Kang Shen - US grants

DESCRIPTION (provided by applicant): Chemical synapses are specialized cellular junction structures that are essential for communication between neurons. During development, synapses form between specific neurons at defined subcellular compartments. Synaptic target selection, axonal transport and presynaptic assembly are integral steps of synapse formation that are poorly understood. Here, I propose to expand our research to understand two essential aspects of synapse formation: polarized axonal trafficking and how aggregation of active zone proteins is regulated. Synapses are usually formed on distal axon and dendrites, creating a challenging problem for effective exchange of intracellular material between cell bodies and synapses. Microtubules and MT associated motors mediate intracellular trafficking. It is generally believed that the direction of transport depends on two factors: the polarity of MTs and the type of motor involved. Based on our published and unpublished data, we have identified two cyclin-dependent kinase pathways that are essential for the trafficking of presynaptic components. In the absence of both pathways, the vast majority of synaptic vesicle proteins and active zone markers fail to localize to axon and instead are found in dendrites due to misregulation of kinesin motors. Another poorly understood question in synapse formation is how the pool size of synaptic vesicles is determined. Many synapses display stereotyped size of synaptic vesicle clusters, suggesting that molecular mechanisms regulate the assembly of synaptic vesicle precursors locally at the presynaptic terminals. When the appropriate number of vesicles is recruited, there might be a negative feedback system to shut down the assembly pathway. We reasoned that if this feedback mechanism is defective, one should expect to see mutant synapses with abnormal vesicle pool. Indeed in a forward genetic screen, we isolated a mutant in which the proximal synapses are abnormally large while the distal synapses contain little material. We have also identified an Arf like GTPase to be responsible for the regulation the location and size of presynaptic specializations. To gain mechanistic insights on the functions of these genes, I specifically plan to understand: 1) how the cyclin-dependent kinases pathways control axonal transport and synapse localization through the regulation of molecular motors, and 2) how an ARF like GTPase, ARL8 regulate the synaptic vesicle pool size and presynaptic assembly. Given that many neural disorders are associated with alterations in synaptic connectivity and that cyclin dependent kinases have been implicated in neurodegenerative diseases, it is hopeful that this project will help to understand brain development under both physiological and pathological conditions.

DESCRIPTION (provided by applicant): This proposal requests partial support for an international meeting on Molecular and Cellular Neurobiology as part of a Gordon Research Conference series to be held at the Hong Kong University of Science and Technology June 6 to 11, 2010. The overall goal of this conference is to increase our understanding of fundamental mechanisms that control development and function of the nervous system in health and disease. In particular we wish to promote scientific interactions between American and Asian scientists to advance this objective. For this purpose, we have identified 30 speakers, including one Nobel Laureate, who will deliver presentations on recent developments in their laboratories to approximately 180 attendees. We have also reserved several time slots for presentations by less established scientists with speaker choice to be based upon submitted abstracts. Poster sessions will provide an opportunity for every attendee to present his/her work. First organized in 1998, this conference has provided a unique bridge between American and Asian neuroscientists. Although initially, much of the information transfer was unidirectional, the interchange is now much more balanced. China, in particular, has initiated scientific efforts in some areas that are unlikely to be duplicated in the United States, such as a massive forward genetic transposon mutagenesis project in mice. This conference will provide an opportunity for leading American and Asian scientists to meet and exchange ideas and hypotheses and establish collaborations. Research into mechanisms of brain function is essential if our society is to conquer neurological diseases that afflict a large portion of our citizens, including autism and mental retardation in children, addiction and mental illness in children and adults, and neurodegenerative diseases that are most prevalent in our senior citizens. The conference covers a broad range of neuroscience from molecules and cells to circuits, behavior, mental illness and neurodegeneration. The conference is directed at communicating exciting new developments in these areas and stimulating discussion among participants from different disciplines and nationalities that will accelerate our efforts to understand mechanisms that control human brain development and function. PUBLIC HEALTH RELEVANCE: This conference will identify issues in basic brain research that are limiting our ability to address effectively diseases and disorders that affect brain function. Speakers at the conference will describe recent progress in studies important for understanding afflictions that include autism, mental retardation, addiction, mental illness, neurodegenerative diseases and postinjury regeneration. The conference venue will provide an opportunity for interactions between scientists of many nationalities who otherwise have few opportunities for exchange of ideas and establishment of collaborations.

