morphological-analysis-drosophila-larval-peripheral-sensory-neuron

Morphological Analysis of <em>Drosophila</em> Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic ...

immunohistological-labeling-microtubules-sensory-neuron-dendrites

Immunohistological Labeling of Microtubules in Sensory Neuron Dendrites, Tracheae, and Muscles in the <em>Drosophila</em> Larva Body Wall

To understand how differences in complex cell shapes are achieved, it is important to accurately follow microtubule organization. The Drosophila larval ...

The dendritic morphology of neurons determines the number and type of inputs they receive. In the Drosophila peripheral nervous system (PNS), the external sensory (ES) neurons have a single nonbranched dendrite, whereas the lineally related multidendritic (MD) neurons have extensively branched dendritic arbors. We report that hamlet is a binary genetic switch between these contrasting morphological types. In hamlet mutants, ES neurons are converted to an MD fate, whereas ectopic hamlet expression in MD precursors results in transformation of MD neurons into ES neurons. Moreover, hamlet expression induced in MD neurons undergoing dendrite outgrowth drastically reduces arbor branching.

hamlet, a binary genetic switch between single- and multiple- dendrite neuron morphology.

Hamlet, ein bin&#xE4;res genetischen Schalter zwischen Single-und Multiple-Dendriten Neuron Morphologie.

Understanding how dendrites establish their territory is central to elucidating how neuronal circuits are built. Signaling between dendrites is thought to be important for defining their territories; however, the strategies by which different types of dendrites communicate are poorly understood. We have shown previously that two classes of Drosophila peripheral da sensory neurons, the class III and class IV neurons, provide complete and independent tiling of the body wall. By contrast, dendrites of class I and class II neurons do not completely tile the body wall, but they nevertheless occupy nonoverlapping territories.

Dendrites of distinct classes of Drosophila sensory neurons show different capacities for homotypic repulsion.

Dendriten unterschiedliche Klassen von Drosophila sensorischen Neuronen zeigen verschiedene Kapazit&#xE4;ten f&#xFC;r homotypische Absto&#xDF;ung.

The Drosophila external sensory organ forms in a lineage elaborating from a single precursor cell via a stereotypical series of asymmetric divisions. HAMLET transcription factor expression demarcates the lineage branch that generates two internal cell types, the external sensory neuron and thecogen. In HAMLET mutant organs, these internal cells are converted to external cells via an unprecedented cousin-cousin cell-fate respecification event. Conversely, ectopic HAMLET expression in the external cell branch leads to internal cell production. The fate-determining signals NOTCH and PAX2 act at multiple stages of lineage elaboration and HAMLET acts to modulate their activity in a branch-specific manner.

Conversion of neurons and glia to external-cell fates in the external sensory organs of Drosophila hamlet mutants by a cousin-cousin cell-type respecification.

Umwandlung von Neuronen und Glia-Zellen auf externe Schicksale in den externen Sinnesorgane von Drosophila-Mutanten Weiler von einem Cousin-Cousine Zelltyp Respezifikation.

Many studies have focused on the mechanisms of axon guidance; however, little is known about the transcriptional control of the navigational components that carryout these decisions. This report describes the functional analysis of Nerfin-1, a nuclear regulator of axon guidance required for a subset of early pathfinding events in the developing Drosophila CNS. Nerfin-1 belongs to a highly conserved subfamily of Zn-finger proteins with cognates identified in nematodes and man. We show that the neural precursor gene prospero is essential for nerfin-1 expression. Unlike nerfin-1 mRNA, which is expressed in many neural precursor cells, the encoded Nerfin-1 protein is only detected in the nuclei of neuronal precursors that will divide just once and then transiently in their nascent neurons. Although nerfin-1 null embryos have no discernible alterations in neural lineage development nor in neuronal or glial identities, CNS pioneering neurons require nerfin-1 function for early axon guidance decisions. Furthermore, nerfin-1 is required for the proper development of commissural and connective axon fascicles. Our studies also show that Nerfin-1 is essential for the proper expression of robo2, wnt5, derailed, G-oalpha47A, Lar, and futsch, genes whose encoded proteins participate in these early navigational events.

Nerfin-1 is required for early axon guidance decisions in the developing Drosophila CNS.

Nerfin-1 ist f&#xFC;r Anfang Lenkungsmolek&#xFC;le Entscheidungen in den sich entwickelnden Drosophila-ZNS erforderlich.

Establishment and maintenance of a functional central nervous system (CNS) requires a highly orchestrated process of neural progenitor cell proliferation, cell cycle exit, and differentiation. An evolutionary conserved program consisting of Notch signalling mediated by basic Helix-Loop-Helix (bHLH) transcription factor activity is necessary for both the maintenance of neural progenitor cell character and the progression of neurogenesis; however, additional players in mammalian CNS neural specification remain largely unknown. In Drosophila we recently characterized Hamlet, a transcription factor that mediates Notch signalling and neural cell fate.

Prdm proto-oncogene transcription factor family expression and interaction with the Notch-Hes pathway in mouse neurogenesis.

Schaffung und Aufrechterhaltung einer funktionellen Zentralnervensystem (CNS) erfordert einen &auml;u&szlig;erst orchestrierte neuronalen Vorl&auml;uferzellen Zellproliferation, Zellzyklus-Ausfahrt und Differenzierung. Ein evolution&auml;r konservierte Programm bestehend aus Notch Signalisierung von grundlegenden Helix-Loop-Helix (bHLH) vermittelt ist Transkription Faktor-Aktivit&auml;t f&uuml;r die Aufrechterhaltung der neuronalen Vorl&auml;uferzellen Zelle Charakter und das Fortschreiten der Neurogenese erforderlich; zus&auml;tzliche Spieler in S&auml;ugetieren CNS neuronale Spezifikation bleiben jedoch weitgehend unbekannt. In Drosophila charakterisiert wir k&uuml;rzlich Hamlet, ein Transkriptionsfaktor, der Signalisierung von Notch vermittelt und neuronale Zelle Schicksal.

Prdm Proto-oncogene Transkription Faktor Familie Ausdruck und Interaktion mit der Kerbe-Hes-Stoffwechselweg in Maus Neurogenese.

The fruitfly Drosophila melanogaster is well established as a model system in the study of human neurodegenerative diseases. Utilizing RNAi, we have carried out a high-throughput screen for modifiers of aggregate formation in Drosophila larval CNS-derived cells expressing mutant human Huntingtin exon 1 fused to EGFP with an expanded polyglutamine repeat (62Q). 7200 genes, encompassing around 50% of the Drosophila genome, were screened, resulting in the identification of 404 candidates that either suppress or enhance aggregation. These candidates were subjected to secondary screening in normal length (18Q)-expressing cells and pruned to remove dsRNAs with greater than 10 off-target effects (OTEs). De novo RNAi probes were designed and synthesized for the remaining 68 candidates. Following a tertiary round of screening, 21 high confidence candidates were analyzed in vivo for their ability to modify mutant Huntingtin-induced eye degeneration and brain aggregation. We have established useful models for the study of human HD using the fly, and through our RNAi screen, we have identified new modifiers of mutant human Huntingtin aggregation and aggregate formation in the brain. Newly identified modifiers including genes related to nuclear transport, nucleotide processes, and signaling, may be involved in polyglutamine aggregate formation and Huntington disease cascades.

RNAi screening in Drosophila cells identifies new modifiers of mutant huntingtin aggregation.

