The intercellular transport of lactate is crucial for the astrocyte-to-neuron lactate shuttle (ANLS), a model of brain energetics according to which neurons are fueled by astrocytic lactate. In this study we show that the Drosophila chaski gene encodes a monocarboxylate transporter protein (MCT/SLC16A) which functions as a lactate/pyruvate transporter, as demonstrated by heterologous expression in mammalian cell culture using a genetically encoded FRET nanosensor. chaski expression is prominent in the Drosophila central nervous system and it is particularly enriched in glia over neurons. chaski mutants exhibit defects in a high energy demanding process such as synaptic transmission, as well as in locomotion and survival under nutritional stress. Remarkably, locomotion and survival under nutritional stress defects are restored by chaski expression in glia cells. Our findings are consistent with a major role for intercellular lactate shuttling in the brain metabolism of Drosophila.The function of the nervous system requires a large supply of energy, as exemplified by the fact that in the mammalian brain, 50-60% of total ATP produced in the brain is used to support ion transport 1 ; in flies, retinal photoreceptor cells consume about 10% of the ATP production of the whole animal 2 . Our current view about the field of brain energetics has evolved from a one centered in neurons into a one in which astrocytes and neurons play complementary roles to support the high demand of excitability and synaptic activity. In this view, the metabolic communication between neurons and glia is crucial to sustain brain function, relevating the need to unravel the mechanisms that underly this communication.Within cells, several glucose-derived metabolic intermediates can subsequently be oxidized for energy production (i.e. lactate, pyruvate, glutamate, or acetate) 3 , while ketone bodies are mainly used during development and starvation 4,5 . In mammals, it has been estimated that over 10% of glucose entering the brain is converted to lactate despite normal oxygen levels, a metabolic process known as aerobic glycolysis 6 . Lactate production through aerobic glycolysis is a metabolic feature of astrocytes 7,8 . The high-energy demand as the result of glutamatergic synaptic activity is thought to stimulate aerobic glycolysis in astrocytes 9 producing lactate that is secreted and used by neurons as energy source. This metabolic interaction has been termed the astrocyte-neuron lactate shuttle (ANLS) hypothesis 9,10 . Recent evidence from invertebrates supports that metabolic compartmentalization and coupling of neurons and glial cells is a conserved, fundamental feature of bilaterian nervous systems independent of their size 11 . Moreover, the lack of an apparent detrimental effect of glycolytic enzyme deletion in Drosophila neurons suggests that insects may have evolved an extreme version of ANLS, in which neurons would be fueled by lactate and/or alanine produced by glial cells 11 . In vertebrates, lactate is co-transported with proton...

BackgroundCLCA is a family of metalloproteases that regulate Ca2+-activated Cl− fluxes in epithelial tissues. In HEK293 cells, CLCA1 promotes membrane expression of an endogenous Anoctamin 1 (ANO1, also termed TMEM16A)-dependent Ca2+-activated Cl− current. Motif architecture similarity with CLCA2, 3 and 4 suggested that they have similar functions. We previously detected the isoform CLCA4L in rat olfactory sensory neurons, where Anoctamin 2 is the principal chemotransduction Ca2+-activated Cl− channel. We explored the possibility that this protein plays a role in odor transduction.ResultsWe cloned and expressed CLCA4L from rat olfactory epithelium in HEK293 cells. In the transfected HEK293 cells we measured a Cl−-selective Ca2+-activated current, blocked by niflumic acid, not present in the non-transfected cells. Thus, CLCA4L mimics the CLCA1 current on its ability to induce the ANO1-dependent Ca2+-activated Cl− current endogenous to these cells. By immunocytochemistry, a CLCA protein, presumably CLCA4L, was detected in the cilia of olfactory sensory neurons co-expressing with ANO2.ConclusionThese findings suggests that a CLCA isoform, namely CLCA4L, expressed in OSN cilia, might have a regulatory function over the ANO2-dependent Ca2+-activated Cl− channel involved in odor transduction.Electronic supplementary materialThe online version of this article (doi:10.1186/s12868-017-0379-7) contains supplementary material, which is available to authorized users.

Odour-mediated signal transduction is a complex process that occurs in the cilia of olfactory sensory neurons. To gain insight in to the molecular organization of the odour transduction machinery, we developed a procedure to purify olfactory cilia membranes by differential centrifugation of rat olfactory epithelium extracts. We tested whether known scaffolding proteins that might participate in the assembly of the complex chemotransduction apparatus are present in the purified membrane fraction. Utilizing immunoblotting and immunohistochemistry, we show that the multidomain scaffolding proteins ProSAP/Shanks and calcium/calmodulin-dependent serine protein kinase CASK are present in the olfactory cilia. Ion channels involved in chemotransduction could be reconstituted into planar lipid bilayers for electrophysiological recordings. Our procedure should allow the identification of further chemotransduction-related proteins.

No abstract

Thanks to the power of Drosophila genetics, this animal model has been a precious tool for scientists to uncover key processes associated to innate immunity. The fly immune system relies on a population of macrophage-like cells, also referred to as hemocytes, which are highly migratory and phagocytic, and can easily be followed in vivo. These cells have shown to play important roles in fly development, both at the embryonic and pupal stages. However, there is no robust assay for the study of hemocyte migration in vitro, which limits our understanding of the molecular mechanisms involved. Here, we contribute to fill this gap by showing that hemocytes adopt a polarized morphology upon ecdysone stimulation, allowing the study of the cytoskeleton rearrangements and organelle reorganization that take place during the first step of cell locomotion.