Filamin, a synaptic organizer in Drosophila, determines glutamate receptor composition and membrane growth

Lee, GaYoung; Schwarz, Thomas L.

doi:10.7554/elife.19991

Cited by 20 publications

(23 citation statements)

References 70 publications

(114 reference statements)

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“…Several different pathways have been reported to act downstream of Ral GTPase, including the exocyst complex, RalBP1 and Filamin (Moghadam et al 2017; Shirakawa & Horiuchi 2015). Ral interaction with RalBP1 is mostly involved in endocytosis, Filamin and Ral act as scaffold/synaptic organizers (Lee & Schwarz 2016), and the Ral/Exocyst pathway has been shown to be required for membrane addition of postsynaptic membranes and for the polarized trafficking of vesicles to exocytic places (Teodoro et al 2013; Armenti et al 2014; Balasubramanian et al 2010; Wang et al 2004; Hase et al 2009). From these interactors, the exocyst is an excellent candidate to mediate Ral-dependent wrapping glia growth.…”

Section: Resultsmentioning

confidence: 99%

“…The following fly strains were used: w 1118 (BDSC 3605); ral G05010 (BDSC 12283); ral EE1 (BDSC 25095); sec8 PI (BDSC 12937); sec5 E10 (Murthy et al 2003), sec6 Ex15 (Murthy et al 2005); Nrv2-GAL4 (BDSC 6800); Repo-GAL4 (BDSC 7415); nSyb-GAL4 (BDSC 19183); moody-GAL4 (Stork et al 2008); perineurial-GAL4 (Bsg. DGRC-Kyoto 105188); Vkg-GFP (VDRC 318167); UAS-RalHA (Lee & Schwarz 2016); UAS-CD4-GFP (BDSC 35836); NrxIV-GFP (Buszczak et al 2006), UAS-FasII-Flag (Bornstein et al 2015). RNAi knockdown strains UAS-Ral-IR (BDSC 29580) and UAS-Sec5-IR (VDRC- w 1118 ; P(GD13789) v28873).…”

Section: Methodsmentioning

confidence: 99%

“…Given the nature of this process, genes involved in membrane addition are likely to be required. A pathway that has recurrently been reported to orchestrate the polarized targeting of vesicles and to regulate membrane growth events is the exocyst complex, via its interaction with the small GTPase Ral (Lee & Schwarz 2016; Teodoro et al 2013; Armenti et al 2014; Balasubramanian et al 2010; Patrício-Rodrigues & Teodoro 2018). The exocyst is an octameric protein complex conserved from yeast to human that is an effector to many GTPases, including Ral.…”

Section: Introductionmentioning

confidence: 99%

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Peripheral axonal ensheathment is regulated by Ral GTPase and the exocyst complex

Silva-Rodrigues

Patrício-Rodrigues

Sousa-Xavier

et al. 2019

Preprint

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16Axon ensheathment is fundamental for fast impulse conduction and the normal 17 physiological functioning of the nervous system. Defects in axonal insulation lead to 18 debilitating conditions, but despite its importance, the molecular players responsible are 19 poorly defined. Here, we identify Ral GTPase as a key player in axon ensheathment in 20 Drosophila larval peripheral nerves. We demonstrate through genetic analysis that Ral 21 action through the exocyst complex is sufficient and necessary in wrapping glial cells to 22 regulate their growth and development. We suggest that the Ral-exocyst pathway 23 controls the targeting of secretory vesicles for membrane growth or for the secretion of a 24 wrapping glia-specific factor that itself regulates growth. In summary, our findings 25 provide a new molecular understanding of the process by which axons are ensheathed 26 in vivo, a process critical for normal neuronal function. 27 28 29 93Sec8 has also been shown to contribute to myelin formation in culture (Bolis et al. 2009). 94Together, these data hint at a function for Ral and for the exocyst in the process of 95 axonal wrapping, but whether they are required for myelin formation or axonal 96 ensheathing, or whether they are in the same pathway, is not known. 4 98Here we show that Ral GTPase and the exocyst are critical regulators of nerve bundle 99 development in the Drosophila PNS. We demonstrate that ral mutants have severely 100 underdeveloped wrapping glia but have morphologically normal subperineurial and 101 perineurial glia, implying a specific role for Ral GTPase in wrapping glia and not in 102 general growth. We show that wrapping glia defects result from a failure to grow rather 103 than a failure to maintain membrane integrity. In addition, we demonstrate that these 104 mutants have thicker ISNs, often with defasciculated axons and signs of a disrupted 105 BNB. These defects in the mutants result in abnormal locomotion, possibly due to 106 altered axonal insulation. Genetic analyses show that Ral is both sufficient and 107 necessary in wrapping glia to regulate its growth and development. Furthermore, we 108 show that Ral GTPase functions via the exocyst complex in the regulation of these 109 developmental processes. Given the known roles of this pathway, we propose that the 110 Ral/exocyst pathway regulates axonal wrapping directly through the control of the 111 targeting of secretory vesicles for membrane addition or, alternatively, by controlling the 112 secretion of a wrapping glia-specific factor, that would itself regulate growth. In 113 summary, our findings establish Ral GTPase and the exocyst as novel players required 114 for wrapping glia development, and axonal ensheathment in vivo, a process critical for 115 normal impulse conduction. 116 117 118 5 Results 119 ral mutants have abnormal nerve bundles 120 Postembryonic PNS development requires substantial growth to accommodate the 121 increase in larval size. Specifically, PNS axons and their surrounding glial cells must 122 grow coordin...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Peripheral axonal ensheathment is regulated by Ral GTPase and the exocyst complex

