NCAM-fibronectin-type-III-domain substrata with and without a six-amino-acid-long proline-rich insert increase the dendritic and axonal arborization of spinal motoneurons.
The neural cell adhesion molecule (NCAM) is a modulator of neurite outgrowth in vitro and in vivo. To see if single or tandem extracellular NCAM domains can influence neurite outgrowth, motoneurons from embryonic rat spinal cord were cultured on several NCAM fusion protein substrata. Motoneurons growing on either of two fusion proteins comprising the combined two fibronectin type III homology domains of NCAM with or without a six-amino-acid-long, proline-rich insert (F3I,II+ and F3I,II, respectively) usually developed three or more neurites per cell. Motoneurons grown on NCAM-immunoglobulin domain I (IgI), by contrast, developed many unipolar and bipolar cells, a situation also seen when motoneurons were cultured on control substrata. The neuritic trees of motoneurons grown on F3I,II and F3I,II+ appeared broader and rounder than motoneurons cultured on either control or IgI substrata, and the spreading indices of motoneurons grown on F3I,II and F3I,II+ were significantly lower than when the other substrata were used. Neither of the NCAM-F3 fusion proteins stimulated the outgrowth of single neurites. By contrast, IgI substratum was able to stimulate neurite outgrowth over control substrata. Both NCAM-F3 substrata induced branches in axons and dendrites, whereas IgI substratum did not affect neurite branching significantly. These data indicated that neurite outgrowth and neurite branching on the chosen substrata were not closely linked to each other. Furthermore, the branching characteristics of motoneuron neurites potentially depend on their differentiation states and, possibly, on the conformation of the two NCAM-F3 domains.
Stahlhut
M
M
Protein Laboratory, Panum Institute, University of Copenhagen, Denmark. stahlhut@biobase.dk
Berezin
V
V
Bock
E
E
Ternaux
J P
JP
D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000737:chemistry / Q000187:drug effects; D015816:Cell Adhesion Molecules, Neuronal / Q000737:chemistry / Q000494:pharmacology*; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D003712:Dendrites / Q000737:chemistry / Q000187:drug effects; D005069:Evaluation Studies as Topic; D005260:Female; D005353:Fibronectins / Q000737:chemistry / Q000494:pharmacology*; D009046:Motor Neurons / Q000737:chemistry* / Q000166:cytology / Q000648:ultrastructure; D016501:Neurites / Q000737:chemistry / Q000187:drug effects*; D011247:Pregnancy; D011392:Proline / Q000737:chemistry; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D013116:Spinal Cord / Q000166:cytology
D015816:Cell Adhesion Molecules, Neuronal; D005353:Fibronectins; D011993:Recombinant Fusion Proteins; D011392:Proline