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André M, Dinvaut S, Castellani V, Falk J. 3D exploration of gene expression in chicken embryos through combined RNA fluorescence in situ hybridization, immunofluorescence, and clearing. BMC Biol 2024; 22:131. [PMID: 38831263 PMCID: PMC11149291 DOI: 10.1186/s12915-024-01922-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
BACKGROUND Fine characterization of gene expression patterns is crucial to understand many aspects of embryonic development. The chicken embryo is a well-established and valuable animal model for developmental biology. The period spanning from the third to sixth embryonic days (E3 to E6) is critical for many organ developments. Hybridization chain reaction RNA fluorescent in situ hybridization (HCR RNA-FISH) enables multiplex RNA detection in thick samples including embryos of various animal models. However, its use is limited by tissue opacity. RESULTS We optimized HCR RNA-FISH protocol to efficiently label RNAs in whole mount chicken embryos from E3.5 to E5.5 and adapted it to ethyl cinnamate (ECi) tissue clearing. We show that light sheet imaging of HCR RNA-FISH after ECi clearing allows RNA expression analysis within embryonic tissues with good sensitivity and spatial resolution. Finally, whole mount immunofluorescence can be performed after HCR RNA-FISH enabling as exemplified to assay complex spatial relationships between axons and their environment or to monitor GFP electroporated neurons. CONCLUSIONS We could extend the use of HCR RNA-FISH to older chick embryos by optimizing HCR RNA-FISH and combining it with tissue clearing and 3D imaging. The integration of immunostaining makes possible to combine gene expression with classical cell markers, to correlate expressions with morphological differentiation and to depict gene expressions in gain or loss of function contexts. Altogether, this combined procedure further extends the potential of HCR RNA-FISH technique for chicken embryology.
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Affiliation(s)
- Maëlys André
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France.
| | - Sarah Dinvaut
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France
| | - Valérie Castellani
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France
| | - Julien Falk
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France.
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2
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Huang H, Majumder T, Khot B, Suriyaarachchi H, Yang T, Shao Q, Tirukovalluru S, Liu G. The role of microtubule-associated protein tau in netrin-1 attractive signaling. J Cell Sci 2024; 137:jcs261244. [PMID: 38197773 PMCID: PMC10906489 DOI: 10.1242/jcs.261244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 11/24/2023] [Indexed: 01/11/2024] Open
Abstract
Direct binding of netrin receptors with dynamic microtubules (MTs) in the neuronal growth cone plays an important role in netrin-mediated axon guidance. However, how netrin-1 (NTN1) regulates MT dynamics in axon turning remains a major unanswered question. Here, we show that the coupling of netrin-1 receptor DCC with tau (MAPT)-regulated MTs is involved in netrin-1-promoted axon attraction. Tau directly interacts with DCC and partially overlaps with DCC in the growth cone of primary neurons. Netrin-1 induces this interaction and the colocalization of DCC and tau in the growth cone. The netrin-1-induced interaction of tau with DCC relies on MT dynamics and TUBB3, a highly dynamic β-tubulin isotype in developing neurons. Netrin-1 increased cosedimentation of DCC with tau and TUBB3 in MTs, and knockdown of either tau or TUBB3 mutually blocked this effect. Downregulation of endogenous tau levels by tau shRNAs inhibited netrin-1-induced axon outgrowth, branching and commissural axon attraction in vitro, and led to defects in spinal commissural axon projection in vivo. These findings suggest that tau is a key MT-associated protein coupling DCC with MT dynamics in netrin-1-promoted axon attraction.
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Affiliation(s)
- Huai Huang
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Tanushree Majumder
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Bhakti Khot
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Harindi Suriyaarachchi
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Tao Yang
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Qiangqiang Shao
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Shraddha Tirukovalluru
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Guofa Liu
- Department of Biological Sciences, University of Toledo, M. S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
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Vargovic M, Papic N, Samadan L, Balen Topic M, Vince A. Association of Immune Semaphorins with COVID-19 Severity and Outcomes. Biomedicines 2023; 11:2786. [PMID: 37893159 PMCID: PMC10604420 DOI: 10.3390/biomedicines11102786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/08/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
Semaphorins have recently been recognized as crucial modulators of immune responses. In the pathogenesis of COVID-19, the activation of immune responses is the key factor in the development of severe disease. This study aimed to determine the association of serum semaphorin concentrations with COVID-19 severity and outcomes. Serum semaphorin concentrations (SEMA3A, -3C, -3F, -4D, -7A) were measured in 80 hospitalized adult patients with COVID-19 (moderate (n = 24), severe (n = 32), critical, (n = 24)) and 40 healthy controls. While SEMA3C, SEMA3F and SEMA7A serum concentrations were significantly higher in patients with COVID-19, SEMA3A was significantly lower. Furthermore, SEMA3A and SEMA3C decreased with COVID-19 severity, while SEMA3F and SEMA7A increased. SEMA4D showed no correlation with disease severity. Serum semaphorin levels show better predictive values than CRP, IL-6 and LDH for differentiating critical from moderate/severe COVID-19. SEMA3F and SEMA7A serum concentrations were associated with the time to recovery, requirement of invasive mechanical ventilation, development of pulmonary thrombosis and nosocomial infections, as well as with in-hospital mortality. In conclusion, we provide the first evidence that SEMA3A, SEMA3C, SEMA3F and SEMA7A can be considered as new biomarkers of COVID-19 severity.
