المؤلفون: Grintsevich, Elena E, Ahmed, Giasuddin, Ginosyan, Anush A, Wu, Heng, Rich, Shannon K, Reisler, Emil, Terman, Jonathan R

المصدر: Nature communications. 12(1)

مصطلحات موضوعية: Neurons, Growth Cones, Animals, Rabbits, Humans, Drosophila melanogaster, Actins, DNA-Binding Proteins, Cell Adhesion Molecules, Semaphorins, Nerve Tissue Proteins, Protein Binding, Oxidation-Reduction, Mutation, Models, Biological, Profilins, Polymerization, Actin Cytoskeleton, Axon Guidance, Formins, 2.1 Biological and endogenous factors

الوصف: Cellular events require the spatiotemporal interplay between actin assembly and actin disassembly. Yet, how different factors promote the integration of these two opposing processes is unclear. In particular, cellular monomeric (G)-actin is complexed with profilin, which inhibits spontaneous actin nucleation but fuels actin filament (F-actin) assembly by elongation-promoting factors (formins, Ena/VASP). In contrast, site-specific F-actin oxidation by Mical promotes F-actin disassembly and release of polymerization-impaired Mical-oxidized (Mox)-G-actin. Here we find that these two opposing processes connect with one another to orchestrate actin/cellular remodeling. Specifically, we find that profilin binds Mox-G-actin, yet these complexes do not fuel elongation factors'-mediated F-actin assembly, but instead inhibit polymerization and promote further Mox-F-actin disassembly. Using Drosophila as a model system, we show that similar profilin-Mical connections occur in vivo - where they underlie F-actin/cellular remodeling that accompanies Semaphorin-Plexin cellular/axon repulsion. Thus, profilin and Mical combine to impair F-actin assembly and promote F-actin disassembly, while concomitantly facilitating cellular remodeling and plasticity.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/45p7250gTest

المؤلفون: Onishi, Keisuke, Tian, Runyi, Feng, Bo, Liu, Yiqiong, Wang, Junkai, Li, Yinan, Zou, Yimin

المصدر: Proceedings of the National Academy of Sciences of the United States of America. 117(30)

مصطلحات موضوعية: Neurosciences, Aetiology, 2.1 Biological and endogenous factors, Neurological, Animals, Axons, Dopaminergic Neurons, Frizzled Receptors, Gene Knockdown Techniques, Growth Cones, Humans, Leucine-Rich Repeat Serine-Threonine Protein Kinase-2, Mice, Models, Biological, Mutation, Neurogenesis, Neurons, Phosphorylation, Signal Transduction, Spinal Cord, axon guidance, growth cone-growth cone interaction, Wnt/planar cell polarity, LRRK2, Frizzled3-Vangl2 interaction, Frizzled3–Vangl2 interaction, growth cone–growth cone interaction

الوصف: Axon-axon interactions are essential for axon guidance during nervous system wiring. However, it is unknown whether and how the growth cones communicate with each other while sensing and responding to guidance cues. We found that the Parkinson's disease gene, leucine-rich repeat kinase 2 (LRRK2), has an unexpected role in growth cone-growth cone communication. The LRRK2 protein acts as a scaffold and induces Frizzled3 hyperphosphorylation indirectly by recruiting other kinases and also directly phosphorylates Frizzled3 on threonine 598 (T598). In LRRK1 or LRRK2 single knockout, LRRK1/2 double knockout, and LRRK2 G2019S knockin, the postcrossing spinal cord commissural axons are disorganized and showed anterior-posterior guidance errors after midline crossing. Growth cones from either LRRK2 knockout or G2019S knockin mice showed altered interactions, suggesting impaired communication. Intercellular interaction between Frizzled3 and Vangl2 is essential for planar cell polarity signaling. We show here that this interaction is regulated by phosphorylation of Frizzled3 at T598 and can be regulated by LRRK2 in a kinase activity-dependent way. In the LRRK1/2 double knockout or LRRK2 G2019S knockin, the dopaminergic axon bundle in the midbrain was significantly widened and appeared disorganized, showing aberrant posterior-directed growth. Our findings demonstrate that LRRK2 regulates growth cone-growth cone communication in axon guidance and that both loss-of-function mutation and a gain-of-function mutation (G2019S) cause axon guidance defects in development.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/9p63h2jrTest

المؤلفون: Bott, Christopher J.¹, McMahon, Lloyd P.¹, Keil, Jason M.¹, Chan Choo Yap¹, Kwan, Kenneth Y.¹, Winckler, Bettina¹ BWinckler@virginia.edu

المصدر: Journal of Neuroscience. 5/6/2020, Vol. 40 Issue 19, p3720-3740. 21p.

