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RAB GDP dissociation inhibitor-1 gene (GDI1) encodes for αGDI, a protein controlling the cycling of small GTPases orchestrating intracellular vesicular trafficking. Mutations in human GDI1 are responsible for X-linked intellectual disability (XLID). Adult mice lacking Gdi1 gene (Gdi1 KO), a model of XLID, showed working and associative memory deficits. The cognitive phenotype was explained by a large decrease in the reserve pool of synaptic vesicles (SVs) at the hippocampal synapses, resulting in a slow SV recovery after SV depletion. Thus, cognitive deficits may reflect the temporary depletion of the immediately available SVs. Because Gdi1 is ubiquitously expressed in neurons and in astrocytes, GDI1 mutations could affect trafficking of both cell types impairing astrocyte-neuron cross talk, leading to cognitive defects. To dissect the role of αGDI in neurons and in astrocytes, two conditional models in which Gdi1 is deleted respectively in neurons (CamkII-Cre+-Gdi1flox/Y) or in astrocytes (Glast-CreERT2+-Gdi1flox/Y) were generated. The CamkII-Cre+-Gdi1flox/Y mice phenocopied the Gdi1 KO mouse instead, Glast-CreERT2+-Gdi1flox/Y mice have a selective impairment in working memory which was rescued by inhibiting glycolysis by 2-deoxy-D-glucose administration. Proteomic analysis showed significant changes in astrocyte-resident glucose handling enzymes. Imaging with [18F]-fluoro-2-deoxy-D-glucose revealed an increased D-glucose uptake in Gdi1-null brain, consistent with the facilitated D-glucose utilisation. These results support a new astrocyte-based mechanism in XLID, opening a novel therapeutic opportunity of targeting aerobic glycolysis, advocating a change in clinical practice. Gen za inhibitor disociacije GDP-1 (GDI1) RAB kodira beljakovino αGDI, ki nadzoruje kroženje majhnih GTPaz, ki uravnavajo znotrajcelični transport mešičkov. Mutacije v človeškem GDI1 so odgovorne za od X-kromosoma odvisno nespecifično umsko manjzmožnost (XLID). Odrasle miši brez gena Gdi1 (Gdi1-null), model XLID, imajo oslabljeno tvorbo delovnega in asociativnega spomina. Kognitivni fenotip je bil pojasnjen z zmanjšanjem rezervnega bazena sinaptičnih mešičkov (SV) v hipokampalnih sinapsah, zaradi česar se SV po izpraznitvi prepočasi nadomeščajo. Pomanjkanje takoj razpoložljivih SV se lahko odraža kot kognitivni primanjkljaj. Zaradi izražanja Gdi1 tako v nevronih kot astrocitih, bi lahko mutacije v Gdi1 vplivale na transport mešičkov v obeh tipih celic, kar lahko ovira navzkrižno komunikacijo med astrociti in nevroni in s tem povzroča kognitivne okvare. Da bi bolje razumeli vlogo αGDI v nevronih in astrocitih, sta bila ustvarjena dva pogojna modela miši, v katerih je Gdi1 izbrisan v nevronih (CamkII-Cre+-Gdi1flox/Y) ali v astrocitih (GLAST-CreERT2+-Gdi1flox/Y). Miši CamkII-Cre+-Gdi1flox/Y so imele enak fenotip kot miši Gdi1-null, medtem ko so imele miši GLAST-CreERT2+-Gdi1flox/Y selektivno okvaro delovnega spomina, ki je bil obnovljen z inhibicijo glikolize z intraperitonealnim vnosom 2-deoksi-D-glukoze. Proteomska analiza astrocitov je pokazala spremembe v encimih, ki uravnavajo presnovo glukoze. Slikanje s [18F]-fluoro-2-deoksi-D-glukozo je razkrilo zvečan privzem D-glukoze v možganih miši Gdi1-null. Rezultati razkrivajo nov mehanizem pri XLID, ki temelji na astrocitih in uravnavanju aerobne glikolize. Predstavljajo novo terapevtsko priložnost, kar je relevantno za spremembo klinične prakse.

This presentation has been given at the 3rd General Meeting of the project ECOPOTENTIAL (Matalasca��as, Spain, 2018) and it shows the progress made and the results of the assessment of the threats that affect the habitat of the iconic species Salmo letnica.

