Genetic dissection of the function of hindbrain axonal commissures.
In Bilateria, many axons cross the midline of the central nervous system, forming well-defined commissures. Whereas in mammals the functions of commissures in the forebrain and in the visual system are well established, functions at other axial levels are less clearly understood. Here, we have dissected the function of several hindbrain commissures using genetic methods. By taking advantage of multiple Cre transgenic lines, we have induced site-specific deletions of the Robo3 receptor. These lines developed with the disruption of specific commissures in the sensory, motor, and sensorimotor systems, resulting in severe and permanent functional deficits. We show that mice with severely reduced commissures in rhombomeres 5 and 3 have abnormal lateral eye movements and auditory brainstem responses, respectively, whereas mice with a primarily uncrossed climbing fiber/Purkinje cell projection are strongly ataxic. Surprisingly, although rerouted axons remain ipsilateral, they still project to their appropriate neuronal targets. Moreover, some Cre;Robo3 lines represent potential models that can be used to study human syndromes, including horizontal gaze palsy with progressive scoliosis (HGPPS). To our knowledge, this study is one of the first to link defects in commissural axon guidance with specific cellular and behavioral phenotypes.
INSERM, U968, Paris, F-75012, France.
Nicolas
N
Renier
Martijn
M
Schonewille
Fabrice
F
Giraudet
Aleksandra
A
Badura
Marc
M
Tessier-Lavigne
Paul
P
Avan
Chris I
CI
De Zeeuw
Alain
A
Chédotal
D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D001522:Behavior, Animal / Q000502:physiology; D019521:Body Patterning / Q000235:genetics / Q000502:physiology; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005133:Eye Movements / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity / Q000502:physiology; D009069:Movement Disorders / Q000235:genetics / Q000503:physiopathology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D015835:Ocular Motility Disorders / Q000235:genetics; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012249:Rhombencephalon / Q000033:anatomy & histology / Q000502:physiology; D045442:Rotarod Performance Test; D000097905:Roundabout Proteins
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C118348:Robo3 protein, mouse; D000097905:Roundabout Proteins