Regulation of Lgl1 and its role in hyperoxic injury of the newborn lung

Bronchopulmonary dysplasia (BPD), a leading cause of morbidity in very low birth weight infants, is characterized by an arrest in alveolar development. An improved insight into the genes and mechanisms that regulate alveolarization is essential to enhance our understanding of the lung pathophysiology of BPD. LGL1, is a developmentally regulated, glucocorticoid induced, secreted glycoprotein in the lung. In order to establish the role of Lgl1 in alveolarization, I studied Lgl1 expression in two rat models of oxygen toxicity (BPD) that reproduce many of the characteristic features of BPD. I showed that in hyperoxia, Lgl1 levels are reduced and that these levels normalize during recovery in air. The 5' promoter region of Lgl1 has binding sites for the glucocorticoid (GC), retinoic acid (RA) and vitamin D (Vit D) receptors and for Smad3 (mediates transforming growth factor-beta (TGF-β) signalling), all of which modulate alveolarization and are considered to have a role in neonatal lung injury. Exposure of primary rat lung fibroblasts to GC, RA, Vit D and TGF-β1, alone or in combination, confirmed that all these agents regulate Lgl1 expression. Interestingly, the individual inhibitory effects of Vit D and RA on GC induction of Lgl1 were abrogated when both agents were present. Results of Luciferase assays were consistent with a role for all of these agents in transcriptional regulation. Interestingly, an analysis of the proximity (<50 base pairs) of binding sites for overlapping Vit D and RA receptors to that of the GC receptor identified 81% of promoters in 65 genes (including Lgl1) important in human lung development compared to 48% in a random set of 1000 genes. This suggests that steric hindrance may influence promoter accessibility when more than one of these agents is present simultaneously. In order to further explore the functional role of Lgl1, an Lgl1 knockout mouse model was generated. Absence of Lgl1 is embryonic lethal. Haploinsufficiency for Lgl1 deficiency was associated with a complex phenotype including: goblet cell hyperplasia, mucus production, increased expression of interleukins 4 and 13, elastin fragmentation and disruption of adult lung function. This phenotype was exacerbated by oxygen exposure. The combined results of my studies suggest that Lgl1 deficiency may contribute to neonatal lung injury in BPD.La dysplasie bronchopulmonaire (DBP), une maladie caractérisée par l'arrêt du développement alvéolaire, demeure une des causes principales de morbidité chez les nouveau-nés de faible poids. Plus d'informations sur les mécanismes et les gènes impliqués dans l'alvéolarisation sont nécessaires afin de mieux comprendre la physiopathologie de cette maladie et aider au développement de nouvelles interventions thérapeutiques. LGL1 est une glycoprotéine sécrétée dans le poumon qui est induite par les glucocorticoïdes et est finement régulée lors du développement. Afin d'éclaircir le rôle de Lgl1 dans l'alvéolarisation, j'ai étudié l'expression de Lgl1 dans deux modèles de toxicité d'oxygène chez le rat. Sous hyperoxie, les niveaux de Lgl1 sont réduits puis redeviennent normaux lors de la récupération dans l'air. Le promoteur (région 5') de Lgl1 contient des sites de liaisons pour les récepteurs de glucocorticoïdes (GC), d'acide rétinoïque (AR), de la vitamine D (Vit D), ainsi que pour le facteur de transcription Smad3 (transmet le signal de « transforming growth factor-beta », TGF-β). L'exposition de cellules fibroblastes pulmonaires primaires de rat à ces agents, ensemble ou en combinaison, confirme qu'ils régulent tous l'expression de Lgl1. Fait intéressant, la Vit D ou l'AR seules peuvent inhiber l'expression de Lgl1 induite par GC. Par contre, quand la Vit D et l'AR sont présentes ensemble, aucune inhibition n'est observée sur l'expression de Lgl1 induite par GC. Des analyses de luciférase ont démontrées que ces agents agissent au niveau de la transcription de Lgl1. Une analyse de la localisation des sites de liaisons des récepteurs de GC, AR et Vit D indique que l'emplacement particulier de ces sites sur le promoteur de Lgl1 est aussi trouvé sur 81% des promoteurs de 65 gènes ayant un rôle connu dans le développement des poumons (comparé à seulement 48% d'un groupe de 1000 gènes aléatoires). Ceci suggère que l'encombrement stérique peut influencer l'accessibilité au promoteur quand plus d'un de ces agents est présent à la fois. Afin de déterminer si une déficience de Lgl1 est associée à une arrestation de l'alvéolarisation et contribue à la physiopathologie de la DBP, une souris mutante pour le gène Lgl1 a été générée. Un déficit de Lgl1 a révélé un phénotype complexe, incluant notamment : l'hyperplasie des cellules caliciformes, la production de mucus, l'augmentation de l'expression des interleukines 4 et 13, la perturbation du développement pulmonaire, la fragmentation de l'élastine et la perturbation de la fonction mécanique du poumon. Ce phénotype est aggravé par l'hyperoxie, suggérant que la carence de Lgl1 pourrait contribuer à la DBP dans la période néonatale

