Chemoattraction and chemorepulsion of olfactory bulb axons by different secreted semaphorins.
During development, growth cones can be guided at a distance by diffusible factors, which are attractants and/or repellents. The semaphorins are the largest family of repulsive axon guidance molecules. Secreted semaphorins bind neuropilin receptors and repel sensory, sympathetic, motor, and forebrain axons. We found that in rat embryos, the olfactory epithelium releases a diffusible factor that repels olfactory bulb axons. In addition, Sema A and Sema IV, but not Sema III, Sema E, or Sema H, are able to orient in vitro the growth of olfactory bulb axons; Sema IV has a strong repulsive action, whereas Sema A appears to attract those axons. The expression patterns of sema A and sema IV in the developing olfactory system confirm that they may play a cooperative role in the formation of the lateral olfactory tract. This also represents a further evidence for a chemoattractive function of secreted semaphorins.
de Castro
F
F
Institut National de la Santé et de la Recherche Médicale U106, Hôpital de la Salpêtrière, 75013 Paris, France.
Hu
L
L
Drabkin
H
H
Sotelo
C
C
Chédotal
A
A
D000818:Animals; D001369:Axons / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D002633:Chemotaxis / Q000502:physiology*; D005314:Embryonic and Fetal Development / Q000502:physiology; D006023:Glycoproteins / Q000378:metabolism; D009414:Nerve Growth Factors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009830:Olfactory Bulb / Q000196:embryology / Q000502:physiology* / Q000648:ultrastructure; D009831:Olfactory Mucosa / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D040121:Semaphorin-3A
D002352:Carrier Proteins; D006023:Glycoproteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; C488218:Sema3a protein, rat; D040121:Semaphorin-3A; C099436:semaphorin IV