Axon–glial interactions at the Drosophila CNS midline

Crews, Stephen T.

doi:10.4161/cam.4.1.10208

Cited by 19 publications

(24 citation statements)

References 41 publications

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“…Levels of wrapper expression in AMG are higher than in PMG, and this is likely to be a key determinant of why AMG ensheath commissures, and PMG do not, because loss of wrapper expression results in incomplete migration and ensheathment (Noordermeer et al, 1998;Stork et al, 2009;Wheeler et al, 2009). Recent work has demonstrated that sim directly regulates wrapper expression, and spitz signaling from axons might also form a positive feedback loop to control wrapper levels and strengthen Nrx-IV-Wrapper interactions (Crews, 2009;Estes et al, 2008). As en genetically reduces wrapper levels in PMG, it will be interesting to determine if this regulation is direct or indirect.…”

Section: Discussionmentioning

confidence: 99%

Drosophila hedgehogsignaling andengrailed-runtmutual repression direct midline glia to alternative ensheathing and non-ensheathing fates

et al. 2011

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SUMMARYThe Drosophila CNS contains a variety of glia, including highly specialized glia that reside at the CNS midline and functionally resemble the midline floor plate glia of the vertebrate spinal cord. Both insect and vertebrate midline glia play important roles in ensheathing axons that cross the midline and secreting signals that control a variety of developmental processes. The Drosophila midline glia consist of two spatially and functionally distinct populations. The anterior midline glia (AMG) are ensheathing glia that migrate, surround and send processes into the axon commissures. By contrast, the posterior midline glia (PMG) are nonensheathing glia. Together, the Notch and hedgehog signaling pathways generate AMG and PMG from midline neural precursors. Notch signaling is required for midline glial formation and for transcription of a core set of midline glial-expressed genes. The Hedgehog morphogen is secreted from ectodermal cells adjacent to the CNS midline and directs a subset of midline glia to become PMG. Two transcription factor genes, runt and engrailed, play important roles in AMG and PMG development. The runt gene is expressed in AMG, represses engrailed and maintains AMG gene expression. The engrailed gene is expressed in PMG, represses runt and maintains PMG gene expression. In addition, engrailed can direct midline glia to a PMG-like nonensheathing fate. Thus, two signaling pathways and runt-engrailed mutual repression initiate and maintain two distinct populations of midline glia that differ functionally in gene expression, glial migration, axon ensheathment, process extension and patterns of apoptosis.

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Section: Discussionmentioning

confidence: 99%

Drosophila hedgehogsignaling andengrailed-runtmutual repression direct midline glia to alternative ensheathing and non-ensheathing fates

et al. 2011

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“…Midline glia play a central role in axon pathfinding, separation of the major commissures of the CNS axon scaffold, and ultimately they ensheath axons at the CNS midline. These have been the subject of excellent reviews (Jacobs 2000;Crews 2010) and will not be covered here.…”

Section: Cns Glial Subtypes Closely Associated With Neuronsmentioning

confidence: 99%

DrosophilaCentral Nervous System Glia

Freeman

2015

Cold Spring Harb Perspect Biol

256

282

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Molecular genetic approaches in small model organisms like Drosophila have helped to elucidate fundamental principles of neuronal cell biology. Much less is understood about glial cells, although interest in using invertebrate preparations to define their in vivo functions has increased significantly in recent years. This review focuses on our current understanding of the three major neuron-associated glial cell types found in the Drosophila central nervous system (CNS)-astrocytes, cortex glia, and ensheathing glia. Together, these cells act like mammalian astrocytes: they surround neuronal cell bodies and proximal neurites, are coupled to the vasculature, and associate closely with synapses. Exciting recent work has shown essential roles for these CNS glial cells in neural circuit formation, function, plasticity, and pathology. As we gain a more firm molecular and cellular understanding of how Drosophila CNS glial cells interact with neurons, it is becoming clear they share significant molecular and functional attributes with mammalian astrocytes. Invertebrate preparations have contributed enormously to our understanding of fundamental principles of nervous system biology, including the chemical and electrophysiological basis of the action potential, synaptic vesicle release, neural cell fate specification, and axon pathfinding. This is largely thanks to the high experimental accessibility, ease of culture, rapid growth, and the panoply of molecular genetic tools with which to manipulate individual cells in vivo in organisms like Drosophila and Caenorhabditis elegans. The focus of many neuroscientists has shifted in recent years toward careful exploration of how glial cells participate in nervous system development, neural circuit function and plasticity, and neurological disease. Based on the remarkable success with which invertebrates were used to dissect fundamental aspects of the cell biology of the neuron, interest in the potential of small genetic model organisms to contribute to unraveling the mysteries of glial cells has grown significantly. This article will provide a brief overview of Drosophila glial cell biology, then focus on fly glial cell subtypes that are tightly associated with neurons in the central nervous system (CNS)-astrocytes, ensheathing glia, and cortex glia. A growing body of work argues strongly that these glia share a range morphological and functional features with mammalian astrocytes, and recent molecular studies indicate that conservation of basic glial cell biology extends, perhaps not surprisingly, to the molecular level.

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“…Hence, Drosophila midline glia constitute an amenable model system for untangling the complex and still largely unknown molecular mechanisms that underlie neuron-glia interactions. This, in turn, is essential for our in-depth understanding of the myelination process in development and disease (Bhat, 2003;Crews, 2010;Edenfeld et al, 2005;Jacobs, 2000;Sherman and Brophy, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Intricate and reciprocal neuron-glia interactions are essential for proper nervous system development across species (Crews, 2010;Klambt, 2009;Lemke, 2001). Early on during neuronal development, glial cells act as guidepost cells, i.e.…”

Section: Introductionmentioning

confidence: 99%

Canoe functions at the CNS midline glia in a complex with Shotgun and Wrapper-Nrx-IV during neuron-glia interactions

Slováková

Carmena

2011

Development

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SUMMARYVertebrates and insects alike use glial cells as intermediate targets to guide growing axons. Similar to vertebrate oligodendrocytes, Drosophila midline glia ensheath and separate axonal commissures. Neuron-glia interactions are crucial during these events, although the proteins involved remain largely unknown. Here, we show that Canoe (Cno), the Drosophila ortholog of AF-6, and the DE-cadherin Shotgun (Shg) are highly restricted to the interface between midline glia and commissural axons. cno mutant analysis, genetic interactions and co-immunoprecipitation assays unveil Cno function as a novel regulator of neuronglia interactions, forming a complex with Shg, Wrapper and Neurexin IV, the homolog of vertebrate Caspr/paranodin. Our results also support additional functions of Cno, independent of adherens junctions, as a regulator of adhesion and signaling events in non-epithelial tissues.

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Axon–glial interactions at the Drosophila CNS midline

Cited by 19 publications

References 41 publications

Drosophila hedgehogsignaling andengrailed-runtmutual repression direct midline glia to alternative ensheathing and non-ensheathing fates

Drosophila hedgehogsignaling andengrailed-runtmutual repression direct midline glia to alternative ensheathing and non-ensheathing fates

DrosophilaCentral Nervous System Glia

Canoe functions at the CNS midline glia in a complex with Shotgun and Wrapper-Nrx-IV during neuron-glia interactions

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