Der Fruitfly Drosophila Melanogaster ist weit verbreitet als Modellsystem in der Studie der menschlichen Neurodegenerative Krankheiten. Verwendung von RNAi, haben wir einen Hochdurchsatz-Screen f&uuml;r Modifikatoren der Aggregat-Formation in Drosophila durchgef&uuml;hrt larvalen CNS-abgeleitete Zellen auszudr&uuml;cken mutierten menschlichen Chorea Huntington Exon 1 zu EGFP mit einer erweiterten bei Polyglutamin-Wiederholung (62Q) verschmolzen. 7200 Gene, umfasst rund 50 % des Genoms Drosophila, wurden gezeigt, was bei der Identifizierung von 404 Kandidaten, die entweder unterdr&uuml;cken oder Aggregation zu verbessern. Diese Kandidaten wurden sekund&auml;re Screening in normale L&auml;nge (18Q) unterworfen-Ausdruck Zellen und beschnitten, um DsRNAs mit mehr als 10 aus den Zielgruppen-Effekte (OTEs) zu entfernen. De Novo RNAi Sonden wurden entworfen und f&uuml;r die restlichen 68 Kandidaten synthetisiert. Nach einer terti&auml;ren Runde des Screenings wurden 21 Kandidaten in hohes Vertrauen in-vivo f&uuml;r ihre M&ouml;glichkeit, mutant Chorea Huntington-induzierte Auge Degeneration und Gehirn Aggregation &auml;ndern analysiert. Wir haben n&uuml;tzliche Modelle f&uuml;r die Erforschung der menschlichen HD mit die Fliege, und durch unsere RNAi-Bildschirm, haben wir neue Modifikatoren der mutierten menschlichen Chorea Huntington-Aggregation und aggregierte Bildung im Gehirn identifiziert. Neu identifizierte Modifizierer einschlie&szlig;lich Gene nukleare Verkehrsbereich, Nukleotid-Prozesse, und Signaltechnik, m&ouml;glicherweise bei Polyglutamin Aggregat Bildung und Huntington Krankheit Kaskaden beteiligt.

RNAi Filmvorf&uuml;hrung Drosophila Zellen identifiziert neue Modifikatoren mutant Chorea Huntington-Aggregation.

Huntington's disease is an autosomal dominant neurodegenerative disorder that is caused by abnormal expansion of a polyglutamine tract in the huntingtin protein, resulting in intracellular aggregate formation and neurodegeneration. How neuronal cells are affected by such a polyglutamine tract expansion remains obscure. To dissect the ways in which polyglutamine expansion can cause neural dysfunction, the authors generated Drosophila transgenic strains expressing either a nuclear targeted or cytoplasmic form of pathogenic (NHtt-152Q(NLS), NHtt-152Q), or nonpathogenic (NHtt-18Q(NLS), NHtt-18Q) N-terminal human huntingtin. These proteins were expressed in the dendritic arborization neurons of the larval peripheral nervous system and their effects on neuronal survival, morphology, and larval locomotion were examined. The authors found that NHtt-152Q(NLS) larvae had altered dendrite morphology and larval locomotion, whereas NHtt-152Q, NHtt-18Q(NLS), and NHtt-18Q larvae did not. Furthermore, the authors examined the physiological defect underlying this disrupted larval locomotion in detail by recording spontaneous ongoing segmental nerve activity. NHtt-152Q(NLS) larvae displayed uncoordinated activity between anterior and posterior segments. Moreover, anterior segments had shorter bursts and longer interburst intervals in NHtt-152Q(NLS) larvae than in NHtt-18Q(NLS) larvae, whereas posterior segments had longer bursts and shorter interburst intervals. These results suggest that the pathogenic protein disrupts neuron function without inducing cell death, and describe how this dysfunction leads to a locomotor defect. These results also suggest that sensory inputs are necessary for the coordination of anterior and posterior body parts during locomotion. From these analyses the authors show that examination of motor behaviors in the Drosophila larvae is a powerful new model to dissect non-cell-lethal mechanisms of mutant Htt toxicity.

Selection of behaviors and segmental coordination during larval locomotion is disrupted by nuclear polyglutamine inclusions in a new Drosophila Huntington's disease-like model.

