TRAP-seq Profiling and RNAi-Based Genetic Screens Identify Conserved Glial Genes Required for Adult Drosophila Behavior

Abstract

Although, glial cells have well characterized functions in the developing and mature brain, it is only in the past decade that roles for these cells in behavior and plasticity have been delineated. Glial astrocytes and glia-neuron signaling, for example, are now known to have important modulatory functions in sleep, circadian behavior, memory and plasticity. To better understand mechanisms of glia-neuron signaling in the context of behavior, we have conducted cell-specific, genome-wide expression profiling of adult Drosophila astrocyte-like brain cells and performed RNA interference (RNAi)-based genetic screens to identify glial factors that regulate behavior. Importantly, our studies demonstrate that adult fly astrocyte-like cells and mouse astrocytes have similar molecular signatures; in contrast, fly astrocytes and surface glia—different classes of glial cells—have distinct expression profiles. Glial-specific expression of 653 RNAi constructs targeting 318 genes identified multiple factors associated with altered locomotor activity, circadian rhythmicity and/or responses to mechanical stress (bang sensitivity). Of interest, 1 of the relevant genes encodes a vesicle recycling factor, 4 encode secreted proteins and 3 encode membrane transporters. These results strongly support the idea that glia-neuron communication is vital for adult behavior.

Glial overexpression of Dube3a causes seizures and synaptic impairments in Drosophila concomitant with down regulation of the Na+/K+ pump ATPα

“…Prior work demonstrated that Drosophila with reduced levels of ATPα protein display a bang-sensitive seizure phenotype (Schubiger et al, 1994, Sun et al, 2001, Palladino et al, 2003). Glial specific knockdown of the β subunit of the Na + /K + pump nrv2 also results in seizure-like behaviors (Ng et al, 2016), thereby supporting the idea that impaired glial-dependent regulation of extracellular ion concentration contributes to the pathogenesis of seizures. Na + /K + homeostasis is critically important for proper central nervous system function, while perturbation of Na + /K + balance has been identified as an underlying cause of epilepsy in humans (Somjen, 2002, Scharfman, 2007).…”

Drosophila glia: Few cell types and many conserved functions

“…They transform into phagocytes through activation of a cell autonomous, steroid dependent program at the end of larval life and are the primary phagocytic cell type in the pupal neuropil before they are replaced by newly generated astrocyte‐like glial cells (Omoto et al, ; Tasdemir‐Yilmaz & Freeman, ). The transcriptome of larval and adult astrocyte‐like glial cells has been determined and now allows further comparative analyses between mice and Drosophila (Huang, Ng, & Jackson, ; Ng et al, ; Zhang et al, ).…”

“…They express enzymes regulating neurotransmitter homeostasis at the synapse, which are also found in mammalian astrocytes (Featherstone, 2011;Jackson & Haydon, 2008;Suh & Jackson, 2007). Further comparative analyses of different staged Drosophila and mammalian astrocytes revealed many additional conserved molecular signatures between these cell types (Huang et al, 2015;Ng et al, 2016).…”

Regulation of rhythmic behaviors by astrocytes

“…Such a mechanism was directly demonstrated in recent studies of larval fly astrocytes (Ma et al, ). Mammalian and fly astrocytes have conserved gene expression profiles and evidence suggests that vesicle trafficking and secretion mechanisms of the two species and well as certain secreted factors such as thrombospondin may be important in both species (Ng et al, ). In flies, there are known roles for specific astrocyte factors in circadian behavior, including two predicted to regulate secretion (Ng & Jackson, ; Ng et al, ).…”

“…Mammalian and fly astrocytes have conserved gene expression profiles and evidence suggests that vesicle trafficking and secretion mechanisms of the two species and well as certain secreted factors such as thrombospondin may be important in both species (Ng et al, ). In flies, there are known roles for specific astrocyte factors in circadian behavior, including two predicted to regulate secretion (Ng & Jackson, ; Ng et al, ). Additionally, the inhibition of specific microRNAs (miRs) in fly astrocytes also causes arrhythmic behavior (You, Fulga, Van, & Jackson, ).…”