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.

Population-based epidemiology of amyotrophic lateral sclerosis (ALS) in an ageing Europe--the French register of ALS in Limousin (FRALim register).

BACKGROUND AND PURPOSE: The main objective of establishing the French register of amyotrophic lateral sclerosis (ALS) in the Limousin region (FRALim), was to assess the incidence of ALS, in this ageing region of Europe, over a 12-year period (2000-2011). METHODS: Patients were included if they lived in Limousin at the time of diagnosis of ALS according to El Escorial revised criteria and were identified by at least one of the following sources: (i) the French national body coordinating ALS referral centres; (ii) public and private hospitals in the region; (iii) health insurance data related to long-term diseases. RESULTS: The FRALim register identified 279 incident cases (2000-2011). The crude and European population standardized incidences of ALS were as high as 3.19/100,000 person-years of follow-up (95% CI 2.81-3.56) and 2.58/100,000 person-years of follow-up (95% CI 2.27-2.89) respectively. Median age at onset was 70.8 years (interquartile range 63.1-77.1). The standardized sex incidence ratio (male/female) was 1.3 overall, but 1.1 under the age of 65 years, 1.7 between 65 and 75 years and 1.9 above 75 years. The exhaustiveness of the register has been estimated at 98.4% (95% CI 95.6-99.4) by capture-recapture analysis. CONCLUSION: It was possible for the first time in France to monitor accurately the incidence of ALS over a long time period. It appears to be in the upper range of data reported in western countries. Patterns displayed here might anticipate the epidemiology of ALS in ageing western countries.