@article {68429, title = {Cell-Surface Proteomic Profiling in the Fly Brain Uncovers Wiring Regulators.}, journal = {Cell}, volume = {180}, year = {2020}, month = {01/2020}, pages = {373-386.e15}, abstract = {

Molecular interactions at the cellular interface mediate organized assembly of single cells into tissues and, thus, govern the development and physiology of multicellular organisms. Here, we developed a cell-type-specific, spatiotemporally resolved approach to profile cell-surface proteomes in intact tissues. Quantitative profiling of cell-surface proteomes of Drosophila olfactory projection neurons (PNs) in pupae and adults revealed global downregulation of wiring molecules and upregulation of synaptic molecules in the transition from developing to mature PNs. A proteome-instructed in\ vivo screen identified 20 cell-surface molecules regulating neural circuit assembly, many of which belong to evolutionarily conserved protein families not previously linked to neural development. Genetic analysis further revealed that the lipoprotein receptor LRP1 cell-autonomously controls PN dendrite targeting, contributing to the formation of a precise olfactory map. These findings highlight the power of temporally resolved in situ cell-surface proteomic profiling in discovering regulators of brain wiring.

}, keywords = {Animals, Axons, Brain, Dendrites, Drosophila melanogaster, Drosophila Proteins, Gene Expression Profiling, Gene Expression Regulation, Developmental, Membrane Proteins, Neurogenesis, Olfactory Nerve, Olfactory Pathways, Olfactory Receptor Neurons, Proteomics, Receptors, Lipoprotein, Smell}, issn = {1097-4172}, doi = {10.1016/j.cell.2019.12.029}, author = {Li, Jiefu and Han, Shuo and Li, Hongjie and Udeshi, Namrata D and Svinkina, Tanya and Mani, D R and Xu, Chuanyun and Guajardo, Ricardo and Xie, Qijing and Li, Tongchao and Luginbuhl, David J and Wu, Bing and McLaughlin, Colleen N and Xie, Anthony and Kaewsapsak, Pornchai and Quake, Stephen R and Carr, Steven A and Ting, Alice Y and Luo, Liqun} } @article {68428, title = {Single-Cell Transcriptomes Reveal Diverse Regulatory Strategies for Olfactory Receptor Expression and Axon Targeting.}, journal = {Curr Biol}, volume = {30}, year = {2020}, month = {04/2020}, pages = {1189-1198.e5}, abstract = {

The regulatory mechanisms by which neurons coordinate their physiology and connectivity are not well understood. The Drosophila olfactory receptor neurons (ORNs) provide an excellent system to investigate this question. Each ORN type expresses a unique olfactory receptor, or a combination thereof, and sends their axons to a stereotyped glomerulus. Using single-cell RNA sequencing, we identified 33 transcriptomic clusters for ORNs and mapped 20 to their glomerular types, demonstrating that transcriptomic clusters correspond well with anatomically and physiologically defined ORN types. Each ORN type expresses hundreds of transcription factors. Transcriptome-instructed genetic analyses revealed that (1) one broadly expressed transcription factor (Acj6) only regulates olfactory receptor expression in one ORN type and only wiring specificity in another type, (2) one type-restricted transcription factor (Forkhead) only regulates receptor expression, and (3) another type-restricted transcription factor (Unplugged) regulates both events. Thus, ORNs utilize diverse strategies and complex regulatory networks to coordinate their physiology and connectivity.

}, keywords = {Animals, Axons, Drosophila melanogaster, Drosophila Proteins, Forkhead Transcription Factors, Homeodomain Proteins, Nerve Tissue Proteins, Olfactory Receptor Neurons, POU Domain Factors, Receptors, Odorant, Single-Cell Analysis, Smell, Transcriptome}, issn = {1879-0445}, doi = {10.1016/j.cub.2020.01.049}, author = {Li, Hongjie and Li, Tongchao and Horns, Felix and Li, Jiefu and Xie, Qijing and Xu, Chuanyun and Wu, Bing and Kebschull, Justus M and McLaughlin, Colleen N and Kolluru, Sai Saroja and Jones, Robert C and Vacek, David and Xie, Anthony and Luginbuhl, David J and Quake, Stephen R and Luo, Liqun} } @article {68430, title = {Transsynaptic Fish-lips signaling prevents misconnections between nonsynaptic partner olfactory neurons.}, journal = {Proc Natl Acad Sci U S A}, volume = {116}, year = {2019}, month = {08/2019}, pages = {16068-16073}, abstract = {

