, the predistortion characteristics, the PAPR of the input signal and the clipping threshold. We show through simulations that the proposed expressions present very good accuracy, even when limiting the series expansion to an order of 4. Finally, a simple scenario is proposed to demonstrate the benefit of our EVM expressions in controlling the average transmitted power with the aim to guarantee a high quality of service

Two Strategies for Reducing Non-Linear Distortions in Multi-Carrier Signals

International audienc

Long-chain fatty acids regulate liver carnitine palmitoyltransferase I gene (L-CPT I) expression through a peroxisome-proliferator-activated receptor α (PPARα)-independent pathway

International audienc

Leptin decreases BC cell susceptibility to NK lysis via PGC1A pathway

International audienceLarge prospective studies established a link between obesity and breast cancer (BC) development. Yet, the mechanisms underlying this association are not fully understood. Among the diverse adipocytokine secreted by hypertrophic adipose tissue, leptin is emerging as a key candidate molecule linking obesity and cancer, since it promotes proliferation and invasiveness of tumors. However, the potential implication of leptin on tumor escape mechanisms remains unknown. This study aims to explore the effect of leptin on tumor resistance to NK lysis and the underlying mechanism. We found that leptin promotes both BC resistance to NK92-mediated lysis and β oxidation on MCF-7, by the up-regulation of a master regulator of mitochondrial biogenesis, the peroxisome proliferator activated receptor coactivator-1 α (PGC1A). Using adenoviral approaches, we show that acute elevation of PGC1A enhances the fatty acid oxidation pathway and decreases the susceptibility of BC cells to NK92-mediated lysis. Importantly, we identified the involvement of PGC1A and leptin in the regulation of hypoxia inducible factor-1 alpha (HIF1A) expression by tumor cells. We further demonstrate that basal BC cells MDA-MB-231 and BT-20 exhibit an increased PGC1A mRNA level and an enhanced oxidative phosphorylation activity; in comparison with luminal BC cells MCF7 and MDA-361, which are associated with more resistance NK92 lysis. Altogether, our results demonstrate for the first time how leptin could promote tumor resistance to immune attacks. Reagents blocking leptin or PGC1A activity might aid in developing new therapeutic strategies to limit tumor development in obese BC patients

A circulating subset of BRAFV600E-positive cells in infants with high-risk Langerhans cell histiocytosis treated with BRAF inhibitors

International audienceBRAF inhibitors are an effective treatment for BRAFV600E-mutated, risk-organ-positive Langerhans cell histiocytosis (RO+ LCH). However, cell-free BRAFV600E DNA often persists during therapy and recurrence frequently occurs after therapy discontinuation. To identify a pathological reservoir of BRAFV600E-mutated cells, we studied peripheral blood cells obtained from six infants with RO+ multisystem (MS) LCH that received targeted therapy. After cell sorting, the BRAFV600E mutation was detected in monocytes (n = 5), B lymphocytes (n = 3), T lymphocytes (n = 2), and myeloid and plasmacytoid dendritic cells (n = 2 each). This biomarker may offer an interesting tool for monitoring the effectiveness of new therapeutic approaches for weaning children with RO+ LCH from targeted therapy

Conte et cinéma

Ce numéro 18 de Féeries est consacré aux adaptations cinématographiques des contes merveilleux français. Résolument transdisciplinaire, il réunit sept contributions de chercheurs français et étrangers, spécialistes de cinéma, de musicologie et du conte littéraire. Les articles portent chacun sur une ou plusieurs adaptations de contes des XVIIe et XVIIIe siècles incluant le recueil des Mille et Une Nuits adapté par Galland. Longs et courts métrages ou films d’animation produits entre 1951 et 2017, certains célèbres et d’autres moins, sont examinés ici sous des angles inédits. La question étant de montrer ce que le conte apporte au cinéma et réciproquement, toutes les œuvres sont considérées sans hiérarchisation de genre ni d’auteur. Si la transdisciplinarité est un domaine bien établi de la recherche, le champ récent des études intermédiales trouve dans le conte une forme plastique, ouverte aux migrations de toute nature. Plusieurs articles de ce numéro mettent en avant les interactions entre les arts embrassés par le cinéma (peinture, photo, musique…), qui enrichissent le dialogue entretenu par les cinéastes avec les contes

Childhood Langerhans cell histiocytosis with severe lung involvement: A nationwide cohort study

International audienceBackground: Lung involvement in childhood Langerhans cell histiocytosis (LCH) is infrequent and rarely life threatening, but occasionally, severe presentations are observed. Methods: Among 1482 children (< 15 years) registered in the French LCH registry (1994-2018), 111 (7.4%) had lung involvement. This retrospective study included data for 17 (1.1%) patients that required one or more intensive care unit (ICU) admissions for respiratory failure. Results: The median age was 1.3 years at the first ICU hospitalization. Of the 17 patients, 14 presented with lung involvement at the LCH diagnosis, and 7 patients (41%) had concomitant involvement of risk-organ (hematologic, spleen, or liver). Thirty-five ICU hospitalizations were analysed. Among these, 22 (63%) were secondary to a pneumothorax, 5 (14%) were associated with important cystic lesions without pneumothorax, and 8 (23%) included a diffuse micronodular lung infiltration in the context of multisystem disease. First-line vinblastine-corticosteroid combination therapy was administered to 16 patients; 12 patients required a second-line therapy (cladribine: n = 7; etoposide-aracytine: n = 3; targeted therapy n = 2). A total of 6 children (35%) died (repeated pneumothorax: n = 3; diffuse micronodular lung infiltration in the context of multisystem disease: n = 2; following lung transplantation: n = 1). For survivors, the median follow-up after ICU was 11.2 years. Among these, 9 patients remain asymptomatic despite abnormal chest imaging. Conclusions: Severe lung involvement is unusual in childhood LCH, but it is associated with high mortality. Treatment guidelines should be improved for this group of patients: viral infection prophylaxis and early administration of a new LCH therapy, such as targeted therapy

Lung transplantation as a rescue option in childhood critical pulmonary Langerhans cell histiocytosis

International audienc