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Affiliation(s)
- Martina Vargovic
- Department for Infections in the Immunocompromised, University Hospital for Infectious Diseases, 10000 Zagreb, Croatia;
| | - Neven Papic
- Department for Viral Hepatitis, University Hospital for Infectious Diseases, 10000 Zagreb, Croatia;
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia; (L.S.); (M.B.T.)
| | - Lara Samadan
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia; (L.S.); (M.B.T.)
| | - Mirjana Balen Topic
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia; (L.S.); (M.B.T.)
- Department for Gastrointestinal Infections, University Hospital for Infectious Diseases, 10000 Zagreb, Croatia
| | - Adriana Vince
- Department for Viral Hepatitis, University Hospital for Infectious Diseases, 10000 Zagreb, Croatia;
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia; (L.S.); (M.B.T.)
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Zuñiga NR, Dumoulin A, Vaccaro G, Stoeckli ET. Cables1 links Slit/Robo and Wnt/Frizzled signaling in commissural axon guidance. Development 2023; 150:dev201671. [PMID: 37747104 PMCID: PMC10617602 DOI: 10.1242/dev.201671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 09/07/2023] [Indexed: 09/26/2023]
Abstract
During neural circuit formation, axons navigate from one intermediate target to the next, until they reach their final target. At intermediate targets, axons switch from being attracted to being repelled by changing the guidance receptors on the growth cone surface. For smooth navigation of the intermediate target and the continuation of their journey, the switch in receptor expression has to be orchestrated in a precisely timed manner. As an alternative to changes in expression, receptor function could be regulated by phosphorylation of receptors or components of signaling pathways. We identified Cables1 as a linker between floor-plate exit of commissural axons, regulated by Slit/Robo signaling, and the rostral turn of post-crossing axons, regulated by Wnt/Frizzled signaling. Cables1 localizes β-catenin, phosphorylated at tyrosine 489 by Abelson kinase, to the distal axon, which in turn is necessary for the correct navigation of post-crossing commissural axons in the developing chicken spinal cord.
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Affiliation(s)
- Nikole R. Zuñiga
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Alexandre Dumoulin
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
- University Research Priority Program (URPP) ‘Adaptive Brain Circuits in Development and Learning (AdaBD)’, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Giuseppe Vaccaro
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Esther T. Stoeckli
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
- University Research Priority Program (URPP) ‘Adaptive Brain Circuits in Development and Learning (AdaBD)’, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Dailey-Krempel B, Martin AL, Jo HN, Junge HJ, Chen Z. A tug of war between DCC and ROBO1 signaling during commissural axon guidance. Cell Rep 2023; 42:112455. [PMID: 37149867 DOI: 10.1016/j.celrep.2023.112455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/07/2023] [Accepted: 04/14/2023] [Indexed: 05/09/2023] Open
Abstract
Dynamic and coordinated axonal responses to changing environments are critical for establishing neural connections. As commissural axons migrate across the CNS midline, they are suggested to switch from being attracted to being repelled in order to approach and to subsequently leave the midline. A molecular mechanism that is hypothesized to underlie this switch in axonal responses is the silencing of Netrin1/Deleted in Colorectal Carcinoma (DCC)-mediated attraction by the repulsive SLIT/ROBO1 signaling. Using in vivo approaches including CRISPR-Cas9-engineered mouse models of distinct Dcc splice isoforms, we show here that commissural axons maintain responsiveness to both Netrin and SLIT during midline crossing, although likely at quantitatively different levels. In addition, full-length DCC in collaboration with ROBO3 can antagonize ROBO1 repulsion in vivo. We propose that commissural axons integrate and balance the opposing DCC and Roundabout (ROBO) signaling to ensure proper guidance decisions during midline entry and exit.
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Affiliation(s)
| | - Andrew L Martin
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ha-Neul Jo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Harald J Junge
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhe Chen
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
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Appelbaum T, Aguirre GD, Beltran WA. Identification of circular RNAs hosted by the RPGR ORF15 genomic locus. RNA Biol 2023; 20:31-47. [PMID: 36593651 PMCID: PMC9817113 DOI: 10.1080/15476286.2022.2159165] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/23/2022] [Accepted: 12/07/2022] [Indexed: 01/04/2023] Open
Abstract
Mutations in the retina-specific isoform of the gene encoding retinitis pigmentosa GTPase regulator (RPGRorf15) cause X-linked retinitis pigmentosa, a severe and early onset inherited retinal degeneration. The underlying pathogenic mechanisms and variability in disease severity remain to be fully elucidated. The present study examines structural features of the ORF15 exonic region to provide new insights into the disease pathogenesis. Using canine and human RNA samples, we identified several novel RPGR ORF15-like linear RNA transcripts containing cryptic introns (exitrons) within the annotated exon ORF15. Furthermore, using outward-facing primers designed inside exitrons in the ORF15 exonic region, we found many of previously unidentified circular RNAs (circRNAs) that formed via back fusion of linear parts of the RPGRorf15 pre-mRNAs. These circRNAs (resistant to RNAse R treatment) were found in all studied cells and tissues. Notably, some circRNAs were present in cytoplasmic and polysomal RNA fractions. Although certain RPGR circRNAs may be cell type specific, we found some of the same circRNAs expressed in different cell types, suggesting similarities in their biogenesis and functions. Sequence analysis of RPGR circRNAs revealed several remarkable features, including identification of N6-methyladenosine (m6A) consensus sequence motifs and high prevalence of predictive microRNA binding sites pointing to the functional roles of these circRNAs. Our findings also illustrate the presence of non-canonical RPGR circRNA biogenesis pathways independent of the known back splicing mechanism. The obtained data on novel RPGR circRNAs further underline structural complexity of the RPGR ORF15 region and provide a potential molecular basis for the disease phenotypic heterogeneity.
