Neurofibromatosis-like phenotype in Drosophila caused by lack of glucosylceramide extension.

Glycosphingolipids (GSLs) are of fundamental importance in the nervous system. However, the molecular details associated with GSL function are largely unknown, in part because of the complexity of GSL biosynthesis in vertebrates. In Drosophila, only one major GSL biosynthetic pathway exists, controlled by the glycosyltransferase Egghead (Egh). Here we discovered that loss of Egh causes overgrowth of peripheral nerves and attraction of immune cells to the nerves. This phenotype is reminiscent of the human disorder neurofibromatosis type 1, which is characterized by disfiguring nerve sheath tumors with mast cell infiltration, increased cancer risk, and learning deficits. Neurofibromatosis type 1 is due to a reduction of the tumor suppressor neurofibromin, a negative regulator of the small GTPase Ras. Enhanced Ras signaling promotes glial growth through activation of phosphatidylinositol 3-kinase (PI3K) and its downstream kinase Akt. We find that overgrowth of peripheral nerves in egh mutants is suppressed by down-regulation of the PI3K signaling pathway by expression of either dominant-negative PI3K, the tumor suppressor PTEN, or the transcription factor FOXO in the subperineurial glia. These results show that loss of the glycosyltransferase Egh affects membrane signaling and activation of PI3K signaling in glia of the peripheral nervous system, and suggest that glycosyltransferases may suppress proliferation.

Symphonic resonance: optimizing hypnotic suggestions with music to harmonize depression and rumination.

Depression is a complex, multi-dimensional disorder that is recognized as a leading cause of human suffering and disability. A wide variety of treatments, both physical and psychological, have been developed to lessen the burden on depressed individuals and those they may affect. Hypnosis has been shown to be an effective vehicle for delivering psychological treatments for alleviating depression in a number of studies, but it is always a challenge to increase the effectiveness of suggestions given in hypnosis. The addition of music to enhance hypnotic approaches has been studied and received substantial support for its potential effectiveness. This article explores the merits of incorporating music into the delivery of hypnosis sessions and offers specific recommendations for the use of rhythmic methods as a means of deepening hypnosis and increasing the impact of one's suggestions for reducing depressive ruminations. Five case examples are provided to illustrate the successful use of this integrative approach to treatment.

The structure and function of endophilin proteins.

Members of the BAR domain protein superfamily are essential elements of cellular traffic. Endophilins are among the best studied BAR domain proteins. They have a prominent function in synaptic vesicle endocytosis (SVE), receptor trafficking and apoptosis, and in other processes that require remodeling of the membrane structure. Here, we discuss the role of endophilins in these processes and summarize novel insights into the molecular aspects of endophilin function. Also, we discuss phosphorylation of endophilins and how this and other mechanisms may contribute to disease.

A mutational analysis of the endophilin-A N-BAR domain performed in living flies.

BACKGROUND: Endophilin is a cytoplasmic protein with an important function in clathrin-dependent endocytosis at synapses and elsewhere. Endophilin has a BAR (Bin/Amphiphysin/Rvs-homology) domain, which is implicated in the sensing and induction of membrane curvature. Previous structure-function studies of the endophilin-A BAR domain have almost exclusively been made in reduced systems, either in vitro or ex vivo in cultured cells. To extend and complement this work, we have analyzed the role played by the structural features of the endophilin-A BAR domain in Drosophila in vivo. METHODOLOGY/PRINCIPAL FINDINGS: The study is based on genetic rescue of endophilin-A (endoA) null mutants with wild type or mutated endoA transgenes. We evaluated the viability of the rescuants, the locomotor behavior in adult flies and the neurotransmission at the larval neuromuscular junction. Whereas mutating the endophilin BAR domain clearly affected adult flies, larval endophilin function was surprisingly resistant to mutagenesis. Previous reports have stressed the importance of a central appendage on the convex BAR surface, which forms a hydrophobic ridge able to directly insert into the lipid bilayer. We found that the charge-negative substitution A66D, which targets the hydrophobic ridge and was reported to completely disrupt the ability of endophilin-BAR to tubulate liposomes in vitro, rescued viability and neurotransmission with the same efficiency as wild type endoA transgenes, even in adults. A similar discrepancy was found for the hydrophilic substitutions A63S/A66S and A63S/A66S/M70Q. The A66W mutation, which introduces a bulky hydrophobic side chain and induces massive vesiculation of liposomes in vitro, strongly impeded eye development, even in presence of the endogenous endoA gene. Substantial residual function was observed in larvae rescued with the EndoA(Arf) transgene, which encodes a form of endophilin-A that completely lacks the central appendage. Whereas a mutation (D151P) designed to increase the BAR curvature was functional, another mutation (P143A, DeltaLEN) designed to decrease the curvature was not. CONCLUSIONS/SIGNIFICANCE: Our results provide novel insight into the structure/function relationship of the endophilin-A BAR domain in vivo, especially with relation to synaptic function.