Objectives GDI1 gene encodes for αGDI, a protein controlling the cycling of small GTPases, reputed to orchestrate vesicle trafficking. Mutations in human GDI1 are responsible for intellectual disability (ID). In mice with ablated Gdi1, a model of ID, impaired working and associative short-term memory was recorded. This cognitive phenotype worsens if the deletion of αGDI expression is restricted to neurons. However, whether astrocytes, key homeostasis providing neuroglial cells, supporting neurons via aerobic glycolysis, contribute to this cognitive impairment is unclear. Methods We carried out proteomic analysis and monitored [18F]-fluoro-2-deoxy-d-glucose uptake into brain slices of Gdi1 knockout and wild type control mice. d-Glucose utilization at single astrocyte level was measured by the Förster Resonance Energy Transfer (FRET)-based measurements of cytosolic cyclic AMP, d-glucose and L-lactate, evoked by agonists selective for noradrenaline and L-lactate receptors. To test the role of astrocyte-resident processes in disease phenotype, we generated an inducible Gdi1 knockout mouse carrying the Gdi1 deletion only in adult astrocytes and conducted behavioural tests. Results Proteomic analysis revealed significant changes in astrocyte-resident glycolytic enzymes. Imaging [18F]-fluoro-2-deoxy-d-glucose revealed an increased d-glucose uptake in Gdi1 knockout tissue versus wild type control mice, consistent with the facilitated d-glucose uptake determined by FRET measurements. In mice with Gdi1 deletion restricted to astrocytes, a selective and significant impairment in working memory was recorded, which was rescued by inhibiting glycolysis by 2-deoxy-d-glucose injection. Conclusions These results reveal a new astrocyte-based mechanism in neurodevelopmental disorders and open a novel therapeutic opportunity of targeting aerobic glycolysis, advocating a change in clinical practice., Highlights • Mutations in human Gdi1, encoding αGDI, a protein controlling vesicle traffic, are responsible for Intellectual Disability. • Gdi1 knockout revealed significant changes in astrocyte-resident glycolytic enzymes and facilitated D-glucose utilization. • Astrocyte-selective Gdi1 deletion impairs working memory, which can be rescued by administration of 2-deoxy-D-glucose. • Astrocyte-based glycolysis is a new target to treat Intellectual Disability.

The development of a tractable small animal model faithfully reproducing human coronavirus disease 2019 pathogenesis would arguably meet a pressing need in biomedical research. Thus far, most investigators have used transgenic mice expressing the human ACE2 in epithelial cells (K18-hACE2 transgenic mice) that are intranasally instilled with a liquid severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) suspension under deep anesthesia. Unfortunately, this experimental approach results in disproportionate high central nervous system infection leading to fatal encephalitis, which is rarely observed in humans and severely limits this model’s usefulness. Here, we describe the use of an inhalation tower system that allows exposure of unanesthetized mice to aerosolized virus under controlled conditions. Aerosol exposure of K18-hACE2 transgenic mice to SARS-CoV-2 resulted in robust viral replication in the respiratory tract, anosmia, and airway obstruction but did not lead to fatal viral neuroinvasion. When compared with intranasal inoculation, aerosol infection resulted in a more pronounced lung pathology including increased immune infiltration, fibrin deposition, and a transcriptional signature comparable to that observed in SARS-CoV-2–infected patients. This model may prove useful for studies of viral transmission, disease pathogenesis (including long-term consequences of SARS-CoV-2 infection), and therapeutic interventions.

Spinal cord injury (SCI) is a devastating condition mainly deriving from a traumatic damage of the spinal cord (SC). Immune cells and endogenous SC-neural stem cells (SC-NSCs) play a critical role in wound healing processes, although both are ineffective to completely restore tissue functioning. The role of SC-NSCs in SCI and, in particular, whether such cells can interplay with the immune response are poorly investigated issues, although mechanisms governing such interactions might open new avenues to develop novel therapeutic approaches. Background: Spinal cord injury (SCI) is a devastating condition mainly deriving from a traumatic damage of the spinal cord (SC). Immune cells and endogenous SC-neural stem cells (SC-NSCs) play a critical role in wound healing processes, although both are ineffective to completely restore tissue functioning. The role of SC-NSCs in SCI and, in particular, whether such cells can interplay with the immune response are poorly investigated issues, although mechanisms governing such interactions might open new avenues to develop novel therapeutic approaches. Methods: We used two transgenic mouse lines to trace as well as to kill SC-NSCs in mice receiving SCI. We used Nestin CreERT2 mice to trace SC-NSCs descendants in the spinal cord of mice subjected to SCI. While mice carrying the suicide gene thymidine kinase (TK) along with the GFP reporter, under the control of the Nestin promoter regions (NestinTKmice) were used to label and selectively kill SC-NSCs. Results: We found that SC-NSCs are capable to self-activate after SCI. In addition, a significant worsening of clinical and pathological features of SCI was observed in the NestinTKmice, upon selective ablation of SC-NSCs before the injury induction. Finally, mice lacking in SC-NSCs and receiving SCI displayed reduced levels of different neurotrophic factors in the SC and significantly higher number of M1-like myeloid cells. Conclusion: Our data show that SC-NSCs undergo cell proliferation in response to traumatic spinal cord injury. Mice lacking SC-NSCs display overt microglia activation and exaggerate expression of pro-inflammatory cytokines. The absence of SC-NSCs impaired functional recovery as well as neuronal and oligodendrocyte cell survival. Collectively our data indicate that SC-NSCs can interact with microglia/macrophages modulating their activation/responses and that such interaction is importantly involved in mechanisms leading tissue recovery.