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Affiliation(s)
- Tatyana Appelbaum
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gustavo D. Aguirre
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - William A. Beltran
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Genome-wide CRISPR knockout screening identified G protein pathway suppressor 2 as a novel tumor suppressor for uveal melanoma metastasis. J Cancer Res Clin Oncol 2022:10.1007/s00432-022-04160-5. [PMID: 35941228 DOI: 10.1007/s00432-022-04160-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/16/2022] [Indexed: 10/15/2022]
Abstract
PURPOSE Uveal melanoma (UM) is the most common intraocular malignant tumor in adults. Due to the lack of effective treatments for metastatic UM, the survival of UM has not changed over the past 3 decades. Therefore, it is important to identify essential genes regulating the metastasis of UM. METHODS In this study, a genome-wide CRISPR knockout screen in an orthotopic mouse model of UM was performed to identify the regulatory genes conferring the metastatic phenotype. Loss-of-function analyses were performed to explore the function of G protein pathway suppressor 2 (GPS2) in UM metastasis in vitro and in vivo. RNA sequencing was performed to investigate the molecular mechanism underlying the function of GPS2 as a tumor suppressor in UM. RESULTS Among the highest-ranking genes, we found several validated tumor suppressors, such as SHPRH, GPS2, PRPH2, and hsa-mir-1229; GPS2 was chosen as the candidate gene for further studies. GPS2 was lower expressed in the tumor tissues of UM patients. Furthermore, knocking-down GPS2 promoted the proliferation and metastatic abilities of UM cells both in vivo and in vitro. Finally, analysis of the transcriptome data revealed that silencing GPS2 upregulates oncogenic signaling pathways MAPK and PI3K-Akt, and in the meantime downregulates tumor suppressor signaling pathway Slit/Robo in UM cells. CONCLUSION Altogether, our study proved that the GPS2 gene functions as a tumor suppressor and might be a novel potential therapeutic target for UM treatment.
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Herrera E, Escalante A. Transcriptional Control of Axon Guidance at Midline Structures. Front Cell Dev Biol 2022; 10:840005. [PMID: 35265625 PMCID: PMC8900194 DOI: 10.3389/fcell.2022.840005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
The development of the nervous system is a time-ordered and multi-stepped process that includes neurogenesis and neuronal specification, axonal navigation, and circuits assembly. During axonal navigation, the growth cone, a dynamic structure located at the tip of the axon, senses environmental signals that guide axons towards their final targets. The expression of a specific repertoire of receptors on the cell surface of the growth cone together with the activation of a set of intracellular transducing molecules, outlines the response of each axon to specific guidance cues. This collection of axon guidance molecules is defined by the transcriptome of the cell which, in turn, depends on transcriptional and epigenetic regulators that modify the structure and DNA accessibility to determine what genes will be expressed to elicit specific axonal behaviors. Studies focused on understanding how axons navigate intermediate targets, such as the floor plate of vertebrates or the mammalian optic chiasm, have largely contributed to our knowledge of how neurons wire together during development. In fact, investigations on axon navigation at these midline structures led to the identification of many of the currently known families of proteins that act as guidance cues and their corresponding receptors. Although the transcription factors and the regulatory mechanisms that control the expression of these molecules are not well understood, important advances have been made in recent years in this regard. Here we provide an updated overview on the current knowledge about the transcriptional control of axon guidance and the selection of trajectories at midline structures.
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Ying Z, Wu J, Jiang W, Zhang G, Zhu W, Li X, Pang X, Liu W. Expression of Slit and Robo during remodeling of corticospinal tract in cervical spinal cord in middle cerebral artery occlusion rats. Mol Biol Rep 2021; 48:7831-7839. [PMID: 34652618 DOI: 10.1007/s11033-021-06803-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 09/22/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Slits and Robos were associated with the generation of axons of corticospinal tract during the corticospinal tract (CST) remodeling after the cerebral ischemic stroke (CIS). However, little is known about the mechanism of CST remodeling. In this study, we detected the expression of Slits and Robos in middle cerebral artery occlusion (MCAO) rats to investigate the roles of Slits and Robos in the CIS. METHODS MCAO model was established using modified Zea Longa method. Beam walking test (BWT) was conducted to evaluate the motor function. The images of the track of cortical spinal cord beam on day 7, 14 and 21 were observed by anterograde CST tracing. Biopinylated dextan amine (BDA) was used to mark CST anterogradely. Expression of GAP-43 mRNA and GAP-43 protein in cervical spinal cord was detected by Real-Time PCR and Western blot analysis, respectively. The expression of Slit1, Slit2 and Robo1 in cervical spinal cord was detected by immunofluorescence staining. RESULTS The scores in the model group were significantly reduced compared to sham-operation group on day 7 (P < 0.001), 14 (P < 0.001) and 21 (P < 0.001), respectively. There was no significant difference in the score on day 7, 14 and 21 of the sham-operation groups (P > 0.05). In contrast, significant increase was noticed in the scores in model group, presenting a time-dependent manner. More CST staining fibers could be observed at the degenerative side in the model group compared with that of the sham-operation group on day 21. GAP-43 mRNA expression in the model group showed significant increase compared to that of sham-operation group on day 14 (P = 0.015) and 21 days (P = 0.002). The expression of GAP-43 protein in model group showed significant increase compared to that of sham-operation group on day 14 (P = 0.022) and day 21 (P = 0.008), respectively. The expression of Slit1 and Slit2 showed increase on day 14 and day 21, while the expression of Robo1 showed significant decrease in MCAO rats. CONCLUSION Up-regulation of Slit1 and Slit2 and the downregulation of Robo1 may be related to the axons of CST midline crossing in spinal cord of MCAO rat during the spontaneous recovery of impaired motor function.
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Affiliation(s)
- Zhenhao Ying
- School of Rehabilitation Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China
| | - Junxuan Wu
- School of Rehabilitation Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China
| | - Wenjun Jiang
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, Jinan, 250002, China
| | - Guoli Zhang
- Department of Radiation Oncology, Shandong Tumor Hospital & Institute, Jinan, 250117, Shandong Province, China
| | - Weiming Zhu
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, 300381, China
| | - Xin Li
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250011, China
| | - Xueyun Pang
- Juxian Hospital of Traditional Chinese Medicine, Rizhao, 276599, China
| | - Wei Liu
- Second Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250001, China.
- Department of Cerebral Disease, Second Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250001, China.
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Wurmser M, Muppavarapu M, Tait CM, Laumonnerie C, González-Castrillón LM, Wilson SI. Robo2 Receptor Gates the Anatomical Divergence of Neurons Derived From a Common Precursor Origin. Front Cell Dev Biol 2021; 9:668175. [PMID: 34249921 PMCID: PMC8263054 DOI: 10.3389/fcell.2021.668175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/03/2021] [Indexed: 12/25/2022] Open
Abstract
Sensory information relayed to the brain is dependent on complex, yet precise spatial organization of neurons. This anatomical complexity is generated during development from a surprisingly small number of neural stem cell domains. This raises the question of how neurons derived from a common precursor domain respond uniquely to their environment to elaborate correct spatial organization and connectivity. We addressed this question by exploiting genetically labeled mouse embryonic dorsal interneuron 1 (dI1) neurons that are derived from a common precursor domain and give rise to spinal projection neurons with distinct organization of cell bodies with axons projecting either commissurally (dI1c) or ipsilaterally (dI1i). In this study, we examined how the guidance receptor, Robo2, which is a canonical Robo receptor, influenced dI1 guidance during embryonic development. Robo2 was enriched in embryonic dI1i neurons, and loss of Robo2 resulted in misguidance of dI1i axons, whereas dI1c axons remained unperturbed within the mantle zone and ventral commissure. Further, Robo2 profoundly influenced dI1 cell body migration, a feature that was partly dependent on Slit2 signaling. These data suggest that dI1 neurons are dependent on Robo2 for their organization. This work integrated with the field support of a model whereby canonical Robo2 vs. non-canonical Robo3 receptor expression facilitates projection neurons derived from a common precursor domain to read out the tissue environment uniquely giving rise to correct anatomical organization.
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Affiliation(s)
- Maud Wurmser
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
| | | | | | | | | | - Sara Ivy Wilson
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
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Appelbaum T, Murgiano L, Becker D, Santana E, Aguirre GD. Candidate Genetic Modifiers for RPGR Retinal Degeneration. Invest Ophthalmol Vis Sci 2021; 61:20. [PMID: 33326016 PMCID: PMC7745631 DOI: 10.1167/iovs.61.14.20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Purpose To define genetic variants associated with variable severity of X-linked progressive retinal atrophy 1 (XLPRA1) caused by a five-nucleotide deletion in canine RPGR exon ORF15. Methods A genome-wide association study (GWAS) was performed in XLPRA1 phenotype informative pedigree. Whole genome sequencing (WGS) was used for mutational analysis of genes within the candidate genomic region. Retinas of normal and mutant dogs were used for gene expression, gene structure, and RNA duplex analyses. Results GWAS followed by haplotype phasing identified an approximately 4.6 Mb candidate genomic interval on CFA31 containing seven protein-coding genes expressed in retina (ROBO1, ROBO2, RBM11, NRIP1, HSPA13, SAMSN1, and USP25). Furthermore, we identified and characterized two novel lncRNAs, ROBO1-AS and ROBO2-AS, that display overlapping gene organization with axon guidance pathway genes ROBO1 and ROBO2, respectively, producing sense-antisense gene pairs. Notably, ROBO1-AS and ROBO2-AS act in cis to form lncRNA/mRNA duplexes with ROBO1 and ROBO2, respectively, suggesting important roles for these lncRNAs in the ROBO regulatory network. A subsequent WGS identified candidate genes within the genomic region on CFA31 that might be implicated in modifying severity of XLPRA1. This approach led to discovery of genetic variants in ROBO1, ROBO1-AS, ROBO2-AS, and USP25 that are strongly associated with the XLPRA1 moderate phenotype. Conclusions The study provides new insights into the genetic basis of phenotypic variation in severity of RPGRorf15-associated retinal degeneration. Our findings suggest an important role for ROBO pathways in disease progression further expanding on our previously reported changes of ROBO1 expression in XLPRA1 retinas.