مصطلحات موضوعية: *INTERMEDIATE filament proteins, *CONES, *MORPHOLOGY, *NEURONS, *NESTIN

مستخلص: Nestin, an intermediate filament protein widely used as a marker of neural progenitors, was recently found to be expressed transiently in developing cortical neurons in culture and in developing mouse cortex. In young cortical cultures, nestin regulates axonal growth cone morphology. In addition, nestin, which is known to bind the neuronal cdk5/p35 kinase, affects responses to axon guidance cues upstream of cdk5, specifically, to Sema3a. Changes in growth cone morphology require rearrangements of cytoskeletal networks, and changes in microtubules and actin filaments are well studied. In contrast, the roles of intermediate filament proteins in this process are poorly understood, even in cultured neurons. Here, we investigate the molecular mechanism by which nestin affects growth cone morphology and Sema3a sensitivity. We find that nestin selectively facilitates the phosphorylation of the lissencephaly-linked protein doublecortin (DCX) by cdk5/p35, but the phosphorylation of other cdk5 substrates is not affected by nestin. We uncover that this substrate selectivity is based on the ability of nestin to interact with DCX, but not with other cdk5 substrates. Nestin thus creates a selective scaffold for DCX with activated cdk5/p35. Last, we use cortical cultures derived from Dcx KO mice to show that the effects of nestin on growth cone morphology and on Sema3a sensitivity are DCX-dependent, thus suggesting a functional role for the DCX-nestin complex in neurons. We propose that nestin changes growth cone behavior by regulating the intracellular kinase signaling environment in developing neurons. The sex of animal subjects is unknown. [ABSTRACT FROM AUTHOR]

المؤلفون: Baba, Kentarou, Yoshida, Wataru, Toriyama, Michinori, Shimada, Tadayuki, Manning, Colleen F, Saito, Michiko, Kohno, Kenji, Trimmer, James S, Watanabe, Rikiya, Inagaki, Naoyuki

المصدر: eLife. 7(26)

مصطلحات موضوعية: Growth Cones, Cells, Cultured, Animals, Mice, Inbred C57BL, Mice, Knockout, Mice, Rats, Rats, Wistar, Actins, Neural Cell Adhesion Molecule L1, Nerve Tissue Proteins, Cell Adhesion, Signal Transduction, Mechanotransduction, Cellular, Chemotaxis, Phosphorylation, Embryo, Mammalian, p21-Activated Kinases, Axon Guidance, Netrin-1, axon guidance, cell biology, chemotaxis, clutch, gradient sensing, growth cone, mouse, neuroscience, rat, shootin1, Cells, Cultured, Inbred C57BL, Knockout, Wistar, Mechanotransduction, Cellular, Embryo, Mammalian, Biochemistry and Cell Biology

الوصف: Growth cones navigate axonal projection in response to guidance cues. However, it is unclear how they can decide the migratory direction by transducing the local spatial cues into protrusive forces. Here we show that knockout mice of Shootin1 display abnormal projection of the forebrain commissural axons, a phenotype similar to that of the axon guidance molecule netrin-1. Shallow gradients of netrin-1 elicited highly polarized Pak1-mediated phosphorylation of shootin1 within growth cones. We demonstrate that netrin-1-elicited shootin1 phosphorylation increases shootin1 interaction with the cell adhesion molecule L1-CAM; this, in turn, promotes F-actin-adhesion coupling and concomitant generation of forces for growth cone migration. Moreover, the spatially regulated shootin1 phosphorylation within growth cones is required for axon turning induced by netrin-1 gradients. Our study defines a mechano-effector for netrin-1 signaling and demonstrates that shootin1 phosphorylation is a critical readout for netrin-1 gradients that results in a directional mechanoresponse for axon guidance.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/1gz2197bTest

