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Sullivan KG, Bashaw GJ. Intracellular Trafficking Mechanisms that Regulate Repulsive Axon Guidance. Neuroscience 2023; 508:123-136. [PMID: 35863679 PMCID: PMC9839465 DOI: 10.1016/j.neuroscience.2022.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/01/2022] [Accepted: 07/13/2022] [Indexed: 01/17/2023]
Abstract
Friedrich Bonhoeffer made seminal contributions to the study of axon guidance in the developing nervous system. His discoveries of key cellular and molecular mechanisms that dictate wiring specificity laid the foundation for countless investigators who have followed in his footsteps. Perhaps his most significant contribution was the cloning and characterization of members of the conserved ephrin family of repulsive axon guidance cues. In this review, we highlight the major contributions that Bonhoeffer and his colleagues made to the field of axon guidance, and discuss ongoing investigations into the diverse array of mechanisms that ensure that axon repulsion is precisely regulated to allow for accurate pathfinding. Specifically, we focus our discussion on the post-translational regulation of two major families of repulsive axon guidance factors: ephrin ligands and their Eph receptors, and slit ligands and their Roundabout (Robo) receptors. We will give special emphasis to the ways in which regulated endocytic trafficking events allow navigating axons to adjust their responses to repellant signals and how these trafficking events are intimately related to receptor signaling. By highlighting parallels and differences between the regulation of these two important repulsive axon guidance pathways, we hope to identify key outstanding questions for future investigation.
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Affiliation(s)
- Kelly G Sullivan
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States.
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Zhong G, Ahimaz P, Edwards NA, Hagen JJ, Faure C, Lu Q, Kingma P, Middlesworth W, Khlevner J, El Fiky M, Schindel D, Fialkowski E, Kashyap A, Forlenza S, Kenny AP, Zorn AM, Shen Y, Chung WK. Identification and validation of candidate risk genes in endocytic vesicular trafficking associated with esophageal atresia and tracheoesophageal fistulas. HGG Adv 2022; 3:100107. [PMID: 35519826 PMCID: PMC9065433 DOI: 10.1016/j.xhgg.2022.100107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 04/06/2022] [Indexed: 11/15/2022] Open
Abstract
Esophageal atresias/tracheoesophageal fistulas (EA/TEF) are rare congenital anomalies caused by aberrant development of the foregut. Previous studies indicate that rare or de novo genetic variants significantly contribute to EA/TEF risk, and most individuals with EA/TEF do not have pathogenic genetic variants in established risk genes. To identify the genetic contributions to EA/TEF, we performed whole genome sequencing of 185 trios (probands and parents) with EA/TEF, including 59 isolated and 126 complex cases with additional congenital anomalies and/or neurodevelopmental disorders. There was a significant burden of protein-altering de novo coding variants in complex cases (p = 3.3 × 10-4), especially in genes that are intolerant of loss-of-function variants in the population. We performed simulation analysis of pathway enrichment based on background mutation rate and identified a number of pathways related to endocytosis and intracellular trafficking that as a group have a significant burden of protein-altering de novo variants. We assessed 18 variants for disease causality using CRISPR-Cas9 mutagenesis in Xenopus and confirmed 13 with tracheoesophageal phenotypes. Our results implicate disruption of endosome-mediated epithelial remodeling as a potential mechanism of foregut developmental defects. Our results suggest significant genetic heterogeneity of EA/TEF and may have implications for the mechanisms of other rare congenital anomalies.
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Affiliation(s)
- Guojie Zhong
- Department of Systems Biology, Columbia University Irving Medical Center, New York, NY, USA
- Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, New York, NY, USA
| | - Priyanka Ahimaz
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, USA
| | - Nicole A. Edwards
- Center for Stem Cell & Organoid Medicine (CuSTOM), Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Jacob J. Hagen
- Department of Systems Biology, Columbia University Irving Medical Center, New York, NY, USA
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, USA
| | - Christophe Faure
- Division of Pediatric Gastroenterology, CHU Sainte-Justine, Montreal, QC, Canada
| | - Qiao Lu
- Department of Systems Biology, Columbia University Irving Medical Center, New York, NY, USA
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, USA
| | - Paul Kingma
- Division of Neonatology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - William Middlesworth
- Division of Pediatric Surgery, Columbia University Irving Medical Center, New York, NY, USA
| | - Julie Khlevner
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Columbia University Irving Medical Center, New York, NY, USA
| | - Mahmoud El Fiky
- Pediatric Surgery, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - David Schindel
- Division of Pediatric Surgery, UT Southwestern School of Medicine Dallas, Texas, USA
| | - Elizabeth Fialkowski
- Division of Pediatric Surgery, Oregon Health and Science University, Portland, OR, USA
| | - Adhish Kashyap
- Center for Stem Cell & Organoid Medicine (CuSTOM), Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Sophia Forlenza
- Division of Neonatology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Alan P. Kenny
- Division of Neonatology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Aaron M. Zorn
- Center for Stem Cell & Organoid Medicine (CuSTOM), Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Yufeng Shen
- Department of Systems Biology, Columbia University Irving Medical Center, New York, NY, USA
- Department of Biomedical Informatics, Columbia University Irving Medical Center, New York, NY, USA
| | - Wendy K. Chung
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, USA
- Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
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