Hoxa2 Selects Barrelette Neuron Identity and Connectivity in the Mouse Somatosensory Brainstem.
Mouse whiskers are somatotopically mapped in brainstem trigeminal nuclei as neuronal modules known as barrelettes. Whisker-related afferents form barrelettes in ventral principal sensory (vPrV) nucleus, whereas mandibular input targets dorsal PrV (dPrV). How barrelette neuron identity and circuitry is established is poorly understood. We found that ectopic Hoxa2 expression in dPrV neurons is sufficient to attract whisker-related afferents, induce asymmetrical dendrite arbors, and allow ectopic barrelette map formation. Moreover, the thalamic area forming whisker-related barreloids is prenatally targeted by both vPrV and dPrV axons followed by perinatal large-scale pruning of dPrV axons and refinement of vPrV barrelette input. Ectopic Hoxa2 expression allows topographically directed targeting and refinement of dPrV axons with vPrV axons into a single whisker-related barreloid map. Thus, a single HOX transcription factor is sufficient to switch dPrV into a vPrV barrelette neuron program and coordinate input-output topographic connectivity of a dermatome-specific circuit module.
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Ahmad
A
Bechara
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Christophe
C
Laumonnerie
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Nathalie
N
Vilain
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Claudius F
CF
Kratochwil
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Vanja
V
Cankovic
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Nicola A
NA
Maiorano
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Moritz A
MA
Kirschmann
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Sebastien
S
Ducret
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland. Electronic address: filippo.rijli@fmi.ch.
Filippo M
FM
Rijli
D000818:Animals; D001369:Axons / Q000502:physiology*; D001933:Brain Stem / Q000166:cytology / Q000502:physiology*; D018398:Homeodomain Proteins / Q000378:metabolism*; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D014738:Vibrissae / Q000166:cytology / Q000502:physiology*
D018398:Homeodomain Proteins; C489833:Hoxa2 protein, mouse