The 10 October 1999 HIP 9369 occultation by the northern polar region of Jupiter: ingress and egress lightcurves analysis

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“Chronic fatigue, quality of life and long-term side-effects of chemotherapy in patients treated for non-epithelial ovarian cancer: national case-control protocol study of the GINECO-Vivrovaire rare tumors INCa French network for rare malignant ovarian tumors”

Abstract Background Germ cell tumors and sex cord stromal tumors are rare cancers of the ovary. They mainly affect young women and are associated with a high survival rate. The standard treatment mainly involves conservative surgery combined with chemotherapy [bleomycin, etoposide and cisplatin (BEP)] depending on the stage and the prognostic factors, as for testicular cancers. As reported in testicular cancer survivors, chemotherapy may induce sequelae impacting quality of life, which has not yet been evaluated in survivors of germ cell tumors and sex cord stromal tumors. The GINECO-VIVROVAIRE-Rare tumor study is a two-step investigation aiming to assess i) chronic fatigue and quality of life and ii) long-term side-effects of chemotherapy with a focus on cardiovascular and pulmonary disorders. Methods Using self-reported questionnaires, chronic fatigue and quality of life are compared between 134 ovarian cancer survivors (cancer-free ≥2 years after treatment) treated with surgery and chemotherapy and 2 control groups (67 ovarian cancer survivors treated with surgery alone and 67 age-matched healthy women). Medical data are collected from patient records. In the second step evaluating the long-term side-effects of chemotherapy, a subgroup of 90 patients treated with chemotherapy and 45 controls undergo the following work-up: cardiovascular evaluation (clinical examination, non-invasive cardiovascular tests to explore heart disease, blood tests), pulmonary function testing, audiogram, metabolic and hormonal blood tests. Costs of sequelae will be also assessed. Patients are selected from the registry of the INCa French Network for Rare Malignant Ovarian Tumors, and healthy women by the ‘Seintinelles’ connected network (collaborative research platform). Discussion This study will provide important data on the potential long-term physical side-effects of chemotherapy in survivors of Germ Cell Tumors (GCT) and Sex Cord Stromal Tumors (SCST), especially cardiovascular and pulmonary disorders, and neurotoxicity. The identification of long-term side-effects can contribute to adjusting the treatment of ovarian GCT or SCST patients and to managing follow-up with adapted recommendations regarding practices and chemotherapy regimens, in order to reduce toxicity while maintaining efficacy. Based on the results, intervention strategies could be proposed to improve the management of these patients during their treatment and in the long term. Trial registration This trial was registered at clinicaltrials.gov : 03418844 , on 1 February 2018. This trial was registered on 25 October 2017 under the unique European identification number (ID-RCB): 2017-A03028–45. Recruitment Status: Recruiting. Protocol version Version n° 4.2 dated from Feb 19, 2021. Trial sponsor Centre François Baclesse, 3 avenue du Général Harris, F-14076 Caen cedex 05, France