Spatial distributions of guidance molecules regulate chemorepulsion and chemoattraction of growth cones.
It is generally assumed that gradients of chemotropic molecules are instrumental to the wiring of the nervous system. Recently, two members of the secreted class III semaphorin protein family have been implicated as repulsive (Sema3A) and attractive (Sema3C) guidance molecules for cortical axons (). Here, we show that stabilized gradients of increasing semaphorin concentrations elicit stereotyped responses from cortical growth cones, independent of the absolute concentration and the slope of these gradients. In contrast, neither repulsive effects of Sema3A nor attractive effects of Sema3C were observed when axons were growing toward decreasing semaphorin concentrations. Thus, growth cone guidance by gradients of chemotropic molecules is robust and reproducible, because it is primarily independent of the exact dimensions of the gradients.
Bagnard
D
D
Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 371, Cerveau et Vision, 69500 Bron, France.
Thomasset
N
N
Lohrum
M
M
Püschel
A W
AW
Bolz
J
J
D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002630:Chemotactic Factors / Q000502:physiology*; D006023:Glycoproteins / Q000378:metabolism*; D020439:Growth Cones / Q000502:physiology*; D006801:Humans; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009994:Osmolar Concentration; D011994:Recombinant Proteins / Q000378:metabolism; D040121:Semaphorin-3A; D014018:Tissue Distribution
D002352:Carrier Proteins; D002630:Chemotactic Factors; D006023:Glycoproteins; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; C108639:SEMA3A protein, human; D040121:Semaphorin-3A