Our understanding of the mechanisms of neural circuit assembly is far from complete. Identification of wiring molecules with novel mechanisms of action will provide insights into how complex and heterogeneous neural circuits assemble during development. In the olfactory system, 50 classes of olfactory receptor neurons (ORNs) make precise synaptic connections with 50 classes of partner projection neurons (PNs). Here, we performed an RNA interference screen for cell surface molecules and identified the leucine-rich repeat-containing transmembrane protein known as Fish-lips (Fili) as a novel wiring molecule in the assembly of the olfactory circuit. Fili contributes to the precise axon and dendrite targeting of a small subset of ORN and PN classes, respectively. Cell-type-specific expression and genetic analyses suggest that Fili sends a transsynaptic repulsive signal to neurites of nonpartner classes that prevents their targeting to inappropriate glomeruli in the antennal lobe.

}, keywords = {Animals, Axons, Dendrites, Drosophila melanogaster, Drosophila Proteins, Leucine-Rich Repeat Proteins, Membrane Proteins, Mutation, Olfactory Receptor Neurons, Phenotype, Proteins, Signal Transduction, Synapses}, issn = {1091-6490}, doi = {10.1073/pnas.1905832116}, author = {Xie, Qijing and Wu, Bing and Li, Jiefu and Xu, Chuanyun and Li, Hongjie and Luginbuhl, David J and Wang, Xin and Ward, Alex and Luo, Liqun} } @article {68432, title = { Stepwise wiring of the Drosophila olfactory map requires specific Plexin B levels}, journal = {Elife}, volume = {7}, year = {2018}, month = {08/2018}, abstract = {

The precise assembly of a neural circuit involves many consecutive steps. The conflict between a limited number of wiring molecules and the complexity of the neural network impels each molecule to execute multiple functions at different steps. Here, we examined the cell-type specific distribution of endogenous levels of axon guidance receptor Plexin B (PlexB) in the developing antennal lobe, the first olfactory processing center in . We found that different classes of olfactory receptor neurons (ORNs) express PlexB at different levels in two wiring steps - axonal trajectory choice and subsequent target selection. In line with its temporally distinct patterns, the proper levels of PlexB control both steps in succession. Genetic interactions further revealed that the effect of high-level PlexB is antagonized by its canonical partner Sema2b. Thus, PlexB plays a multifaceted role in instructing the assembly of the olfactory circuit through temporally-regulated expression patterns and expression level-dependent effects.

}, keywords = {Animals, Arthropod Antennae, Axons, Drosophila melanogaster, Drosophila Proteins, Models, Biological, Nerve Tissue Proteins, Olfactory Receptor Neurons, Receptors, Cell Surface, Smell}, issn = {2050-084X}, doi = {10.7554/eLife.39088}, author = {Li, Jiefu and Guajardo, Ricardo and Xu, Chuanyun and Wu, Bing and Li, Hongjie and Li, Tongchao and Luginbuhl, David J and Xie, Xiaojun and Luo, Liqun} } @article {68437, title = {Classifying Drosophila Olfactory Projection Neuron Subtypes by Single-Cell RNA Sequencing.}, journal = {Cell}, volume = {171}, year = {2017}, month = {11/2017}, pages = {1206-1220.e22}, abstract = {

The definition of neuronal type and how it relates to the transcriptome are open questions. Drosophila olfactory projection neurons (PNs) are among the best-characterized neuronal types: different PN classes target dendrites to distinct olfactory glomeruli, while PNs of the same class exhibit indistinguishable anatomical and physiological properties. Using single-cell RNA sequencing, we comprehensively characterized the transcriptomes of most PN classes and unequivocally mapped transcriptomes to specific olfactory function for six classes. Transcriptomes of\ closely related PN classes exhibit the largest differences during circuit assembly but become indistinguishable in adults, suggesting that neuronal subtype diversity peaks during development. Transcription factors and cell-surface molecules are the most differentially expressed genes between classes and are highly informative in encoding cell identity, enabling us to identify a new lineage-specific transcription factor that instructs PN dendrite targeting. These findings establish that neuronal transcriptomic identity corresponds with anatomical and physiological identity defined by connectivity and function.

