Functional study in NSE-Hu-Bcl-2 transgenic mice: a model for retinal diseases starting in Müller cells

In NSE-Hu-Bcl-2 transgenic mice, line 71, retina undergoes early postnatal degeneration linked to the prior death of Müller cells. The purpose of this study was to complete the characterization of this retinal dysfunction by using electroretinographic (ERG) recordings in both scotopic and photopic conditions. Here, we showed that both rod and cone systems were profoundly affected in NSE-Hu-Bcl-2 transgenic mice as soon as 15 postnatal days in accordance with histological study performed previousl

Caractérisation in vivo et in vitro de la dégénérescence rétinienne de la souris transgénique NSE-Hu-Bcl-2 (lignée 71) (étude des interactions entre un tissu rétinien en dégénérescence et les cellules souches neurales)

L objectif de cette thèse a été de caractériser in vivo et in vitro la dégénérescence rétinienne de la souris transgénique NSE-Hu-Bcl-2 (lignée 71) et d étudier les interactions entre un tissu rétinien en dégénérescence et les cellules souches neurales dans un système in vitro. La souris transgénique NSE-Hu-Bcl-2 (lignée 71) présente une dystrophie rétinienne caractérisée par la mort initiale des cellules gliales de Müller (CGM). Des études récentes utilisant des cellules souches neurales transplantées dans le système nerveux central et la moelle épinière lésés ou dystrophiques ont montré un effet réciproque entre les cellules greffées et le tissu hôte en terme de survie, de différenciation et de plasticité. Nous avons donc recherché dans un système in vitro si de telles interactions existaient entre des cellules souches neurales, issues des éminences ganglionnaires d embryons de souris, et les rétines dégénérescentes issues des souris NSE-Hu-Bcl-2. Notre étude a mis en exergue d une part la nécessité d évaluer le comportement tissulaire d un explant après sa mise en culture et d autre part un effet réciproque entre les cellules souches neurales et l explant rétinien en terme de survie, de différenciation et de plasticité. Ces résultats nous permettent d envisager la transplantation de ces cellules souches neurales dans des modèles animaux présentant une dystrophie rétinienne.The aim of this work was to characterize the retinal degeneration of the NSE-Hu-Bcl-2 transgenic mouse (line 71) both in vivo and in vitro and to study interactions between degenerating retinae and neural stem cells in an in vitro system. The NSE-Hu-Bcl-2 transgenic mouse (line 71) shows a retinal dystrophy initiated by Müller glial cell (MGC) death. Recent studies using neural stem cells transplanted in injured or dystrophic brains or spinal cords showed a reciprocal effect between the transplanted cells and the host tissue in term of survival, differentiation and plasticity. We thus assessed in culture if such interactions were existing between neural stem cells isolated from ganglionic eminences of mouse embryos and degenerating retinae of NSE-Hu-Bcl-2 transgenic mice. Our study highlighted first the necessity of assessing the behaviour of explants in culture and secondly the reciprocal effect between neural stem cells and retinae in term of survival, differentiation and plasticity. These results allow us to envisage the transplantation of these neural stem cells in animal models with retina dystrophy.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Induction of enhanced green fluorescent protein expression in response to lesions in the nervous system

We have generated a mouse strain carrying a transgene driven by a strong and ubiquitous promoter (human cytomegalovirus hCMV/beta-actin) and containing an enhanced green fluorescent protein (eGFP) coding sequence upstream of the 3' untranslated region (3'UTR) of tissue-type plasminogen activator (t-PA) mRNA. The 3'UTR of t-PA mRNA is known to be involved in the reversible deadenylation and translational repression of transcripts in mouse oocytes. hCMV/beta-actin-eGFP-3'UTR t-PA transgenic mice express eGFP mRNA in all brain structures analyzed but lack eGFP fluorescence, with the exception of blood vessels, choroid plexus, and Purkinje cells. Taking advantage of these features, we tested whether certain pathological conditions, in particular injuries of the nervous system, might trigger eGFP fluorescence in traumatized cells or neurons. From this perspective, we analyzed eGFP mRNA expression and eGFP fluorescence in experimental models of nervous system lesions, such as motoneuron axotomy and cerebral stroke induced by middle cerebral artery occlusion. We found an increase in eGFP fluorescence in specific brain areas in cells suffering or reacting to these injuries. This increased fluorescence is correlated with an increased transcription of eGFP in lesioned cells, presumably enhanced by a release of the translational silencing mediated by the 3'UTR region of the t-PA mRNA. This transgenic mouse model may prove useful to study the development of neurodegenerative lesions

The presenilin-1 familial Alzheimer's disease mutation P117L decreases neuronal differentiation of embryonic murine neural progenitor cells

The presenilin-1 gene is mutated in early-onset familial Alzheimer's disease. The mutation Pro117Leu is implicated in a very severe form of the disease, with an onset of less than 30 years. The consequences of this mutation on neurogenesis in the hippocampus of adult transgenic mice have already been studied in situ. The survival of neural progenitor cells was impaired resulting in decreased neurogenesis in the dentate gyrus. Our intention was to verify if similar alterations could occur in vitro in progenitor cells from the murine ganglionic eminences isolated from embryos of this same transgenic mouse model. These cells were grown in culture as neurospheres and after differentiation the percentage of neurons generated as well as their morphology were analysed. The mutation results in a significant decrease in neurogenesis compared to the wild type mice and the neurons grow longer and more ramified neurites. A shift of differentiation towards gliogenesis was observed that could explain decreased neurogenesis despite increased proliferation of neural precursors in transgenic neurospheres. A diminished survival of the newly generated mutant neurons is also proposed. Our data raise the possibility that these alterations in embryonic development might contribute to increase the severity of the Alzheimer's disease phenotype later in adulthood