Drosophila microRNA-34 Impairs Axon Pruning of Mushroom Body γ Neurons by Downregulating the Expression of Ecdysone Receptor

Lai, Yen-Wei; Chu, Sao-Yu; Wei, Jiayi; Cheng, Chu-Ya; Li, Jian-Chiuan; Chen, Po‐Lin; Chen, Chunhong; Yu, Hung–Hsiang

doi:10.1038/srep39141

Cited by 20 publications

(17 citation statements)

References 35 publications

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“…4). These findings support the idea that the miR-34-induced MB axon pruning defect in our previous study was probably due to downregulation of the Babo expression 8 . Taken together, our data suggest that babo is a miR-34 target gene, which participates in crucial biological processes such as the axon pruning of MB neurons.…”

Section: Visualization Of Endogenous Babo Expression Using a Babo Ha supporting

confidence: 92%

Visualization of Endogenous Type I TGF-β Receptor Baboon in the Drosophila Brain

Lai

Chu

et al. 2020

Sci Rep

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the transforming growth factor β (tGf-β) signaling pathway is evolutionarily conserved and widely used in the animal kingdom to regulate diverse developmental processes. prior studies have shown that Baboon (Babo), a Drosophila type i tGf-β receptor, plays essential roles in brain development and neural circuit formation. However, the expression pattern for Babo in the developing brain has not been previously reported. We generated a knock-in fly with a human influenza hemagglutinin (HA) tag at the C-terminus of Babo and assessed its localization. Babo::HA was primarily expressed in brain structures enriched with neurites, including the mushroom body lobe and neuropils of the optic lobe, where Babo has been shown to instruct neuronal morphogenesis. Since the babo 3' untranslated region contains a predicted microRNA-34 (miR-34) target sequence, we further tested whether Babo::HA expression was affected by modulating the level of miR-34. We found that Babo was upregulated by mir-34 deletion and downregulated by miR-34 overexpression, confirming that it is indeed a miR-34 target gene. Taken together, our results demonstrate that the babo HA fly permits accurate visualization of endogenous Babo expression during brain development and the construction of functional neural circuits.The transforming growth factor β (TGF-β) signaling pathway is evolutionarily conserved and widely utilized in animals as a regulator of diverse and complex processes, such as cell growth, differentiation and morphogenesis during development 1,2 . In Drosophila, two major groups of ligands, Activins and Bone morphogenetic proteins, stimulate distinct TGF-β signaling pathways that involve different sets of downstream effectors (reviewed by Upadhyay et al. 1 ). Activin signals bind to Baboon (Babo), a type I TGF-β receptor that transduces TGF-β signaling by binding to type II TGF-β receptors, Punt and Wishful thinking (Wit), to regulate several essential processes in brain development and neural circuit formation 1,3-5 . For instance, Activin-β and an Activin-like protein Dawdle were shown to signal through Babo to regulate neuroblast proliferation in the larval brain, with loss of babo function resulting in fewer cells within the central brain and optic lobe 4 . Besides controlling neuroblast proliferation, Babo also transduces the signals of Activin-β and Activin-like protein Myoglianin to control neuronal morphogenesis during neural circuit formation, including in mushroom body (MB) neurons of the central brain and in medulla projection (Tm) neurons of the optic lobe 3,5,6 . When babo is mutated, MB neurons display both axon growth and pruning defects 3,7 , while Tm neurons exhibit multiple dendritic patterning phenotypes 5 . Taken together, these studies demonstrate the crucial role of Babo in brain development and in neural circuit formation.Despite the fact that Babo is known to act as an important regulator, the Babo pattern expression in the brain has not been previously reported. In this study, we overcame a lack of reliable Babo antib...

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Section: Visualization Of Endogenous Babo Expression Using a Babo Ha supporting

confidence: 92%

Visualization of Endogenous Type I TGF-β Receptor Baboon in the Drosophila Brain

Lai

Chu

et al. 2020

Sci Rep

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“…A single axon projects anteriorly, bifurcates, and then projects both dorsally and medially to form the α and β lobes. Several previous studies have used this technique to investigate whether certain proteins are required to study cell division autonomously for many aspects of axonogenesis, including extension, pathfinding, branching, and/or pruning 10 11 12 13 14 15 16 17 34 .…”

Section: Representative Resultsmentioning

confidence: 99%

“…While the embryonic fly CNS has been used extensively in the past to identify ligands, receptors, and intracellular signaling proteins required for axonal guidance 8 9 , recent work has investigated the ways in which many of these proteins also control pathfinding decisions during later stages of development. Specifically, investigation of mushroom body (MB) and retinal photoreceptor neuron development ( Figure 1 ) has provided insight into the mechanisms that control pathfinding, synapse formation, axon pruning, and several other aspects of neuronal development 10 11 12 13 14 15 16 17 . Photoreceptor neurons connect the fly retina to regions of the adult brain called the lamina and medulla and are critical for relaying visual information to the brain (reviewed by 18 19 ), while mushroom body neurons are centrally located in the fly brain and are required for learning and memory 20 21 .…”