}, keywords = {Animals, Brain, Cluster Analysis, Dendrites, Drosophila melanogaster, Gene Expression Profiling, Neurons, Olfactory Bulb, Organ Specificity, Pupa, Sequence Analysis, RNA, Single-Cell Analysis, Transcription Factors}, issn = {1097-4172}, doi = {10.1016/j.cell.2017.10.019}, author = {Li, Hongjie and Horns, Felix and Wu, Bing and Xie, Qijing and Li, Jiefu and Li, Tongchao and Luginbuhl, David J and Quake, Stephen R and Luo, Liqun} } @article {68439, title = {Fibroblast growth factor signaling instructs ensheathing glia wrapping of olfactory glomeruli.}, journal = {Proc Natl Acad Sci U S A}, volume = {114}, year = {2017}, month = {07/2017}, pages = {7505-7512}, abstract = {

The formation of complex but highly organized neural circuits requires interactions between neurons and glia. During the assembly of the olfactory circuit, 50 olfactory receptor neuron (ORN) classes and 50 projection neuron (PN) classes form synaptic connections in 50 glomerular compartments in the antennal lobe, each of which represents a discrete olfactory information-processing channel. Each compartment is separated from the adjacent compartments by membranous processes from ensheathing glia. Here we show that Thisbe, an FGF released from olfactory neurons, particularly from local interneurons, instructs ensheathing glia to wrap each glomerulus. The Heartless FGF receptor acts cell-autonomously in ensheathing glia to regulate process extension so as to insulate each neuropil compartment. Overexpressing Thisbe in ORNs or PNs causes overwrapping of the glomeruli their axons or dendrites target. Failure to establish the FGF-dependent glia structure disrupts precise ORN axon targeting and discrete glomerular formation.

}, keywords = {Animals, Animals, Genetically Modified, Axons, Drosophila, Drosophila Proteins, Fibroblast Growth Factors, Genotype, Microscopy, Confocal, Neuroglia, Neuropil, Olfactory Bulb, Olfactory Pathways, Olfactory Receptor Neurons, Signal Transduction}, issn = {1091-6490}, doi = {10.1073/pnas.1706533114}, author = {Wu, Bing and Li, Jiefu and Chou, Ya-Hui and Luginbuhl, David and Luo, Liqun} } @article {47623, title = {Superresolution imaging reveals structural features of EB1 in microtubule plus-end tracking.}, journal = {Molecular biology of the cell}, volume = {25}, year = {2014}, month = {2014 Dec 15}, pages = {4166-73}, abstract = {

Visualization of specific molecules and their interactions in real time and space is essential to delineate how cellular dynamics and the signaling circuit are orchestrated. Spatial regulation of conformational dynamics and structural plasticity of protein interactions is required to rewire signaling circuitry in response to extracellular cues. We introduce a method for optically imaging intracellular protein interactions at nanometer spatial resolution in live cells, using photoactivatable complementary fluorescent (PACF) proteins. Subsets of complementary fluorescent protein molecules were activated, localized, and then bleached; this was followed by the assembly of superresolution images from aggregate position of sum interactive molecules. Using PACF, we obtained precise localization of dynamic microtubule plus-end hub protein EB1 dimers and their distinct distributions at the leading edges and in the cell bodies of migrating cells. We further delineated the structure-function relationship of EB1 by generating EB1-PACF dimers (EB1(wt):EB1(wt), EB1(wt):EB1(mt), and EB1(mt):EB1(mt)) and imaging their precise localizations in culture cells. Surprisingly, our analyses revealed critical role of a previously uncharacterized EB1 linker region in tracking microtubule plus ends in live cells. Thus PACF provides a unique approach to delineating spatial dynamics of homo- or heterodimerized proteins at the nanometer scale and establishes a platform to report the precise regulation of protein interactions in space and time in live cells.

}, keywords = {Amino Acid Sequence, Cell Movement, Hela Cells, Humans, MCF-7 Cells, Microscopy, Fluorescence, Microtubule-Associated Proteins, Microtubules, Molecular Sequence Data, Protein Transport}, issn = {1939-4586}, doi = {10.1091/mbc.E14-06-1133}, author = {Xia, Peng and Liu, Xing and Wu, Bing and Zhang, Shuyuan and Song, Xiaoyu and Yao, Phil Y and Lippincott-Schwartz, Jennifer and Yao, Xuebiao} }