DESCRIPTION (provided by applicant): Dendritic arbors adopt diverse, branched morphologies of varying complexity that are characteristic for a given neuron type. The organization of the dendritic arbors is fundamental to the connectivity and function of a neuron. Although critical to the shape and connectivity of the nervous system, the mechanisms that regulate dendrite morphology are not well understood. In particular, our understandings of membrane molecules that promote and guide patterned dendritic branches are lacking. The overall goal of this grant is to identify novel molecule ligands and receptors that generate the complex and orderly dendrite branches of the nociceptive PVD neurons in C. elegans. Our hypothesis is that interactions between membrane molecules guide dendritic growth and branching in its environment. Following up on our recent discovery of a transmembrane leucine-rich repeat molecule DMA-1 that is essential for PVD dendritic morphogenesis, in specific aim 1, we will further understand the function of DMA-1 by further characterizing its loss-of-function phenotypes, testing its sufficiency and searching for its interaction partners. In specific aim 2, we will explore the function of cell adhesion L1CAM/SAX-7 in generating patterned dendritic branches. We will examine the loss- and gain-of-function phenotype of sax-7, determine its cellular requirement and examine its subcellular localization. We will also study the function of a novel transmembrane protein W01F3.1, which we isolated from a forward genetic screen. In specific aim3, we will test if DMA-1, SAX-7 and W01F3.1 form a tripartite ligand-receptor complex that pattern PVD dendrite using genetic and biochemical means.

Summary This proposal requests R13 support for a longstanding, well-attended, and well-received Gordon Research Conference (GRC) on Excitatory Synapses and Brain Function. The synapse is central to our understanding of circuit function and behavior. In the central nervous system, excitatory synapses represent the primary means of information processing by local circuits and communication between brain regions. Synapses serve as the site of action for many commonly prescribed medications and their disruption contributes to many neurological and psychiatric disorders. These include schizophrenia, autism, depression, substance abuse and addiction, Parkinson's disease, Alzheimer's disease, traumatic brain injury, stroke and epilepsy. In some cases, synaptic dysfunction is causal in disease, whereas in other cases it represents the downstream sequelae of one or more underlying molecular defects. In either case, a fundamental understanding of the formation, structure, molecular organization, signaling function, and plasticity of synapses is essential to progress in lessening the burden of human neurological disease and for predicting and improving mental health. This conference is unique in its focus on the excitatory synapse, and in its multidisciplinary group of participants including structural biologists, molecular and developmental biologists, cell biologists, biochemists, cell/molecular imagers, biophysicists and neurophysiologists. The conference is intended to relate fundamental insights in excitatory synaptic function to the impairments in synaptic function that occur in disease, as well as the maladaptive plasticity that occurs in substance abuse. The goal of the conference is to identify and highlight fundamental new insights into synaptic function, neural circuit dynamics and dysfunction from a thematic approach. The program has been designed to also highlight cutting edge approaches and to stimulate new concepts, methods and technologies within a sound biological framework of fundamental neuroscience. The conference will bring together expert scientists worldwide in an environment that is conducive to discussion and exchange of ideas. The exchange of ideas at this conference has been a driving force for the field. We expect the 2017 GRC on Excitatory Synapses and Brain Function will shape future scientific directions, and provide critical support for the mission of multiple institutes at NIH including NINDS, NIMH, NIDA and NIA.

Project Summary/Abstract This shared instrument proposal seeks funding for the purchase of a BIOSORTER-PRO large particle flow cytometer from Union Biometrica and a robotic arm assembly from BioSera. These instruments will support 14 NIH-funded grants awarded to researchers in the School of Humanities and Sciences and the School of Medicine at Stanford University and at University of California, Santa Cruz and San Jose State University. The requested instruments will be housed in the High Throughput Biosciences Center at Stanford University, a well-funded and centrally located core facility with the technical expertise required to operate and maintain the BIOSORTER-PRO and associated accessories. The BIOSORTER-PRO has the unique capability to sort and analyze samples such as whole organisms, large cells, and cell clusters that are too large or too fragile to be used with conventional cell sorters. The robotic arm assembly will facilitate large scale screening efforts performed on the BIOSORTER-PRO. This technology would support a diverse array of research projects from 12 independent investigators working on a broad range of topics including aging, cell and developmental biology, neuroscience, genetics, genomics, and infectious disease. The research goals will impact our understanding of basic biology as well as have a transformative impact on health-related problems such as aging, neurodegenerative disease, cardiac congenital defects and disease, the regenerative capacity of stem cells, and infectious diseases caused by schistosomes and parasitic nematodes. The majority of this work is done using the model organism C. elegans, which has a rich history of defining the mechanisms controlling an array of biological processes. The use of the BIOSORTER-PRO by additional labs working on other diverse models such as schistosomes and cells of the mouse heart, vasculature, and placenta is a testament to its versatility. The acquisition of the BIOSORTER-PRO and robotic arm assembly will make possible a number of novel and large-scale screening efforts that would otherwise not be possible, pushing forward the level of cutting edge research being done at and around Stanford University with the goal of making a significant impact on human health.