Diversity and specificity of actions of Slit2 proteolytic fragments in axon guidance.
The Slits are secreted proteins that bind to Robo receptors and play a role in axon guidance and neuronal migration. In vertebrates, Slit2 is a major chemorepellent for developing axons and is involved in the control of midline crossing. In vivo, Slit2 is cleaved into 140 kDa N-terminal (Slit2-N) and 55-60 kDa C-terminal (Slit2-C) fragments, although the uncleaved/full-length form can also be isolated from brain extract. We explored the functional activities of Slit2 fragments by engineering mutant and truncated versions of Slit2 representing the N-, C-, and full/uncleavable (Slit2-U) fragments. Only Slit2-N and Slit2-U bind the Robo proteins. We found that in collagen gel, olfactory bulb (OB) but not dorsal root ganglia (DRG) axons are repelled by Slit2-N and Slit2-U. Moreover, only Slit2-N membranes or purified protein-induced OB growth cones collapse. Finally, we found that only recombinant Slit2-N could induce branching of DRG axons and that this effect was antagonized by Slit2-U. Therefore, different axons have distinct responses to Slit2 fragments, and these proteins have different growth-promoting capacities.
Nguyen Ba-Charvet
K T
KT
Institut National de la Santé et de la Recherche Médicale U106, Bâtiment de Pédiatrie, Hôpital de la Salpêtrière, 75013 Paris, France.
Brose
K
K
Ma
L
L
Wang
K H
KH
Marillat
V
V
Sotelo
C
C
Tessier-Lavigne
M
M
Chédotal
A
A
D000469:Alkaline Phosphatase / Q000235:genetics; D000818:Animals; D001369:Axons / Q000187:drug effects* / Q000378:metabolism*; D019556:COS Cells; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D020439:Growth Cones / Q000187:drug effects; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects; D009830:Olfactory Bulb / Q000166:cytology / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D011485:Protein Binding / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011971:Receptors, Immunologic / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
D000469:Alkaline Phosphatase; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein