Regulation of Dopamine Release by CASK-β Modulates Locomotor Initiation in Drosophila melanogaster

CASK is an evolutionarily conserved scaffolding protein that has roles in many cell types. In Drosophila, loss of the entire CASK gene or just the CASK- transcript causes a complex set of adult locomotor defects. In this study, we show that the motor initiation component of this phenotype is due to loss of CASK- in dopaminergic neurons and can be specifically rescued by expression of CASK- within this subset of neurons. Functional imaging demonstrates that mutation of CASK- disrupts coupling of neuronal activity to vesicle fusion. Consistent with this, locomotor initiation can be rescued by artificially driving activity in dopaminergic neurons. The molecular mechanism underlying this role of CASK- in dopaminergic neurons involves interaction with Hsc70-4, a molecular chaperone previously shown to regulate calcium-dependent vesicle fusion. These data suggest that there is a novel CASK- -dependent regulatory complex in dopaminergic neurons that serves to link activity and neurotransmitter release.Fil: Slawson, Justin B. Brandeis University; Estados UnidosFil: Kuklin, Elena A. Brandeis University; Estados UnidosFil: Mukherjee, Konark. Brandeis University; Estados UnidosFil: Pírez, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; Argentina. Fundación Instituto Leloir; Argentina. Brandeis University; Estados UnidosFil: Donelson, Nathan C. Brandeis University; Estados UnidosFil: Griffith, Leslie C. Brandeis University; Estados Unido

The circadian system: plasticity at many levels

Over the years it has become crystal clear that a variety of processes encode time-of-day information, ranging from gene expression, protein stability, or subcellular localization of key proteins, to the fine tuning of network properties and modulation of input signals, ultimately ensuring that physiology and behavior are properly synchronized to a changing environment. The purpose of this review is to put forward examples (as opposed to generate a comprehensive revision of all the available literature) in which the circadian system displays a remarkable degree of plasticity, from cell autonomous to circuit-based levels. In the literature, the term circadian plasticity has been used to refer to different concepts. The obvious one, more literally, refers to any change that follows a circadian (circa=around, diem=day) pattern, i.e. a daily change of a given parameter. The discovery of daily remodeling of neuronal structures will be referred herein as structural circadian plasticity, and represents an additional and novel phenomenon modified daily. Finally, any plasticity that has to do with a circadian parameter would represent a type of circadian plasticity; as an example, adjustments that allow organisms to adapt their daily behavior to the annual changes in photoperiod is a form of circadian plasticity at a higher organizational level, which is an emergent property of the whole circadian system. Throughout this work we will revisit these types of changes by reviewing recent literature delving around circadian control of clock outputs, from the most immediate ones within pacemaker neurons to the circadian modulation of rest-activity cycles.Fil: Muraro, Nara Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Pírez, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ceriani, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

The Drosophila Neuropeptides PDF and sNPF Have Opposing Electrophysiological and Molecular Effects on Central Neurons

Neuropeptides have widespread effects on behavior, but how these molecules alter the activity of their target cells is poorly understood. We employed a new model system in Drosophila melanogaster to assess the electrophysiological and molecular effects of neuropeptides, recording in situ from larval motor neurons, which transgenically express a receptor of choice. We focused on two neuropeptides, pigment-dispersing factor (PDF) and small neuropeptide F (sNPF), which play important roles in sleep/rhythms and feeding/metabolism. PDF treatment depolarized motor neurons expressing the PDF receptor (PDFR), increasing excitability. sNPF treatment had the opposite effect, hyperpolarizing neurons expressing the sNPF receptor (sNPFR). Live optical imaging using a genetically encoded fluorescence resonance energy transfer (FRET)-based sensor for cyclic AMP (cAMP) showed that PDF induced a large increase in cAMP, whereas sNPF caused a small but significant decrease in cAMP. Coexpression of pertussis toxin or RNAi interference to disrupt the G-protein Gαo blocked the electrophysiological responses to sNPF, showing that sNPFR acts via Gαo signaling. Using a fluorescent sensor for intracellular calcium, we observed that sNPF-induced hyperpolarization blocked spontaneous waves of activity propagating along the ventral nerve cord, demonstrating that the electrical effects of sNPF can cause profound changes in natural network activity in the brain. This new model system provides a platform for mechanistic analysis of how neuropeptides can affect target cells at the electrical and molecular level, allowing for predictions of how they regulate brain circuits that control behaviors such as sleep and feeding.Fil: Pírez, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; Argentina. Brandeis University. Department of Biology; Estados UnidosFil: Vecsey, Christopher G.. Brandeis University. Department of Biology; Estados UnidosFil: Griffith, Leslie C.. Brandeis University. Department of Biology; Estados Unido

