A regulatory network involving Foxn4, Mash1 and delta-like 4/Notch1 generates V2a and V2b spinal interneurons from a common progenitor pool.
In the developing central nervous system, cellular diversity depends in part on organising signals that establish regionally restricted progenitor domains, each of which produces distinct types of differentiated neurons. However, the mechanisms of neuronal subtype specification within each progenitor domain remain poorly understood. The p2 progenitor domain in the ventral spinal cord gives rise to two interneuron (IN) subtypes, V2a and V2b, which integrate into local neuronal networks that control motor activity and locomotion. Foxn4, a forkhead transcription factor, is expressed in the common progenitors of V2a and V2b INs and is required directly for V2b but not for V2a development. We show here in experiments conducted using mouse and chick that Foxn4 induces expression of delta-like 4 (Dll4) and Mash1 (Ascl1). Dll4 then signals through Notch1 to subdivide the p2 progenitor pool. Foxn4, Mash1 and activated Notch1 trigger the genetic cascade leading to V2b INs, whereas the complementary set of progenitors, without active Notch1, generates V2a INs. Thus, Foxn4 plays a dual role in V2 IN development: (1) by initiating Notch-Delta signalling, it introduces the asymmetry required for development of V2a and V2b INs from their common progenitors; (2) it simultaneously activates the V2b genetic programme.
Del Barrio
Marta G
MG
Wolfson Institute for Biomedical Research and Department of Biology, University College London, Gower Street, London WC1E 6BT, UK.
Taveira-Marques
Raquel
R
Muroyama
Yuko
Y
Yuk
Dong-In
DI
Li
Shengguo
S
Wines-Samuelson
Mary
M
Shen
Jie
J
Smith
Hazel K
HK
Xiang
Mengqing
M
Rowitch
David
D
Richardson
William D
WD
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002135:Calcium-Binding Proteins; D002642:Chick Embryo; D017931:DNA Primers / Q000235:genetics; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D051858:Forkhead Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization; D007395:Interneurons / Q000166:cytology* / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008959:Models, Neurological; D051881:Receptor, Notch1 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013127:Spinal Nerves / Q000166:cytology / Q000196:embryology / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D051792:Basic Helix-Loop-Helix Proteins; D002135:Calcium-Binding Proteins; D017931:DNA Primers; D005136:Eye Proteins; D051858:Forkhead Transcription Factors; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051881:Receptor, Notch1; C499317:Ascl1 protein, mouse; C519665:DLL4 protein, mouse; C438622:Foxn4 protein, mouse; C497762:Notch1 protein, mouse