Gene transfer engineering for astrocyte-specific silencing in the CNS.

Cell-type-specific gene silencing is critical to understand cell functions in normal and pathological conditions, in particular in the brain where strong cellular heterogeneity exists. Molecular engineering of lentiviral vectors has been widely used to express genes of interest specifically in neurons or astrocytes. However, we show that these strategies are not suitable for astrocyte-specific gene silencing due to the processing of small hairpin RNA (shRNA) in a cell. Here we develop an indirect method based on a tetracycline-regulated system to fully restrict shRNA expression to astrocytes. The combination of Mokola-G envelope pseudotyping, glutamine synthetase promoter and two distinct microRNA target sequences provides a powerful tool for efficient and cell-type-specific gene silencing in the central nervous system. We anticipate our vector will be a potent and versatile system to improve the targeting of cell populations for fundamental as well as therapeutic applications

Lentiviral vectors in Huntington's disease research and therapy

We describe here the potential of viral-mediated gene transfer for the modeling and treatment of Huntington's disease, focusing in particular on strategies for the tissue-specific targeting of various CNS cells. The protocols described here cover the design of lentiviral vectors, strategies for modifying their tropism, including the use of various envelopes and tissue-specific promoters, and the potential of miRNA to regulate transgene expression

Lentiviral vectors: a powerful tool to target astrocytes in vivo.

The morphological and functional diversity of astrocytes, and their essential contribution in physiological and pathological conditions, are starting to emerge. However, experimental systems to investigate neuron-glia interactions and develop innovative approaches for the treatment of central nervous system (CNS) disorders are still very limited. Fluorescent reporter genes have been used to visualize populations of astrocytes and produce an atlas of gene expression in the brain. Knock-down or knock-out of astrocytic proteins using transgenesis have also been developed, but these techniques remain complex and time-consuming. Viral vectors have been developed to overexpress or silence genes of interest as they can be used for both in vitro and in vivo studies in adult mammalian species. In most cases, high transduction efficiency and long-term transgene expression are observed in neurons but there is limited expression in astrocytes. Several strategies have been developed to shift the tropism of lentiviral vectors (LV) and allow local and controlled gene expression in glial cells. In this review, we describe how modifications of the interaction between the LV envelope glycoprotein and the surface receptor molecules on target cells, or the integration of cell-specific promoters and miRNA post-transcriptional regulatory elements have been used to selectively express transgenes in astrocytes

Population based epidemiology of amyotrophic lateral sclerosis using capture-recapture methodology

Item does not contain fulltextBACKGROUND: Variation in the incidence rate in epidemiological studies on amyotrophic lateral sclerosis (ALS) may be due to a small population size and under ascertainment of patients. The previously reported incidence decline in the elderly and a decrease in the male:female ratio in postmenopausal age groups have yet to be confirmed. METHODS: ALS epidemiology in a large population based register in The Netherlands was studied between 1 January 2006 and 31 December 2009, and applied capture-recapture methodology in separate age and gender groups to adjust for the number of unobserved patients. RESULTS: 1217 incident patients were observed, and a capture-recapture incidence of 2.77 per 100 000 person-years (95% CI 2.63 to 2.91). Prevalence on 31 December 2008 was 10.32 per 100 000 individuals (95% CI 9.78 to 10.86). The incident cohort had a higher median age at onset (63.0 vs 58.1 years) and more bulbar onset patients (30.0% vs 19.1%) compared with the prevalent cohort. Incidence and prevalence peaked in the 70-74 year age group followed by a rapid decline in older age. The male:female ratio in the premenopausal age group (1.91, 95% CI 1.32 to 2.79) was not significantly higher than that in the postmenopausal age group (1.50, 95% CI 1.34 to 1.67). CONCLUSION: The marked difference in patient characteristics between incident and prevalent cohorts underscores the importance of including incident patients when studying susceptibility or disease modifying factors in ALS. The incidence decline in the elderly may suggest that ALS is not merely the result of ageing. Absence of a significant postmenopausal drop in the male:female ratio suggests that the protective role of female sex hormones in ALS is limited

CRISPR/Cas9-Mediated Genome Editing for Huntington's Disease.

This chapter describes the potential use of viral-mediated gene transfer in the central nervous system for genome editing in the context of Huntington's disease. Here, we provide protocols that cover the design of various genome editing strategies, the cloning of CRISPR/Cas9 elements into lentiviral vectors, and the assessment of cleavage efficiency, as well as potential unwanted effects

Optimization of adeno-associated viral vector-mediated transduction of the corticospinal tract: comparison of four promoters.

Funder: This research was funded by a Nathalie Rose Barr award (NRB110) from the International Spinal Research Trust, and support from Medical Research Council (MR/R004544/1 & MR/R004463/1), NWO (013-16-002), Czech Ministry of Education (CZ.02.1.01/0.0./0.0/15_003/0000419), ERA-NET NEURON AxonRepair, Christopher and Dana Reeve Foundation, International Foundation for Research in Paraplegia, Hersenstichting Nederland.Adeno-associated viral vectors are widely used as vehicles for gene transfer to the nervous system. The promoter and viral vector serotype are two key factors that determine the expression dynamics of the transgene. A previous comparative study has demonstrated that AAV1 displays efficient transduction of layer V corticospinal neurons, but the optimal promoter for transgene expression in corticospinal neurons has not been determined yet. In this paper, we report a side-by-side comparison between four commonly used promoters: the short CMV early enhancer/chicken β actin (sCAG), human cytomegalovirus (hCMV), mouse phosphoglycerate kinase (mPGK) and human synapsin (hSYN) promoter. Reporter constructs with each of these promoters were packaged in AAV1, and were injected in the sensorimotor cortex of rats and mice in order to transduce the corticospinal tract. Transgene expression levels and the cellular transduction profile were examined after 6 weeks. The AAV1 vectors harbouring the hCMV and sCAG promoters resulted in transgene expression in neurons, astrocytes and oligodendrocytes. The mPGK and hSYN promoters directed the strongest transgene expression. The mPGK promoter did drive expression in cortical neurons and oligodendrocytes, while transduction with AAV harbouring the hSYN promoter resulted in neuron-specific expression, including perineuronal net expressing interneurons and layer V corticospinal neurons. This promoter comparison study contributes to improve transgene delivery into the brain and spinal cord. The optimized transduction of the corticospinal tract will be beneficial for spinal cord injury research