Ping Shen - US grants

DESCRIPTION (applicant's abstract): Recent molecular and genetic studies indicate that a neuropeptide Y (NPY) mediated signaling pathway, which is conserved among animals including worms and humans, is involved in regulating feeding behavior. However, the mechanism for its regulation is not understood. The long term goal of this proposal is to understand the role of Drosophila neuropeptide F(NPF), a human NPY homolog, in modulating feeding behavior, the underlying mechanism(s), and its functional relationship to vertebrate neuropeptide Y family molecules. Drosophila is the only invertebrate model organism where homologs of NPY and its receptors have been identified. Using whole mount in situ RNA hybridization and immunocytochemistry, we showed that dNPF is expressed in both CNS and gut In larval CNS, dNPFergic neurons of the brain innervate subesophageal, thoracic, and abdominal ganglia, and may thereby act as neurotransmitters for mediating brain control of feeding behavior. We also found that gustatory stimulation by sugars induces dNPF expression in two additional neurons of larval subesophageal ganglion. The expression remains strong long after sugar withdrawl, implicating dNPF in mediating carbohydrate conditioning of fly CNS. The dNPF midgut expression is enhanced by food uptake, and reduced by starvation. One of the putative dNPF receptors is expressed in larval gut, brain and possibly salivary glands. Thus, dNPF may also function as a gut hormone that coordinates feeding associated activities in diverse tissues. In this application, we propose to directly test the specific roles of dNPF in transgenic flies by addressing the following specific aims: 1) Constructing gain-of-function transgenic Drosophila larvae through controlled ectopic dNPF expression and analyzing their feeding behaviors; 2) Cloning and characterization of cis regulatory elements of dNPF using UAStauGFP reporter system; 3) constructing loss-of-function transgenic larvae through targeted functional knockout of dNPF and determining the specific roles of brain, subesophageal ganglion and midgut dNPF in feeding behavior. These studies should provide general insights into the signaling mechanism for feeding regulation in invertebrates as well as higher animals including humans.