المؤلفون: Pavez, Macarena¹, Thompson, Adrian C.¹, Arnott, Hayden J.¹, Mitchell, Camilla B.², D'Atri, Ilaria³, Don, Emily K.⁴, Chilton, John K.³, Scott, Ethan K.^5,6, Lin, John Y.¹, Young, Kaylene M.², Gasperini, Robert J.¹, Foa, Lisa¹ lisa.foa@utas.edu.au

المصدر: Journal of Neuroscience. 6/26/2019, Vol. 39 Issue 26, p5095-5114. 20p.

مصطلحات موضوعية: *ENDOPLASMIC reticulum, *CONES, *CYTOSKELETON, *MOTOR neurons, *CARRIER proteins, *TUBULINS

مستخلص: The spatial and temporal regulation of calcium signaling in neuronal growth cones is essential for axon guidance. In growth cones, the endoplasmic reticulum (ER) is a significant source of calcium signals. However, it is not clear whether the ER is remodeled during motile events to localize calcium signals in steering growth cones. The expression of the ER-calcium sensor, stromal interacting molecule 1 (STIM1) is necessary for growth cone steering toward the calcium-dependent guidance cue BDNF, with STIM1 functioning to sustain calcium signals through store-operated calcium entry. However, STIM1 is also required for growth cone steering away from semaphorin-3a, a guidance cue that does not activate ER-calcium release, suggesting multiple functions of STIM1 within growth cones (Mitchell et al., 2012). STIM1 also interacts with microtubule plus-end binding proteins EB1/EB3 (Grigoriev et al., 2008). Here, we show that STIM1 associates with EB1/EB3 in growth cones and that STIM1 expression is critical for microtubule recruitment and subsequent ER remodeling to the motile side of steering growth cones. Furthermore, we extend our data in vivo, demonstrating that zSTIM1 is required for axon guidance in actively navigating zebrafish motor neurons, regulating calcium signaling and filopodial formation. These data demonstrate that, in response to multiple guidance cues, STIM1 couples microtubule organization and ER-derived calcium signals, thereby providing a mechanism where STIM1-mediated ER remodeling, particularly in filopodia, regulates spatiotemporal calcium signals during axon guidance. [ABSTRACT FROM AUTHOR]

المؤلفون: Gujar, Mahekta R.¹, Stricker, Aubrie M.¹, Lundquist, Erik A.¹ erikl@ku.edu

المصدر: PLoS Genetics. 6/24/2019, Vol. 15 Issue 6, p1-29. 29p.

مصطلحات موضوعية: *CAENORHABDITIS elegans, *CONES, *MICROTUBULES, *GUANOSINE triphosphatase, *SPINAL cord, *CELL polarity

مستخلص: UNC-6/Netrin is a conserved axon guidance cue that directs growth cone migrations in the dorsal-ventral axis of C. elegans and in the vertebrate spinal cord. UNC-6/Netrin is expressed in ventral cells, and growth cones migrate ventrally toward or dorsally away from UNC-6/Netrin. Recent studies of growth cone behavior during outgrowth in vivo in C. elegans have led to a polarity/protrusion model in directed growth cone migration away from UNC-6/Netrin. In this model, UNC-6/Netrin first polarizes the growth cone via the UNC-5 receptor, leading to dorsally biased protrusion and F-actin accumulation. UNC-6/Netrin then regulates protrusion based on this polarity. The receptor UNC-40/DCC drives protrusion dorsally, away from the UNC-6/Netrin source, and the UNC-5 receptor inhibits protrusion ventrally, near the UNC-6/Netrin source, resulting in dorsal migration. UNC-5 inhibits protrusion in part by excluding microtubules from the growth cone, which are pro-protrusive. Here we report that the RHO-1/RhoA GTPase and its activator GEF RHGF-1 inhibit growth cone protrusion and MT accumulation in growth cones, similar to UNC-5. However, growth cone polarity of protrusion and F-actin were unaffected by RHO-1 and RHGF-1. Thus, RHO-1 signaling acts specifically as a negative regulator of protrusion and MT accumulation, and not polarity. Genetic interactions are consistent with RHO-1 and RHGF-1 acting with UNC-5, as well as with a parallel pathway, to regulate protrusion. The cytoskeletal interacting molecule UNC-33/CRMP was required for RHO-1 activity to inhibit MT accumulation, suggesting that UNC-33/CRMP might act downstream of RHO-1. In sum, these studies describe a new role of RHO-1 and RHGF-1 in regulation of growth cone protrusion by UNC-6/Netrin. [ABSTRACT FROM AUTHOR]