Chorea Huntington ist eine autosomal dominante Neurodegenerative Erkrankung, die durch abnorme Ausweitung der eine bei Polyglutamin-Darm-Trakt in der Chorea Huntington-Protein, wodurch intrazellul&auml;re Aggregat Bildung und Neurodegeneration verursacht wird. Wie Nervenzellen betroffen sind bleibtverborgen solch eine bei Polyglutamin-Trakt-Expansion. Zu sezieren, die M&ouml;glichkeiten, in welche bei Polyglutamin Erweiterung kann durch neuronale Dysfunktion, die Autoren generiert Drosophila transgene St&auml;mme auszudr&uuml;cken entweder eine nukleare gezielt, oder zellplasmatische Form von pathogenen (NHtt-152Q(NLS), NHtt-152Q) oder nonpathogenic (NHtt-18Q(NLS), NHtt-18Q) N-terminalen menschlichen Chorea Huntington. Diese Proteine wurden in den dendritischen Arborization Neuronen des larvalen peripheren Nervensystems ausgedr&uuml;ckt und deren Auswirkungen auf die neuronale &uuml;berleben, der Morphologie und der larvalen Fortbewegung wurden untersucht. Die Autoren gefunden, dass NHtt-152Q(NLS) Larven Dendrit Morphologie und larval Fortbewegung, ver&auml;ndert hatte, w&auml;hrend NHtt-152Q, NHtt-18Q(NLS) und NHtt-18Q Larven nicht tat. Dar&uuml;ber hinaus untersucht die Autoren den physiologischen Mangel zugrunde liegen diese gest&ouml;rte larvalen Fortbewegung im Detail durch spontane laufenden segmentale Nerven Aktivit&auml;t aufzeichnen. NHtt-152Q(NLS) Larven angezeigt unkoordinierte Aktivit&auml;t zwischen Front- und Seitenzahnbereich Segmenten. Dar&uuml;ber hinaus hatte anterioren Segmente k&uuml;rzer platzt und mehr interburst Intervalle in NHtt-152Q(NLS) Larven als in NHtt-18Q(NLS) Larven, w&auml;hrend die hinteren Segmente l&auml;nger platzt und k&uuml;rzeren interburst Abst&auml;nden hatte. Diese Ergebnisse legen nahe, dass das pathogene Protein Neuron-Funktion ohne Zelltod Induktion st&ouml;rt, und beschreiben, wie diese Dysfunktion zu einer e-Lok defekt f&uuml;hrt. Diese Ergebnisse suggerieren, dass sensorische Eingaben f&uuml;r die Koordinierung der vorderen und hinteren K&ouml;rperteile w&auml;hrend der Fortbewegung notwendig sind. Aus diesen Analysen, die die Autoren, dass zeigen ist die Untersuchung der motorische Verhaltensweisen in der Taufliege-Larven ein leistungsf&auml;higes neues Modell, nicht-Zelle-t&ouml;dliche Mechanismen der mutant Htt Toxizit&auml;t zu zergliedern.

Auswahl der Verhaltensweisen und segmentale Koordination w&auml;hrend der larvalen Fortbewegung ist durch nukleare bei Polyglutamin-Einschl&uuml;sse in ein neues Modell der Drosophila-Chorea Huntington-&auml;hnliche gest&ouml;rt.

Neuronal-class diversification is central during neurogenesis. This requirement is exemplified in the olfactory system, which utilizes a large array of olfactory receptor neuron (ORN) classes. We discovered an epigenetic mechanism in which neuron diversity is maximized via locus-specific chromatin modifications that generate context-dependent responses from a single, generally used intracellular signal. Each ORN in Drosophila acquires one of three basic identities defined by the compound outcome of three iterated Notch signaling events during neurogenesis. Hamlet, the Drosophila Evi1 and Prdm16 proto-oncogene homolog, modifies cellular responses to these iteratively used Notch signals in a context-dependent manner, and controls odorant receptor gene choice and ORN axon targeting specificity. In nascent ORNs, Hamlet erases the Notch state inherited from the parental cell, enabling a modified response in a subsequent round of Notch signaling. Hamlet directs locus-specific modifications of histone methylation and histone density and controls accessibility of the DNA-binding protein Suppressor of Hairless at the Notch target promoter.