Daily rhythms in locomotor circuits in Drosophila involve PDF

The neuropeptide pigment-dispersing factor (PDF) has been studied extensively in Drosophila, and its role in circadian time-keeping has been firmly established. The role of PDF outside of the clock circuit, however, is poorly understood. A recent study suggested that PDF may act on the ellipsoid body (EB) to link the clock and sleep/activity circuits. We performed whole brain optical imaging with the fluorescence resonance energy transfer (FRET)-based cAMP sensor Epac1-camps expressed under control of the pdfR promoter to address how the clock and sleep deprivation affect the physiology of these cells. Basal cAMP levels in EB were regulated both by PDF and synaptic inputs that are controlled by the circadian clock. Acute application of PDF to the brain caused a significant, and PDF-receptor-dependent, increase in cAMP in EB cells. Application of TTX to block circuit-mediated effects of PDF increased the morning response but not the response at night, implying the existence of a temporally regulated, PDF-stimulated input that blocks cAMP generation. ACh produced both direct (TTX-insensitive) and indirect (TTX-sensitive) increases in cAMP during the day but was totally TTX-insensitive at night, indicating that ACh-stimulated inputs to the EB are suppressed at night. Sleep deprivation did not affect the cAMP responses of these cells to either PDF or ACh. These results suggest a novel role for PDF as a modulator of activity outside of the clock circuit. By elucidating the mechanisms by which the neuropeptide PDF act on its target cells, our work contributes to our understating of how the central clock coordinates activity and sleep.Fil: Pírez, Nicolas. Brandeis University. Department of Biology; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Christmann, Bethany L.. Brandeis University. Department of Biology; Estados UnidosFil: Griffith, Leslie C.. Brandeis University. Department of Biology; Estados Unido

Circadian structural plasticity drives remodeling of E Cell Output

Behavioral outputs arise as a result of highly regulated yet flexible communication among neurons. The Drosophila circadian network includes 150 neurons that dictate the temporal organization of locomotor activity; under light-dark (LD) conditions, flies display a robust bimodal pattern. The pigment-dispersing factor (PDF)-positive small ventral lateral neurons (sLNv) have been linked to the generation of the morning activity peak (the “M cells”), whereas the Cryptochrome (CRY)-positive dorsal lateral neurons (LNds) and the PDF-negative sLNv are necessary for the evening activity peak (the “E cells”) [1, 2]. While each group directly controls locomotor output pathways [3], an interplay between them along with a third dorsal cluster (the DN1ps) is necessary for the correct timing of each peak and for adjusting behavior to changes in the environment [4–7]. M cells set the phase of roughly half of the circadian neurons (including the E cells) through PDF [5, 8–10]. Here, we show the existence of synaptic input provided by the evening oscillator onto the M cells. Both structural and functional approaches revealed that E-to-M cell connectivity changes across the day, with higher excitatory input taking place before the day-to-night transition. We identified two different neurotransmitters, acetylcholine and glutamate, released by E cells that are relevant for robust circadian output. Indeed, we show that acetylcholine is responsible for the excitatory input from E cells to M cells, which show preferential responsiveness to acetylcholine during the evening. Our findings provide evidence of an excitatory feedback between circadian clusters and unveil an important plastic remodeling of the E cells’ synaptic connections.Fil: Duhart, José Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Thomas Jefferson National Accelerartor Facility; Estados UnidosFil: Herrero, Anastasia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. IRB Barcelona; EspañaFil: de la Cruz, Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ispizua, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Pírez, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Ceriani, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

El derecho a la ciudad en América Latina : visiones desde la política

En un contexto internacional y local donde las contradicciones urbanas y sociales son un escenario recurrente es impostergable e imprescindible discutir sobre el Derecho a la Ciudad, el cual es una utopía de justicia espacial construida por diversos colectivos sociales en distintas partes de América Latina y del mundo. Esta utopía urbana no reivindica la reconquista de una ciudad perdida, sino la conquista de una ciudad que no hemos sabido construir: una ciudad para todos. El Derecho a la Ciudad implica la búsqueda de una gestión urbana democrática e incluyente en la que no sólo decidan qué hacer en ella el capital inmobiliario y el gobierno, sino también quienes la habitan, trabajan y/o disfrutan de la ciudad. Las ciudades con mejor calidad de vida son aquellas capaces de comprometer e involucrar a sus ciudadanos y de garantizar, por tanto, una gestión urbana participativa y democrática. La participación activa de la ciudadanía en los procesos de construcción, apropiación y administración colectiva de la ciudad son claves para construir una ciudad socialmente justa, que posibilite a los ciudadanos defender el interés público