PICK1 expression in the Drosophila central nervous system primarily occurs in the neuroendocrine system.

The protein interacting with C kinase 1 (PICK1) protein was first identified as a novel binding partner for protein kinase C. PICK1 contains a membrane-binding BAR domain and a PDZ domain interacting with many synaptic proteins, including the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subunit GluR2 and the dopamine transporter. PICK1 is strongly implicated in GluR2 trafficking and synaptic plasticity. In mammals, PICK1 has been characterized extensively in cell culture studies. To study PICK1 in an intact system, we characterized PICK1 expression immunohistochemically in the adult and larval Drosophila central nervous system. PICK1 was found in cell bodies in the subesophageal ganglion, the antennal lobe, the protocerebrum, and the neuroendocrine center pars intercerebralis. The cell types that express PICK1 were identified using GAL4 enhancer trap lines. The PICK1-expressing cells form a subpopulation of neurons. PICK1 immunoreactivity was neither detected in glutamatergic nor in dopaminergic neurons. Also, we observed PICK1 expression in only a few GABAergic neurons, located in the antennal lobe. In contrast, we detected robust PICK1 immunolabeling of peptidergic neurons in the neuroendocrine system, which express the transcription factor DIMM and the amidating enzyme peptidylglycine-alpha-hydroxylating monooxygenase (PHM). The PICK1-positive cells include neurosecretory cells that produce the insulin-like peptide dILP2. PICK1 expression in insulin-producing cells also occurs in mammals, as it was also observed in a rat insulinoma cell line derived from pancreatic beta-cells. At the subcellular level, PICK1 was found in the perinuclear zone but surprisingly not in synaptic domains. We conclude that PICK1 may serve an important role in the neuroendocrine system both in insects and vertebrates.

The fatty acid elongase NOA is necessary for viability and has a somatic role in Drosophila sperm development.

The essential gene noa (CG 3971; also known as Baldspot) encodes a very long chain fatty acid elongase which is most similar to the mammalian elongase ELOVL6. noa is expressed in the nervous system from embryogenesis on, in imaginal discs, the fat body, malpighian tubules and in the gonads of both sexes. Its function is dose dependent, since reduced levels of noa RNA lead to impaired motility and severely reduced viability. In testes, noa RNA is detected in the cyst cells during the postmeiotic phase of germ cell development. An RNAi construct selectively driven in cyst cells leads to male sterility, demonstrating the necessity of noa function for male germline development and the interaction of the somatic cyst cells with the developing sperm.

Axonal accumulation of synaptic markers in APP transgenic Drosophila depends on the NPTY motif and is paralleled by defects in synaptic plasticity.

Alzheimer's disease (AD) is characterized by neurofibrillary tangles and extracellular plaques, which consist mainly of beta-amyloid derived from the beta-amyloid precursor protein (APP). An additional feature of AD is axonopathy, which might contribute to impairment of cognitive functions. Specifically, axonal transport defects have been reported in AD animal models, including mice and flies that overexpress APP and tau. Here we demonstrate that the APP-induced traffic jam of vesicles in peripheral nerves of Drosophila melanogaster larvae depends on the four residues NPTY motif in the APP intracellular domain. Furthermore, heterologous expression of Fe65 and JIP1b, scaffolding proteins interacting with the NPTY motif, also perturb axonal transport. Together, these data indicate that JIP1b or Fe65 may be involved in the APP-induced axonal transport defect. Moreover, we have characterized neurotransmission at the neuromuscular junction in transgenic larvae that express human APP. Consistent with the observation that these larvae do not show any obvious movement deficits, we found no changes in basal synaptic transmission. However, short-term synaptic plasticity was affected by overexpression of APP. Together, our results show that overexpression of APP induces partial stalling of axonal transport vesicles, paralleled by abnormalities in synaptic plasticity, which may provide a functional link to the deterioration of cognitive functions observed in AD.