[unreadable] DESCRIPTION (provided by applicant): The neuropeptide Y (NPY) signaling system is both structurally and functionally conserved between Drosophila and mammals. Recent studies from this laboratory have shown that Drosophila neuropeptide F (NPF), the single NPY homologue in the fly genome, plays important roles in modulating motivational feeding, locomotion and alcohol response. Parallel phenotypes have been observed between NPF-deficient flies and NPY-knockout mice: both animals displayed normal baseline feeding but deficits in motivational feeding; NPF-deficient fly larvae showed food-elicited hyperactive locomotion whereas NPY knockouts exhibited increased susceptibility to seizure; both NPF-deficient flies and NPY knockout mice displayed decreased ethanol sensitivity. Moreover, flies overexpressing NPF showed increased sensitivity to ethanol sedation, similar to the phenotypes of NPY-overexpressing mice. These observations strongly suggest that Drosophila is a suitable genetic model for the study of the neural, cellular and molecular mechanisms underlying the action the NPF/NPY signaling system. [unreadable] This proposed research aims to further elucidate the neurobiological basis of. NPY-mediated regulation of ethanol related behaviors. The specific aims of this application include: 1) Identification and functional analysis of the neuroanatomical sites of the NPF system involved in modulation of ethanol response; 2) EMS-mutagenesis screen of genes involved in NPF/NPFR1-mediated ethanol response; 3) gain-of-function screen for genes involved in NPF/NPFR1 -mediated ethanol response.. The results from these studies should provide novel insights into understanding why a common neural signaling system underlies the controls of feeding and alcohol related behaviors, what components of the signaling pathway are conserved, and how genetic factors contribute to ethanol sensitivity in diverse organisms [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): The recent research from this laboratory provides direct evidence that Drosophila is a suitable genetic model for studying molecular, cellular and neural basis of feeding behavioral control and eating disorders. We have shown that Drosophila neuropeptide F (NPF), the fly homologue of mammalian NPY, plays an important role in regulating hunger-driven foraging and feeding behaviors. Parallel behavioral phenotypes have been observed between NPF-deficient flies and NPY-knockout mice: both animals were normal in baseline feeding and body weight control but displayed feeding deficits in the deprived state; NPF-deficient flies and NPY knockout mice also displayed decreased acute sensitivity to ethanol sedation. More recently, we have obtained evidence that analogous to mammalian insulin, Drosophila insulin-like peptides (DILPs) suppress feeding response by acting oh different neuronal networks including the NPY-like neuronal pathway. For example, DILPs appear to directly inhibit the signaling activity of NPFR1 neurons through the insulin-like receptor (lnR)/ribosomal S6 kinase (S6K) pathway. Taken together, our findings strongly suggest that signaling mechanisms for the regulation of foraging and feeding behaviors are largely conserved between flies and mammals. The proposed research aims to identify and characterize additional genes and molecular and neuronal pathways critical for hunger-driven behaviors. We are particularly interested in genes and neurons that differentially regulate distinct aspects of hunger response such as enhanced food seeking, motivated intake of less-preferred foods, and increased ingestion rate. The specific aims of this application include: 1) Analysis of genes and molecular pathways underlying the regulation of hunger-motivated foraging by NPFR1 neurons; 2) Analysis of genes and molecular pathways underlying the regulation of hunger-driven behaviors by DILP neurons; 3) Gain-of-function screen for genes critical for DILP/NPFR1 neuron-mediated hunger response. The results from these studies may provide general insights into how genetic and neural factors contribute to hunger regulation of food response in diverse organisms including mammals. [unreadable] [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): The recent research from this laboratory provides direct evidence that Drosophila is a suitable genetic model for studying molecular, cellular and neural basis of feeding behavioral control and eating disorders. We have shown that Drosophila neuropeptide F (NPF), the fly homologue of mammalian NPY, plays an important role in regulating hunger-driven foraging and feeding behaviors. Parallel behavioral phenotypes have been observed between NPF-deficient flies and NPY-knockout mice: both animals were normal in baseline feeding and body weight control but displayed feeding deficits in the deprived state; NPF-deficient flies and NPY knockout mice also displayed decreased acute sensitivity to ethanol sedation. More recently, we have obtained evidence that analogous to mammalian insulin, Drosophila insulin-like peptides (DILPs) suppress feeding response by acting oh different neuronal networks including the NPY-like neuronal pathway. For example, DILPs appear to directly inhibit the signaling activity of NPFR1 neurons through the insulin-like receptor (lnR)/ribosomal S6 kinase (S6K) pathway. Taken together, our findings strongly suggest that signaling mechanisms for the regulation of foraging and feeding behaviors are largely conserved between flies and mammals. The proposed research aims to identify and characterize additional genes and molecular and neuronal pathways critical for hunger-driven behaviors. We are particularly interested in genes and neurons that differentially regulate distinct aspects of hunger response such as enhanced food seeking, motivated intake of less-preferred foods, and increased ingestion rate. The specific aims of this application include: 1) Analysis of genes and molecular pathways underlying the regulation of hunger-motivated foraging by NPFR1 neurons; 2) Analysis of genes and molecular pathways underlying the regulation of hunger-driven behaviors by DILP neurons; 3) Gain-of-function screen for genes critical for DILP/NPFR1 neuron-mediated hunger response. The results from these studies may provide general insights into how genetic and neural factors contribute to hunger regulation of food response in diverse organisms including mammals. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): The sensory world of animals and humans alike is enormously complex. Our current understanding of how multisensory inputs are processed in the brain for perception and behavior remains rudimentary at best in any animals. The genetically tractable Drosophila larva offers a unique opportunity for behavioral and neurobiological studies of the integration of multiple sensory modalities for perception and behavior. Fly larvae display a rich repertoire of complex behaviors, and have a highly evolved yet numerically simple central nervous system (CNS). The brain of fly larvae shares many similarities with the human brain including two hemispheres with high local clustering of neurons (also named the local processing unit or LPU) and long-range projections, six major neurotransmitters, a variety of neuropeptides. An increasingly large set of powerful molecular genetic and neurobiological tools available will further allow us to perform in- depth follow-up studies of the neural substrates and processes underlying a neural process or behavior of interest. We have recently shown that like in mammals, attractive food odors elicited reward-driven overeating of readily accessible sugar-rich food in Drosophila larvae. Deficiencies in the dopamine (DA) system blocked the capacity of the appetitive odor to elicit the appetitive behavior. We have also identified a small number of third-order olfactory neurons that synthesize DA. Activation of these DA neurons mimicked the behavioral effect of appetitive odor stimulation. On the other hand, the OA system mediates larval feeding response to readily available sugar media. This application will be focused on exploring multisensory integration for food perception and behavior in the fly larva model by testing several key aspects of a novel working model. The proposal has two specific aims: 1) behavioral and neurobiological studies of integration of multiple olfactory and gustatory modalities in modulating appetite for palatable food; 2) analyses of the effects of brain states on integration of olfactory and gustatory modalities in modulating appetite for palatable food. We expect that the successful outcomes of these studies will provide novel insights into integration of different olfactory and gustatory modalities in modulating appetite for palatable food. Furthermore, the knowledge gained from these studies will contribute to the general understanding of the integration of multisensory modalities for perception and behavior as well as related neurological disorders.

DESCRIPTION (provided by applicant): Understanding how smell is transformed to behavior remains highly challenging. The higher-order olfactory centers, which are two synapses away from the periphery in insects and mammals, are crucial for interpreting the motivational significance of environmental odor cues. At present, molecular and circuit mechanisms underlying the functioning of higher-order olfactory centers have been rarely explored in any organisms. Genetically tractable Drosophila larvae have a highly evolved nervous system that is yet numerically simple. In this application, we will use the fly larva model to elucidate: 1) how a small subset of dopaminergic neurons postsynaptic to second-order projection neurons (analogous to mitral cells in mammals) receives and processes odor representations; 2) how such DA neurons mediate the transformation of olfactory inputs into motivational values to drive appetite for palatable food. Our recent findings demonstrate that Drosophila larvae fed ad libitum display olfactory reward-driven appetite for palatable food, and this non-homeostatic control mechanism requires the neuropil (named the lateral horn) for higher-order olfactory processing. We have found that a small subset of DA neurons as well as four neuropeptide Y-like NPF-producing neurons project to larval lateral horns, and they mediate the transformation of odor representations to appetitive motivation. This application has three objectives: 1) Functional analyses of dopamine (DA) in reception of appetitive olfactory information; 2) Genetic analysis of a neuropeptide F and other molecular pathways in DA neurons; 3) Functional analyses of DA receptor neurons in transforming odor inputs to appetitive motivation. We expect that the successful outcomes from the proposed studies will provide validations of the fly larva model for elucidating the molecular and neural basis of transformation of odor representations to appetitive motivation. Such knowledge should also provide better understanding of the pathophysiology of appetite-related disorders, and aid the genetic risk assessment for such disorders.