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Affiliation(s)
- Tatyana Appelbaum
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Leonardo Murgiano
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Doreen Becker
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States.,Leibniz Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Dummerstorf, Germany
| | - Evelyn Santana
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Gustavo D Aguirre
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
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12
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Dorskind JM, Kolodkin AL. Revisiting and refining roles of neural guidance cues in circuit assembly. Curr Opin Neurobiol 2021; 66:10-21. [PMID: 32823181 PMCID: PMC10725571 DOI: 10.1016/j.conb.2020.07.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/16/2020] [Accepted: 07/27/2020] [Indexed: 12/14/2022]
Abstract
Neural guidance mechanisms ensure the precise targeting and synaptogenesis events essential for normal circuit function. Neuronal growth cones encounter numerous attractive and repulsive cues as they navigate toward their intermediate and final targets; temporal and spatial regulation of these responses are critical for circuit assembly. Recent work highlights the complexity of these events throughout neural development and the multifaceted functions of a wide range of guidance cues. Here, we discuss recent studies that leverage advances in genetics, single cell tracing, transcriptomics and proteomics to further our understanding of the molecular mechanisms underlying neural guidance and overall circuit organization.
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Affiliation(s)
- Joelle M Dorskind
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Alex L Kolodkin
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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13
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Zang Y, Chaudhari K, Bashaw GJ. New insights into the molecular mechanisms of axon guidance receptor regulation and signaling. Curr Top Dev Biol 2021; 142:147-196. [PMID: 33706917 DOI: 10.1016/bs.ctdb.2020.11.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
As the nervous system develops, newly differentiated neurons need to extend their axons toward their synaptic targets to form functional neural circuits. During this highly dynamic process of axon pathfinding, guidance receptors expressed at the tips of motile axons interact with soluble guidance cues or membrane tethered molecules present in the environment to be either attracted toward or repelled away from the source of these cues. As competing cues are often present at the same location and during the same developmental period, guidance receptors need to be both spatially and temporally regulated in order for the navigating axons to make appropriate guidance decisions. This regulation is exerted by a diverse array of molecular mechanisms that have come into focus over the past several decades and these mechanisms ensure that the correct complement of surface receptors is present on the growth cone, a fan-shaped expansion at the tip of the axon. This dynamic, highly motile structure is defined by a lamellipodial network lining the periphery of the growth cone interspersed with finger-like filopodial projections that serve to explore the surrounding environment. Once axon guidance receptors are deployed at the right place and time at the growth cone surface, they respond to their respective ligands by initiating a complex set of signaling events that serve to rearrange the growth cone membrane and the actin and microtubule cytoskeleton to affect axon growth and guidance. In this review, we highlight recent advances that shed light on the rich complexity of mechanisms that regulate axon guidance receptor distribution, activation and downstream signaling.
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Affiliation(s)
- Yixin Zang
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Karina Chaudhari
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
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14
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Ducuing H, Gardette T, Pignata A, Kindbeiter K, Bozon M, Thoumine O, Delloye-Bourgeois C, Tauszig-Delamasure S, Castellani V. SlitC-PlexinA1 mediates iterative inhibition for orderly passage of spinal commissural axons through the floor plate. eLife 2020; 9:e63205. [PMID: 33345773 PMCID: PMC7775108 DOI: 10.7554/elife.63205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/18/2020] [Indexed: 12/12/2022] Open
Abstract
Spinal commissural axon navigation across the midline in the floor plate requires repulsive forces from local Slit repellents. The long-held view is that Slits push growth cones forward and prevent them from turning back once they became sensitized to these cues after midline crossing. We analyzed with fluorescent reporters Slits distribution and FP glia morphology. We observed clusters of Slit-N and Slit-C fragments decorating a complex architecture of glial basal process ramifications. We found that PC2 proprotein convertase activity contributes to this pattern of ligands. Next, we studied Slit-C acting via PlexinA1 receptor shared with another FP repellent, the Semaphorin3B, through generation of a mouse model baring PlexinA1Y1815F mutation abrogating SlitC but not Sema3B responsiveness, manipulations in the chicken embryo, and ex vivo live imaging. This revealed a guidance mechanism by which SlitC constantly limits growth cone exploration, imposing ordered and forward-directed progression through aligned corridors formed by FP basal ramifications.
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Affiliation(s)
- Hugo Ducuing
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
| | - Thibault Gardette
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
| | - Aurora Pignata
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
| | - Karine Kindbeiter
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
| | - Muriel Bozon
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, UMR CNRS 5297 - University of BordeauxBordeauxFrance
| | - Céline Delloye-Bourgeois
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
| | - Servane Tauszig-Delamasure
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
| | - Valerie Castellani
- Institut NeuroMyoGène - CNRS UMR 5310 - INSERM U1217 de Lyon- UCBL Lyon 1, Faculté de Médecine et de PharmacieLyonFrance
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15
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Alvarez S, Varadarajan SG, Butler SJ. Dorsal commissural axon guidance in the developing spinal cord. Curr Top Dev Biol 2020; 142:197-231. [PMID: 33706918 DOI: 10.1016/bs.ctdb.2020.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Commissural axons have been a key model system for identifying axon guidance signals in vertebrates. This review summarizes the current thinking about the molecular and cellular mechanisms that establish a specific commissural neural circuit: the dI1 neurons in the developing spinal cord. We assess the contribution of long- and short-range signaling while sequentially following the developmental timeline from the birth of dI1 neurons, to the extension of commissural axons first circumferentially and then contralaterally into the ventral funiculus.
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Affiliation(s)
- Sandy Alvarez
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Molecular Biology Interdepartmental Doctoral Program, University of California, Los Angeles, CA, United States
| | | | - Samantha J Butler
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, CA, United States.
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16
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Corradi E, Baudet ML. In the Right Place at the Right Time: miRNAs as Key Regulators in Developing Axons. Int J Mol Sci 2020; 21:ijms21228726. [PMID: 33218218 PMCID: PMC7699167 DOI: 10.3390/ijms21228726] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/12/2020] [Accepted: 11/16/2020] [Indexed: 01/02/2023] Open
Abstract
During neuronal circuit formation, axons progressively develop into a presynaptic compartment aided by extracellular signals. Axons display a remarkably high degree of autonomy supported in part by a local translation machinery that permits the subcellular production of proteins required for their development. Here, we review the latest findings showing that microRNAs (miRNAs) are critical regulators of this machinery, orchestrating the spatiotemporal regulation of local translation in response to cues. We first survey the current efforts toward unraveling the axonal miRNA repertoire through miRNA profiling, and we reveal the presence of a putative axonal miRNA signature. We also provide an overview of the molecular underpinnings of miRNA action. Our review of the available experimental evidence delineates two broad paradigms: cue-induced relief of miRNA-mediated inhibition, leading to bursts of protein translation, and cue-induced miRNA activation, which results in reduced protein production. Overall, this review highlights how a decade of intense investigation has led to a new appreciation of miRNAs as key elements of the local translation regulatory network controlling axon development.
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17
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Context-Dependent Role of miR-124 in Retinoic Acid-Induced Growth Cone Attraction of Regenerating Motorneurons. Cell Mol Neurobiol 2020; 42:847-869. [PMID: 33094464 DOI: 10.1007/s10571-020-00982-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/14/2020] [Indexed: 10/23/2022]
Abstract
During development and regeneration, growth cones at the tips of extending axons navigate through a complex environment to establish accurate connections with appropriate targets. Growth cones can respond rapidly to classical and non-classical guidance cues in their environment, often requiring local protein synthesis. In vertebrate growth cones, local protein synthesis in response to classical cues can require regulation by microRNAs (miRNAs), a class of small, conserved, non-coding RNAs that post-transcriptionally regulate gene expression. However, less is known of how miRNAs mediate growth cone responses to non-classical cues (such as retinoic acid (RA)), specifically in invertebrates. Here, we utilized adult regenerating invertebrate motorneurons to study miRNA regulation of growth cone attraction to RA, shown to require local protein synthesis. In situ hybridization revealed the presence of miR-124 in growth cones of regenerating ciliary motorneurons of the mollusc Lymnaea stagnalis. Changes in the spatiotemporal distribution of miR-124 occurred following application of RA, and dysregulation of miR-124 (with mimic injection), disrupted RA-induced growth cone turning in a time-dependent manner. This behavioural regulation by miR-124 was altered when the neurite was transected, and the growth cone completely separated from the soma. miR-124 did not, however, appear to be involved in growth cone attraction to serotonin, a response independent of local protein synthesis. Finally, we provide evidence that a downstream effector of RhoGTPases, ROCK, is a potential target of miR-124 during RA-induced growth cone responses. These data advance our current understanding of how microRNAs might mediate cue- and context-dependent behaviours during axon guidance.
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18
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Gorla M, Bashaw GJ. Molecular mechanisms regulating axon responsiveness at the midline. Dev Biol 2020; 466:12-21. [PMID: 32818516 DOI: 10.1016/j.ydbio.2020.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/12/2020] [Accepted: 08/12/2020] [Indexed: 02/06/2023]
Abstract
During embryonic development in bilaterally symmetric organisms, correct midline crossing is important for the proper formation of functional neural circuits. The aberrant development of neural circuits can result in multiple neurodevelopmental disorders, including horizontal gaze palsy, congenital mirror movement disorder, and autism spectrum disorder. Thus, understanding the molecular mechanisms that regulate proper axon guidance at the midline can provide insights into the pathology of neurological disorders. The signaling mechanisms that regulate midline crossing have been extensively studied in the Drosophila ventral nerve cord and the mouse embryonic spinal cord. In this review, we discuss these axon guidance mechanisms, highlighting the most recent advances in the understanding of how commissural axons switch their responsiveness from attractants to repellents during midline crossing.
