Restricted Transgene Expression in the Brain with Cell-Type Specific Neuronal Promoters

Abstract

Tissue-targeted expression is of major interest for studying the contribution of cellular subpopulations to neurodegenerative diseases. However, in vivo methods to investigate this issue are limited. Here, we report an analysis of the cell specificity of expression of fluorescent reporter genes driven by six neuronal promoters, with the ubiquitous phosphoglycerate kinase 1 (PGK) promoter used as a reference. Quantitative analysis of AcGFPnuc expression in the striatum and hippocampus of rodents showed that all lentiviral vectors (LV) exhibited a neuronal tropism; however, there was substantial diversity of transcriptional activity and cell-type specificity of expression. The promoters with the highest activity were those of the 67 kDa glutamic acid decarboxylase (GAD67), homeobox Dlx5/6, glutamate receptor 1 (GluR1), and preprotachykinin 1 (Tac1) genes. Neuron-specific enolase (NSE) and dopaminergic receptor 1 (Drd1a) promoters showed weak activity, but the integration of an amplification system into the LV overcame this limitation. In the striatum, the expression profiles of Tac1 and Drd1a were not limited to the striatonigral pathway, whereas in the hippocampus, Drd1a and Dlx5/6 showed the expected restricted pattern of expression. Regulation of the Dlx5/6 promoter was observed in a disease condition, whereas Tac1 activity was unaffected. These vectors provide safe tools that are more selective than others available, for the administration of therapeutic molecules in the central nervous system (CNS). Nevertheless, additional characterization of regulatory elements in neuronal promoters is still required.

Selective Optogenetic Control of Purkinje Cells in Monkey Cerebellum

“…Such specificity is unusual for viral vector-mediated gene delivery in primates. The modest payload of viral vectors and the presumed length of cell type-specific promoters challenge the feasibility of this approach, and several attempts to achieve targeting in this way have yielded only moderate specificity (Delzor et al, 2012; Klein et al, 2016; Kügler, 2015; Nathanson et al, 2009a). However, the present study shows that some types of primate neurons can be targeted with precision using short promoters, complementing recent promising efforts described below.…”

Lentiviral vectors as tools to understand central nervous system biology in mammalian model organisms

“…Ubiquitous promoters that cause expression of non-native proteins in virtually all transduced cells include elongation factor 1 alpha (EF1α), cytomegalovirus enhancer/promoter element (CMV), β-actin, β-globin chimeric promoter (CAG), and phosphoglycerate kinase promoter (PGK; for a comparison see ( Qin et al, 2010 ) and ( Yaguchi et al, 2013 ). Promoters providing specific expression in all neurons include synapsin 1 (syn; Hioki et al, 2007 ; Nathanson et al, 2009 ; van Hooijdonk et al, 2009 ; Yaguchi et al, 2013 ) and neuron specific enolase (NSE; Delzor et al, 2012 ). Neuronal type specific promoters, that have a size compatible with lentiviral vectors are still limited, but include calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα; Dittgen et al, 2004 ; van Hooijdonk et al, 2009 ; Seeger-Armbruster et al, 2015 ), which restricts expression to excitatory glutamatergic neurons and glutamate decarboxylase 67 (GAD67; Delzor et al, 2012 ) that should restrict expression to inhibitory GABAergic neurons.…”

“…Promoters providing specific expression in all neurons include synapsin 1 (syn; Hioki et al, 2007 ; Nathanson et al, 2009 ; van Hooijdonk et al, 2009 ; Yaguchi et al, 2013 ) and neuron specific enolase (NSE; Delzor et al, 2012 ). Neuronal type specific promoters, that have a size compatible with lentiviral vectors are still limited, but include calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα; Dittgen et al, 2004 ; van Hooijdonk et al, 2009 ; Seeger-Armbruster et al, 2015 ), which restricts expression to excitatory glutamatergic neurons and glutamate decarboxylase 67 (GAD67; Delzor et al, 2012 ) that should restrict expression to inhibitory GABAergic neurons. The parvalbumin promoter targets a subset of GABAergic neurons ( Sohal et al, 2009 ) and ppHcrt targets hypocretin neurons ( Zhang et al, 2010 ).…”

A MicroRNA-Based Gene-Targeting Tool for Virally Labeling Interneurons in the Rodent Cortex

“…While transgenic mouse lines have revolutionized our ability to target specific interneuron types (Taniguchi et al, 2011), it remains difficult to cross-breed transgenic driver lines with transgenic disease models. Virally targeting interneurons has been demonstrated using shortened or non-mammalian promoters (Nathanson et al, 2009a; Delzor et al, 2012) or short cell-type-specific enhancer elements (Lee et al, 2014; Vogt et al, 2014; Dimidschstein et al, 2016). miRNA regulation is orthogonal to promoter and enhancer regulatory elements and represents an additional strategy to achieve interneuron targeting from viral vectors.…”