SlgA, the homologue of the human schizophrenia associated PRODH gene, acts in clock neurons to regulate <i>Drosophila </i>aggression

Mutations in the proline dehydrogenase gene PRODH are linked to behavioral alterations in schizophrenia and as part of DiGeorge and velo-cardio-facial syndromes, but the role of PRODH in their etiology remains unclear. Here, we establish a Drosophila model to study the role of PRODH in behavioral disorders. We determine the distribution of the Drosophila PRODH homolog slgA in the brain and show that knockdown and overexpression of human PRODH and slgA in the lateral neurons ventral (LNv) lead to altered aggressive behavior. SlgA acts in an isoform-specific manner and is regulated by casein kinase II (CkII). Our data suggest that these effects are, at least partially, due to effects on mitochondrial function. We thus show that precise regulation of proline metabolism is essential to drive normal behavior and we identify Drosophila aggression as a model behavior relevant for the study of the mechanisms that are impaired in neuropsychiatric disorders

Bacteriocyte cell death in the pea aphid/ Buchnera symbiotic system

International audienceSymbiotic associations play a pivotal role in multicellular life by facilitating acquisition of new traits and expanding the ecological capabilities of organisms. In insects that are obligatorily dependent on intracellular bacterial symbionts, novel host cells (bacteriocytes) or organs (bacteriomes) have evolved for harboring beneficial microbial partners. The processes regulating the cellular life cycle of these endosymbiont-bearing cells, such as the cell-death mechanisms controlling their fate and elimination in response to host physiology, are fundamental questions in the biology of symbiosis. Here we report the discovery of a cell-death process involved in the degeneration of bacteriocytes in the hemipteran insect Acyrthosiphon pisum This process is activated progressively throughout aphid adulthood and exhibits morphological features distinct from known cell-death pathways. By combining electron microscopy, immunohistochemistry, and molecular analyses, we demonstrated that the initial event of bacteriocyte cell death is the cytoplasmic accumulation of nonautophagic vacuoles, followed by a sequence of cellular stress responses including the formation of autophagosomes in intervacuolar spaces, activation of reactive oxygen species, and Buchnera endosymbiont degradation by the lysosomal system. We showed that this multistep cell-death process originates from the endoplasmic reticulum, an organelle exhibiting a unique reticular network organization spread throughout the entire cytoplasm and surrounding Buchnera aphidicola endosymbionts. Our findings provide insights into the cellular and molecular processes that coordinate eukaryotic host and endosymbiont homeostasis and death in a symbiotic system and shed light on previously unknown aspects of bacteriocyte biological functioning

Nucleotide-sequence of a transactivating bombyx-mori nuclear polyhedrosis-virus immediate early gene

The open reading frame (ORF) of 1572 bp contained in the 3.8 kb ClaI fragment of BmNPV encodes a viral regulatory protein which transactivates the delayed early AcMNPV 39K gene. Transactivation is induced in uninfected cells following transfection with a plasmid containing only the ClaI fragment. Hitherto immediate early gene promoter activity of the included 631 bp leader sequence is evident since no other viral elements are needed for the transcription of the regulatory gene.status: publishe

Growth control through regulation of insulin-signaling by nutrition-activated steroid hormone

Abstract Growth and maturation are coordinated processes in all animals. Integration of internal cues, such as signalling pathways, with external cues such as nutritional status is paramount for an orderly progression of development in function of growth. In Drosophila , this coordination involves insulin and steroid signalling, but the mechanisms by which this occurs and how they are coordinated are incompletely understood. We show that production of the bioactive 20-hydroxyecdysone by the enzyme Shade in the fat body is a nutrient-dependent process. We demonstrate that during fed conditions, Shade plays a role in growth regulation, as knockdown of shade in the fat body resulted in growth defects and perturbed expression and release of the Drosophila insulin-like peptides from the insulin-producing cells (IPCs). We identify the trachea and IPCs as direct targets through which 20-hydroxyecdysone regulates insulin-signaling. The identification of the trachea-dependent regulation of insulin-signaling exposes an important variable that may have been overlooked in other studies focusing on insulin-signaling in Drosophila . Finally, we show with IPC-specific manipulations that 20E may both be a growth-promoting and growth-inhibiting signal in the IPCs acting through different nuclear receptors. Our findings provide a potentially conserved, novel mechanism by which nutrition can modulate steroid hormone bioactivation, reveal an important caveat of a commonly used transgenic tool to study IPC function and yield further insights as to how steroid and insulin signalling are coordinated during development to regulate growth and developmental timing.status: publishe

