Migration of sympathetic preganglionic neurons in the spinal cord is regulated by Reelin-dependent Dab1 tyrosine phosphorylation and CrkL.
The actions of Reelin in neuronal positioning in the developing cortex and cerebellum are relayed by Src-family kinase (SFK)-mediated phosphorylation of Dab1. Biochemical studies show that after phosphorylation Dab1 binds to an adaptor protein, CrkL. Whether CrkL is important for Reelin signaling in vivo is unknown, because crkl(-/-) embryos die before cortical development is complete. In the developing spinal cord, Reelin and components of its signaling pathway, VLDLR, ApoER2, and Dab1, control the positioning of sympathetic preganglionic neurons (SPN); however, it is not known whether SFKs or Dab1 tyrosine phosphorylation is required. In the present study, we asked whether Reelin-controlled SPN migration depends on tyrosine phosphorylation of Dab1 by SFKs and whether CrkL is involved in SPN migration. To answer these questions, we examined the location of SPN in various mutant mouse embryos. Results showed that, in dab1(5F/5F) embryos, which express a nonphosphorylated mutant of Dab1, and in src(-/-)fyn(-/-) double knockout embryos, the location of SPN is identical to that of reeler. These results show that tyrosine phosphorylation of Dab1 by SFKs is required for Reelin-regulated SPN positioning. In addition, we found that SPN migration in crkl(-/-) showed a partial reeler phenotype, suggesting a partial loss of response of SPN to Reelin signaling. These results suggest a role for CrkL in the Reelin signaling pathway to control neuronal migration.
Yip
Yee Ping
YP
Department of Neurobiology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Kronstadt-O'Brien
Priscilla
P
Capriotti
Christine
C
Cooper
Jonathan A
JA
Yip
Joseph W
JW
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013116:Spinal Cord / Q000196:embryology* / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000196:embryology* / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D015816:Cell Adhesion Molecules, Neuronal; C103773:Dab1 protein, mouse; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D000091042:Reelin Protein; D014443:Tyrosine; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases