@article {48766, title = {Imp and Syp RNA-binding proteins govern decommissioning of Drosophila neural stem cells.}, journal = {Development (Cambridge, England)}, volume = {144}, year = {2017}, month = {2017 Aug 29}, pages = {3454-64}, abstract = {

The termination of the proliferation of Drosophila neural stem cells, also known as neuroblasts (NBs), requires a "decommissioning" phase that is controlled in a lineage-specific manner. Most NBs, with the exception of those of the Mushroom body (MB), are decommissioned by the ecdysone receptor and mediator complex causing them to shrink during metamorphosis, followed by nuclear accumulation of Prospero and cell cycle exit. Here, we demonstrate that the levels of Imp and Syp RNA-binding proteins regulate NB decommissioning. Descending Imp and ascending Syp expression have been shown to regulate neuronal temporal fate. We show that Imp levels decline slower in the MB than other central brain NBs. MB NBs continue to express Imp into pupation, and the presence of Imp prevents decommissioning partly by inhibiting the mediator complex. Late-larval induction of transgenic Imp prevents many non-MB NBs from decommissioning in early pupae. Moreover, the presence of abundant Syp in aged NBs permits Prospero accumulation that, in turn, promotes cell cycle exit. Together our results reveal that progeny temporal fate and progenitor decommissioning are co-regulated in protracted neuronal lineages.

}, issn = {1477-9129}, doi = {10.1242/dev.149500}, author = {Yang, Ching-Po and Samuels, Tamsin J and Huang, Yaling and Yang, Lu and Ish-Horowicz, David and Davis, Ilan and Lee, Tzumin} } @article {46471, title = {An enhanced gene targeting toolkit for Drosophila: golic+.}, journal = {Genetics}, volume = {199}, year = {2015}, month = {2015 Mar}, pages = {683-94}, abstract = {

Ends-out gene targeting allows seamless replacement of endogenous genes with engineered DNA fragments by homologous recombination, thus creating designer "genes" in the endogenous locus. Conventional gene targeting in Drosophila involves targeting with the preintegrated donor DNA in the larval primordial germ cells. Here we report G: ene targeting during O: ogenesis with L: ethality I: nhibitor and C: RISPR/Cas (Golic+), which improves on all major steps in such transgene-based gene targeting systems. First, donor DNA is integrated into precharacterized attP sites for efficient flip-out. Second, FLP, I-SceI, and Cas9 are specifically expressed in cystoblasts, which arise continuously from female germline stem cells, thereby providing a continual source of independent targeting events in each offspring. Third, a repressor-based lethality selection is implemented to facilitate screening for correct targeting events. Altogether, Golic+ realizes high-efficiency ends-out gene targeting in ovarian cystoblasts, which can be readily scaled up to achieve high-throughput genome editing.

}, issn = {1943-2631}, doi = {10.1534/genetics.114.173716}, author = {Chen, Hui-Min and Huang, Yaling and Pfeiffer, Barret D and Yao, Xiaohao and Lee, Tzumin} } @article {6898, title = {Making Drosophila lineage-restricted drivers via patterned recombination in neuroblasts.}, journal = {Nature Neuroscience}, volume = {17}, year = {2014}, month = {2014 Apr}, pages = {631-7}, abstract = {

The Drosophila cerebrum originates from about 100 neuroblasts per hemisphere, with each neuroblast producing a characteristic set of neurons. Neurons from a neuroblast are often so diverse that many neuron types remain unexplored. We developed new genetic tools that target neuroblasts and their diverse descendants, increasing our ability to study fly brain structure and development. Common enhancer-based drivers label neurons on the basis of terminal identities rather than origins, which provides limited labeling in the heterogeneous neuronal lineages. We successfully converted conventional drivers that are temporarily expressed in neuroblasts, into drivers expressed in all subsequent neuroblast progeny. One technique involves immortalizing GAL4 expression in neuroblasts and their descendants. Another depends on loss of the GAL4 repressor, GAL80, from neuroblasts during early neurogenesis. Furthermore, we expanded the diversity of MARCM-based reagents and established another site-specific mitotic recombination system. Our transgenic tools can be combined to map individual neurons in specific lineages of various genotypes.

}, issn = {1546-1726}, doi = {10.1038/nn.3654}, author = {Awasaki, Takeshi and Kao, Chih-Fei and Lee, Ying-Jou and Yang, Ching-Po and Huang, Yaling and Pfeiffer, Barret D and Luan, Haojiang and Jing, Xiaotang and Huang, Yu-Fen and He, Yisheng and Schroeder, Mark David and Kuzin, Alexander and Brody, Thomas and Zugates, Christopher T and Odenwald, Ward F and Lee, Tzumin} } @article {6454, title = {Extremes of lineage plasticity in the Drosophila brain.}, journal = {Current Biology}, volume = {23}, year = {2013}, month = {2013 Sep 19}, pages = {1908-13}, abstract = {

An often-overlooked aspect of neural plasticity is the plasticity of neuronal composition, in which the numbers of neurons of particular classes are altered in response to environment and experience. The Drosophila brain features several well-characterized lineages in which a single neuroblast gives rise to multiple neuronal classes in a stereotyped sequence during development [1]. We find that in the\ intrinsic mushroom body neuron lineage, the numbers for each class are highly plastic, depending on the timing of temporal fate transitions and the rate of neuroblast proliferation. For example, mushroom body neuroblast cycling can continue under starvation conditions, uncoupled from\ temporal fate transitions that depend on extrinsic cues reflecting organismal growth and development. In contrast, the proliferation rates of antennal lobe lineages are closely associated with organismal development, and\ their temporal fate changes appear to be cell cycle-dependent, such that the same numbers and types of uniglomerular projection neurons innervate the antennal lobe following various perturbations. We propose that this surprising difference in plasticity for these brain lineages is adaptive, given their respective roles as parallel\ processors versus discrete carriers of olfactory information.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2013.07.074}, author = {Lin, Suewei and Marin, Elizabeth C and Yang, Ching-Po and Kao, Chih-Fei and Apenteng, Bettye A and Huang, Yaling and O{\textquoteright}Connor, Michael B and Truman, James W and Lee, Tzumin} } @article {6303, title = {The bHLH repressor Deadpan regulates the self-renewal and specification of Drosophila larval neural stem cells independently of Notch.}, journal = {PLoS One}, volume = {7}, year = {2012}, month = {2012 Oct 8}, pages = {e46724}, abstract = {

Neural stem cells (NSCs) are able to self-renew while giving rise to neurons and glia that comprise a functional nervous system. However, how NSC self-renewal is maintained is not well understood. Using the Drosophila larval NSCs called neuroblasts (NBs) as a model, we demonstrate that the Hairy and Enhancer-of-Split (Hes) family protein Deadpan (Dpn) plays important roles in NB self-renewal and specification. The loss of Dpn leads to the premature loss of NBs and truncated NB lineages, a process likely mediated by the homeobox protein Prospero (Pros). Conversely, ectopic/over-expression of Dpn promotes ectopic self-renewing divisions and maintains NB self-renewal into adulthood. In type II NBs, which generate transit amplifying intermediate neural progenitors (INPs) like mammalian NSCs, the loss of Dpn results in ectopic expression of type I NB markers Asense (Ase) and Pros before these type II NBs are lost at early larval stages. Our results also show that knockdown of Notch leads to ectopic Ase expression in type II NBs and the premature loss of type II NBs. Significantly, dpn expression is unchanged in these transformed NBs. Furthermore, the loss of Dpn does not inhibit the over-proliferation of type II NBs and immature INPs caused by over-expression of activated Notch. Our data suggest that Dpn plays important roles in maintaining NB self-renewal and specification of type II NBs in larval brains and that Dpn and Notch function independently in regulating type II NB proliferation and specification.

}, keywords = {Animals, Basic Helix-Loop-Helix Transcription Factors, Drosophila, Drosophila Proteins, Larva, Neural Stem Cells, Notch, Nuclear Proteins, Receptors}, issn = {1932-6203}, doi = {10.1371/journal.pone.0046724}, author = {Zhu, Sijun and Wildonger, Jill and Barshow, Suzanne and Younger, Susan and Huang, Yaling and Lee, Tzumin} } @article {6290, title = {Lineage analysis of Drosophila lateral antennal lobe neurons reveals notch-dependent binary temporal fate decisions.}, journal = {PLoS Biology}, volume = {10}, year = {2012}, month = {2012 Nov 20}, pages = {e1001425}, abstract = {

Binary cell fate decisions allow the production of distinct sister neurons from an intermediate precursor. Neurons are further diversified based on the birth order of intermediate precursors. Here we examined the interplay between binary cell fate and birth-order-dependent temporal fate in the Drosophila lateral antennal lobe (lAL) neuronal lineage. Single-cell mapping of the lAL lineage by twin-spot mosaic analysis with repressible cell markers (ts-MARCM) revealed that projection neurons (PNs) and local interneurons (LNs) are made in pairs through binary fate decisions. Forty-five types of PNs innervating distinct brain regions arise in a stereotyped sequence; however, the PNs with similar morphologies are not necessarily born in a contiguous window. The LNs are morphologically less diverse than the PNs, and the sequential morphogenetic changes in the two pairs occur independently. Sanpodo-dependent Notch activity promotes and patterns the LN fates. By contrast, Notch diversifies PN temporal fates in a Sanpodo-dispensable manner. These pleiotropic Notch actions underlie the differential temporal fate specification of twin neurons produced by common precursors within a lineage, possibly by modulating postmitotic neurons{\textquoteright} responses to Notch-independent transcriptional cascades.

}, keywords = {Animals, Biological Markers, Brain, Cell Division, Cell Lineage, Cellular, Developmental, Drosophila, Drosophila Proteins, Embryo, Gene Expression Regulation, Genes, Immunohistochemistry, Insect, Larva, Mechanotransduction, Nerve Tissue Proteins, Neurogenesis, Neurons, Nonmammalian, Notch, Receptors, Single-Cell Analysis}, issn = {1545-7885}, doi = {10.1371/journal.pbio.1001425}, author = {Lin, Suewei and Kao, Chih-Fei and Yu, Hung-Hsiang and Huang, Yaling and Lee, Tzumin} } @article {4300, title = {Glia instruct developmental neuronal remodeling through TGF-β signaling.}, journal = {Nature Neuroscience}, volume = {14}, year = {2011}, month = {2011 Jun 19}, pages = {821-3}, abstract = {

We found that glia secrete myoglianin, a TGF-β ligand, to instruct developmental neural remodeling in Drosophila. Glial myoglianin upregulated neuronal expression of an ecdysone nuclear receptor that triggered neurite remodeling following the late-larval ecdysone peak. Thus glia orchestrate developmental neural remodeling not only by engulfment of unwanted neurites but also by enabling neuron remodeling.

}, keywords = {Animals, Developmental, Double-Stranded, Drosophila, Drosophila Proteins, Gene Expression Regulation, Genetically Modified, Green Fluorescent Proteins, MicroRNAs, Models, Mushroom Bodies, Mutation, Neurogenesis, Neuroglia, Neurological, RNA, Signal Transduction, Transforming Growth Factor beta}, issn = {1546-1726}, doi = {10.1038/nn.2833}, author = {Awasaki, Takeshi and Huang, Yaling and O{\textquoteright}Connor, Michael B and Lee, Tzumin} } @article {796, title = {Endodomain diversity in the Drosophila Dscam and its roles in neuronal morphogenesis.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {29}, year = {2009}, month = {2009 Feb 11}, pages = {1904-14}, abstract = {

Drosophila Down syndrome cell adhesion molecule (Dscam) can be variably spliced to encode 152,064 distinct single-pass transmembrane proteins. In addition to 19,008 possible ectodomains and two alternative transmembrane segments, it may carry endodomains containing or lacking exons 19 and 23. Here, we determine the role of Dscam endodomain diversity in neural development. Dscam with full-length endodomain is largely restricted to embryogenesis. In contrast, most Dscams lack exons 19 and 23 at postembryonic stages. As implicated from the expression patterns, removal of Dscam exon 19-containing variants disrupts wiring of embryonic neurons while silencing of Dscam transcripts lacking exon 19 or exon 23 effectively blocks postembryonic neuronal morphogenesis. Furthermore, compared with exon 19-containing Dscam, transgenic Dscam without exon 19 is more efficiently targeted to neurites and more potently suppresses axon bifurcation in Dscam mutant neurons. In sum, Dscam with or without exon 19 in its endodomain is used to govern different stage-specific neuronal morphogenetic processes, possibly due to differences in protein targeting.

}, keywords = {Amino Acid Motifs, Amino Acid Sequence, Animals, Cell Adhesion Molecules, Drosophila, Drosophila Proteins, Gene Targeting, Genetically Modified, Molecular Sequence Data, Morphogenesis, Neurogenesis, Neurons, Protein Structure, Tertiary}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.5743-08.2009}, author = {Yu, Hung-Hsiang and Yang, Jacob S and Wang, Jian and Huang, Yaling and Lee, Tzumin} } @article {4274, title = {Nuclear receptor unfulfilled regulates axonal guidance and cell identity of Drosophila mushroom body neurons.}, journal = {PLoS One}, volume = {4}, year = {2009}, month = {2009 Dec 22}, pages = {e8392}, abstract = {

Nuclear receptors (NRs) comprise a family of ligand-regulated transcription factors that control diverse critical biological processes including various aspects of brain development. Eighteen NR genes exist in the Drosophila genome. To explore their roles in brain development, we knocked down individual NRs through the development of the mushroom bodies (MBs) by targeted RNAi. Besides recapitulating the known MB phenotypes for three NRs, we found that unfulfilled (unf), an ortholog of human photoreceptor specific nuclear receptor (PNR), regulates axonal morphogenesis and neuronal subtype identity. The adult MBs develop through remodeling of gamma neurons plus de-novo elaboration of both alpha{\textquoteright}/beta{\textquoteright} and alpha/beta neurons. Notably, unf is largely dispensable for the initial elaboration of gamma neurons, but plays an essential role in their re-extension of axons after pruning during early metamorphosis. The subsequently derived MB neuron types also require unf for extension of axons beyond the terminus of the pruned bundle. Tracing single axons revealed misrouting rather than simple truncation. Further, silencing unf in single-cell clones elicited misguidance of axons in otherwise unperturbed MBs. Such axon guidance defects may occur as MB neurons partially lose their subtype identity, as evidenced by suppression of various MB subtype markers in unf knockdown MBs. In sum, unf governs axonal morphogenesis of multiple MB neuron types, possibly through regulating neuronal subtype identity.

}, keywords = {Aging, Animals, Axons, Biological Markers, Cytoplasmic and Nuclear, Drosophila melanogaster, Drosophila Proteins, Gene Knockdown Techniques, Gene Silencing, MicroRNAs, Morphogenesis, Mushroom Bodies, Phenotype, Receptors}, issn = {1932-6203}, doi = {10.1371/journal.pone.0008392}, author = {Lin, Suewei and Huang, Yaling and Lee, Tzumin} } @article {781, title = {Twin-spot MARCM to reveal the developmental origin and identity of neurons.}, journal = {Nature Neuroscience}, volume = {12}, year = {2009}, month = {2009 Jul}, pages = {947-53}, abstract = {

A comprehensive understanding of the brain requires the analysis of individual neurons. We used twin-spot mosaic analysis with repressible cell markers (twin-spot MARCM) to trace cell lineages at high resolution by independently labeling paired sister clones. We determined patterns of neurogenesis and the influences of lineage on neuron-type specification. Notably, neural progenitors were able to yield intermediate precursors that create one, two or more neurons. Furthermore, neurons acquired stereotyped projections according to their temporal position in various brain sublineages. Twin-spot MARCM also permitted birth dating of mutant clones, enabling us to detect a single temporal fate that required chinmo in a sublineage of six Drosophila central complex neurons. In sum, twin-spot MARCM can reveal the developmental origins of neurons and the mechanisms that underlie cell fate.

}, keywords = {Animals, Brain, Cell Lineage, Central Nervous System, Drosophila, Drosophila Proteins, Gene Knockout Techniques, Genetic Techniques, Genetically Modified, Mushroom Bodies, Nerve Tissue Proteins, Neurogenesis, Neurons, RNA Interference, Time Factors}, issn = {1546-1726}, doi = {10.1038/nn.2345}, author = {Yu, Hung-Hsiang and Chen, Chun-Hong and Shi, Lei and Huang, Yaling and Lee, Tzumin} }