EphB receptor forward signaling regulates area-specific reciprocal thalamic and cortical axon pathfinding.
In early brain development, ascending thalamocortical axons (TCAs) navigate through the ventral telencephalon (VTel) to reach their target regions in the young cerebral cortex. Descending, deep-layer cortical axons subsequently target appropriate thalamic and subcortical target regions. However, precisely how and when corticothalamic axons (CTAs) identify their appropriate, reciprocal thalamic targets remains unclear. We show here that EphB1 and EphB2 receptors control proper navigation of a subset of TCA and CTA projections through the VTel. We show in vivo that EphB receptor forward signaling and the ephrinB1 ligand are required during the early navigation of L1-CAM(+) thalamic fibers in the VTel, and that the misguided thalamic fibers in EphB1/2 KO mice appear to interact with cortical subregion-specific axon populations during reciprocal cortical axon guidance. As such, our findings suggest that descending cortical axons identify specific TCA subpopulations in the dorsal VTel to coordinate reciprocal cortical-thalamic connectivity in the early developing brain.
Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, MA 02478.
Michael A
MA
Robichaux
George
G
Chenaux
Hsin-Yi Henry
HY
Ho
Michael J
MJ
Soskis
Christopher
C
Dravis
Kenneth Y
KY
Kwan
Nenad
N
Šestan
Michael Eldon
ME
Greenberg
Mark
M
Henkemeyer
Christopher W
CW
Cowan
D000818:Animals; D001369:Axons; D002540:Cerebral Cortex / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D036081:Receptors, Eph Family / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013788:Thalamus / Q000378:metabolism*
D036081:Receptors, Eph Family