Characterization of a cloned locust tyramine receptor cDNA by functional expression in permanently transformed Drosophila S2 cells

The cDNA for Tyr-Loc, a G protein-coupled receptor that clearly shows homology to a number of mammalian and fruit fly receptors for biogenic amines, was cloned from the nervous system of Locusta migratoria. Functional expression of the cloned cDNA was obtained in cultured insect cells, i.e., in Spodoptera SF9 cells using a baculoviral expression system and in stably transformed Drosophila Schneider 2 (S2) cells. Multiple copies of the receptor expression construct are inserted into the genome of these permanently transformed cells. The expression of the receptor cDNA was driven by the upstream sequences of a Bombyx mori baculoviral immediate early gene. Tyramine shows a much higher binding affinity to this receptor than other possible endogenous ligands. It also reduces forskolin-induced cyclic AMP production in the permanently transformed S2 cells. The pharmacological profile of the Tyr-Loc receptor is distinct from that of any locust receptor-type described so far, but it is similar to that of the Drosophila tyramine/octopamine receptor. In the locust CNS, the Tyr-Loc mRNA is not present in the distal part of the optic lobes but has a widespread distribution in the brain ventral nerve cord.status: publishe

SlgA, the homologue of the human schizophrenia associated PRODH gene, acts in clock neurons to regulate Drosophila aggression

Mutations in proline dehydrogenase (PRODH) are linked to behavioral alterations in schizophrenia and as part of DiGeorge and velo-cardio-facial syndromes, but the role of PRODH in their etiology remains unclear. We here establish a Drosophila model to study the role of PRODH in behavioral disorders. We determine the distribution of the Drosophila PRODH homolog slgA in the brain and show that knock-down and overexpression of human PRODH and slgA in the lateral neurons ventral (LNv) lead to altered aggressive behavior. SlgA acts in an isoform-specific manner and is regulated by casein kinase II (CkII). Our data suggest that these effects are, at least partially, due to effects on mitochondrial function. We thus show that precise regulation of proline metabolism is essential to drive normal behavior and we identify Drosophila aggression as a model behavior relevant for the study of mechanisms impaired in neuropsychiatric disorders.status: publishe

Growth control through regulation of insulin signalling by nutrition-activated steroid hormone in Drosophila

Growth and maturation are coordinated processes in all animals. Integration of internal cues, such as signalling pathways, with external cues, such as nutritional status, is paramount for an orderly progression of development and growth. In Drosophila, this involves insulin and steroid signalling, but the underlying mechanisms and their coordination are incompletely understood. We show that bioactive 20-hydroxyecdysone production by the enzyme Shade in the fat body is a nutrient-dependent process. We demonstrate that under fed conditions, Shade plays a role in growth control. We identify the trachea and the insulin-producing cells in the brain as direct targets through which 20-hydroxyecdysone regulates insulin signalling. The identification of trachea-dependent regulation of insulin signalling exposes an important variable that may have been overlooked in other studies focusing on insulin signalling in Drosophila Our findings provide a potentially conserved, novel mechanism by which nutrition can modulate steroid hormone bioactivation, reveal an important caveat of a commonly used transgenic tool to study insulin-producing cell function, and yield further insights into how steroid and insulin signalling are coordinated during development to regulate growth and developmental timing.status: publishe

Baculovirus immediate early gene promoter based expression vectors for transient and stable transformation of insect cells

A recombinant plasmid vector was constructed in which the bacterial LacZ gene was placed under the control of a Bombyx mori baculovirus early promoter. The vector proved to be active in transfected cultured dipteran and lepidopteran cells. Co-transfection carried out with this recombinant plasmid vector and a plasmid containing the hygromycin phosphotransferase gene followed by selection with the antibiotic hygromycin B, resulted in stable transformation of cultured Drosophila melanogaster Schneider 2 cells. Southern blot analysis of the host cell's genomic DNA in combination with chromosomal in situ hybridization demonstrated that multiple copies of both plasmids were integrated in the host cell's genome.status: publishe

Recombinant protein expression in insect cell systems

Since the introduction of baculovirus expression vectors, the suitability of insect cells for the expression of functionally active genes of eukaryotic origin has been exhaustively documented. Originally realization of a functional viral expression vector was laborious and depended on double homologous in vivo recombination success as well as successful purification of recombinant baculovirus by plaque assay. Using the commercial Bac to Bac(TM) expression system we confirm that transposon-assisted recombination and cloning of recombinant transfectable bacmid DNA in bacteria now allow fast productive expression of a gene of interest.status: publishe