Section: Introductionmentioning

confidence: 99%

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult <em>Drosophila melanogaster</em> Brains

Kelly

Elchert

Kahl

2017

JoVE

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Nervous system development involves a sequential series of events that are coordinated by several signaling pathways and regulatory networks. Many of the proteins involved in these pathways are evolutionarily conserved between mammals and other eukaryotes, such as the fruit fly Drosophila melanogaster, suggesting that similar organizing principles exist during the development of these organisms. Importantly, Drosophila has been used extensively to identify cellular and molecular mechanisms regulating processes that are required in mammals including neurogenesis, differentiation, axonal guidance, and synaptogenesis. Flies have also been used successfully to model a variety of human neurodevelopmental diseases. Here we describe a protocol for the step-by-step microdissection, fixation, and immunofluorescent localization of proteins within the adult Drosophila brain. This protocol focuses on two example neuronal populations, mushroom body neurons and retinal photoreceptors, and includes optional steps to trace individual mushroom body neurons using Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. Example data from both wild-type and mutant brains are shown along with a brief description of a scoring criteria for axonal guidance defects. While this protocol highlights two well-established antibodies for investigating the morphology of mushroom body and photoreceptor neurons, other Drosophila brain regions and the localization of proteins within other brain regions can also be investigated using this protocol.

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“…Previous studies have shown that extra dorsal projections can arise due to defects in  neuron remodeling that occur during pupal morphogenesis [41][42][43] . During the larval stages of development, MB  neurons project both dorsally and medially.…”

Section: The Pbap Complex Is Required For Axon Pruning During  Neuromentioning

confidence: 99%

“…This is followed by re-extension of the  neurons medially, but not dorsally, to form the adult  lobe 39 (Figure 4A). The appearance of extra dorsal projections in adult flies is often caused by a failure to prune larval  axons [41][42][43] . To investigate whether the extra dorsal projections we observed were the result of unpruned  neurons, and not from aberrantly formed / neurons, we performed RNAi knockdown using two -neuron specific Gal4 drivers; MB607B-Gal4 (data not shown) and MB009B-Gal4 (Figure 4B) The final observed morphological phenotype, described as faded  lobes, is characterized by normal MB morphology, with a shift in the intensity of fluorescent labeling by GFP.…”

Section: The Pbap Complex Is Required For Axon Pruning During  Neuromentioning

confidence: 99%

Systematic functional characterization of the intellectual disability-associated SWI/SNF complex reveals distinct roles for the BAP and PBAP complexes in post-mitotic memory forming neurons of theDrosophilamushroom body

Chubak

Stone

Raun

et al. 2018

Preprint

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Technology has led to rapid progress in the identification of genes involved in neurodevelopmental disorders like intellectual disability (ID), but our functional understanding of the causative genes is lagging. Here, we show that the SWI/SNF chromatin remodeling complex is one of the most overrepresented cellular components disrupted in ID. We systematically investigated the role of individual subunits of this large protein complex in post-mitotic memory forming neurons of the Drosophila mushroom body (MB). Using this approach, we have identified novel differential roles for the two prominent conformations of the Drosophila SWI/SNF complex, known as BAP and PBAP. The PBAP conformation is required post-mitotically for remodeling of the MB  neurons during morphogenesis and is essential for both short and long-term memory. In contrast, the BAP conformation appears to preferentially effect long-term memory and is associated with  neuron survival. Our results suggest that different subunits of the SWI/SNF complex may influence learning and memory through diverse and distinct roles in regulating structural plasticity, survival, and functionality of postmitotic neurons. This study provides novel insight into the neuronal function of individual SWI/SNF subunits and will serve as a basis for understanding SWI/SNF-mediated gene regulatory mechanisms in post-mitotic neurons.

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Drosophila microRNA-34 Impairs Axon Pruning of Mushroom Body γ Neurons by Downregulating the Expression of Ecdysone Receptor

Cited by 20 publications

References 35 publications

Visualization of Endogenous Type I TGF-β Receptor Baboon in the Drosophila Brain

Visualization of Endogenous Type I TGF-β Receptor Baboon in the Drosophila Brain

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult <em>Drosophila melanogaster</em> Brains

Systematic functional characterization of the intellectual disability-associated SWI/SNF complex reveals distinct roles for the BAP and PBAP complexes in post-mitotic memory forming neurons of theDrosophilamushroom body

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