DUAL-ACTION OF A LIGAND FOR EPH RECEPTOR TYROSINE KINASES ON SPECIFICPOPULATIONS OF AXONS DURING THE DEVELOPMENT OF CORTICAL CIRCUITS

Citation
V. Castellani et al., DUAL-ACTION OF A LIGAND FOR EPH RECEPTOR TYROSINE KINASES ON SPECIFICPOPULATIONS OF AXONS DURING THE DEVELOPMENT OF CORTICAL CIRCUITS, The Journal of neuroscience, 18(12), 1998, pp. 4663-4672
Citations number
68
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
0270-6474
Volume
18
Issue
12
Year of publication
1998
Pages
4663 - 4672
Database
ISI
SICI code
0270-6474(1998)18:12<4663:DOALFE>2.0.ZU;2-3
Abstract
The structural basis of cortical columns are radially oriented axon co llaterals that form precise connections between distinct cortical laye rs. During development, these connections are highly specified from th e initial outgrowth of collateral branches. Our previous work provided evidence for positional cues confined to individual layers that induc e and/or prevent the formation of axon collaterals in specific populat ions of cortical neurons. Here we demonstrated with in situ hybridizat ion techniques that mRNA of the Eph receptor tyrosine kinase EphA5 and one of its ligands, ephrin-A5, are present in distinct cortical layer s, at a time when intrinsic connections are being formed in the cortex . Axonal guidance assays indicate that ephrin-A5 is a repellent signal for a populations of axons that in vivo avoid the cortical layer expr essing ephrin-A5, In contrast to its established role as a repulsive a xonal guidance signal, ephrin-A5 specifically mediates sprouting of th ose cortical axons that target the ephrin-A5-expressing layer in vivo. These results identify a novel function of ephrin-A5 on axonal arbor formation. The laminar distribution and the dual action on specific po pulations of axons suggest that ephrin-A5 plays a role in the assembly of local cortical circuits.