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Affiliation(s)
- Madhavi Gorla
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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19
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Expression of Genes Involved in Axon Guidance: How Much Have We Learned? Int J Mol Sci 2020; 21:ijms21103566. [PMID: 32443632 PMCID: PMC7278939 DOI: 10.3390/ijms21103566] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 05/15/2020] [Accepted: 05/16/2020] [Indexed: 12/20/2022] Open
Abstract
Neuronal axons are guided to their target during the development of the brain. Axon guidance allows the formation of intricate neural circuits that control the function of the brain, and thus the behavior. As the axons travel in the brain to find their target, they encounter various axon guidance cues, which interact with the receptors on the tip of the growth cone to permit growth along different signaling pathways. Although many scientists have performed numerous studies on axon guidance signaling pathways, we still have an incomplete understanding of the axon guidance system. Lately, studies on axon guidance have shifted from studying the signal transduction pathways to studying other molecular features of axon guidance, such as the gene expression. These new studies present evidence for different molecular features that broaden our understanding of axon guidance. Hence, in this review we will introduce recent studies that illustrate different molecular features of axon guidance. In particular, we will review literature that demonstrates how axon guidance cues and receptors regulate local translation of axonal genes and how the expression of guidance cues and receptors are regulated both transcriptionally and post-transcriptionally. Moreover, we will highlight the pathological relevance of axon guidance molecules to specific diseases.
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20
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Pignata A, Ducuing H, Boubakar L, Gardette T, Kindbeiter K, Bozon M, Tauszig-Delamasure S, Falk J, Thoumine O, Castellani V. A Spatiotemporal Sequence of Sensitization to Slits and Semaphorins Orchestrates Commissural Axon Navigation. Cell Rep 2019; 29:347-362.e5. [PMID: 31597096 DOI: 10.1016/j.celrep.2019.08.098] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/05/2019] [Accepted: 08/28/2019] [Indexed: 01/24/2023] Open
Abstract
Accurate perception of guidance cues is crucial for cell and axon migration. During initial navigation in the spinal cord, commissural axons are kept insensitive to midline repellents. Upon midline crossing in the floor plate, they switch on responsiveness to Slit and Semaphorin repulsive signals and are thus propelled away and prevented from crossing back. Whether and how the different midline repellents control specific aspects of this navigation remain to be elucidated. We set up a paradigm for live-imaging and super-resolution analysis of PlexinA1, Neuropilin-2, and Robo1/2 receptor dynamics during commissural growth cone navigation in chick and mouse embryos. We uncovered a remarkable program of sensitization to midline cues achieved by unique spatiotemporal sequences of receptor allocation at the growth-cone surface that orchestrates receptor-specific growth-cone behavior changes. This reveals post-translational mechanisms whereby coincident guidance signals are temporally resolved to allow the generation of specific guidance responses.
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Affiliation(s)
- Aurora Pignata
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Hugo Ducuing
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Leila Boubakar
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Thibault Gardette
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Karine Kindbeiter
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Muriel Bozon
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Servane Tauszig-Delamasure
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Julien Falk
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, UMR CNRS 5297, University of Bordeaux 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Valérie Castellani
- University of Lyon, University of Lyon 1 Claude Bernard Lyon1, NeuroMyoGene Institute, CNRS UMR5310, INSERM U1217, 8 Avenue Rockefeller, 69008 Lyon, France.
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21
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Kinoshita-Kawada M, Hasegawa H, Hongu T, Yanagi S, Kanaho Y, Masai I, Mishima T, Chen X, Tsuboi Y, Rao Y, Yuasa-Kawada J, Wu JY. Explant Culture of the Embryonic Mouse Spinal Cord and Gene Transfer by ex vivo Electroporation. Bio Protoc 2019; 9:e3373. [PMID: 33654869 DOI: 10.21769/bioprotoc.3373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/15/2019] [Accepted: 08/18/2019] [Indexed: 11/02/2022] Open
Abstract
Developing axons change responsiveness to guidance cues during the journey to synapse with target cells. Axon crossing at the ventral midline serves as a model for studying how axons accomplish such a switch in their response. Although primary neuron culture has been a versatile technique for elucidating various developmental mechanisms, many in vivo characteristics of neurons, such as long axon-extending abilities and axonal compartments, are not thoroughly preserved. In explant cultures, such properties of differentiated neurons and tissue architecture are maintained. To examine how the midline repellent Slit regulated the distribution of the Robo receptor in spinal cord commissural axons upon midline crossing and whether Robo trafficking machinery was a determinant of midline crossing, novel explant culture systems were developed. We have combined an "open-book" spinal cord explant method with that devised for flat-mount retinae. Here we present our protocol for explant culture of embryonic mouse spinal cords, which allows flexible manipulation of experimental conditions, immunostaining of extending axons and quantitative analysis of individual axons. In addition, we present a modified method that combines ex vivo electroporation and "closed-book" spinal cord explant culture. These culture systems provide new platforms for detailed analysis of axon guidance, by adapting gene knockdown, knockout and genome editing.
