AAV-mediated transcription factor EB (TFEB) gene delivery ameliorates muscle pathology and function in the murine model of Pompe Disease

Pompe disease (PD) is a metabolic myopathy due to acid alpha-glucosidase deficiency and characterized by extensive glycogen storage and impaired autophagy. We previously showed that modulation of autophagy and lysosomal exocytosis by overexpression of the transcription factor EB (TFEB) gene was effective in improving muscle pathology in PD mice injected intramuscularly with an AAV-TFEB vector. Here we have evaluated the effects of TFEB systemic delivery on muscle pathology and on functional performance, a primary measure of efficacy in a disorder like PD. We treated 1-month-old PD mice with an AAV2.9-MCK-TFEB vector. An animal cohort was analyzed at 3 months for muscle and heart pathology. A second cohort was followed at different timepoints for functional analysis. In muscles from TFEB-treated mice we observed reduced PAS staining and improved ultrastructure, with reduced number and increased translucency of lysosomes, while total glycogen content remained unchanged. We also observed statistically significant improvements in rotarod performance in treated animals compared to AAV2.9-MCK-eGFP-treated mice at 5 and 8 months. Cardiac echography showed significant reduction in left-ventricular diameters. These results show that TFEB overexpression and modulation of autophagy result in improvements of muscle pathology and of functional performance in the PD murine model, with delayed disease progression

Role of dorsal and ventral hippocampus in working memory load capacity

In this study we found functional differences between the dorsal and ventral subregions of the HP in regulating object WMC but any difference was found in regulating allocentric spatial WMC. A major involvement of the ventral HP in regulating egocentric spatial memory was found. A recent study in CD1 mice reported a role for the dorsal HP in WM in high memory load (Sannino, Russo et al. 2012) confirming the results found in monkeys and in humans (Levy, Manns et al., 2003, Beason-Held, Rosene et al., 1999). Anatomic, genetic and behavioral studies suggested that the HP is subdivided into a dorsal and a ventral portion (Swanson and Cowan, 1977, Moser and Moser, 1993; Thompson and Pathak, 2008). Whether these two HP subregions differently regulate WMC has never been explorated. In this study we investigated if there is a functional differentiation between the dorsal and the ventral HP in regulating the limited capacity of WM using a neurotoxic selective dorsal and ventral HP lesion approach. First, we explorated the role of these two subregions in object WMC testing the dorsal HP and the ventral HP lesion groups in the 6 DOT described in Sannino et al., 2012. Here, we confirmed the role of the dorsal HP in object WMC and we did not find any involvement of the ventral part of the HP. Then, we investigated the role of these two regions in spatial WMC testing both lesion groups in a WMC version of the classical radial arm maze task using a modified protocol of the version described in Olivito et al., 2016. In our study we modulated the memory load by changing the number of open arms between 3, 6 and 8 open arms and exposing the mice to an allocentric version of the task (the confinement procedure) in the first 4 days and to a version where both allocentric and egocentric spatial memory can be used (the no-confinement procedure) in the last 4 days. In the confinement procedure the animals were confined in the 90 central zone of the apparatus to prevent the use of the egocentric strategies that are otherwise developed when the animals are free to explore the maze (noconfinement procedure). In this procedure we found an impairment in both dorsal HP and ventral HP lesion groups in high memory load suggesting a complementary role of the dorsal and ventral HP in mediating allocentric spatial WMC. A dissociation between the two regions was found in the no-confinement procedure where the involvement of the ventral HP was major than the dorsal HP. This major involvement of the ventral HP is parallel to a major impairment in the use of the sequential strategy found in the ventral HP lesion group suggesting a crucial role for the ventral HP in mediating the acquisition of egocentric strategies to solve the task. A no- confinement procedure, not preceded by a confinement procedure confirmed the crucial role of the ventral HP in regulating the use of egocentric strategies. In a final analysis of the effects of our dorsal HP and ventral HP lesions on a classical task used in literature to dissociate their function, we found the specific involvement of the ventral HP in mediating anxiety-like behavior confirming the results present in literature

Role of dorsal and ventral hippocampus in working memory load capacity.

Objectives: The hippocampus (HP) regulates working memory capacity (WMC) in conditions of high memory load (Sannino et al., 2012). Anatomic, genetic and behavioral studies suggested that the HP is subdivided into a dorsal (dHP) and a ventral (vHP) portion. Whether these two HP subregions differently regulate WMC is not known. Purpose: Investigate functional differences between the ventral and dorsal hippocampus in regulating the limited capacity of working memory (WM). Methods: Selective excitotoxic lesions of the dHP and vHP were performed in adult CD1 male mice. We tested control and lesioned animals in the different objects/identical objects task and in a modified version of the radial maze task (Olivito et al., 2016) to study object and spatial WMC, respectively. In the radial maze task the use of the sequential strategy to lower the memory load was prevented and allowed by the introduction and removal of a confinement procedure, respectively, in two consecutive phases of the task. Results: Both dHP lesioned and vHP lesioned impaired spatial WMC; however, vHP also impaired egocentric navigation, when animals were allowed to use of the sequential strategy. The dHP, but not the vHP, impaired object WMC. Conclusions: Our study reports that activation of the HP along its septo-temporal axis is necessary for spatial WMC, consistent with its role in allocentric navigation. The selective contribution of the dHP in object WM in condition of high memory load might be to support novelty detection processes in complex stimulus arrays. This suggests that a functional differentiation exists between the dHP and the vHP in regulating object WMC, but both subregions similarly regulate spatial WMC

Altered heparan sulfate metabolism during development triggers dopamine-dependent autistic-behaviours in models of lysosomal storage disorders

Lysosomal storage disorders, characterized by altered metabolism of heparan sulfate, cause autistic symptoms followed by dementia in children. Here, the authors show that embryonic dopaminergic neurodevelopmental defects due to altered function of heparan sulfate cause autistic behaviours in mice

Sex-biasing influence of autism-associated Ube3a gene overdosage at connectomic, behavioral, and transcriptomic levels

Genomic mechanisms enhancing risk in males may contribute to sex bias in autism. The ubiquitin protein ligase E3A gene (Ube3a) affects cellular homeostasis via control of protein turnover and by acting as transcriptional coactivator with steroid hormone receptors. Overdosage of Ube3a via duplication or triplication of chromosomal region 15q11-13 causes 1 to 2% of autistic cases. Here, we test the hypothesis that increased dosage of Ube3a may influence autism-relevant phenotypes in a sex-biased manner. We show that mice with extra copies of Ube3a exhibit sex-biasing effects on brain connectomics and autism-relevant behaviors. These effects are associated with transcriptional dysregulation of autism-associated genes, as well as genes differentially expressed in 15q duplication and in autistic people. Increased Ube3a dosage also affects expression of genes on the X chromosome, genes influenced by sex steroid hormone, and genes sex-differentially regulated by transcription factors. These results suggest that Ube3a overdosage can contribute to sex bias in neurodevelopmental conditions via influence on sex-differential mechanisms