المؤلفون: Akin, Orkun, Zipursky, S Lawrence

مصطلحات موضوعية: Eye, Growth Cones, Axons, Animals, Drosophila melanogaster, Drosophila Proteins, Repressor Proteins, Chemotactic Factors, Cell Adhesion, Signal Transduction, Gene Expression Regulation, Developmental, Basic Helix-Loop-Helix Transcription Factors, Axon Guidance, Netrin Receptors, D. melanogaster, axon guidance, developmental biology, live imaging, neuroscience, stem cells, two-photon microscopy, Gene Expression Regulation, Developmental, Biochemistry and Cell Biology

الوصف: Axon guidance is proposed to act through a combination of long- and short-range attractive and repulsive cues. The ligand-receptor pair, Netrin (Net) and Frazzled (Fra) (DCC, Deleted in Colorectal Cancer, in vertebrates), is recognized as the prototypical effector of chemoattraction, with roles in both long- and short-range guidance. In the Drosophila visual system, R8 photoreceptor growth cones were shown to require Net-Fra to reach their target, the peak of a Net gradient. Using live imaging, we show, however, that R8 growth cones reach and recognize their target without Net, Fra, or Trim9, a conserved binding partner of Fra, but do not remain attached to it. Thus, despite the graded ligand distribution along the guidance path, Net-Fra is not used for chemoattraction. Based on findings in other systems, we propose that adhesion to substrate-bound Net underlies both long- and short-range Net-Fra-dependent guidance in vivo, thereby eroding the distinction between them.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/1rw6300cTest

المؤلفون: Vicenzi, Silvia, Foa, Lisa, Gasperini, Robert J.

المصدر: Cellular & Molecular Life Sciences; Mar2021, Vol. 78 Issue 5, p2247-2262, 16p

مصطلحات موضوعية: SEROTONIN, HIGH resolution imaging, NEURAL circuitry, AXONS, CONES, SEROTONIN receptors

مستخلص: The neurotransmitter serotonin has been implicated in a range of complex neurological disorders linked to alterations of neuronal circuitry. Serotonin is synthesized in the developing brain before most neuronal circuits become fully functional, suggesting that serotonin might play a distinct regulatory role in shaping circuits prior to its function as a classical neurotransmitter. In this study, we asked if serotonin acts as a guidance cue by examining how serotonin alters growth cone motility of rodent sensory neurons in vitro. Using a growth cone motility assay, we found that serotonin acted as both an attractive and repulsive guidance cue through a narrow concentration range. Extracellular gradients of 50 µM serotonin elicited attraction, mediated by the serotonin 5-HT2a receptor while 100 µM serotonin elicited repulsion mediated by the 5-HT1b receptor. Importantly, high resolution imaging of growth cones indicated that these receptors signalled through their canonical pathways of endoplasmic reticulum-mediated calcium release and cAMP depletion, respectively. This novel characterisation of growth cone motility in response to serotonin gradients provides compelling evidence that secreted serotonin acts at the molecular level as an axon guidance cue to shape neuronal circuit formation during development. [ABSTRACT FROM AUTHOR]