Chromatin modification of Notch targets in olfactory receptor neuron diversification.

Neuronal-Klasse Diversifizierung ist zentrale w&auml;hrend der Neurogenese. Diese Anforderung ist im olfaktorischen System veranschaulicht, die eine gro&szlig;e Palette von olfaktorisches Neuron (ORN) Klassen verwendet. Wir entdeckten einen epigenetischen Mechanismus in welche, den Neuron Vielfalt &uuml;ber Locus-spezifische Chromatin-&Auml;nderungen maximiert ist, die kontextabh&auml;ngig Antworten aus einem einzigen, allgemein verwendeten intrazellul&auml;ren Signal zu erzeugen. Jede ORN in Drosophila erwirbt eine der drei grundlegenden Identit&auml;ten bei der Neurogenese durch das zusammengesetzte Ergebnis der drei iterierten Notch Signalling Ereignisse definiert. Weiler, die Taufliege Evi1 und Prdm16 Proto-oncogene Homolog, &auml;ndert die zellul&auml;re Reaktionen auf diese iterativ gebrauchten Notch-Signale in einem kontextabh&auml;ngigen Weise und Steuerelemente Odoriermittel Rezeptor Gen Wahl und ORN Axon Zielgruppenadressierung Spezifit&auml;t. Im Entstehen begriffenen ORNs l&ouml;scht Hamlet den Notch-Zustand geerbt von der elterlichen Zelle, eine ver&auml;nderte Reaktion in einer sp&auml;teren Runde Kerbe zu signalisieren. Weiler leitet Locus-spezifische &Auml;nderungen der Histon-Methylierung und Histon-Dichte und Steuerelemente Zug&auml;nglichkeit des DNA-bindenden Proteins Suppressor of Hairless an der Kerbe vorbei Projekttr&auml;ger.

ArticleTotal : 2	Year
Publication title Cited by 16	2011
Publication title Cited by 11	2011

Article	Year
hamlet, a binary genetic switch between single- and multiple- dendrite neuron morphology. Science (New York, N.Y.)\| PubMed ID: 12193790	2002
Dendrites of distinct classes of Drosophila sensory neurons show different capacities for homotypic repulsion. Current biology : CB\| PubMed ID: 12699617	2003
Conversion of neurons and glia to external-cell fates in the external sensory organs of Drosophila hamlet mutants by a cousin-cousin cell-type respecification. Genes & development\| PubMed ID: 15075290	2004
Nerfin-1 is required for early axon guidance decisions in the developing Drosophila CNS. Developmental biology\| PubMed ID: 15617679	2005
Prdm proto-oncogene transcription factor family expression and interaction with the Notch-Hes pathway in mouse neurogenesis. PloS one\| PubMed ID: 19050759	2008
RNAi screening in Drosophila cells identifies new modifiers of mutant huntingtin aggregation. PloS one\| PubMed ID: 19789644	2009
Selection of behaviors and segmental coordination during larval locomotion is disrupted by nuclear polyglutamine inclusions in a new Drosophila Huntington's disease-like model. Journal of neurogenetics\| PubMed ID: 21087194	2010
The Journal of neuroscience : the official journal of the Society for Neuroscience\| PubMed ID: 22114271	2011
Chromatin modification of Notch targets in olfactory receptor neuron diversification. Nature neuroscience\| PubMed ID: 22197833	2011

Adrian W. Moore

Biography

JoVE Journal Publications

Other Publications