Netrin1/DCC signaling promotes neuronal migration in the dorsal spinal cord

Abstract

BackgroundNewborn neurons often migrate before undergoing final differentiation, extending neurites, and forming synaptic connections. Therefore, neuronal migration is crucial for establishing neural circuitry during development. In the developing spinal cord, neuroprogenitors first undergo radial migration within the ventricular zone. Differentiated neurons continue to migrate tangentially before reaching the final positions. The molecular pathways that regulate these migration processes remain largely unknown. Our previous study suggests that the DCC receptor is important for the migration of the dorsal spinal cord progenitors and interneurons. In this study, we determined the involvement of the Netrin1 ligand and the ROBO3 coreceptor in the migration.ResultsBy pulse labeling neuroprogenitors with electroporation, we examined their radial migration in Netrin1 (Ntn1), Dcc, and Robo3 knockout mice. We found that all three mutants exhibit delayed migration. Furthermore, using immunohistochemistry of the BARHL2 interneuron marker, we found that the mediolateral and dorsoventral migration of differentiated dorsal interneurons is also delayed. Together, our results suggest that Netrin1/DCC signaling induce neuronal migration in the dorsal spinal cord.ConclusionsNetrin1, DCC, and ROBO3 have been extensively studied for their functions in regulating axon guidance in the spinal commissural interneurons. We reveal that during earlier development of dorsal interneurons including commissural neurons, these molecules play an important role in promoting cell migration.Electronic supplementary materialThe online version of this article (doi:10.1186/s13064-016-0074-x) contains supplementary material, which is available to authorized users.

Diverse spinal commissural neuron populations revealed by fate mapping and molecular profiling using a novel Robo3Cre mouse

“…Mouse monoclonal antibodies raised against Barhl2 (1:100, Novus #NBP2‐32013), Calretinin (CR) (1:1000, Swant #6B3), GABA (1:200, Sigma‐Aldrich #A0310), glutamic acid decarboxylase (GAD)67 (1:500, Millipore #MAB5406), Isl1/2 (1:200, DSHB #39.4D5), LIM homeobox (Lhx)‐1/5 (1:200, DSHB #4F2), NeuN (1:100, Millipore #MAB377), and neurofilament (NF) (1:1,000, DSHB #2H3), as well as a rat polyclonal antibody raised against Bhlhb5 (1:5,000, Ross et al (), University of Pittsburgh, Pittsburgh PA) were used. The antibody against recombinant Barhl2 protein was validated using a protein array and used in previous reports (Junge, Yung, Goodrich, & Chen, ; Leggere et al, ). The anti‐CR antibody () recognizes an epitope within the first four EF‐hands domains common to both calretinin and calretinin‐22k, and stains a band corresponding to the molecular weight of calretinin in western blot of brain extracts from various vertebrate species (Zimmermann & Schwaller, ).…”

Neurophilic Descending Migration of Dorsal Midbrain Neurons Into the Hindbrain

“…Hence, our results suggest that the role of DCC in dm-TH cell migration is mostly indirect by determining the TmesV axon projection. This contrasts with the role proposed for DCC in other developing neural cell types such as DA neurons (Xu et al, 2010 ), oligodendrocyte precursor cells (Spassky et al, 2002 ), dorsal spinal interneurons (Junge et al, 2016 ), and cerebellar neurons (Alcántara et al, 2000 ) in which it appears to mediate the direct effects of the chemotropic molecule netrin1.…”

Pou2f2 Regulates the Distribution of Dorsal Interneurons in the Mouse Developing Spinal Cord

“…Oppositely to Robo1 and Robo2 receptors, Robo3 does not bind Slits but instead interacts with Dcc and Netrin-1. This mechanism of action mediates attraction (Zelina et al, 2014) and, probably through Dcc and Robo3, Netrin-1 promotes dINs migration (Junge et al, 2016). Additionally, Slit/Robo repellent signaling, in parallel with Netrin-1/DCC attractive cues, ensures correct positioning of spinal motor neurons in the ventral horn (Kim et al, 2015).…”

“…Neuronal positioning and the cellular and molecular mechanisms involved in this process have been extensively studied in the developing brain (Marín et al, 2010). Although the molecules directing neuronal migration in the developing spinal cord start to be identified (Andrews et al, 2006; Kim et al, 2015; Junge et al, 2016; Leggere et al, 2016), much less is known about the genetic programs that control this essential process.…”