: Copyright of Cellular & Molecular Life Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Cook, Geoffrey Mw, Sousa, Catia, Schaeffer, Julia, Wiles, Katherine, Jareonsettasin, Prem, Kalyanasundaram, Asanish, Walder, Eleanor, Casper, Catharina, Patel, Serena, Chua, Pei Wei, Riboni-Verri, Gioia, Raza, Mansoor, Swaddiwudhipong, Nol, Hui, Andrew, Abdullah, Ameer, Wajed, Saj, Keynes, Roger J

مصطلحات موضوعية: axon guidance, chicken, developmental biology, human, neuroscience, rat, repeat patterning, somite, spinal nerve, Animals, Astrocytes, Cell Line, Chick Embryo, Chickens, Gene Knockdown Techniques, Growth Cones, Humans, Membrane Proteins, Neurosciences, Nitric Oxide, Procollagen-Proline Dioxygenase, Protein Disulfide-Isomerases, Rats, Signal Transduction, Somites, Spinal Nerves

الوصف: Contact repulsion of growing axons is an essential mechanism for spinal nerve patterning. In birds and mammals the embryonic somites generate a linear series of impenetrable barriers, forcing axon growth cones to traverse one half of each somite as they extend towards their body targets. This study shows that protein disulphide isomerase provides a key component of these barriers, mediating contact repulsion at the cell surface in chick half-somites. Repulsion is reduced both in vivo and in vitro by a range of methods that inhibit enzyme activity. The activity is critical in initiating a nitric oxide/S-nitrosylation-dependent signal transduction pathway that regulates the growth cone cytoskeleton. Rat forebrain grey matter extracts contain a similar activity, and the enzyme is expressed at the surface of cultured human astrocytic cells and rat cortical astrocytes. We suggest this system is co-opted in the brain to counteract and regulate aberrant nerve terminal growth.

وصف الملف: Electronic; application/pdf

العلاقة: https://www.repository.cam.ac.uk/handle/1810/309391Test

الإتاحة: https://doi.org/10.17863/CAM.56480Test
https://www.repository.cam.ac.uk/handle/1810/309391Test

المؤلفون: Takabatake, Masaru, Goshima, Yoshio, Sasaki, Yukio

المصدر: Frontiers in Neural Circuits; 2/28/2020, Vol. 14, p1-9, 9p

مصطلحات موضوعية: PROTEASOMES, INTELLECTUAL disabilities, DWARFISM, RNA-binding proteins, CONES, MICROTUBULE-associated proteins

مستخلص: Fragile X mental retardation protein (FMRP) is an RNA-binding protein that regulates local translation in dendrites and spines for synaptic plasticity. In axons, FMRP is implicated in axonal extension and axon guidance. We previously demonstrated the involvement of FMRP in growth cone collapse via a translation-dependent response to Semaphorin-3A (Sema3A), a repulsive axon guidance factor. In the case of attractive axon guidance factors, RNA-binding proteins such as zipcode binding protein 1 (ZBP1) accumulate towards the stimulated side of growth cones for local translation. However, it remains unclear how Sema3A effects FMRP localization in growth cones. Here, we show that levels of FMRP in growth cones of hippocampal neurons decreased after Sema3A stimulation. This decrease in FMRP was suppressed by the ubiquitin-activating enzyme E1 enzyme inhibitor PYR-41 and proteasome inhibitor MG132, suggesting that the ubiquitin-proteasome pathway is involved in Sema3A-induced FMRP degradation in growth cones. Moreover, the E1 enzyme or proteasome inhibitor suppressed Sema3A-induced increases in microtubule-associated protein 1B (MAP1B) in growth cones, suggesting that the ubiquitin-proteasome pathway promotes local translation of MAP1B, whose translation is mediated by FMRP. These inhibitors also blocked the Sema3A-induced growth cone collapse. Collectively, our results suggest that Sema3A promotes degradation of FMRP in growth cones through the ubiquitin-proteasome pathway, leading to growth cone collapse via local translation of MAP1B. These findings reveal a new mechanism of axon guidance regulation: degradation of the translational suppressor FMRP via the ubiquitin-proteasome pathway. [ABSTRACT FROM AUTHOR]

: Copyright of Frontiers in Neural Circuits is the property of Frontiers Media S.A. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)