Silva-Rodrigues

Patrício-Rodrigues

Sousa-Xavier

et al. 2019

Preprint

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“…The post-synaptic membrane consists of the SSR, the periactive zone, and the active zone with the latter two organized in the muscle membrane prior to the arrival of the bouton. Pak, which is a major regulator of postsynaptic active site formation, is attracted by high levels of Dlg in the island corrals, probably contacting Dlg through the spectrin fence, but also Dlg released from the corrals by transient breaks in the cytoskeleton (Albin and Davis, 2004;Lee and Schwarz, 2016;Parnas et al, 2001;Ramos et al, 2015;Wang et al, 2016). This interpretation is based on our PLA and colocalization studies indicating close proximity between Pak and Dlg, and the finding that excessive amounts of Pak are recruited to the muscle membrane adjacent to high levels of Dlg in drpr MB06916 mutants and larvae bearing the Df(3L)BSC181 deficiency.…”

Section: A Model For Guidance Of Post-synaptic Membrane Formation By mentioning

confidence: 99%

The engulfment receptor Draper organizes the postsynaptic spectrin cytoskeleton into corrals containing synaptic proteins and promotes synaptic renewal

Wang

Kim

Yoo

et al. 2019

Preprint

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2 SummaryThe spectrin cytoskeleton is required for development of the Drosophila neuromuscular junction (NMJ) but its role is unclear. Here we show that the muscle spectrin lattice functions to corral membrane-associated synaptic proteins and limit their lateral mobility. Drosophila adducin, Hts, is required for integrity of the spectrin cytoskeleton and disruption of Hts function results in failure of the corrals. The spectrin cytoskeleton is itself patterned at the muscle membrane by the engulfment receptor Draper (Drpr) through regulation of Hts. We find patches of membrane where the spectrin cytoskeleton is organized into bilaterally symmetric patterns, which coincide with a field of Drprdependent structures similar to phagocytic pseudopods. The bilaterally symmetric patterns are likely created by folds of the muscle membrane in the pseudopods. We present evidence that the folds trap nascent boutons of motor neurons, leading to boutons with a bilaterally symmetric organization of the postsynaptic membrane. Drpr thus acts as a sensor of synaptic damage that promotes synaptogenesis.

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“…Moreover, mutants with altered synaptic iGluR levels also show altered bouton numbers. For instance, neto and filamin (cheerio) mutants show reduced iGluR levels and bouton numbers (Kim et al, 2012;Lee and Schwarz, 2016). One of the possible mechanisms by which glutamate receptors can alter the NMJ morphology is through regulation of synaptic phospho-MAD levels (Sulkowski et al, 2014).…”

Section: Regulation Of Glutamate Receptor Clusters By Ica69mentioning

confidence: 99%

Regulation of neuromuscular junction organization by Rab2 and its effector ICA69 in Drosophila

et al. 2017

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The mechanisms underlying synaptic differentiation, which involves neuronal membrane and cytoskeletal remodeling, are not completely understood. We performed a targeted RNAi-mediated screen of Drosophila BAR-domain proteins and identified islet cell autoantigen 69 kDa (ICA69) as one of the key regulators of morphological differentiation of the larval neuromuscular junction (NMJ). We show that Drosophila ICA69 colocalizes with α-Spectrin at the NMJ. The conserved N-BAR domain of ICA69 deforms liposomes in vitro. Fulllength ICA69 and the ICAC but not the N-BAR domain of ICA69 induce filopodia in cultured cells. Consistent with its cytoskeleton regulatory role, ICA69 mutants show reduced α-Spectrin immunoreactivity at the larval NMJ. Manipulating levels of ICA69 or its interactor PICK1 alters the synaptic level of ionotropic glutamate receptors (iGluRs). Moreover, reducing PICK1 or Rab2 levels phenocopies ICA69 mutation. Interestingly, Rab2 regulates not only synaptic iGluR but also ICA69 levels. Thus, our data suggest that: (1) ICA69 regulates NMJ organization through a pathway that involves PICK1 and Rab2, and (2) Rab2 functions genetically upstream of ICA69 and regulates NMJ organization and targeting/ retention of iGluRs by regulating ICA69 levels.

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Filamin, a synaptic organizer in Drosophila, determines glutamate receptor composition and membrane growth

Cited by 20 publications

References 70 publications

Peripheral axonal ensheathment is regulated by Ral GTPase and the exocyst complex

Peripheral axonal ensheathment is regulated by Ral GTPase and the exocyst complex

The engulfment receptor Draper organizes the postsynaptic spectrin cytoskeleton into corrals containing synaptic proteins and promotes synaptic renewal

Regulation of neuromuscular junction organization by Rab2 and its effector ICA69 in Drosophila

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