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Affiliation(s)
- Mariko Kinoshita-Kawada
- Department of Neurology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.,Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan.,Department of Neurology, Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Hiroshi Hasegawa
- Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.,Department of Hygienic Sciences, Kobe Pharmaceutical University, Kobe, Japan
| | - Tsunaki Hongu
- Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.,Heidelberg Institute for Stem Cell Technology and Experimental Medicine, German Cancer Research Center, Heidelberg, Germany
| | - Shigeru Yanagi
- Laboratory of Molecular Biochemistry, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| | - Yasunori Kanaho
- Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Ichiro Masai
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Takayasu Mishima
- Department of Neurology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Xiaoping Chen
- Department of Neurology, Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Yoshio Tsuboi
- Department of Neurology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Yi Rao
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University School of Life Sciences, Beijing, China.,Chinese Institute for Brain Research, Beijing, China
| | - Junichi Yuasa-Kawada
- Department of Neurology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.,Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan.,Department of Neurology, Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Center for Advanced Medical Innovation, Kyushu University, Fukuoka, Japan
| | - Jane Y Wu
- Department of Neurology, Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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22
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Johnson V, Junge HJ, Chen Z. Temporal regulation of axonal repulsion by alternative splicing of a conserved microexon in mammalian Robo1 and Robo2. eLife 2019; 8:e46042. [PMID: 31392959 PMCID: PMC6687390 DOI: 10.7554/elife.46042] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 07/25/2019] [Indexed: 11/13/2022] Open
Abstract
Proper connectivity of the nervous system requires temporal and spatial control of axon guidance signaling. As commissural axons navigate across the CNS midline, ROBO-mediated repulsion has traditionally been thought to be repressed before crossing, and then to become upregulated after crossing. The regulation of the ROBO receptors involves multiple mechanisms that control protein expression, trafficking, and activity. Here, we report that mammalian ROBO1 and ROBO2 are not uniformly inhibited precrossing and are instead subject to additional temporal control via alternative splicing at a conserved microexon. The NOVA splicing factors regulate the developmental expression of ROBO1 and ROBO2 variants with small sequence differences and distinct guidance activities. As a result, ROBO-mediated axonal repulsion is activated early in development to prevent premature crossing and becomes inhibited later to allow crossing. Postcrossing, the ROBO1 and ROBO2 isoforms are disinhibited to prevent midline reentry and to guide postcrossing commissural axons to distinct mediolateral positions.
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Affiliation(s)
- Verity Johnson
- Department of Molecular, Cellular and Developmental BiologyUniversity of ColoradoBoulderUnited States
| | - Harald J Junge
- Department of Molecular, Cellular and Developmental BiologyUniversity of ColoradoBoulderUnited States
| | - Zhe Chen
- Department of Molecular, Cellular and Developmental BiologyUniversity of ColoradoBoulderUnited States
- Linda Crnic Institute for Down SyndromeUniversity of Colorado school of MedicineAuroraUnited States
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23
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Liu GF, Yang T. Identification of a microRNA switch in spinal commissural axon guidance. Neural Regen Res 2019; 14:1208-1209. [PMID: 30804247 PMCID: PMC6425835 DOI: 10.4103/1673-5374.251300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Guo-fa Liu
- Department of Biological Sciences, University of Toledo, Toledo, OH, USA,Correspondence to: Guo-fa Liu, .
| | - Tao Yang
- Department of Biological Sciences, University of Toledo, Toledo, OH, USA
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24
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Tong M, Jun T, Nie Y, Hao J, Fan D. The Role of the Slit/Robo Signaling Pathway. J Cancer 2019; 10:2694-2705. [PMID: 31258778 PMCID: PMC6584916 DOI: 10.7150/jca.31877] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 04/28/2019] [Indexed: 12/25/2022] Open
Abstract
The Slit family is a family of secreted proteins that play important roles in various physiologic and pathologic activities via interacting with Robo receptors. Slit/Robo signaling was first identified in the nervous system, where it functions in neuronal axon guidance; nevertheless, an increasing number of studies have shown that Slit/Robo signaling even regulates other activities, such as angiogenesis, inflammatory cell chemotaxis, tumor cell migration and metastasis. Although the precise role of the ligand-receptor in organisms has been obscure and the conclusions drawn are sometimes paradoxical, tremendous advances in understanding the Slit/Robo signaling pathway have been made. As such, our review summarizes the characteristics of the Slit/Robo signaling pathway and its role in various cell types.
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Affiliation(s)
- Mingfu Tong
- Department of Gastroenterology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China.,State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Tie Jun
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Yongzhan Nie
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Jianyu Hao
- Department of Gastroenterology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Daiming Fan
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
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25
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Zampa F, Hartzell AL, Zolboot N, Lippi G. Non-coding RNAs: the gatekeepers of neural network activity. Curr Opin Neurobiol 2019; 57:54-61. [PMID: 30743177 DOI: 10.1016/j.conb.2019.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 01/08/2019] [Accepted: 01/10/2019] [Indexed: 01/24/2023]
Abstract
Non-coding RNAs have emerged as potent regulators of numerous cellular processes. In neurons and circuits, these molecules serve especially critical functions that ensure neural activity is maintained within appropriate physiological parameters. Their targets include synaptic proteins, ion channels, neurotransmitter receptors, and components of essential signaling cascades. Here, we discuss how several species of non-coding RNAs (ncRNAs) regulate intrinsic excitability and synaptic transmission, both during development and in mature circuits. Furthermore, we present the relationships between aberrant ncRNA expression and psychiatric disorders. The research presented here demonstrates how ncRNAs can be useful tools for elucidating fundamental neurobiology mechanisms and identifying the key molecular players.
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Affiliation(s)
- Federico Zampa
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Andrea L Hartzell
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Norjin Zolboot
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Giordano Lippi
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, 92037, USA.
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